EUROCODES - IS-Argebau · 2008-02-29 · 2 EN 1991-1-1: Densities, self-weight, imposed loads for...

EUROCODESBackground and Applications

“Dissemination of information for training” workshop 18-20 February 2008 Brussels

EN 1991 Eurocode 1: Actions on structures Organised by European Commission: DG Enterprise and Industry, Joint Research Centre with the support of CEN/TC250, CEN Management Centre and Member States

Tuesday, February 19 – Palais des Académies EN 1991 - Eurocode 1: Actions on structures Baron Lacquet room

9:00-9:10 Introduction by chairman H. Gulvanessian CEN/TC250

9:10-9:45 Introduction to EN 1991 N. Malakatas Ministry of Environment, Physical Planning & Public Works of Greece

9:45-10:30 EN 1991-1-1 N. Malakatas Ministry of Environment, Physical Planning & Public Works of Greece

10:30-11:00 Coffee

11:00-11:45 EN 1991-1-3 P. Formichi University of Pisa

11:45-12:45 EN 1991-1-4 S. O. Hansen Svend Ole Hansen ApS

12:45-14:00 Lunch

14:00-14:35 EN 1991-1-5 M. Holicky Czech Technical University in Prague

14:35-15:10 EN 1991-1-6 P. Formichi University of Pisa

15:10-15:40 Coffee

15:40-16:30 EN 1991-1-7 A. Vrouwenvelder TNO

16:30-17:30 EN 1991-2 J.-A. Calgaro CGPC, CEN/TC250 Chairman M. Tschumi SBB-CFF-FFS

17:30-18:00 Discussion and close All workshop material will be available at http://eurocodes.jrc.ec.europa.eu

INTRODUCTION TO EN 1991

N. Malakatas Ministry of Environment, Physical Planning &

Public Works of Greece

1

Introduction to EN 1991(Eurocode 1: Actions on structures)

Dr-Ing. Nikolaos E. MalakatasHead of Department - Ministry of Environment,

Planning and Public Works - GREECEChairman of CEN/TC250/SC1

LINKS BETWEEN THE EUROCODES

EN 1990

EN 1991

EN 1992 EN 1993 EN 1994EN 1995 EN 1996 EN 1999

EN 1998EN 1997

Actions on structures

Design and detailing

Geotechnical and Seismic design

Structural safety, serviceability and durability

Past and future of the EN 1991 (and the other Eurocodes)

Time Period Phase CEN/TC250 Chairman

CEN/TC250/SC1Chairman

1980 ’sTechnical

preparation under EC Steering Committee

1990 –1998/2000 ENV (under CEN)

Dr Breitschaft(until 1993)Dr Lazenby

Dr Menzies

1998/2000 –2007 EN (under CEN) Prof.

BossenmeyerProf.

Gulvanessian

2008 - ?

• Implementation• Maintenance• Harmonization• Dissemination

• Further development

Prof. Calgaro Dr Malakatas

Parts and implementation of EN 1991

Part of Eurocode 1 : Actions on structures Title (Subject) Issued

EN 1991-1-1 General actions – Densities, self-weight, imposed loads for buildings

April 2002

EN 1991-1-2 General actions – Actions on structures exposed to fire

November 2002

EN 1991-1-3 General actions – Snow loads July 2003

EN 1991-1-4 General actions – Wind actions April 2005

EN 1991-1-5 General actions – Thermal actions November 2003

EN 1991-1-6 General actions – Actions during execution

June 2005

EN 1991-1-7 General actions – Accidental actions July 2006

EN 1991-2 Traffic loads on bridges September 2003

EN 1991-3 Actions induced by cranes and machinery

July 2006

EN 1991-4 Silos and tanks May 2006

Partitioning of the NDPsamong the Eurocodes Types of NDPs in the Eurocodes

Type 1: Value (s) of (a) parameter (s).Type 2: Reference to some set of values – table (s).Type 3: Acceptance of the recommended procedure, choice of calculation approach, when alternatives are given, or introduction of a new procedure.Type 4: Country specific data (geographical, climatic, etc.). Type 5: Optional National chart (s) or table (s) of a parameter.Type 6: Diagram (s).Type 7: References to non-contradictory complementary information to assist the user to apply the Eurocodes.Type 8: Decisions on the application of informative annexes. Type 9: Provision of further, more detailed information.Type 10: Reference to information

4 0 0

16 3

50 1

115 2 3

2 4 7

10 4

2 918

0

10 0

2 0 0

3 0 0

4 0 0

5 0 0

6 0 0

Ty pe 1 Ty pe 2 Ty pe 3 Ty pe 4 Ty pe 5 Ty pe 6 Ty pe 7 Ty pe 8 Ty pe 9 Ty pe 10

2

EN 1991-1-1: Densities, self-weight, imposed loads for buildings

ForwardSection 1 – GeneralSection 2 – Classification of actionsSection 3 – Design situationsSection 4 – Densities of construction and stored materialsSection 5 – Self-weight of construction worksSection 6 – Imposed loads on buildingsAnnex A (informative) – Tables for nominal density of construction materials, and nominal density and angles of repose for stored materials.Annex B (informative) – Vehicle barriers and parapets for car parks

EN 1991-1-2: Actions on structures exposed to fire

ForwardSection 1 – GeneralSection 2 – Structural Fire design procedureSection 3 – Thermal actions for temperature analysisSection 4 – Mechanical actions for temperature analysisAnnex A (informative) – Parametric temperature-time curvesAnnex B (informative) – Thermal actions for external members –Simplified calculation method Annex C (informative) – Localised firesAnnex D (informative) – Advanced fire modelsAnnex E (informative) – Fire load densitiesAnnex F (informative) – Equivalent time of fire exposureAnnex G (informative) – Configuration factor

EN 1991-1-2: Actions on structures exposed to fire ( cont.) EN 1991-1-3: Snow loads

ForwardSection 1 – GeneralSection 2 – Classification of actionsSection 3 – Design situationsSection 4 – Snow load on the groundSection 5 – Snow load on roofsSection 6 – Local effects

EN 1991-1-3: Snow loads (cont.)

Annex A (normative) – Design situations and load arrangements to be used for different locationsAnnex B (normative) – Snow load shape coefficients for exceptional snow driftsAnnex C (informative) – European Ground Snow Load MapsAnnex D (informative) – Adjustment of the ground snow load according to the return periodAnnex E (informative) – Bulk weight density of snow

EN 1991-1-3: Snow loads (cont.)

3

EN 1991-1-4: Wind actions

ForwardSection 1 – GeneralSection 2 – Design situationsSection 3 – Modelling of wind actionsSection 4 – Wind velocity and velocity pressureSection 5 – Wind actionsSection 6 – Structural factor cs cd Section 7 – Pressure and force coefficientsSection 8 – Wind actions on bridges

EN 1991-1-4: Wind actions (cont.)

EN 1991-1-4: Wind actions (cont.) EN 1991-1-4: Wind actions (cont.)

Annex A (informative) – Terrain effectsAnnex B (informative) – Procedure 1 for determining the structural factor cs cd Annex C (informative) – Procedure 2 for determining the structural factor cs cd

Annex D (informative) – cs cd values for different types of structuresAnnex E (informative) – Vortex shedding and aeroelastic instabilitiesAnnex F (informative) – Dynamic characteristics of structures

EN 1991-1-5: Thermal actions

ForwardSection 1 – GeneralSection 2 – Classification of actionsSection 3 – Design situationsSection 4 – Representation of actionsSection 5 – Temperature changes in buildingsSection 6 – Temperature changes in bridgesSection 7 – Temperature changes in industrial chimneys, pipelines, silos, tanks and cooling towers

EN 1991-1-5: Thermal actions (cont.)

Annex A (normative) – Isotherms of national minimum and maximum shade air temperatures.Annex B (normative) – Temperature differences for various surfacing depthsAnnex C (informative) – Coefficients of linear expansionAnnex D (informative) – Temperature profiles in buildings and other construction works

4

EN 1991-1-6: Actions during execution

ForwardSection 1 – GeneralSection 2 – Classification of actionsSection 3 – Design situations and limit statesSection 4 – Representation of actionsAnnex A1 (normative) – Supplementary rules for buildingsAnnex A2 (normative) – Supplementary rules for bridgesAnnex B (informative) – Actions on structures during alteration, reconstruction or demolition

EN 1991-1-7: Accidental actions

ForwardSection 1 – GeneralSection 2 – Classification of actionsSection 3 – Design situationsSection 4 – ImpactSection 5 – Internal explosionsAnnex A (informative) – Design for consequences of localisedfailure in buildings from an unspecified causeAnnex B (informative) – Information on risk assessmentAnnex C (informative) – Dynamic design for impactAnnex D (informative) – Internal explosions- D.1 : Dust explosions in rooms, vessels and bunkers- D.2 : Natural gas explosions- D.3 : Explosions in road and rail tunnels

EN 1991-1-7: Accidental actions EN 1991-1-7: Accidental actions

EN 1991-2: Traffic loads on bridges

ForwardSection 1 – GeneralSection 2 – Classification of actionsSection 3 – Design situationsSection 4 – Road traffic actions and other actions specifically for road bridgesSection 5 – Actions on footways, cycle tracks and footbridgesSection 6 – Traffic actions and other actions specifically for railway bridges

EN 1991-2: Traffic loads on bridges (cont.)

Annex A (informative) – Models of special vehicles for road bridgesAnnex B (informative) – Fatigue life assessment for road bridges assessment method based on recorded trafficAnnex C (normative) – Dynamic factors 1 + φ for real trains Annex D (normative) – Basis for the fatigue assessment of railway structuresAnnex E (informative) – Limits of validity of load model HSLM and the selection of the critical universal train from HSLM-AAnnex F (informative) – Criteria to be satisfied if a dynamic analysis is not requiredAnnex G (informative) – Method for determining the combined response of a structure and track to variable actionsAnnex F (informative) – Load models for rail traffic loads in transient design situations

5

EN 1991-2: Traffic loads on bridges (cont.) EN 1991-2: Traffic loads on bridges (cont.)

EN 1991-2: Traffic loads on bridges (cont.) EN 1991-2: Traffic loads on bridges (cont.)

EN 1991-3: Actions induced by cranes and machinery

ForwardSection 1 – GeneralSection 2 – Actions induced by hoists and cranes on runway beamsSection 3 – Actions induced by machineryAnnex A (normative) – Basis of design - Supplementary clauses to EN 1990 for runway beams loaded by cranesAnnex B (informative) – Guidance for crane classification for fatigue

EN 1991-4: Silos and tanks

ForwardSection 1 – GeneralSection 2 – Representation an classification of actionsSection 3 – Design situationsSection 4 – Properties of particulate solidsSection 5 – Loads on the vertical walls of silosSection 6 – Loads on silo hoppers and silo bottomsSection 7 – Loads on tanks from liquids

6

EN 1991-4: Silos and tanks (cont.)

Annex A (normative) – Basis of design – Supplementary paragraphs to EN 1990 for silos and tanksAnnex B (normative) – Partial factors and combinations of actions on tanksAnnex C (informative) – Measurements of properties of solids for silo load evaluationAnnex D (informative) – Evaluation of properties of solids for silo load evaluationAnnex E (informative) – Values of the properties of particulate solidsAnnex F (informative) – Flow pattern determinationAnnex G (informative) – Alternative rules for pressures in hoppersAnnex H (informative) – Actions due to dust explosions

EN 1991-4: Silos and tanks (cont.)

Background Documentsand other supporting material

Almost all Eurocodes represent the state-of-the-art in the respective scientific and technical field at the time of their draftingThe scientific and technical basis of EN 1991 included mainly :- the systematic review of the existing relevant national codes and practices- consideration of relevant international standards (e.g. ISO Standards) or codes (e.g. JCSS Model Codes)- recent (prenormative) research results (e.g. European Snow Map)- calibration of load models based on probabilistic approaches and appropriate measurements (e.g. traffic loads for road bridges)

Background Documents and other supporting material (cont.)

- Well-established relevant international literatureStrictly speaking, as Background Documents (BD) are considered all of the aforementioned material that has been taken into account by the relevant Project Team, during the drafting of theEurocodes.All other relevant material, including literature, workshops and seminars, handbooks, guides and books or articles, are considered to be additional information and supporting material.A typical example are the 5 handbooks prepared in the framework of a Leonardo Da Vinci European Project (Handbook 3 is very closely linked to EN 1991, since it is dedicated to “Action Effects on Buildings”, and Handbook 4 is dedicated to the “Design of Bridges”). This material is accessible on the Eurocodes website.

Background Documents and other supporting material (cont.)

The uploading of the Background Documents (BD) for EN 1991 is under way by the Secretary of EN/TC250/SC1. Until recently BD have been uploaded for the following Parts of EN 1991 :- EN 1991-1-1- EN 1991-1-2- EN 1991-1-3- EN 1991-1-6- EN 1991-1-7and Handbooks 1 to 5Additional information can also be found in the relevant websites, e.g. http://eurocodes.jrc.ec.europa.eu, and other links (e.g. NSO et al.)

Present and Future of the EN 1991

Finalising the preparation of some Corrigenda (target date June 2008)Detecting the eventual need for some Amendments (target date June 2009)On national level : Full implementation. Several countries have already issued their national standard EN 1991, but uploading of the NDPs in the ad-hoc data base of JRC Ispra goes on at a slow paceProspects for the future :- Extending the snow map and other climatic data to cover the new EU Member States- Including eventually the ISO Standards on “Waves and Currents” and on “Atmospheric Icing”- Extending the Eurocodes to include glass and FRPs

7

THANK YOU FOR THANK YOU FOR YOUR ATTENTIONYOUR ATTENTION

EN 1991-1-1

N. Malakatas Ministry of Environment, Physical Planning &

Public Works of Greece

1

Eurocode 1: Actions on structures –Part 1-1: General actions - Densities,

self-weight, imposed loads for buildings

Dr-Ing. Nikolaos E. MalakatasHead of Department - Ministry of Environment,

Planning and Public Works - GREECEChairman of CEN/TC250/SC1

Use of EN 1991-1-1

•Gives design guidance and actions for the structural design of buildings and civil engineering works, including the following aspects :- densities of construction materials and stored materials- self-weight of construction elements, and- imposed loads for buildings•Is intended for Clients, Designers, Contractors and Public Authorities •Is intended to be used with EN 1990 (Basis of Structural Design), other parts of EN 1991 (Actions) and EN 1992 to EN 1999 (Materials Eurocodes) for the design of structures.

LINKS BETWEEN THE EUROCODES

EN 1990

EN 1991

EN 1992 EN 1993 EN 1994EN 1995 EN 1996 EN 1999

EN 1998EN 1997

Actions on structures

Design and detailing

Geotechnical and Seismic design

Structural safety, serviceability and durability

Programme of implementation of EN 1991-1-1

•Received positive vote as EN in April 2002 (Supersedes ENV 1991-2-1 : 1995)•Published by CEN in July 2002•Confirmed in 2007 for a further period of 5 years•Implementation on a national level in the Member States (National Standard EN 1991-1-1 and National Annex) still in process•Withdrawal of conflicting standards – probably by 2009/2010

Contents of EN 1991-1-1

• Foreword• Section 1 General• Section 2 Classification of Actions• Section 3 Design Situations• Section 4 Densities of Construction and Stored

Materials• Section 5 Self-weight of Construction Works• Section 6 Imposed Loads on Buildings• Annex A (Informative) Tables for Nominal

Density of Construction Materials, and Nominal Density and Angles of Repose for StoredMaterials

• Annex B (Informative) Vehicle Barriers and Parapets for Car Parks

Scope of EN 1991-1-1

• Design guidance and actions for the structural design of buildings and civil engineering works, including:

- densities of construction materials, additional materials for bridges and stored materials (Section 4 & Annex A),

- self-weight of construction elements (Section 5), and - imposed loads for building floors and roofs (Section 6), according to category of use :- residential, social, commercial and administration areas;- garage and vehicle traffic areas (for gross vehicle weight < 160 kN);- areas for storage and industrial activity;- roofs;- helicopter landing areas.

• Actions on silos and tanks caused by water or other materials are dealt in EN 1991-4

• Snow load on roofs is dealt in EN 1991-1-3

2

Classification of actions

(Reminder from EN 1990)

• Variation in time: Permanent, Variable orAccidental

• Origin: Direct or Indirect• Spatial Variation: Fixed or Free• Nature and/or structural response: Static or

Dynamic

Classification of actions (cont.)

• Self-weight of construction works: generally a Permanent Fixed action, however

• If Variable with time then represented by upper and lower characteristic values, and

• If Free (e.g. moveable partitions) then treated as an additional imposed load.

• Ballast and earth loads on roofs/terraces: Permanent with variations in properties (moisture content, depth) during the design life being taken into account.

Classification of actions (cont.)

• Imposed loads (on buildings) : generally Variable Free actions, however loads resulting from impacts on buildings due to vehicles or accidental loads should be determined from EN 1991-1-7. Imposed loads for bridges are given in EN 1991-2. Also :

• Imposed loads generally Quasi-static actions and allow for limited dynamic effects in static structures, if there is no risk of resonance.

• Actions causing significant acceleration of structural members are classified as Dynamic and need to be considered via a dynamic analysis

• However for fork-lift trucks and helicopters additional inertial loads from hoisting and take-off/landing are accounted for through a dynamic magnification factor φ applied to appropriate static load values

Design situations – Permanent loads

• The total self-weight of structural and non-structural members is taken as a single action when combinations of actions are being considered

• Where it is intended to add or remove structural or non-structural members after construction critical load cases need to be identified and taken into account.

• Water level is taken into account for relevant design situations, as is the source and moisture content of materials in buildings used for storage purposes.

Design situations – Imposed loads

• Where areas are likely to be subjected to different categories of loadings, the critical load case needs to be identified and considered

• When imposed loads act simultaneously with other variable actions (e.g. wind, snow, cranes or machinery) the total of those imposed loads may be considered as a single action. However, for roofs of buildings, imposed loads should not be considered to act simultaneously with snow loads or wind actions.

Probabilistic aspects

• Self-weight may be usually determined as a product of the volume and the density, which both as random variables that may be described by normal distributions, with a mean value very close to their nominal value.

• Imposed loads are usually described by a Gumbeldistribution, although Gamma distributions may also be used for the sustained (long-term) loads and exponential distributions for the intermittent (short-term) loads.

3

Densities of construction and stored materials

• Characteristic values of densities of construction and stored materials should generally be used. (If there is a significant scatter - e.g. due to their source, water content etc. – an upper and a lower value should be used).

• Where only mean values are available, they should be taken as characteristic values in the design.

• Mean values for a large number of different materials are given in EN 1991-1-1 Annex A.

• For materials not in Annex A either:- the characteristic value of density needs to be determined in the National Annex,- a reliable direct assessment is carried out (eventually according to EN 1990 Annex D).

Self-weight of construction works

• Generally represented by a single characteristic valuecalculated from nominal dimensions, characteristic values of densities and including, where appropriate, ancillary elements, e.g. non-structural elements and fixed services, weight of earth and ballast.

• Non-structural elements include :- roofing;- surfacing and coverings;- partitions and linings;- hand rails, safety barriers, parapets and curbs;- wall cladding;- suspended ceilings;- thermal insulation;- fixed services

Self-weight of construction works (cont.)

• Fixed services include :- equipments for lifts and moving stairways;- heating, ventilating and air conditioning equipment;- electrical equipment;- pipes without their contents;- cable trunking and conduits

• Loads due to movable partitions are treated as imposed loads, but an equivalent uniformly distributed load may be used.

Self-weight of construction works (cont.)

Additional provisions specific for bridges :• For ballast on railway bridges or fill above buried structures

the upper and lower characteristic values of densities should be taken into account.

• The upper and lower characteristic values of the ballast depth should be considered as deviating from the nominal depth by ± 30% .

• The upper and lower characteristic values of the thickness due to waterproofing, surfacing and other coatings should be considered as deviating from the nominal value by ± 20% (if a post-execution coating is included in the nominal value) otherwise +40% and –20%, respectively.

• The upper and lower characteristic values of the self-weight of cables, pipes and service ducts should be considered as deviating from the mean value by ± 20% .

Imposed loads on buildings

• Characteristic values of imposed loads for floors and roofs for the following types of occupancy and use:- residential, social, commercial and administration areas- garage and vehicle traffic- areas for storage and industrial activities- roofs- helicopter landing areas- barriers and walls having the function of barriers.

Representation of actions

• Imposed loads on buildings are those arising from occupancy and the values given include :- normal use by persons; - furniture and moveable objects;- vehicles;- rare events such as concentrations of people and furniture, or the moving or stacking of objects during times of re-organisation and refurbishment

• Floor and roof areas in buildings are sub-divided into 11 categories according to use; loads specified are represented by uniformly distributed loads (UDL), concentrated loads, line loads or combinations thereof. Heavy equipment (e.g. in communal kitchens, radiology or boiler rooms) are not included in EN 1991-1-1. (To be agreed with the Client and/or the relevant Authority).

4

Categories of use

Main Categories of Use :

• Residential, social, commercial and administration areas- 4 categories (A, B, C and D)

• Areas for storage and industrial activities- 2 categories (E1 and E2)

• Garages and vehicle traffic (excluding bridges)- 2 categories (F and G)

• Roofs- 3 categories (H, I and K)

Residential, social, commercial and administration areas

Table 6.1 – Categories of use Category Specific use Exam ple

A Areas for dom estic and residentia l activities

Room s in residential bu ildings and houses; bedroom s and wards in hospitals; bedroom s in hote ls and hoste ls kitchens and toilets.

B

O ffice areas

C

Areas where people m ay congregate (with the exception of areas defined under category A, B and D 1))

C1 : Areas with tables, etc e.g. areas in schools, cafes, restaurants, dining halls, reading room s, receptions C2 : Areas with fixed seats, e.g. areas in churches, theatres or cinem as, conference room s, lecture ha lls, assem bly ha lls, waiting room s, railway waiting room s. C3 : A reas without obstac les for m oving people, e .g. areas in m useum s, exh ibition room s, etc. and access areas in public and adm inistration buildings, hotels, hospitals, railway station forecourts C4 :A reas with possible physical activ ities, e.g. dance halls , gym nastic room s, stages . C5 :A reas susceptible to large crowds, e.g . in buildings for public events like concert halls, sports halls inc luding stands, terraces and access areas and railway platform s.

D Shopping areas D1: Areas in general retail shops D2 : A reas in departm ent stores.

1) A ttention is drawn to 6.3.1.1(2), in particular for C4 and C5. See EN 1990 when dynam ic effects need to be considered. For Category E , see Table 6.3 NO TE 1. Depending on their anticipated uses, areas likely to be categorised as C2, C3, C4 m ay be categorised as C5 by decision of the c lient and/or National annex.

Imposed loads on floors, balconiesand stairs in buildings

Table 6.2 – Imposed loads on floors, balconies and stairs in buildings Categories of loaded areas qk

[kN/m2] Qk

[kN] Category A - Floors - Stairs - Balconies Category B Category C - C1 - C2 - C3 - C4 - C5 Category D -D1 -D2

1,5 to 2,0 2,0 to 4,0 2,5 to 4,0

2,0 to 3,0

2,0 to 3,0 3,0 to 4,0 3,0 to 5,0 4,5 to 5,0 5,0 to 7,5

4,0 to 5,0 4,0 to 5,0

2,0 to 3,0 2,0 to 4,0 2,0 to 3,0

1, 5 to 4,5

3,0 to 4,0 2,5 to 7,0 (4,0)

4,0 to 7,0 3,5 to 7,0 3,5 to 4,5

3,5 to 7,0 (4,0) 3,5 to 7,0

NOTE: Where a range is given in this table, the value may be set by the National annex. The recommended values, intended for separate application, are underlined. qk is intended for the determination of general effects and Qk for local effects. The National annex may define different conditions of use of this Table.

Additional loading from movable partitions

• Provided that a floor allows a lateral distribution of loads, the self-weight of movable partitions may be taken into account by a uniformly distributed load qkwhich should be added to the imposed loads of floors obtained from Table 6.2 (Cat. A to D). This load depends on the self-weight of the movable partitions, as follows :

- self-weight < 1 kN/m, qk = 0,5 kN/m2

- 1 kN/m < self-weight < 2 kN/m, qk = 0,8 kN/m2

- 2 kN/m < self-weight < 3 kN/m, qk = 1,2 kN/m2

Load arrangements

• Floors, beams and roofs

Chess board arrangement Simplification in EN 1991-1-1

Mid span bending moment of a floor structure

Load arrangements (cont.)

• For the design of a floor structure within one storey or a roof, the imposed load shall be applied as a free action at the most unfavourable part of the influence area.

• Effect of actions that cannot exist simultaneously should not be considered together (EN 1990).

• For the design of a column loaded from several storeys, load assumed to be distributed uniformly.

• For local verification concentrated load Qk acting alone should be considered.

• Reduction factors αA (for floors, beams and roofs) and αn (for columns and walls) may be applied, but factors ψψ and and ααn n should not be considered together..

5

Reduction factors αn and αA

2 4 6 8 100.5

0.6

0.7

0.8

0.9

1

n)

n( )

2 n( )

n)

n1)

n( )

αn

2 4 10 8 6

0,8

0,7

0,6

0,5

0,9

ČR (A, B)

UK

CEN, DE

FR (A, B)

n

ČR (C, D)

FR (C, D)

20 30 40 50 600.5

0.6

0.7

0.8

0.9

1

A)

N A( )

N1 A( )

)

A)

A)

1 A( )

2 A( )

A

0,9

0,7

0,5 30 40 50 6020

ČR (A, B)

UK

FI

CEN DE (A, B)

FR

DE (C, D)

A [m2]

αA

ČR (C, D) 0,8

0,6

AAψα

nψnα An

00

0

75,)2(2

+=−+

=

Factors ψi

(Reminder from EN 1990)

Actions ψ0 ψ1 ψ2

Imposed Cat. A, B 0,7 0,5 0,3 Imposed Cat. C, D 0,7 0,7 0,6 Imposed Cat. E 1,0 0,9 0,8

Snow 0,5-0,7 0,2-0,5 0,0-0,2Wind 0,6 0,2 0,0Temperature 0,6 0,5 0,0

Reduction factor αA for floors

A (m2) αA (EN 1991-1-1 αA (EN 1991-1-1 with ψo = 0,7) with ψo = 1,0)

40 0,75 0,9680 0,63 0,84120 0,59 0,80160 0,56 0,78240 0,54 0,76

Reduction factor αn for columns

n αA (EN 1991-1-1 with ψo = 0,7)

1 1,002 1,003 0,904 0,855 0,826 0,807 0,798 0,789 0,7710 0,76

Imposed loads on floors due to storage

Table 6.3 – Categories of storage and industrial use Category Specific Use Example

E1 Areas susceptible to accumulation of goods, including access areas

Areas for storage use including storage of books and other documents

E2 Industrial use Table 6.4 – Imposed loads on floors due to storage Categories of loaded areas qk

[kN/m2] Qk

[kN] Category E1 7,5 7,0 NOTE The values may be changed if necessary according to the usage (see Table 6.3 and Annex A) for the particular project or by the National annex. qk is intended for the determination of general effects and Qk for local effects. The National annex may define different conditions of use of Table 6.4.

Actions induced by forklifts

Forklifts and transport vehicles•Forklifts are classified into 6 classes via their hoisting capacity, which is reflected in other characteristics such as weight and plan dimensions. •For each class, a static axle load is defined which is then increased by a dynamic (multiplication) factor φ dependent on whether the forklift has solid (φ = 2,00)or pneumatic (φ = 1,40)tyres. That factor is intended to account for the inertial effects caused by acceleration and deceleration of the hoisted load. •Where transport vehicles move on floors, either freely or guidedby rails, the actions need to be determined from the pattern of the vehicle’s wheel loads. The static value of those wheel loads is determined from permanent weights and pay loads and the spectra of loads should be used to define appropriate combination factors and fatigue loads.

6

Actions induced by forklifts Garages and vehicle traffic areas

NOTE 1 For category F qk may be selected within the range 1,5 to 2,5 kN/m2 and Qkmay be selected within the range 10 to 20 kN.NOTE 2 For category G, Qk may be selected within the range 40 to 90 kNNOTE 3 Where a range of values are given in Notes 1 & 2, the value may be set by the National annex.The recommended values are underlined.

Qk

Qk

qk

5,0Category F Gross vehicle weight: ≤ 30kN Category G 30kN < gross vehicle weight ≤ 160 kN

Qk[kN]

qk[kN/m2]

Categories of traffic areas

Table 6.8 – Imposed loads on garages and vehicle traffic areas

•Category F (e.g. garages, parking areas, parking halls)•Category G (e.g. access routes, delivery zones, zones accessible to fire engines)

Categorization of roofs

Categories of loaded area (of a roof) :• Category H – Accessible for normal maintenance and repair only• Category I – Accessible with occupancy according to categories A to G• Category K – Accessible for special services e.g. helicopter landing areas

Imposed loads on roofs of Cat. H

•The minimum values given in Table 6.10 do not take into account uncontrolled accumulations of construction materials that may occur during maintenance•Separate verifications to be performed for Qk and qk , acting independently

NOTE 1 For category H qk may be selected within the range 0,0 to 1,0 kN/m2 and Qk may be selected within the range 0,9 to 1,5 kN. Where a range is given the values may be set by the National Annex. The recommended values are: qk = 0,4 kN/m2, Qk = 1,0kNNOTE 2 qk may be varied by the National Annex dependent upon the roof slopeNOTE 3 qk may be assumed to act on an area A which may be set by the National Annex. The recommended value for A is 10m2, within the range of zero to the whole area of the roof.NOTE 4 See also 3.3.2 (1)

QkqkCategory H

Qk[kN]

qk[kN/m2]

Roof

Table 6.10 – Imposed loads on roofs of category H

Imposed loads on roofs of Cat. K for helicopters

•The dynamic factor φ to be applied to the take-off load Qk to take account of impact effects may be taken as φ = 1,40

0,2 x 0,20,3 x 0,3

Qk = 20 kNQk = 60 kN

Q ≤ 20 kN20 kN < Q ≤60 kN

HC1HC2

Dimension of the loaded area (m x m)

Take-off load QkTake-off load Q of helicopter

Class of Helicopter

Table 6.11 – Imposed loads on roofs of category K for helicopters

Horizontal loads on partition walls and parapets

Table 6.12 – Horizontal loads on partition walls and parapets Loaded areas qk

[kN/m] Category A Category B and C1 Categories C2 to C4 and D Category C5 Category E Category F Category G

qk

qk

qk

qk

qk

See Annex B

See Annex B

NOTE 1 For categories A,B and C1, qk may be selected within the range 0,2 to 1,0 (0,5) NOTE 2 For categories C2 to C4 and D qk may be selected within the range 0,8 kN/m to -1,0 kN/m NOTE 3 For category C5, qk may be selected within the range 3,0 kN/m to 5,0 kN/m NOTE 4 For category E qk may be selected within the range 0,8 kN/m to 2,0 kN/m. For areas of category E the horizontal loads depend on the occupancy. Therefore the value of qk is defined as a minimum value and should be checked for the specific occupancy. NOTE 5 Where a range of values is given in Notes 1, 2, 3 and 4, the value may be set by the National Annex. The recommended value is underlined. NOTE 6 The National Annex may prescribe additional point loads Qk and/or hard or soft body impact specification for analytical or experimental verification.

7

Annex A (informative) : Nominal densities and angles of repose

• Table A.1 - Construction materials-concrete and mortar• Table A.2 - Construction materials-masonry• Table A.3 - Construction materials-wood• Table A.4 - Construction materials-metals• Table A.5 - Construction materials- other materials• Table A.6 - Bridge materials• Table A.7 - Stored materials - building and construction• Table A.8 - Stored products – agricultural• Table A.9 - Stored products - foodstuffs• Table A.10 - Stored products - liquids• Table A.11 - Stored products - solid fuels• Table A.12 - Stored products - industrial and general

Annex B (informative) : Vehicle barriers and parapets for car parks

0 100 2000

100

200

.

δc=100 mm

δc=200 mm

δc=50 mm

δc

F [kN]

The force in kN acting on 1,5 m of a barrier :

F = 0,5 m v2 / (δc + δ b) [kN]

the deformation of the vehicle (mm)the deformation of the barrier (mm)

m the gross mass of the vehicle (kg)

v the velocity of the vehicle (m/s)

δb

δc

For vehicles < 2500 kg: m = 1500 kg, v = 4,5 m/s, δc = 100 mm

Backgound Documents and other supporting material

• A more general reference to Background Documents (BD) and related supporting material has been included and presented in the Introduction to EN 1991. The BD on the imposed loads on floors and roofs is already uploaded on the relevant website.

• Handbook 3 (Action Effects for Buildings) and Handbook 4(Design of Bridges) of the Leonardo Da Vinci Pilot Projectfor the Development of Skills Facilitating the Implementation of Structural Eurocodes are considerd to be an appropriate first approach for the deeper understanding of EN 1991.

• Since a few years various books are being available (e.g. the Thomas Telford collection of Guides)

Message for the near future

Please try on a national level to finalise and issue the National Annex and upload the NDPs

in the ad-hoc data base of JRC Ispra (if not already done so)

THANK YOU FOR THANK YOU FOR YOUR ATTENTIONYOUR ATTENTION

EN 1991-1-3

P. Formichi University of Pisa

Brussels, 18-20 February 2008 – Dissemination of information workshop 1

Background and ApplicationsEUROCODES

EN 1991 – Eurocode 1: Actions on structuresPart 1-3 General actions – Snow Loads

Paolo FormichiDepartment of Structural Engineering

University of Pisa - Italy


EUROCODESBackground and Applications Scope of the presentation

Description of EN 1991-1-3 Eurocode 1: Part 1-3: Snow

Loads

Background research for snow maps for Europe,

Accidental (exceptional) loads, Shape Coefficients,

Combination Factors, etc.

Examples

Paolo Formichi, University of Pisa Italy


EUROCODESBackground and Applications Background research

Many clauses of EN 1991-1-3 are based on the results of a research work, carried out between 1996 and 1999, under a contract specific to this Eurocode, to DGIII/D3 of the European Commission.

They were identified four main research items:study of the European ground snow loads mapinvestigation and treatment of exceptional snow loadsstudy of conversion factors from ground to roof loadsdefinition of ULS and SLS combination factors for snow loads.



EUROCODESBackground and Applications Background research

The research results are contained in two final reports.


http://www2.ing.unipi.it/dis/snowloads/


EUROCODESBackground and Applications EN 1991-1-3 Field of application

EN 1991-1-3 provides guidance for the determination of the snow load to be used for the structural design of buildings and civil engineering works for sites at altitudes under 1500m.

In the case of altitudes above 1500m advice may be found in the appropriate National Annex.



EUROCODESBackground and Applications EN 1991-1-3 Field of application

EN 1991-1-3 does not give guidance on the following specialist aspects of snow loading:

“impact loads” due to snow sliding off or falling from a higher roof;additional wind loads resulting from changes in shape or size of the roof profile due to presence of snow or to the accretion of ice;loads in areas where snow is present all the year;loads due to ice;lateral loading due to snow (e.g. lateral loads due to dirfts);snow loads on bridges



EUROCODESBackground and Applications Contents of EN 1991-1-3

ForewordSection 1: GeneralSection 2: Classification of actionsSection 3: Design situationsSection 4: Snow load on the groundSection 5: Snow load on roofsSection 6: Local effects

ANNEX A: Design situations and load arrangements to be used for different locations

ANNEX B: Snow load shape coefficients for exceptional snow drifts

ANNEX C: European Ground Snow Load MapsANNEX D: Adjustment of the ground snow load according to

return periodANNEX E: Bulk weight density of snow



EUROCODESBackground and Applications Classification of actions

Actions due to snow are classified, in accordance with EN 1990, as:

Variable: action for which the variation in magnitude with time is neither negligible nor monotonic

Fixed: action that has a fixed distribution and position over the structure….

Static: action that does not cause significant acceleration of the structure or structural members



EUROCODESBackground and Applications Classification of actions

For particular conditions may be treated as accidental actions: action, usually of short duration but of significant magnitude, that is unlikely to occur on a given structure during the design working life


Exceptionalsnow load on

the ground

Exceptionalsnow drifts


EUROCODESBackground and Applications Definition of Exceptional snow load on the ground

Exceptional snow load on the ground

“load of the snow layer on the ground resulting from a snow fall which has an exceptionally infrequent likelihood of occurring”



EUROCODESBackground and Applications Exceptional snow load on the ground

In some regions, particularly southern Europe, isolated very heavy snow falls have been observed resulting in snow loads which are significantly larger than those that normally occur. Including these snowfalls with the more regular snow events for the lengths of records available may significantly disturb the statistical processing of more regular snowfalls.


Gumbel probability paper: Pistoia (IT)

N° of recorded years = 51N° of no snowy winters = 26sm = Max. snow Load = 1.30 kN/m2

50yrs load incl. Max Load = 1.00 kN/m2

sk = 50yrs load excluded Max Load = 0.79 kN/m2

k = sm/sk = 1,65

0.79

1.00


EUROCODESBackground and Applications Exceptional snow load on the ground

The National Annex should specify the geographical locations where exceptional ground snow loads are likely to occur.

When the maximum ground snow load is to be considered as exceptional?

“If the ratio of the largest load value to the characteristic load determined without the inclusion of that value is greater than 1.5 then the largest value should be treated as an exceptional value”

According to this definition over 2600 weather stations from 18 CEN countries (1997), in 159 they were registered exceptional ground snow loads.


?


EUROCODESBackground and Applications Definition of Exceptional snow drift

Exceptional snow drift “load arrangement which describes the load of the snow layer on the roof resulting from a snow deposition pattern which has an exceptionally infrequent likelihood of occurring”

These load arrangements (treated in Annex B of EN 1991-1-3) may result from wind redistribution of snow deposited during single snow events. Localised snow concentrations may develop at obstructions and abrupt changes in height, leaving other areas of the roof virtually clear of snow.



EUROCODESBackground and Applications Design Situations

Different climatic conditions will give rise to different designsituations. The four following possibilities are identified:

- Case A: normal case (non exceptional falls and drifts)- Case B1: exceptional falls and non exceptional drifts- Case B2: non exceptional falls and exceptional drifts- Case B3: exceptional falls and drifts.

The national competent Authority may choose in the National Annex the case applicable to particular locations for their own territory.



EUROCODESBackground and Applications Design Situations


Persistent: Conditions of normal useTransient: temporary conditions (e.g. execution or repair)

Accidental: refers only to exceptional conditions


EUROCODESBackground and Applications Snow load on the ground

Section 4 of EN 1991-1-3Snow load on the ground




The snow load on the roof is derived from the snow load on the ground, multiplying by appropriate conversion factors (shape, thermal and exposure coefficients).




sk is intended as the upper value of a random variable, for which a given statistical distribution function applies, with the annual probability of exceedence set to 0,02 (i.e. a probability of not being exceeded on the unfavourable side during a “reference period” of 50 years).

For locations where exceptional ground snow loads are recorded, these value must be excluded from the data sample of the random variable. The exceptional values may be considered outside the statistical methods.

The characteristic ground snow loads (sk) are given by the National Annex for each CEN country.




Needs for harmonization – Development of European ground snow load map

Inconsistencies at borders between existing national maps;

Different procedures for measuring snow load (mainly ground snow data): snow depths + density conversion, water equivalent measures, direct load measures;

Different approaches for statistical data analysis (Gumbel, Weibull, Log-normal distributions).

The research developed a consistent approach

Produced regional maps (Annex C of EN 1991-1-3)

Snow load with Altitude relationshipZone numbers & altitude functions Geographical boundaries


!



For maps in Annex C of EN 1991-1-3 the following common approach has been followed:

Statistical analysis of yearly maxima, using the Gumbel Type ICDF (best fitting in the majority of data points);LSM for the calculation of the best fitting regression curve;Both zero and non zero values have been analysed according to the “mixed distribution approach” ;Approximately 2600 weather stations consistently analysed;Regionalization of CEN area (18 countries 1997) into 10 climatic regions;Smoothing of maps across borderlines between neighbouring climatic regions (buffer zones 100 km).




10 European regions, with homogeneous climatic features





Alpine Region – Snow load at sea level (France, Italy, Austria, Germany and Switzerland)




z = Zone number given on the mapA = site altitude above Sea Level [m]

Zone 1

Zone 2

Zone 3

Zone 4



Alpine Region – Snow load at sea level





Map for Mediterranean region

Annex C EN 1991-1-3(geographical boundaries)

Zone 2

Zone 3

Zone 1 Med.

Zone 1 Alp.

Italian National Annex(administrative boundaries)


EUROCODESBackground and Applications Snow load on the ground - Example

Italian ground Snow load Map:- 4 different zones (3 Med. + 1 Alpine) - Administrative boundaries (110 provinces)- 4 Altitude correlation functions


0.00

2.00

4.00

6.00

8.00

10.00

12.00

0 200 400 600 800 1000 1200 1400

Altitude [m]

Gro

und

Snow

Loa

d kN

/m2 Zone 1 alp

Zone 1 medZone 2Zone 3

Example of calculation of ground snow load at a given location:

Inputs:- zone n. 3 - altitude = 600m a.s.l.

sk = 1,30 kN/m2


EUROCODESBackground and Applications Other representative values of ground snow loads

Combination valueψ0 sk

The combination factor ψ0 is applied to the snow load effect when the dominating load effect is due to some other external load, such as wind.

Based upon the available data ψ0 values were calculated through the Borges-Castanheta method.


ik,i0,1>i

iQ,k,1Q,1Pjk,1

, "+""+""+" QQPGj

jG ψγγγγ ∑∑≥

Eq. 6.10

EN 1990



Frequent value ψ1 sk

The frequent value ψ1sk is chosen so that the time it is exceeded is 0,10 of the reference period.

Quasi-permanent value ψ2 sk

The quasi-permanent value ψ2sk (used for the calculation of long-term effects) is usually chosen so that the proportion of the time it is exceeded is 0,50 of the reference period.

ψ1 and ψ2 values were calculated from daily data series available at 59 weather stationsrepresentative of all 10 different climatic regions.

∑∑≥ 1>i

ik,i2,k,11,11

jk, "+""+""+" QQPGj

ψψ


∑∑≥ 1>i

ik,i2,1

jk, "+""+" QPGj

ψ

Eq. 6.15b

EN 1990

Eq. 6.16b

EN 1990





EUROCODESBackground and Applications Treatment of exceptional loads on the ground

Maps given in National Annexes are determined without taking into account “exceptional falls”

How to determine design values for accidental ground snow loads?

For locations where exceptional loads may occur (National Annex), the ground snow load may be treated as accidental action with the value:

sAd = Cesl skWhere:Cesl (set by the National Annex) - recommended value = 2,0sk = characteristic ground snow load at the site considered


?

∑∑≥ 1>i

ik,i2,k,11,2 1,1d1

jk, "+")or("+"A"+""+" QQPGj

ψψψ Eq. 6.11b

EN 1990


EUROCODESBackground and Applications Snow load on roofs

Section 5 of EN 1991-1-3Snow load on roofs




The snow the snow layers on a roof can have many different shapes depending on roof’s characteristics:

its shape;its thermal properties;the roughness of its surface;the amount of heat generated under the roof;the proximity of nearby buildings;the surrounding terrain;the local meteorological climate, in particular its windiness, temperature variations, and likelihood of precipitation (either as rain or as snow).



EUROCODESBackground and Applications Snow load on roofs – Load arrangements

In absence of wind, or with very low wind velocities (<2 m/s) snow deposits on the roof in a balanced way and generally a uniform cover is formed

UNDRIFTED LOAD ARRANGEMENT




With wind speeds in the range of 4 to 5 m/s, much of the snow is deposited in areas of ’aerodynamic shade’

DRIFTED SNOW LOAD ARRANGEMENT

Model in wind tunnelwind velocity of 4m/s

Aerodynamic shade wind wind




For situations where the wind velocity increases above 4 ÷ 5 m/s snow particles can be picked up from the snow cover and re-deposited on the lee sides, or on lower roofs in the lee side, or behind obstructions on the roof.

DRIFTED SNOW LOAD ARRANGEMENT


Model in wind tunnel for multi - pitched roofwind velocity > 5 m/s

wind



EXCEPTIONAL DRIFTS

In maritime climates (e.g. UK and Eire), where snow usually melts and clears between the individual weather systems and where moderate to high wind speeds occur during the individual weathersystem, the amount of the drifted load is considered to be of a high magnitude compared to the ground snow load, and the drifted snowis considered an exceptional load and treated as an accidental load using the accidental design situation (Annex B of EN 1991-1-3).


Model in wind tunnel for multi - pitched roofwind velocity > 5 m/s

wind



Snow load on the roof (s) is determined converting the characteristic ground snow load into an undrifted or driftedroof load for persistent/transient and, where required by the National Annex, accidental design situations by the use of:

an appropriate shape coefficient which depends on the shape of the roof;

considering the influence of thermal effects from inside the building and the terrain around the building.




For the persistent / transient design situations i.e. no exceptional snow falls or drifts:

s = μi Ce Ct sk (5.1 EN 1991-1-3)

For the accidental design situations, where exceptional ground snow load is the accidental action:

s = μi Ce Ct sAd (5.2 EN 1991-1-3)

For the accidental design situations where exceptional snow drift is the accidental action and where Annex B applies:

s = μi sk (5.3 EN 1991-1-3)



EUROCODESBackground and Applications Snow load on roofs – Shape coefficients

EN 1991-1-3 gives shape coefficients for the following types of roofs (non exceptional drifted cases):


Monopitch Pitched

Multi-span

Roofs abutting and close to

taller construction

works

Cylindrical



Annex B of EN 1991-1-3 gives shape coefficients for the following types of roofs (exceptional drifted cases):


Multi-span

Roofs abutting and close to taller

construction works

Drifting at projections, obstructions and

parapets



Values for shape coefficients μi given in EN 1991-1-3 are calibrated on a wide experimental campaign, both in situ and in wind tunnel.

Paolo Formichi, University of Pisa ItalyMulti-span drifted case

1,49 1,92

Average = 1,67

30°



μs is for snow falling from the higher roof (α>15°)

μw is the snow shape coefficient due to wind:

μw= (b1+b2)/2h < γ h /sk

γ = 2 kN/m3

0.8 < μ w < 4ls = 2h

5m < ls < 15m

Roof abutting and close to taller construction works

wind

0,00

1,00

2,00

3,00

4,00

5,00

6,00

7,00

8,00

9,00

10,00

0,0 1,0 2,0 3,0 4,0 5,0 6,0 7,0 8,0

h [m]

w


μw

b1 = 8,0 mb2 = 10,0 msk = 0,8 kN/m2


EUROCODESBackground and Applications Snow load on roofs – Exposure coefficient

A coefficient (Ce) defining the reduction or increase of snow load on a roof of an unheated building, as a fraction of the characteristic snow load on the ground.

The choice for Ce should consider the future development around the site.

Ce should be taken as 1,0 unless otherwise specified for different topographies.

The National Annex may give the values of Ce for different topographies, recommended values are given.



EUROCODESBackground and Applications Snow load on roofs – Exposure coefficient

Windswept topography, where (Ce = 0,8 ) are flat unobstructed areas exposed on all sides without, or little shelter afforded by terrain, higher construction works or trees.

Normal topography, where (Ce = 1,0 ) areas where there is no significant removal of snow by wind on construction work, because of terrain, other construction works or trees.

Sheltered topography, where (Ce = 1,2 ) areas in which the construction work being considered is considerably lower than the surrounding terrain or surrounded by high trees and/or surrounded by higher construction works.



EUROCODESBackground and Applications Snow load on roofs – Thermal coefficient

The thermal coefficient Ct is used to account for the reduction of snow loads on roofs with high thermal transmittance (> 1 W/m2K), in particular for some glass covered roofs, because of melting caused by heat loss.

For all other cases: Ct = 1,0

Further guidance may be obtained from ISO 4355



EUROCODESBackground and Applications Snow load on roofs – Example (1)


Multi-span roof in Sweden

Properties of the building:

Location: Sweden - Snow load zone 2, alt. 300 m a.s.l.Normal conditions: no exceptional falls, no exceptional driftsBuilding surroundings: normal Ce = 1,0Effective heat insulation applied to roof: Ct = 1,0

40° 30°



Altitude relationship for Sweden:

where: Z is the Zone Number & A is the altitude


336375,0790,0 AZsk ++=

Zone 2A = 300 m

Characteristic ground snow load at the site:sk = 0,790 x 2 + 0,375 + 300/336 = 2,85 kN/m2



Determination of shape coefficients:

Undrifted load arrangement: Case (i) μ1Drifted load arrangement: Case (ii) μ1, μ2

2.0

1.0

0° 15° 30° 45° 60°

µ 0.8

1.6

µ1

µ2

α α


( )( )

( ) 60,1352

80,03053,040

221

212

111

=°=+

=

=°==°=

αμααα

αμααμα



40° 30°


Case (i)

Case (ii)

1,51 kN/m2

1,51 kN/m2

2,28 kN/m2

1,51 kN/m2

2,28 kN/m2

4,56 kN/m2

2,28 kN/m2

( )( )

( ) 60,1352

80,03053,040

221

212

111

=°=+

=

=°==°=

αμααα

αμααμα

sk = 2,85 kN/m2

s = Ct Ce μi sk

Combination coefficients

Climatic region: Finland, Iceland, Norway Sweden:

ψ0 = 0,70

ψ1 = 0,50

ψ2 = 0,20


EUROCODESBackground and Applications Local Effects


In addition to snow deposition patterns adopted for the global verification of the building, local verifications have to be performed for specific structural elements of the roof or roof’s parts.

Section 6 of EN 1991-1-3 gives the forces to be considered for the verification of:

– drifting at projections and obstructions;– the edge of the roof;– snow fences.

The National Annex may be specify condition of use of this part or different procedures to calculate the forces.


EUROCODESBackground and Applications Local Effects


Drifting at projections and obstructionsμ1 = 0,8 μ2 = γ h/sk

where 0,8 ≤ μ2 ≤ 2,0γ = 2 kN/m3 (weight density of snow)ls = 2h 5 ≤ ls ≤ 15 m

Snow overhanging the edge of a roof(recommended for sites above 800 m a.s.l.)

se=k s2 / γ

where

γ = 3 kN/m3

γk = 3 /d < d γ (National Annex)

d is in meters


EUROCODESBackground and Applications Annexes


Normative Annexes

Annex A – Design situations and load arrangements to be used for different locations

Annex B – Snow load shape coefficients for exceptional snow drifts


EUROCODESBackground and Applications Annexes


Informative Annexes

Annex C – European Ground snow load mapsMajority produced during European Research project

Annex D – Adjustment of ground snow load for return period

Expression for data which follow a Gumbel probability distribution

Annex E – Densities of snowIndicative density values for snow on the ground


EUROCODESBackground and Applications Further developments


Research needs for further developments

1. Examine National Annex maps with the maps of Annex C

of EN 1991-1-3 as a first step to obtain a harmonised

snow map of Europe by ensuring consistency at borders;

2. Enlargement of the European ground snow load map to

cover all the 29 Member States of the EU and EFTA;

3. Influence of roof dimensions on roof shape coefficients

4. Snow loading on glass structures;

5. Freezing/melting effects.




Thank you for your attention

EN 1991-1-4

S. O. Hansen Svend Ole Hansen ApS


EUROCODESBackground and Applications EN 1991 – Eurocode 1: Actions on structures

EN 1991-1-4:2005

Wind actions

Yourlogo


EUROCODESBackground and Applications EN 1991-1-4:2005 Contents

1. General

2. Design situations

3. Modelling of wind actions

4. Wind velocity and velocity pressure

5. Wind actions

6. Structural factor

7. Pressure and force coefficients

8. Wind actions on bridges


EUROCODESBackground and Applications EN 1991-1-4:2005 Contents

Annex

A. Terrain effects

B. Procedure 1 for determining the structural factor

C. Procedure 2 for determining the structural factor

D. Structural factors for different types of structures

E. Vortex shedding and aeroelastic instabilities

F. Dynamic characteristics of structures


EUROCODESBackground and Applications Section 1 General – 1.1 Scope

(2) This Part is applicable to:

- Buildings and civil engineering works with heights up to 200 m

- Bridges having no span greater than 200 m, provided that they satisfy the criteria for dynamic response

(3) This part is intended to predict characteristic wind actions onland-based structures, their components and appendages


EUROCODESBackground and Applications Section 1 General – 1.1 Scope

Draft corrigendum to EN 1991-1-4:200522 January 2008

(11) Guyed masts and lattice towers are treated in EN 1993-3-1 and lighting columns in EN 40

(12) This part does not give guidance on the following aspects:

- torsional vibrations, e.g. tall buildings with a central core

- bridge deck vibrations from transverse wind turbulence

- wind actions on cable supported bridges

- vibrations where more than the fundamental mode needs to beconsidered


EUROCODESBackground and Applications Section 2 Design situations

(1)P The relevant wind actions shall be determined for each design situation identified in accordance with EN 1990, 3.2.

(2) Traffic, snow and ice

(3) Execution

(4) Where in design windows and doors are assumed to be shutunder storm conditions, the effect of these being open should betreated as an accidental design situation


EUROCODESBackground and Applications Section 3 Modelling of wind actions

3.1 Nature

3.2 Representations of wind actions

3.3 Classification of wind actions

(1) Unless otherwise specified, wind actions should be classified as variable fixed actions

3.4 Characteristic values

(1)

Note: All coefficients or models, to derive wind actions from basicvalues, are chosen so that the probability of the calculated windactions does not exceed the probability of these basic values

3.5 Models


EUROCODESBackground and Applications Section 4 Wind vel. and vel. pres. - 4.2 Basic values

0,bseasondirb vccv


EUROCODESBackground and Applications Section 4 Wind vel. and vel. pres. - 4.2 Basic values

ENV 1991-2-4:1995


EUROCODESBackground and Applications Norway: Basic wind velocity. NS 3491-4:2002


EUROCODESBackground and Applications UK: Basic wind velocity. BS 6399-2:1997


EUROCODESBackground and Applications Faroe Islands – extreme winds


EUROCODESBackground and Applications Faroe Islands – extreme winds

Vindklima i Danmark og i udlandet 29


EUROCODESBackground and Applications Faroe Islands – measuring stations


EUROCODESBackground and Applications Faroe Islands - Glyvursnes

Vindklima i Danmark og i udlandet 37


EUROCODESBackground and Applications Faroe Islands – basic wind velocities


EUROCODESBackground and Applications Italy - Messina


EUROCODESBackground and Applications Southerly winds at Messina – bridge deck height


EUROCODESBackground and Applications Basis for updated European wind map?

ENV 1991-2-4:1995


EUROCODESBackground and Applications Climatological changes?


EUROCODESBackground and Applications Influence of terrain - measured wind velocities


EUROCODESBackground and Applications Section 4.3 Mean wind

borm vzczczv )()()(


EUROCODESBackground and Applications Section 4.3.2 Terrain roughness

mzzzk

zzkzc

IIII

r

rr

05,019,0

)/ln()(

,0

07,0

,0

0

0


EUROCODESBackground and Applications Terrain categories and terrain parameters


EUROCODESBackground and Applications Annex A: Terrain category I and II


EUROCODESBackground and Applications Annex A: Terrain category III and IV


EUROCODESBackground and Applications Annex A: Terrain category 0 – coastal area


EUROCODESBackground and Applications Coastal area exposed to the open sea


EUROCODESBackground and Applications Figure 4.1 - Assessment of terrain roughness


EUROCODESBackground and Applications A.2 Transition between roughness categories


EUROCODESBackground and Applications A.2 Transition between roughness categories

Procedure 1

If the structure is situated near a change of terrain roughnessat a distance:

- less than 2 km from the smoother category 0- less than 1 km from the smoother categories I to III

the smoother terrain category in the upwind direction shouldbe used.

Small areas (less than 10% of the area under consideration) with deviating roughness may be ignored.


EUROCODESBackground and Applications A.3 Terrain orography. Figure A.1


EUROCODESBackground and Applications Section 4.4 Wind turbulence. Turbulence intensity

)/ln(1)(

0zzk

czI I

ov


EUROCODESBackground and Applications Section 4.5 Peak velocity pressure, peak velocity

)()(71)(

)(21))(71()( 2

zvzIzv

zvzIzq

mvp

mvp


EUROCODESBackground and Applications Measured wind velocities


EUROCODESBackground and Applications Section 5 Wind actions – 5.1 General


EUROCODESBackground and Applications Section 5.2 Wind pressure on surfaces

peepe czqw )(

piipi czqw )(


EUROCODESBackground and Applications Figure 5.1 – Pressure on surfaces


EUROCODESBackground and Applications Section 7.2 Pressure coeff. for buildings. Figure 7.2


EUROCODESBackground and Applications Section 7.2.2 Vertical walls. Figure 7.5


EUROCODESBackground and Applications Section 7.2.2 Vertical walls. Table 7.1


EUROCODESBackground and Applications Section 7.2.5 Duopitch roofs. Figure 7.8


EUROCODESBackground and Applications Section 7.2.5 Duopitch roofs. Table 7.4a


EUROCODESBackground and Applications Section 5.3 Wind forces

refepfdsw AzqcccF )(


EUROCODESBackground and Applications Section 6 Structural factor

6.2 Determination of structural factor

The structural factor may be taken as 1 for

a) buildings with a height less than 15 m

b) facade and roof elements having a natural frequencygreater than 5 Hz

c) framed buildings which have structural walls and which areless than 100 m high and whose height is less than 4 times thein-wind depth

d) chimneys with circular cross-sections whose height is lessthan 60 m and 6,5 times the diameter


EUROCODESBackground and Applications Annex D Structural factor










EUROCODESBackground and Applications Section 6 Structural factor. Figure 6.1


EUROCODESBackground and Applications Section 6.3 Detailed procedure

2

22

2

22

)(71

)(21

)(71)(71

)(71)(21

BzI

RBzIkc

zIBzIc

zIRBzIk

cc

sv

svpd

sv

svs

sv

svpds


EUROCODESBackground and Applications Backgrund turbulence and resonance turbulence


EUROCODESBackground and Applications Wind vortices versus structural size


EUROCODESBackground and Applications Procedure 1 (dotted line) versus theory (solid line)


EUROCODESBackground and Applications Procedure 2 (dotted line) versus theory (solid line)


EUROCODESBackground and Applications Structural factor. Procedure 1 or 2?

Procedure 2 has a more accurate representation of the theoreticalbackground compared to procedure 1


EUROCODESBackground and Applications Annex E Vortex shedding

Chimneys

Bridges


EUROCODESBackground and Applications Annex E Vortex shedding. Bending vibrations


EUROCODESBackground and Applications Annex E Vortex sheding. Ovalling vibrations


EUROCODESBackground and Applications Annex E Vortex shedding. Critical wind velocity

Stnb

v

Stnb

v

oiicrit

yiicrit

2,

,

,,


EUROCODESBackground and Applications Vortex shedding. Chimneys


EUROCODESBackground and Applications Vortex shdding. Chimneys


EUROCODESBackground and Applications Approach 1 versus approach 2

Approach 1: Vortex-resonance model

Approach 2: Spectral model

Turbulence is an active parameter only in approach 2

E1.5.1 General(3)

Approach 2 allows for the consideration of different turbulenceintensities, which may differ due to meteorological conditions.

For regions where it is likely that it may become very cold and stratified flow condition may occur (e.g. in coastal areas in NorthernEurope), approach 2 may be used.


EUROCODESBackground and Applications Vortex shedding. Bridge cross section


EUROCODESBackground and Applications Vortex shedding. Bridge cross section. Approach 1


EUROCODESBackground and Applications Vortex shedding. Bridge cross section. Approach 2


EUROCODESBackground and Applications Vortex shedding. Approach 1 or 2?

Approach 2 has a more accurate representation of the physicalphenomenon compared to approach 1

EN 1991-1-5

M. Holicky Czech Technical University in Prague

1

•• GeneralGeneral• Classification of actions• Design situations• Representation of actions• Temperature changes in buildings• Temperature changes in bridges• Temperature changes in industrial chimneys, pipelines, etc.• Annexes• A – Isotherm of national temperatures (normative)• B – Temperature differences in bridges decks (normative)• C – Coefficients of linear expansions (informative)• D – Temperature effects in buildings (informative)

EN 1991-1-5 Thermal ActionsMilan Holický and Jana Marková, Czech Technical University in Prague

DAV 2003-11, Conversion of ENV 1991-2-5 (23 NDP)

PPT file include 24 basic slides and additional (informative) slides.19.2.2008 Eurocodes: Background and

Applications2

Background documents- Background Document of New European Code for Thermal Actions, Report

No. 6, Pisa, Italy, 1999.- Luca Sanpaolesi, Stefano Colombini, Thermal Actions on Buildings,

Department of Structural Engineering, University of Pisa, Italy, Chapter 4 of Handbook 3, Leonardo da Vinci project CZ/02/B/F/PP-134007, 2004.

- EN ISO 6946, Building components and building elements – Thermal resistance and thermal transmittance – Calculation methods, 1996.

- EN ISO 13370, Thermal performance of buildings – Heat transfer via the ground – Calculation methods, 1998.

- ISO Technical Report 9492, Bases for Design of Structures – Temperature Climatic Actions, 1987.

- Emerson, M., TRRL Report 696, Bridge temperatures estimated from shade temperatures, UK, 1976.

- JCSS, Probabilistic Model Code, http://www.jcss.ethz.ch/, Zurich.

19.2.2008 Eurocodes: Background and Applications

3

Collapse of the terminal E2 in Paris


4

Scheme of the collapse

Progressive weakening partly due to cracking during cycles of differential thermal movements between concrete shell and curved steel member.


5

Bridge in transient design situation


6

Basic principles and rules- temperature changes are considered as variable and indirect actions - characteristic values have probability of being exceeded 0,02 by annual extremes (return period of 50 years)- the maximum and minimum shade air temperature measured by thermometers in a “Stevenson Screen” by the National Meteorological Service of each Member State- thermal actions shall be considered for both persistent and transient design situations - in special cases temperature changes in accidental design situations should be also verified

2

An example: map of maximum temperatures in CR

Tmin = 32,1 °C Tmax = 40,0 °C mean µT = 37,4 °C

Maximum shade air temperatures of being exceeded by annual extremes with the probability of 0,02.

32,1 to 34 °C34,1 to 36 °C 36,1 to 38 °C 38,1 to 40 °C

Temperature changes in buildings

Thermal actions on buildings shall be considered when ultimate or serviceability limit state s may be affected.

Effect of thermal actions may be influenced by nearby buildings,the use of different materials, structural shape and detailing. Three basic components are usually considered:

- a uniform component ∆Tu

- temperature difference ∆TM

- temperature differences of different structural parts ∆Tp

∆Tu = T – T0

Inner temperatures in buildings

Season Temperature Tin in 0C

T1 (20 °C)

T2 (25 °C)winter

summer

Recommended inner temperaturesin the Czech National Annex- summer 25 °C- winter 20 °C

Outer temperatures Tout

Season Relative absorptivity Temperature Tout in 0C

0,5 bright light surface

0,7 light coloured surface

0,9 dark surface

Tmax + T3

Tmax + T4

Tmax + T5

winter Tmin

summer

Recommended values: T3 0 °C 18 °C

T4 2 °C 30 °C

T5 4 °C 42 °C

N, E, N-E S, W, S-W and H


11

Uniform design temperatures in a buildingAn thermally unprotected steel structure

ČSN 73 1401: ∆TN = 60 °C

ČSN P ENV 1991-2-5: ∆TN = 61 °C

ČSN EN 1991-1-5: in Prague for dark surface and North-East

Te,max = 30 °CTe,min = -30 °C

Te,min = -24 °C Te,max = 37 °C

Te,min = -32 °C Te,max = 40 + T5= 44 °C

∆TNd = 76 × 1,5 = 114 °C

∆TNd = 61 × 1,4 = 85 °C

∆TNd = 60 × 1,2 = 72 °C

∆ TN = 76 °C


12

An example of a fixed member

q [kN/m]∆TNd=(44−10)×1,5=51 °C

122200 0000,6112Steel

1530 0000,5110Concrete

Stress

σ T MPa

Young modulusE MPa

Strain

εT ×10-3

Linear expansionαT×10-6×°C-1

Material

3

A uniform temperature component- National maps of isotherms Tmax, Tmin- Effective temperatures in bridges – graphical tools

Maximum and minimum effective temperatures T∆TN,con = T0 - Te,min∆TN,exp = Te,max - T0The total range ∆TN = Te,max - Te,min

A frame under a uniform component and different support conditions 19.2.2008 Eurocodes: Background and Applications

14

Annex D: temperatures in buildings

)()()( outintot

in TTR

xRTxT −−=inner surface

−20

−10

0

10

20

30

°C

Tin

Tout

X

x

outer surface

T(x) •

outintot RhRRi i

i ++= ∑ λ

∑+=i i

ihRxRλin)(

Thermal resistance [m2K/W]

Temperatures

where λ [W/(mK)] is thermal conductivity


15

Three layers wall - graphical method


16

Input temperatures Ti= 20 To= -20 Heat flow Q= 17,323Transfer coef. Thermal conduct. Thickness Resistance Temperatures

Layer Material W/m2/°C W/m/°C m °CInside 20

0 Surface 9 0,111 18,0751 Gypsum 0,16 0,013 0,081 16,6682 Insulation 0,025 0,05 2,000 -17,9793 Brick 1,5 0,1 0,067 -19,1344 Outside 20 0,050 -20,000

The total resistance of wall Rtot = 2,309

Graph x temp-0,02 20,000

0 18,0750,013 16,6680,063 -17,9790,163 -19,1340,183 -20,000 -25

-20-15-10-505

10152025

-0,05 0 0,05 0,1 0,15 0,2

Three layers wall – EXCEL

sheet

Temperature changes in bridges

1. Steel deck – steel box girder– steel truss or plate girder

2. Composite deck3. Concrete deck – concrete slab

– concrete beam– concrete box girder

Three types of bridge superstructures are considered

Basic temperature componentsa uniform componentvertical temperature differenceshorizontal temperature differences

approach 1 - linear

approach 2 - non-linear minimum

maximum70

60

50

40

30

20

10

0

-10

-20

-30

-40

-50

Type 1

Type 2 Type 3

–50 –40 –30 –20 –10 0 10 20 30 40

Te,max Te,min

Tmax Tmin

Type 3 Type 2 Type 1

C 0C 50forC 8

C 4,5 C 3

C 50C 30for C 1,5 3 Type

C 4,5 2 TypeC 16 1 Type

minmin e,

minmin e,

minmin e,

maxmax e,

maxmax e,

maxmax e,

°≤≤°−

°+=

°+=

°−=

°≤≤°

°+=

°+=

°+=

minmax TTTTTTT

TTTTTTT

Uniform effective temperatures

4

Approach 1: linear vertical differences

Type 1, steel

Type 2, composite

Type 3, concrete

box girder

beam

slab

18

15

10

15

15

18

13

5

8

8

∆TM,heat (oC) ∆TM,cool (oC)

Thickness of surfacing considered by reduction coefficient ksur.

Approach 2: non-linear vertical differenceType 1 (steel)

Approach 2: non-linear vertical differencesTemperature differences

(a) heating (b) cooling

Type 2 Concrete deck on steel box, truss or plate girders

∆T1

∆T2

∆T1

∆T2

∆T1 hh ∆T1

∆T1 = 10 °C

h ∆ T1 ∆ T2 m °C °C 0,2 13 4 0,3 16 4

∆T1 = – 10 °C

h

h ∆ T1 ∆ T2 m °C °C 0,2 –3,5 –8 0,3 –5,0 –8

h2

h1

h1 = 0,6h h2 = 0,4 m

hh1

h2

h

h

Simplified procedure

surfacing 100 mm

surfacing 100 mm

Normal procedure

Type 2 (composite)Approach 2: non-linear vertical differencesType 3 (concrete)

outer face warmer

inner face warmer

90°

∆TM

∆TM

∆TN

15°C

Temperature changes in industrial structures

(a) Uniform component

(b) Stepped component

(c) Linear component

The outer temperatures of a structure depend on absorptivity and orientation of the surface.

Concluding remarks

A uniform temperature component may be derived using national maps of isotherms.

For industrial structures uniform, linear and stepped components are considered; technological temperatures in accordance of design specifications.

Temperature effects may be in some cases significant and shall be considered in structural design.

Two approaches for vertical temperature profile in bridges are given: either linear or non-linear profile should be used.

For bridges the relationship is given for specification of uniform (effective) temperature component.

5

An example: map of minimum temperatures in CR

–28,1 to –30 °C–30,1 to –32 °C –32,1 to –34 °C –34,1 to –36 °C

Tmin = – 35,2 °C Tmax = – 28,1 °C mean µT = – 31,3 °C

Minimum shade air temperatures of being exceeded by annual extremes with the probability of 0,02.


26

Linear expansion coefficients

30-70Timber, across grain5Timber, along grain

6-10Masonry7Concrete with light aggregates10Concrete (except as specified below)12Structural steel16Stainless Steel24Aluminium, aluminium alloys

αT (× 10-6 × °C-1)Material

Constituent components of a temperature profile

a) a uniform component ∆Tu

b) a linear component about z-z, ∆TMy (in the direction of axis y)c) a linear component about y-y-, ∆TMz (in the direction of axis z)d) a non-linear component ∆TE


28

Transient design situations

p = 0,0250 yearst > 1 year

p = 0,110 years3 months < t ≤ 1 year

p = 0,25 years3 days < t ≤ 3 months

p = 0,52 yearsReturn periodR

t ≤ 3 daysNominal period t

Return periods R for the characteristic values Qk

Tmax,p = Tmax {k1 – k2 ln [– ln (1 – p)]}

Tmin,p = Tmin {k3 + k4 ln [– ln (1 – p)]}

The coefficients k1 to k4 are given in EN 1991-1-5.


29

Reduction coefficients k for different return periods R

The characteristic value Qk for return period R

11110,0250 years0,900,830,740,910,110 years0,850,750,630,86 0,25 years0,770,640,450,8 0,52 years

vb,Rwind

sn,Rsnow

Tmin,RTmax,R

Reduction coefficient k forpReturnperiod

R

Qk,R = k Qk,50

A uniform temperature component

Composite bridgeČSN 73 6203: ∆TN = 65 °C Te,min = -25 °C Te,max = 40 °C

ČSN P ENV 1991-2-5: ∆TN = 62 °C Te,min = -20 °C Te,max = 42 °C

ČSN EN 1991-1-5: ∆TN = 73 °C Te,min = -28 °C Te,max = 45 °C

Prestressed concrete bridge

ČSN 73 6203: ∆TN = 55 °C

ČSN P ENV 1991-2-5: ∆TN = 55 °C

ČSN EN 1991-1-5: ∆TN = 66 °C

Te,max = 35 °CTe,min = -20 °C



ENV 1991-2-5: -24°C, 37 °C; in EN 1991-1-5, Prague -32 °C, 40°C

6


31

An example of temperature

profile

Summer

Winter

An example of temperature effects-Čekanice, Czech Republic

Typical section

Load combinations in accordance EN

Support section Midspan sectionExpr. Main M [MNm] σ hor

[MPa]σdol

[MPa]M

[MNm]σhor

[MPa]σdol [MPa]

6.10 Q -36,26 1,23 -8,89 34,97 -6,21 3,546.10 T -32,67 0,85 -8,27 34,65 -6,18 3,486.10a - -27,88 0,34 -7,44 27,61 -5,44 2,27

6.10b Q -28,92 0,45 -7,62 30,6 -5,75 2,78

6.10b T -25,32 0,069 -6,99 30,28 -5,72 2,73

Support section Mid-span section

M[MNm]

σ hor[MPa]

σdol[MPa]

M [MNm] σhor [MPa] σdol [MPa]

-32,85 0,32 -8,48 32,93 -5,83 2,99

ENEN

ČČSNSN

Alternative load combinations in accordance with EN

0

5

10

15

20

25

30

35

T2E T2N K 2E K 2N

CZ6Q6T6a6bQ6bT

Bending moments at mid-span sections T2 and K2 for linear (E) and non-linear (N) temperatures.

Simultaneous temperature components

∆TM, heat (or ∆TM, cool) + ωN ∆TN,exp (or ∆TM, con)

ωM ∆TM, heat (or ∆TM, cool) +∆TN, exp (or ∆TN, con)

ωN = 0,35ωM = 0,75

Coefficients:

- Difference in uniform components of different members

- Differences of temperatures of bridge piers 19.2.2008 Eurocodes: Background and Applications

36

An example of a fixed member

q [kN/m]∆TNd = 76 × 1,5 = 114 °C

Concrete: αT = 10 × 10-6 × °C-1

Linear expansion for αT = 10 × 10-6 × °C-1

Temperature strain εT = 10 × 10-6 × 114 = 1,14 × 10-3

Young modulus for concrete member, E ≈ 30 000 MPaStress σ T = E εT = 1,14 × 10-3 × 30 000 = 34 MPa

Structural steel: αT = 12 × 10-6 × °C-1, E ≈ 200 000 MPaεT = 12 × 10-6 × 114 = 1,37 × 10-3

σT = E εT = 1,40 × 10-3 × 200 000 = 274 MPa

EN 1991-1-6

P. Formichi University of Pisa



EN 1991 – Eurocode 1: Actions on structuresPart 1-6 General actions Actions during execution

Paolo FormichiDepartment of Structural Engineering

University of Pisa - Italy


EUROCODESBackground and Applications EN 1991-1-6: Contents

Foreword

Section 1 General1.1 Scope1.2 Normative references1.3 Assumptions1.4 Distinction between principles and application rules1.5 Terms and definitions1.6 Symbols

Section 2 Classification of Actions

Section 3 Design situations and limit states3.1 General - identification of design situations 3.2 Ultimate limit states3.3 Serviceability limit states



EUROCODESBackground and Applications EN 1991-1-6: Contents

Section 4 Representation of actions

4.1 General4.2 Actions on structural and non structural members during

handling4.3 Geotechnical Actions 4.4 Actions due to prestresssing4.5 Predeformations4.6 Temperature, shrinkage, hydration effects4.7 Wind Actions 4.8 Snow Loads4.9 Actions caused by water4.10 Actions due to atmospheric icing4.11 Construction loads4.12 Accidental Actions 4.13 Seismic Actions



EUROCODESBackground and Applications EN 1991-1-6: Annexes

Annex A1 (Normative)Supplementary rules for buildings

Annexe A2 (Normative)Supplementary rules for bridges

Annexe B (Informative)Actions on structures during alteration, reconstruction or demolition



EUROCODESBackground and Applications EN 1991-1-6: Scope

EN 1991-1-6 gives principles and general rules for the determination of actions to be taken into account during the execution of buildings and civil engineering works.

It may also be used as guidance for the determination of actions to be taken into account during:- structural alterations - reconstruction- partial or full demolition.

It also gives rules for the determination of actions to be used for the design of auxiliary construction works (falsework, scaffolding, propping systems, cofferdam, bracing…), needed for the execution phases.



EUROCODESBackground and Applications EN 1991-1-6: Design Situations and limit states

During execution the following design situations will be taken into account as appropriate:

Transient

Accidental

Seismic

Any selected design situation will be in accordance with the execution process anticipated in the design, and with any revision occurred.




Any selected transient design situation be associated with a nominal duration equal to, or greater than the anticipated duration of the stage of execution under consideration.

The design situations should take into account the likelihood for any corresponding return periods of variable actions (e.g. climatic actions).

The return periods for the assessment of characteristic values of variable actions during execution may be defined in the National Annex or for the individual project.

Recommended return periods of climatic actions are given, depending on the nominal duration of the relevant design situation.




A minimum wind velocity during execution may be defined in the National Annex or for the individual project. The recommended basic value for durations of up to 3 months is 20m/s in accordance with EN 1991-1-4: Wind Actions.

Relationships between characteristic values and return period for climatic actions are given in the appropriate Parts of EN 1991.


Nominal duration of the execution phase Return period (years)



Example: Snow loads according to return period [Annex D of EN 1991-1-3]

If the available data show that the annual maximum snow load can be assumed to follow a Gumbel probability distribution, then the relationship between the characteristic value of the snow load on the ground and the snow load on the ground for a mean recurrence interval of n years is given by:


sk is the characteristic snow load on the ground (with a return period of 50 years)

Pn is the annual probability of exceedence (approx. = 1/n) V is the coefficient of variation of annual max. snow loads

[ ]

⎪⎪⎭

⎪⎪⎬

⎫

⎪⎪⎩

⎪⎪⎨

⎧

+

+−−−=

)5923,21(

57722,0))1ln(ln(61

V

PVss

n

knπ



Snow loads according to return period [EN 1991-1-3]


s n/s

k

Return period (years)

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 5 10 15 20 25 30 35 40 45 50

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 5 10 15 20 25 30 35 40 45 50

V = 0.2

V = 0.6


EUROCODESBackground and Applications EN 1991-1-6: Ultimate Limit States

Ultimate limit states need to be verified for all selected transient, accidental and seismic design situations as appropriate during execution in accordance with EN 1990.

The combinations of actions for accidental design situations can either include the accidental action explicitly or refer to a situation after an accidental event.

Generally, accidental design situations refer to exceptional conditions applicable to the structure or its exposure, such as:

impact, local failure and subsequent progressive collapse, fall of structural or non-structural parts, and, in the case of buildings, abnormal concentrations of building

equipment and/or building materials, water accumulation on steelroofs, fire, etc.




The verifications of the structure should take into account the appropriate geometry and resistance of the partiallycompleted structure corresponding to the selected design situations.


Resistance of the lower floor, which has not necessarily attained its full strength.

Geometry of the partially completed resisting structure




1973 - Bailey’s Crossroad – Fairfax (US) Construction of a 26-story building.Concrete was being placed at the 24th floor and shoring was simultaneously being removed at the 22nd floor cast two weeks before.Insufficient shear resistance of concrete slabs caused progressive collapse (*)

1987 – Bridgeport Connecticut (US)Inadequate temporary connections + instability of steel members (*)

geometry resistance

(*) K. Carper “Beware of vulnerabilities during construction” -Construction and equipment, 3/2004



Ultimate limit states of STR/GEO - Fundamental combination for transient design situations.


Expression (6.10) EN 1990

∑ ∑≥ >

+++1 1

,,0,1,1,,, """"""j i

ikiiQkQPjkjG QQPG ψγγγγ

⎪⎩

⎪⎨

⎧

+++

++

∑∑

∑∑

>≥

≥≥

1,,0,1,1,

1,,

1,,0,

1,,

""""""

""""

iikiiQkQP

jjkjGj

iikiiQP

jjkjG

QQPG

QPG

ψγγγγξ

ψγγγ

0,85 ≤ ξ ≤ 1,00

Expressions (6.10a) and (6.10b) EN 1990



Accidental design situation

∑ ∑≥ >

++++1 1

,,21,1,21,1, "")(""""""j i

ikikdjk QQorAPG ψψψ


Expression (6.11b) EN 1990

Expression (6.12b) EN 1990

Seismic design situation

∑ ∑≥ >

+++1 1

,,2, """"""j i

ikiEdjk QAPG ψ


EUROCODESBackground and Applications EN 1991-1-6: Serviceability Limit States

The SLS for the selected design situations during execution needs to be verified, as appropriate, in accordance with EN 1990.

The criteria associated with the SLS during execution should take into account the requirements for the completed structure.

Operations which can cause excessive cracking and/or early deflection during execution and which may adversely affect the durability, fitness for use and/or aesthetic appearance in the final stage has to be avoided.




The combinations of actions should be established in accordance with EN 1990. In general, the relevant combinations of actions for transient design situations during execution are:

the characteristic combination

the quasi-permanent combination




SLSSLS: combinations of actions: combinations of actions.

∑ ∑≥ >

+++1 1

,,01,, """"""j i

ikikjk QQPG ψ


Characteristic combination (irreversible SLS)

Quasi-permanent combination (reversible SLS)

∑ ∑≥ ≥

++1 1

,,2, """"j i

ikijk QPG ψ


EUROCODESBackground and Applications Classification & representation of actions

Actions during execution are classified in accordance with EN 1990, and may include:

those actions that are not construction loads; and

construction loads

Both types of actions are classified (tables 2.1 and 2.2) depending on:

Variation in time (permanent, variable, accidental)

Origin (direct, indirect)

Spatial variation (fixed, free)

Nature (static, dynamic)Paolo Formichi, University of Pisa Italy


EUROCODESBackground and Applications Classification & representation of actions



EUROCODESBackground and Applications Construction Loads

Construction loads Qc may be represented in the appropriate design situations (see EN 1990), either, as one single variable action, or where appropriate different types of construction loads may be grouped and applied as a single variable action. Single and/or a grouping of construction loads should be considered to act simultaneously with non construction loads as appropriate.

QcaQcbQccQcdQceQcf


6 different sources


EUROCODESBackground and Applications Classification of Construction Loads

Construction loads Qc are classified as variable actions

Where Construction Loads are classified as fixed, they should be defined tolerances for possible deviation from the theoretical position.

Where Construction Loads are classified as free, they should be defined limits of the area where they should be moved or positioned.


Qca

Qcb

Qcc

Qcd

Qce

Qcf

Constr. Load


EUROCODESBackground and Applications Representation of Construction Loads

Construction loads Qca Personnel and hand tools

Working personnel, staff and visitors, possibly with hand tools or other small site equipment.


Modelled as a uniformly distributed load qca and applied as to obtain the most unfavourable effects.The recommended value is : qca,k = 1,0 kN/m2



Construction loads Qca Personnel and hand toolsThe recommended value has been derived from investigations on construction sites(*), with regard to the following stages of construction:

1. before pouring of concrete slab;

2. after pouring of concrete slab, during the preparation of the next floor.

As an example: the 5% fractile value for the 9,25 m2, is 1,23 kN/m2 (Gumbeldistribution of the random variable is assumed).

(*) “Cast-in-place Concrete in Tall Building Design and Construction” – Council on Tall Buildings and Urban Habitat Committee 21 D. Mc Graw-Hill Inc. – 1991 – Chapter 2: Construction loads.


3,342,931,080,312,32

2,392,000,920,305,95

2,682,180,800,299,25

1,941,580,730,3020,90

1,461,430,720,2837,16

0,5% fractileLoad [kN/m2]

1% fractileLoad [kN/m2]

10% fractileLoad [kN/m2]

Mean Load[kN/m2]

Measurement grid size [m2]



Construction loads Qcb Storage of movable items e.g.:1. Building and construction materials, precast elements;2. Equipment.


Modelled as a free action and represented by a UDL qcband a concentrated load FcbFor bridges, the following values are recommended minimum values:

qcb,k = 0,2 kN/m2

Fcb,k = 100 kN



Construction loads Qcc Non-permanent equipment in position for use:Static (e.g. formwork panels, scaffolding, falsework, machinery, containers)During movement (e.g. travelling forms launching griders and nose, counterweights)


Unless more accurate information is available, they may be modelled by a uniformly distributed load with a recommended minimum characteristic value of qcc,k = 0,5 kN/m2



Construction loads Qcd Movable heavy machinery and equipment usually wheeled or tracked e.g.:Cranes, lifts, vehicles, lift trucks, power installations, jacks, heavy lifting devices.


When not defined in the project specification, information for the determination of actions may be found in:- EN 1991-2 for actions due to vehicles- EN 1991-3 for actions due to cranes.



Construction loads Qce Accumulation of waste materials e.g.:surplus construction materials excavated soil or demolition materials.


These loads are taken into account by considering possible mass effects on horizontal, inclined and vertical elements (such as walls).These loads may vary significantly, and over short time periods, depending on types of materials, climatic conditions, build-up and clearance rates.



Construction loads Qcf Loads from part of structure in a temporary state before the final design actions take effect e.g. loads from lifting operations.


Taken into account and modelled according to the planned execution sequences, including the consequences of those sequences (e.g. loadsand reverse load effects due to particular processes of construction, such as assemblage).



Construction loads during the casting of concrete (4.11.2)


Actions to be taken into account simultaneously during the casting of concrete may include:

- working personnel with small site equipment (Qca);

- formwork and load-bearing members (Qcc);

- the weight of fresh concrete (which is one example of Qcf), as appropriate.



Qca, Qcc and Qcf may be given in the National Annex.

Recommended values for fresh concrete (Qcf) may be taken from Table 4.2 and EN 1991-1-1, Table A.1. Other values may have to be defined, for example, when using self-levelling concrete or pre-cast products.



EUROCODESBackground and Applications EN 1991-1-6: Accidental Actions

Accidental actions such as impact from construction vehicles, cranes, building equipment or materials in transit (e.g. skip of fresh concrete), and/or local failure of final or temporary supports, including dynamic effects, that may result in collapse of load-bearing structural members, shall be taken into account, where relevant.

Abnormal concentrations of building equipment and/or building materials on load-bearing structural members should also be taken into account

Dynamic effects may be defined in the National Annex or for the individual project. The recommended value of the dynamic amplification factor is 2. In specific cases a dynamic analysis is needed.



EUROCODESBackground and Applications EN 1991-1-6: Seismic Actions

Seismic actions should be determined according to EN 1998, taking into account the reference period of the considered transient situation.

The design values of ground acceleration and the importance factor γI may be defined in the National Annex or for the individual project.





EN 1991-1-6: Annex A1 (normative)

Supplementary rules for buildings

Representative values of the variable action due to construction loads may be set by the National Annex, within a recommended range of ψ0 = 0,6 to 1,0.

The recommended value of ψ0 is 1,0.

The minimum recommended value of ψ2 is 0,2 and it is further recommended that values below 0,2 are not selected

For the verification of serviceability limit states, the combinations of actions to be taken into account should be the characteristic and the quasi-permanent combinations.





Supplementary rules for bridges

For the incremental launching of bridges the design values for vertical deflections may be found in the National Annex.

The recommended values are:a) ± 10 mm longitudinally for one bearing, the other bearings being

assumed to be at the theoretical level;b) ± 2,5 mm in the transverse direction for one bearing, the other

bearings being assumed to be at the theoretical level.




Supplementary rules for bridges – Construction Loads

For the incremental launching of bridges horizontal forces due to friction effects should be determined, and applied between the bridge structure, the bearings and the supporting structures, with dynamic action effects taken into account where appropriate.

It is recommended that the design value of the total horizontal friction forces should be not less than 10 % of the vertical loads, and should be determined to give the least favourable effects.

The horizontal friction forces at every pier should be determined with the appropriate friction coefficients, µmin and µmax (defined in the National Annex).

Unless more accurate values are available from tests for movements on very low friction surfaces (e.g. PTFE) the recommended values are :

µmin = 0µmax = 0,04





Actions on structures during alteration, reconstruction or demolition

The actual performance of structures affected by deterioration should be taken into account in the verification of the stages for reconstruction or demolition. The investigation of structural conditions to enable the identification of the load-bearing capacity of the structure and to prevent unpredictable behaviour during reconstruction or demolitionshould be undertaken.

The reliability for the remaining structure or parts of the structure under reconstruction, partial or full demolition should be consistent with that considered in the Eurocodes for completed structures or parts ofstructures.

EN 1991-1-6: Annex B (informative)Brussels, 18-20 February 2008 – Dissemination of information workshop 38



Thank you for your attention

EN 1991-1-7

A. Vrouwenvelder TNO



EN 1991-1-7

Eurocode 1 Accidental Actions

Ton Vrouwenvelder

TNO Bouw / TU Delft



EN 1990 Section 2.1 Basic Requirements

(4)P A structure shall be designed and executed in such a way that it will not be damaged by events like

- explosion- impact and- consequences of human errors

to an extent disproportionate to the original cause

Note: Further information is given in EN 1991-1-7



EN 1990 guidance:

reducing hazardslow sensitive structural formsurvival of local damagesufficient warning at collapsetying members





World Trade CenterUSA, 2001



Eurocode EN 1991-1-7

1. General2. Classification3. Design situations4. Impact5. Explosions

AnnexesA. Design for localised failure B. Risk analysisC. DynamicsD. Explosions



3 Design strategies



4. Impact

Type of road Vehicle type Fd,x [kN]

Motorway

Country roads

Urban area

Parking place

Parking place

Truck

Truck

Truck

Truck

Passenger car

1000

750

500

150

50



Annex B: scenario model



0

500

1000

1500

2000

2500

0 1000 2000 3000 4000 5000

upperlowertheorie

E [kNm]

F[kN]

F=v√(km)

model en experiment

Annex C: force model



Table 4.2.1: Data for probabilistic collision force calculation

variable designation type mean stand dev

n number of lorries/day deterministic 5000 -

T reference time deterministic 100 years -

λ accident rate deterministic 10-10 m-1 -

b width of a vehicle deterministic 2.50 m -

α angle of collision course rayleigh 10o 10o

v vehicle velocity lognormal 80 km/hr 10 km/hr

a deceleration lognormal 4 m2/s 1.3 m/s2

m vehicle mass normal 20 ton 12 ton

k vehicle stiffness deterministic 300 kN/m -



0

500

1000

1500

2000

2500

3000

eq 4.3.7

10 20 30 40 50

distance [m]

force [kN]

Life time exceedence probability: 10-3


EUROCODESBackground and Applications Design example: bridge column in motorway

x

H h y

Fdy

a b

b width 0.50 m

h thickness 1.00 m

H column height 5 m

fy yield stress steel 300 MPa

fc concrete strength 50 MPa

ρ reinforcement ratio 0.01



Bending moment:

Mdx = H)aH(a − Fdx = 00.5

)25.100.5(25.1 − 1000 = 940 kNm

Resistance:

MRdx = 0.8 ω h2 b fy

= 0.8 0.01 1.002 0.50 300 000 = 1200 kNm > 940 kNm



5 + Annex D:

gas explosions in buildings

gas explosions in tunnels

dust explosions



INTERNAL NATURAL GAS EXPLOSIONS

The design pressure is the maximum of:

pd = 3 + pvpd = 3 + 0.5 pv+0,04/(Av/V)2

pd = nominal equivalent static pressure [kN/m2]

Av = area of venting components [m2]

V = volume of room [m3]

Validity: V < 1000 m3 ; 0,05 m-1 < Av / V < 0,15 m-1

Annex B: load duration = 0.2 s



Design Example: Compartment in a multi story building

H = 3m pd B = 8 m

Compartment: 3 x 8 x 14 m

Two glass walls (pv =3 kN/m2) and two concrete walls



explosion pressure:

pEd = 3 + pv/2 + 0,04/(Av/V)2

= 3 + 1.5 + 0.04 / 0.1442 = 6.5 kN/m2

self weight = 3.0 kN/m2

live load = 2.0 kN/m2

Design load combination (bottom floor):

pda = pSW + pE + ψ1LL pLL

= 3.00 + 6.50 + 0.5*2.00 = 10.50 kN/m2



Dynamic increase in load carrying capacity

ϕ d = 1 + Rd

SW

pp

2max

)t(gu2Δ

Δt = 0.2 s = load durationg = 10 m/s2

umax = 0.20 m = midspan deflection at collapsepsw = 3,0 kN/m2 and pRd =7.7 kN/m2

ϕd = [1 + 7.73

2)2.0(1020.0*2

] = 1.6

pREd = ϕd pRd = 1.6 * 7.7 = 12.5 kN/m2 > 10.5 kN/m2

Conclusion: bottom floor system okay



Be careful for upper floors and columns

Psw pE edge centre column column B



BLEVE in een overkluizing



X

Y

X

Y

Z



0.1E-2.2E-2.3E-2.4E-2.5E-2.6E-2.7E-2.8E-2.9E-2.1E-1

X

Y

Z



Consequences class Example structures

class 1

class 2, lower group class 2, upper group

class 3

low rise buildings where only few people are present most buildings up to 4 stories most buildings up to 15 stories high rise building, grand stands etc.

Annex A: Classification of buildings



Class 1

No special considerations

Class 2, Lower Group Frames

Horizontal ties in floors

Class 2, Lower group Wall structures

Full cellular shapes Floor to wall anchoring.

Class 2, Upper Group

Horizontal ties and effective vertical ties OR limited damage on notional removal OR special design of key elements

Class 3 Risk analysis and/or advanced mechanical analysis recommended

Annex A: What to do



Class 2a (lower group)

randkolom

alle liggers kunnen wordenontworpen om als trekbandte dienen

interne trekbandTi

omtrek trekband Tp

s = 4 ms = 4 m

L =

5 m

interne trekband Ti



randkolom

interne trekband2Ø12

omtrek trekband 2Ø12

s = 4 ms = 4 m

L =

5 m

interne trekband2Ø12

Class 2a (lower group)

Ti= 0.8 (gk+Ψ qk)sL = 0.8{3+0.5*3}x4x5=88 kN>75 kN

FeB 500: A = 202 mm2 or 2 Ø12mm


EUROCODESBackground and Applications Background horizontal typings

s

s L

LTi = 0,8 s L p Ti

Ti

Ti

middenkolom

total load on center columnR = (gk + ψ qk) L s = p L s



Ti = 0.75 p s LEquilibirum for δ = (s+L)/6

drukkrachten

trekkrachten

R

verplaatsing δ

XX

δ TiR

Background typing forcesBrussels, 18-20 February 2008 – Dissemination of information workshop 30


Suggestion:

design corner column as a key element.



Example structure, Class 2, Upper Group, Framed

L =7.2 m, s =6 m, qk=gk=4 kN/m2, Ψ=1.0

internal ties

perimeter tie

L

s



Example structure

Internal horizontal tie force

Ti = 0.8 (gk + Ψ qk) s L = 0.8 {4+4} (6 x 7.2) = 276 kN

FeB 500: A = 550 mm2 or 2 ø18 mm.

Vertical tying force:

Ti = (gk + Ψ qk) s L = {4+4} (6 x 7.2) = 350 kN

FeB 500: A = 700 mm2 or 3 ø18 mm.



Class 2 higher class – walls

interne trekband Ti

omtrek trekband Tp

z

internetrekband Ti

dragende wand

1,2

m



Tyings

Horizontal: Ti = Ft (gk + ψqk) /7,5 × z/5 kN/m > FtPeriphery: Tp = FtVertical: T = 34 A / 8000 × (H/t)² in N > 100 kN/m

Ft = 20 + 4ns kN/m < 60 kN/m ns = number of storeysz = spanA = horizontal cross section of wall [mm²]H = free storey heightt = wall thickness

Class 2 higher class – walls



Design Example:

L = 7,2 m, H = 2,8 m en t = 250 mm

T = 34×7200×250/8000 × (2800/250)² = = 960 ×10³ N = 960 kN > 720 kN

maximal distance 5 mmaximal distance from edge: 2.5 m

Result: 2 tyings of 480 kN

Class 2 higher class – walls Brussels, 18-20 February 2008 – Dissemination of information workshop 36


Effect of tyings in walls



Effect of vertical tyings

gaping



Guidancecan be found in

Annex B:

Definition of scope and limitations

Qualitative Risk analysis• hazard identification• hazard scenarios• description of consequences Reconsideration• definition of measures of scope and assumptions

Quantitative Risk Analyisis• inventory of uncertainties• modelling of uncertatinties• probabilistic calculations• quantification of consequences• calculation of risks

Risk management• risk acceptance criteria• decision on measures

Presentation

class 3: Risk analysis



Risk Analysis Eastern ScheldtStorm Surge Barrier(1980)



Office building Zwolle (The Netherlands)

London Eye



Points of attention in risk analysis

• list of hazards• irregular structural shapes new• construction types or materials• number of potential casualties • strategic role (lifelines)


EUROCODESBackground and Applications hazards

Internal explosion

External explosion

Internal fire

External fire

Impact by vehicle etc

Mining subsidence

Environmental attack

Vandalism

Demonstrations

Terrorist attack

Design error

Material error

Construction error

User error

Lack of maintenance

Earthquake

Landslide

Tornado

Avalanche

Rock fall

High groundwater

Flood

Volcano eruption



Identifical and modellingof relevant accidental

hazards

Assessment of damage states to structure from

different hazards

Assessment of the performance of thedamaged structure

Assessment of the probability of occurence of different hazards

with different intensities

Assessment of the probability of different states of damage and corresponding consequences

for given hazards

Assessment of the probability of inadequate performance(s) of the damaged structure

together with the corresponding consequence(s)

Step 1 Step 2 Step 3Identifical and modellingof relevant accidental

hazards


different hazards





for given hazards



Identifical and modellingof relevant accidental

hazards


different hazards





for given hazards



Step 1 Step 2 Step 3



Risk calculation:

Step 1: identification of hazard Hi

Step 2: damage Dj at given hazard

Step 3: structural behavour Sk and cpmsequences C(Sk)

)S(C)DS(p)HD(p)H(pRisk kjkiji=

Take sum over all hazards and damage types


EUROCODESBackground and Applications Conclusions

EN 1991-1-7: valuable document,

but not a masterpiece of European harmonisation

Reasons:

large prior differences

member state autonomy in safety matters

legal status different in every country

It will be interesting to see the National Annexes and NDP’s .



Relevant Background Documents

ISO-documents

COST actions C28 and TU0601

Background document for the ENV-version of EC1 Part 2-7 (TNO, The Netherlands, 1999)

Leonardo da Vinci Project CZ/02/B/F/PP-134007Handbooks Implementtion of Eurocodes (2005)

EN 1991-2

J.-A. Calgaro CGPC, CEN/TC250 Chairman

M. Tschumi

SBB-CFF-FFS



Traffic Loads Traffic Loads on Road on Road Bridges Bridges and and FootbridgesFootbridges

JeanJean--Armand Armand CalgaroCalgaroChairman Chairman of CEN/TC250of CEN/TC250

EN 1991EN 1991--2 2 «« Traffic LoadsTraffic Loads on Bridgeson Bridges »»Brussels, 18-20 February 2008 – Dissemination of information workshop 2


EN 1991EN 1991--2 2 «« Traffic LoadsTraffic Loads on Bridgeson Bridges »»

FOREWORD

SECTION 1 GENERAL

SECTION 2 CLASSIFICATION OF ACTIONS

SECTION 3 DESIGN SITUATIONS

SECTION 4 ROAD TRAFFIC ACTIONS AND OTHER ACTIONSSPECIFICALLY FOR ROAD BRIDGES

SECTION 5 ACTIONS ON FOOTWAYS, CYCLE TRACKSAND FOOTBRIDGES

SECTION 6SECTION 6 RAIL TRAFFIC ACTIONS AND OTHER ACTIONSRAIL TRAFFIC ACTIONS AND OTHER ACTIONSSPECIFICALLY FOR RAILWAY BRIDGESSPECIFICALLY FOR RAILWAY BRIDGES

ANNEX A (INFORMATIVE)ANNEX A (INFORMATIVE) MODELS OF SPECIAL VEHICLES FORMODELS OF SPECIAL VEHICLES FORROAD BRIDGESROAD BRIDGES

ANNEX B (INFORMATIVE)ANNEX B (INFORMATIVE) FATIGUE LIFE ASSESSMENT FORFATIGUE LIFE ASSESSMENT FORROAD BRIDGES ROAD BRIDGES –– ASSESSMENT METHODASSESSMENT METHODBASED ON RECORDED TRAFFICBASED ON RECORDED TRAFFIC



GENERAL ORGANISATION FOR ROAD BRIDGESGENERAL ORGANISATION FOR ROAD BRIDGES

TrafficTraffic loadload modelsmodels

-- Vertical forces : LM1, LM2, LM3, LM4Vertical forces : LM1, LM2, LM3, LM4-- Horizontal forces : Horizontal forces : brakingbraking andandaccelerationacceleration, , centrifugalcentrifugal, transverse, transverse

Groups of Groups of loadsloads

-- gr1a, gr1b, gr2, gr3, gr4, gr5gr1a, gr1b, gr2, gr3, gr4, gr5-- characteristiccharacteristic, , frequentfrequent andandquasiquasi--permanent valuespermanent values

CombinationCombination withwith actions actions otherother thanthantraffictraffic actions actions


EUROCODESBackground and Applications EN 1991EN 1991--2 2 «« Traffic LoadsTraffic Loads on Bridgeson Bridges »»

Field of application :Field of application : loadedloaded lengthslengths lessless thanthan 200 m (maximum 200 m (maximum lengthlength takentaken intointo accountaccount for for thethe calibrationcalibration of of thethe EurocodeEurocode ––For For veryvery long long loadedloaded lengthslengths, , seesee National National AnnexAnnex) )

LoadLoad Model Model NrNr. 1. 1ConcentratedConcentrated andand distributeddistributed loadsloads (main model (main model –– general andgeneral andlocal local verificationsverifications))

LoadLoad Model Model NrNr. 2. 2Single Single axleaxle load load (semi(semi--local local and and local local verificationsverifications))

LoadLoad Model Model NrNr. 3. 3Set of Set of specialspecial vehicles vehicles ((general and general and local local verificationsverifications))

LoadLoad Model Model NrNr. 4. 4CrowdCrowd loadingloading : 5 : 5 kNkN/m/m22 ((general verificationsgeneral verifications))

LOAD MODELS FOR LIMIT STATESLOAD MODELS FOR LIMIT STATESOTHER THAN FATIGUE LIMIT STATESOTHER THAN FATIGUE LIMIT STATES



Traffic Load

Models Characteristic values Frequent values Quasi-permanent values

Road bridges LM1

(4.3.2) 1000 year return period (or probability of exceedance of 5% in 50 years) for traffic on the main roads in Europe (α factors equal to 1, see 4.3.2).

1 week return period for traffic on the main roads in Europe (α factors equal to 1, see 4.3.2).

Calibration in accordance with definition given in EN 1990.

LM2 (4.3.3)

1000 year return period (or probability of exceedance of 5% in 50 years) for traffic on the main roads in Europe (β factor equal to 1, see 4.3.3).

1 week return period for traffic on the main roads in Europe (β factor equal to 1, see 4.3.3).

Not relevant

LM3 (4.3.4)

Set of nominal values. Basic values defined in annex A are derived from a synthesis based on various national regulations.

Not relevant Not relevant

LM4 (4.3.5)

Nominal value deemed to represent the effects of a crowd. Defined with reference to existing national standards.

Not relevant Not relevant



CarriagewayCarriageway widthwidth wwwidthwidth measured between kerbs (height more than 100 mm measured between kerbs (height more than 100 mm –– recommended recommended

value) or between the inner limits of vehicle restraint systemsvalue) or between the inner limits of vehicle restraint systems




Division of Division of thethe carriagewaycarriageway intointo notionalnotional laneslanes

1 1 –– LaneLane NrNr. 1 (3m). 1 (3m)

2 2 –– LaneLane NrNr. 2 (3m). 2 (3m)

3 3 –– LaneLane NrNr. 3 (3m). 3 (3m)

4 4 –– RemainingRemaining areaarea

Carriageway

width w Number of

notional lanes Width of a

notional lane lw Width of the

remaining area

mw 4,5< 1=ln 3 m mw 3−

mwm 64,5 <≤ 2=ln 2w 0

wm ≤6 ⎟⎠⎞

⎜⎝⎛=

3wIntnl 3 m lnw ×− 3

NOTE For example, for a carriageway width equal to 11m, 33

=⎟⎠⎞

⎜⎝⎛=

wIntnl , and the

width of the remaining area is 11 - 3×3 = 2m.



TheThe main main loadload model (LM1)model (LM1)

qq1k1k = 9 = 9 kNkN/m/m22

qq2k2k = 2,5 = 2,5 kNkN/m/m22

qq3k3k = 2,5 = 2,5 kNkN/m/m22

qqrkrk = 2,5 = 2,5 kNkN/m/m22

qqrkrk = 2,5 = 2,5 kNkN/m/m22



TheThe main main loadload model for road bridges (LM1) : model for road bridges (LM1) : diagrammaticdiagrammaticrepresentationrepresentation

For For thethe determinationdeterminationof of generalgeneral effectseffects, , thethetandems tandems traveltravelcentrally alongcentrally along thetheaxes of axes of notional lanesnotional lanes

For local For local verificationsverifications, a tandem , a tandem system system should beshould be applied at the applied at the most unfavourablemost unfavourable location.location.

WhereWhere twotwo tandems on tandems on adjacent adjacent notionalnotional laneslanesare are takentaken intointo accountaccount, , theythey maymay bebe broughtbroughtclosercloser, , thethe distance distance betweenbetween axlesaxles beingbeingnot not lessless thanthan 0,50 m 0,50 m



TheThe main main loadload model (LM1)model (LM1)


ExampleExample of values for of values for ααfactorsfactors (National Annexes) (National Annexes)

11stst class : international class : international heavy heavy vehicle trafficvehicle traffic

22ndnd class : class : «« normalnormal »» heavy heavy vehicle trafficvehicle traffic

Classes 1Qα 2≥iQiα 1qα 2≥iqiα qrα

1st class 1 1 1 1 1

2nd class 0,9 0,8 0,7 1 1



Examples of influence surfaces

(transverse bending moment)

for a deck slab



Example of application of LM1 to the concrete slab of

a composite bridge




LoadLoad model model NrNr. 2 (LM2). 2 (LM2)

1QQ αβ =RecommendedRecommended valuevalue :: (National (National AnnexAnnex))



Dispersal of Dispersal of concentratedconcentrated loadsloads

a) Pavement and concrete slaba) Pavement and concrete slab

1 Wheel contact pressure1 Wheel contact pressure

2 Pavement2 Pavement

3 Concrete slab3 Concrete slab

4 Middle surface of concrete 4 Middle surface of concrete slabslab

b) Pavement and orthotropic deck

1 Wheel contact pressure

2 Pavement

3 Bridge floor

4 Middle surface of the bridge floor

5 Transverse member




HORIZONTAL FORCES : HORIZONTAL FORCES : BrakingBraking andand accelerationacceleration ((LaneLane NrNr. 1 ). 1 )

LwqQQ kqkQk 11111 10,0)2(6,0 αα += kNQkN kQ 900180 1 ≤≤α

ααQ1Q1 = = ααq1q1 = 1= 1

QQlklk = 180 + 2,7L= 180 + 2,7L

For 0 For 0 ≤≤ L L ≤≤ 1,2 m1,2 m

QQlklk = 360 + 2,7L= 360 + 2,7L

For L > 1,2 mFor L > 1,2 m



HORIZONTAL FORCES : HORIZONTAL FORCES : CentrifugalCentrifugal forcesforces

r : horizontal radius of r : horizontal radius of curvaturecurvature of of thethe carriagewaycarriagewaycentrelinecentreline [m][m]

QQvv :: total maximum weight of vertical concentrated loads total maximum weight of vertical concentrated loads of the tandem systems of LM1of the tandem systems of LM1

∑i

ikQi Q )2(α

vtk QQ 2,0= (kN) if r < 200 m

rQQ vtk /40= (kN) if 200 ≤ r ≤ 1500 m

0=tkQ if r > 1500 m




Group of Group of loadsloads gr1a : gr1a : LM1 + LM1 + «« reducedreduced »» value value of of pedestrianpedestrian loadload on on footwaysfootways or cycle or cycle tracks tracks (3 (3 kNkN/m/m22))

Group of Group of loadsloads gr1b : LM2 gr1b : LM2 (single (single axleaxle loadload))

Group of Group of loadsloads gr2 : gr2 : characteristiccharacteristic values of values of horizontal forces, horizontal forces, frequentfrequentvalues of LM1values of LM1


Groups of Groups of loadsloads



Group of Group of loadsloads gr4 : gr4 : crowdcrowd loadingloading

Group of Group of loadsloads gr5 : gr5 : specialspecialvehiclesvehicles (+ (+ specialspecialconditions for normal conditions for normal traffictraffic))

Group of Group of loadsloads gr3 : gr3 : loadsloads on on footwaysfootways andandcycle cycle trackstracks




Table 4.4b Table 4.4b –– Assessment of groups of traffic loads (frequent Assessment of groups of traffic loads (frequent values of the multivalues of the multi--component action)component action)

CARRIAGEWAY FOOTWAYS AND CYCLE TRACKS

Load type Vertical forces Reference EN

1991-2 4.3.2 4.3.3 5.3.2(1)

Load system LM1 (TS and UDL systems)

LM2 (single axle) Uniformly distributed load

gr1a Frequent values gr1b Frequent values Groups

of loads gr3 Frequent value a)

a) See 5.3.2.1(3). One footway only should be considered to be loaded if the effect is more unfavourable than the effect of two loaded footways.



LoadLoad Model Model NrNr. 1 (FLM1) : . 1 (FLM1) : SimilarSimilar to to characteristiccharacteristic LoadLoad Model Model NrNr. 1. 10,7 x 0,7 x QQikik -- 0,3 x 0,3 x qqikik -- 0,3 x 0,3 x qqrkrk

LoadLoad Model Model NrNr. 2 (FLM2) : Set of . 2 (FLM2) : Set of «« fequentfequent »» lorrieslorries

LoadLoad Model Model NrNr. 3 (FLM3) : Single . 3 (FLM3) : Single vehiclevehicle

LoadLoad Model Model NrNr. 4 (FLM4) : Set of . 4 (FLM4) : Set of «« equivalentequivalent »» lorrieslorries

LoadLoad Model Model NrNr. 5 (FLM5) : . 5 (FLM5) : RecordedRecorded traffictraffic


FATIGUE LOAD MODELSFATIGUE LOAD MODELS



Table 4.5 Table 4.5 -- Indicative number of heavy vehicles expected per Indicative number of heavy vehicles expected per year and per slow laneyear and per slow lane

(FLM3 (FLM3 andand FLM4 Models)FLM4 Models)

Traffic categories Nobs per year and per slow lane 1 Roads and motorways with 2 or more

lanes per direction with high flow rates of lorries

2,0 × 106

2 Roads and motorways with medium flow rates of lorries

0,5 × 106

3 Main roads with low flow rates of lorries

0,125 × 106

4 Local roads with low flow rates of lorries

0,05 × 106



1 2 3 4 LORRY

SILHOUETTE Axle spacing

(m) Frequent axle loads

(kN)

Wheel type (see Table

4.8)

4,5 90 190

A B

4,20 1,30

80 140 140

A B B

3,20 5,20 1,30 1,30

90 180 120 120 120

A B C C C

3,40 6,00 1,80

90 190 140 140

A B B B

4,80 3,60 4,40 1,30

90 180 120 110 110

A B C C C

FLM2FLM2

Set of Set of «« frequentfrequent »»

lorrieslorries




A X L E /W H E E L T Y PE S G E O M ET R IC A L D E FIN IT IO N

A

B

C

FLM2 : FLM2 : DefinitionDefinition of of wheelswheels andand axlesaxles (Table 4.8)(Table 4.8)



Fatigue Fatigue LoadLoad Model Model NrNr.3 (FLM3).3 (FLM3)

A second A second vehiclevehicle maymay bebe takentaken intointo accountaccount : : RecommendedRecommended axleaxle loadload value Q = 36 value Q = 36 kNkNMinimum distance Minimum distance betweenbetween vehiclesvehicles : 40 m: 40 m




DeterminationDetermination of of thethe maximum maximum andand minimum stresses minimum stresses resultingresulting fromfrom thethe transit of transit of thethe model model alongalong thethe bridgebridge

TheThe stress variation stress variation isis multipliedmultiplied by a local by a local dynamicdynamicamplification amplification factorfactor in in thethe vicinityvicinity of expansion jointsof expansion joints

TheThe model model isis normallynormally centeredcentered in in everyevery slow slow lanelane defineddefined in in thethe projectproject specificationspecification. But . But wherewhere thethe transverse position transverse position isis important, a important, a statisticalstatistical distribution of distribution of thisthis position position shouldshould bebe takentaken intointo accountaccount..

FinallyFinally ::

LMLMLM MinMax σσσ −=Δ

fatϕΔ

VerificationVerification procedureprocedure withwith LoadLoad Model FLM 3Model FLM 3

LMfatfat σϕλσ ΔΔ=Δ



FrequencyFrequency distribution of transverse location of a distribution of transverse location of a vehiclevehicle (Models 3 to 5)(Models 3 to 5)




Fatigue Fatigue LoadLoad Models for road bridgesModels for road bridgesRepresentationRepresentation of of thethe additionaladditional amplification amplification factor factor

Δϕfat : Additional amplification factor

D : Distance of the cross-section under consideration from

the expansion joint



Principle of the fatigue verification with FLM 3Principle of the fatigue verification with FLM 3




VEHICLE TYPE TRAFFIC TYPE

1 2 3 4 5 6 7

Long distance

Medium distance

Local traffic

LORRY

Axle spacing (m)

Equivalent axle loads

(kN)

Lorry persentage

Lorry percentage

Lorry percentage

Wheel type

4,5 70 130

20,0 40,0 80,0 A B

4,20 1,30

70 120 120

5,0 10,0 5,0 A B B

3,20 5,20 1,30 1,30

70 150 90 90 90

50,0 30,0 5,0 A B C C C

3,40 6,00 1,80

70 140 90 90

15,0 15,0 5,0 A B B B

4,80 3,60 4,40 1,30

70 130 90 80 80

10,0 5,0 5,0 A B C C C

FLM4FLM4

Set ofSet of«« equivalentequivalent»»

lorries.lorries.







ACTIONS FROM VEHICLES ON THE BRIDGEACTIONS FROM VEHICLES ON THE BRIDGE

–– VehiclesVehicles on on footwaysfootways andand cycle cycle trackstracks

–– Impact forces on Impact forces on kerbskerbs

–– Impact forces on Impact forces on safetysafety barriersbarriers






LOAD MODELS FOR FOOTWAYS AND FOOTBRIDGES (Section 5)LOAD MODELS FOR FOOTWAYS AND FOOTBRIDGES (Section 5)

LOAD MODEL LOAD MODEL NrNr.3.3Service Service vehiclevehicle QQserv serv

LOAD MODEL LOAD MODEL NrNr.1.1

Uniformly distributed load qUniformly distributed load qfkfk

LOAD MODEL LOAD MODEL NrNr.2.2Concentrated load QConcentrated load Qfwkfwk

(10 (10 kN recommendedkN recommended))




Recommended characteristic value for :Recommended characteristic value for :-- footways and cycle tracks on road bridges,footways and cycle tracks on road bridges,-- short or medium span length footbridges :short or medium span length footbridges :

Recommended expression for long span length footbridges : Recommended expression for long span length footbridges :

LL is the loaded length [m]is the loaded length [m]

2fk kN/m

301200,2+

+=L

q

2fk kN/m5,2≥q

2fk kN/m0,5=q

2fk kN/m0,5≤q



For footbridges only, a horizontal force should be taken into For footbridges only, a horizontal force should be taken into account, to be applied along the deck axis at the surfacing leveaccount, to be applied along the deck axis at the surfacing level l QQflkflk..Its characteristic value, which may be altered in the National Its characteristic value, which may be altered in the National Annex, is equal to the higher of the two following values :Annex, is equal to the higher of the two following values :•• 10% of the total uniformly distributed load as defined in 5.3.210% of the total uniformly distributed load as defined in 5.3.2.1,.1,

•• 60% of the total service vehicle load where relevant (5.3.2.360% of the total service vehicle load where relevant (5.3.2.3--(1)P).(1)P).

The horizontal force is applied simultaneously with the verticalThe horizontal force is applied simultaneously with the verticalload, but not with the concentrated load.load, but not with the concentrated load.




Groups of Groups of loadsloads for for footbridgesfootbridges

Group of Group of loadsloads gr1gr1

Group of Group of loadsloads gr2gr2



ThankThank youyou for for youryourattentionattention


1


EUROCODESBackground and Applications RAILWAY ACTIONS M.T.

RAILWAY ACTIONS. SELECTED CHAPTERS FROM EN 1991-2 AND ANNEX A2 OF EN 1990

Dr. h. c. Marcel TschumiDr. h. c. Marcel Tschumi


EUROCODESBackground and Applications EN 1991EN 1991--2 2 –– CONTENTSCONTENTS

Actions on structures Actions on structures –– TrafficTraffic loadsloads on bridgeson bridges

ForewordForewordSection 1Section 1 GeneralGeneralSection 2Section 2 Classification Classification ofof actionsactionsSection 3Section 3 Design situationsDesign situationsSection 4Section 4 RoadRoad traffictraffic actions actions andand otherother

actions actions specificallyspecifically for for roadroadbridgesbridges

Section 5Section 5 Actions on Actions on footwaysfootways, cycle , cycle trackstracks andand footbridgesfootbridges

Section 6Section 6 Rail Rail traffictraffic actions actions andand otherotheractions actions specificallyspecifically for for railwayrailwaybridgesbridges


EUROCODESBackground and Applications EN 1991EN 1991--2 2 –– CONTENTS (CONTENTS (continuedcontinued))

Actions on structures Actions on structures –– TrafficTraffic loadsloads on bridgeson bridges

AnnexAnnex A (I)A (I) ModelsModels ofof specialspecial vehiclesvehicles for for roadroad bridgesbridgesAnnexAnnex B (I)B (I) Fatigue Fatigue lifelife assessmentassessment for for roadroad bridges. bridges.

AssessmentAssessment methodmethod basedbased on on recordedrecordedtraffictraffic

AnnexAnnex C (N)C (N) DynamicDynamic factorsfactors 1+1+ϕϕ for for realreal trainstrainsAnnexAnnex D (N)D (N) Basis for Basis for thethe fatigue fatigue assessmentassessment ofof railwayrailway

structuresstructuresAnnexAnnex E (I)E (I) LimitsLimits ofof validityvalidity ofof loadload modelmodel HSLM HSLM andand thethe

selectionselection ofof thethe criticalcritical universaluniversal train train fromfromHSLMHSLM--AA

AnnexAnnex F (I)F (I) CriteriaCriteria to to bebe satisfiedsatisfied if a if a dynamicdynamic analysisanalysis isisnotnot requiredrequired

AnnexAnnex G (I)G (I) MethodMethod for for determiningdetermining thethe combinedcombinedresponseresponse ofof a structure a structure andand tracktrack to variable to variable actionsactions

AnnexAnnex H (I)H (I) LoadLoad modelsmodels for rail for rail traffictraffic loadsloads in in transienttransientsituationssituations


EUROCODESBackground and Applications EN 1990 EN 1990 -- AnnexAnnex A2 A2 -- CONTENT

Basis Basis ofof structural design structural design –– Application for bridgesApplication for bridges

Section A2.1 Field of applicationSection A2.2 Combinations of actions

A2.2.1 GeneralA2.2.2…for road bridgesA2.2.3…for footbridgesA2.2.4…for railway bridgesA2.2.5

Section A2.3 Ultimate limit statesSection A2.4 Serviceability limit states

A2.4.1GeneralA2.4.2…serviceability criteria for road bridgesA2.4.3…serviceability criteria for footbridgesA2.4.4 serviceability criteria for railway bridges


EUROCODESBackground and Applications Notations Notations andand dimensions dimensions specificallyspecifically for for railwaysrailways

S : gaugeU : cantQs: noising force

(1) Running surface(2) Longitudinal forces acting along the centreline of the

track


EUROCODESBackground and Applications LoadLoad Model 71Model 71

The characteristic values given in this figure shall be multipliThe characteristic values given in this figure shall be multiplied by a factor ed by a factor αα on lines carrying rail traffic which is heavier or lighter thanon lines carrying rail traffic which is heavier or lighter than normal rail normal rail traffic. traffic. WhenWhen multipliedmultiplied byby thethe factorfactor αα, , thethe loadsloads areare calledcalled ""classifiedclassifiedverticalvertical loadsloads". ". ThisThis factorfactor αα shallshall bebe oneone of of thethe followingfollowing: 0,75 : 0,75 -- 0,83 0,83 -- 0,91 0,91 --1,00 1,00 -- 1,10 1,10 -- 1,21 1,21 -- 1,33 1,33 –– 1,46.1,46.TheThe valuevalue 1,33 1,33 isis normallynormally recommendedrecommended on on lineslines for for freightfreight traffictraffic andandinternational international lineslines (UIC CODE 702, 2003).(UIC CODE 702, 2003).The actions listed below shall be multiplied by the same factor The actions listed below shall be multiplied by the same factor αα ::centrifugal forcescentrifugal forcesnosing forcenosing forcetraction and braking forces traction and braking forces load model SW/0 for continuous span bridgesload model SW/0 for continuous span bridges

2



Relation between LM 71 and the6 „real service trains“ in UIC Code 776-1

(1+ϕ) S real trains 1 - 6 ≤ Φ S LM71

2 of 6 examples

of real servicetrains


EUROCODESBackground and Applications LM SW/0 et LM SW/2 (LM SW/0 et LM SW/2 (heavyheavy traffictraffic))

Load model qvk [kN/m]

a [m]

c [m]

SW/0 SW/2

133 150

15,0 25,0

5,3 7,0


EUROCODESBackground and Applications Example of a heavy weight waggon

Wagon DB with 32 axles, selfweight 246 t, cantilevers included, pay load 457 t, mass per axle 22 t , ltot = 63,3 m


EUROCODESBackground and Applications Equivalent vertical loading for earthworks

α x LM71 (and SW/2 where required), without dynamic factor, uniformlydistributed over a width of 3,00 m at a level 0,70 m below the running surface of the rail.


EUROCODESBackground and Applications Principal factors influencing dynamic behaviour

• the speed of traffic across the bridge,• the span L of the element,• the mass of the structure,• the natural frequencies of the whole structure

and relevant elements of the structure, • the number of axles, axle loads and the spacing

of axles,• the damping of the structure,• vertical irregularities in the track,• the unsprung/sprung mass and suspension

characteristics of the vehicle,• the presence of regularly spaced supports of the

deck slab (cross girders),• vehicle imperfections (wheel flats, out of round

wheels, etc.),• the dynamic characteristics of the track (ballast,

sleepers, track components etc.).



Dynamic factors according to the quality of trackmaintenance

Dynamic factors (6.4.5.2) for static calculations:Φ2 for carefully maintained trackΦ3 for standard track (means:poor track)

TheThe dynamicdynamic factorfactor ΦΦ, , whichwhich enhancesenhances thethe staticstaticloadload effectseffects underunder LoadLoad ModelsModels LM 71, LM SW/0 LM 71, LM SW/0 andandLM SW/2, LM SW/2, isis takentaken as as eithereither ΦΦ2 or 2 or ΦΦ3, 3, accordingaccording to to thethe qualityquality ofof tracktrack maintenance . maintenance . TheThe dynamicdynamicfactorsfactors ΦΦ2 et 2 et ΦΦ3 are 3 are calculatedcalculated on on thethe basis basis ofofformulaeformulae basedbased on a value on a value calledcalled determinantdeterminantlengthlength LLΦΦ givengiven in Table 6.2 in Table 6.2 ofof thethe EurocodeEurocode. If . If nonodynamicdynamic factorfactor isis specifiedspecified ΦΦ3 3 shallshall bebe usedused..

3



The four existing different dynamic factors and enhancementswritten for carefully maintained track

1 /max ' −= statdyndyn yyϕ

•Dynamic enhancement for real trains1 + ϕ = 1 + ϕ' + (½) ϕ''

•Dynamic enhancement for fatigue calculationsϕ = 1 + ½(ϕ' + (½)ϕ'')

•Dynamic factor Φ2(Φ3) for static calculations(determinant lengths LΦ due to table 6.2)

•Dynamic enhancement for dynamic studies


EUROCODESBackground and Applications Vision of future European Network

The freedom for the choice of the factor α could provoke a non homogeneous railway network in Europe! Therefore in UIC Leaflet702 (2003) α = 1,33 is generally recommended for all new bridges constructed for the international freight network, unfortunately notobligatory!

α=1,33

Year 2100Year 2002


EUROCODESBackground and Applications Choice of the factor α

ULS:

For new bridges it should absolutely beadopted

α = 1,33.

Fatigue:All calculations are done with the Load Model 71 and the factor

α = 1,00.



Existing bridges

The question of updated rail traffic actions iscurrently studied within the European ResearchProject « Sustainable Bridges - Assessment for Future Traffic Demands and longer Lives».

See: www.sustainablebridges.net



Serviceability Limit States (SLS)Interaction track – bridge:

Theoretically this is a Seviceability Limit State (SLS) for the bridge and an Ultimate Limit State (ULS ) for the rail. But as the given permissible rail stresses and deformations were obtained by deterministic design methods, calibrated on theexisting practice, the calculations for interaction have to be done – in contradiction to EN1991-2, where there is a mistake - always with

α = 1,00!!



Serviceability Limit States (SLS)Permissible vertical deflections:

To check the permissible vertical deflection with a severeformula given later for speeds less than 200 km/h, to minimise track maintenance and to avoid dynamicstudies (note: more stiffness costs nothing when doingcalculations with LCC),

α = 1,00

shall be adopted, even if α = 1,33 is taken intoconsideration for ULS.

4


EUROCODESBackground and Applications Classification of international lines

E58,8 t/m5

E4D4C48 t/m4

D3C37,2 t/m3

D2C2B26,4 t/m2

B1A5 t/m1

25t22,5t20t18t16tMass per m = p

EDCBA

Mass per axleDue to UIC CODE 700



Heavier loads do not significantly influence the costs of bridges!

Increase of costs in % due to α = 1,33, related to those calculatedwith α = 1,0 / bridges built with traffic interference(ERRI D 192/RP 4, 1996):

2.19

0

0.5

1

1.5

2

2.5

3

3.5

4

Wor

blau

fen

Muo

ta

Men

gbac

h

Nes

s

Buc

hloe

Kem

pten



Heavier loads do not significantly influence the costs of bridges!

Increase of costs in % due to α = 1,33, related to thosecalculated with α = 1,0 / bridges built without trafficinterference,(ERRI D 192/RP 4, 1996):

3.91

0

1

2

3

4

5

6

La S

orm

onne

Sal

laum

ines

Mol

leba

kken

Kam

bobe

kken

RN

2/TG

VN

ord

Ver

berie

Sca

rpe

Hol

enda

len

Vla

ke


EUROCODESBackground and Applications Interaction Interaction tracktrack -- bridgebridge

Relative displacements of the track and of the bridge, caused byRelative displacements of the track and of the bridge, caused bythe combination of the effects of the combination of the effects of thermal variations,thermal variations, train braking train braking and traction forces, as well asand traction forces, as well as deflection of the deck under vertical deflection of the deck under vertical traffic loads (LM 71)traffic loads (LM 71), lead to the track/bridge phenomenon that , lead to the track/bridge phenomenon that results in additional stresses to the bridge and the track.results in additional stresses to the bridge and the track.Take LM 71 with Take LM 71 with αα = = 1.00 (1.00 (eveneven ifif αα > > 1.00 for ULS1.00 for ULS)!)!



Limitation of additional permissible stresses in the rail

Practice with rail UIC 60, steel grade giving at least 900 N/mm2 strength, minimum curve radius r ≥ 1500 m, laid on ballasted track with concrete sleepers and consolidated,> 30 cm deep ballast, the permissible additional stresses in continuous welded rail on the bridge due to interaction is:

compression: 72 N/mm2traction: 92 N/mm2


EUROCODESBackground and Applications Examples of expansion lengths

5


EUROCODESBackground and Applications Avoid where ever possible expansion lengths near the bridge!

Remark:The decks corresponding to L1 or to L2may have additional supports.

L1max. or L2 max. without expansion joints: • 90 m (concrete, composite) • 60 m (steel), but: L1 + L2 = 180 m/ 120 m with fixed bearing in the

middle !!!!!!


EUROCODESBackground and Applications Fatigue: choice for α and λ

For new bridgeseven if taking α = 1,33 for ULS design –note: a slightly overdesigned bridge for ULS has less fatigue problems if the loadings do notincrease!) - fatigue assessments are donewith the load model LM 71 and α = 1,00. In supplement, the calculation of the damageequivalent factors for fatigue λ should be done withthe heavy traffic mix, that means waggons with 25t(250kN) axles, in accordance with Annex D ofEN 1991-2


EUROCODESBackground and Applications Safety verification for steel structures

Mf

c712Ff γ

σσλγ

∆≤∆Φ

is the partial safety factor for fatigue loadingγFf

is the partial safety factor for fatigue strength in the design codes

γMf

is the reference value of the fatigue strength (see EN 1993)∆σC

is the stress range due to the Load Model 71 (and where requiredSW/0) but with α = 1, the loads being placed in the most unfavourable position for the element under consideration.

∆σ71

is the dynamic factor (see 6.4.5 of EN 1991-2)Φ2

is the damage equivalence factor for fatigue which takes accountof the service traffic on the bridge and the span of the member.Values of λ are given in the design codes.

λ


EUROCODESBackground and Applications (Real) train types for fatigue

ExampleExample ofof a train (a train (nono 1 1 ofof 12 12 givengiven types types ofof trains):trains):


EUROCODESBackground and Applications Damage equivalent factors for fatigue

λ is the damage equivalence factor for fatigue which takes account of the span, the service traffic, the annual traffic volume, the intended design life of the structural element and the number of tracks.

λ = λ1 λ2 λ3 λ4

where:λ1 is a factor accounting for the structural member type (e.g.

a continuous beam) and takes into account the damaging effect of the chosen service traffic (e.g. heavy traffic mix), depending on the length of the influence line or area.

λ2 is a factor that takes into account the annual traffic volume.

λ3 is a factor that takes into account the intended design life of the structural member.

λ4 is a factor which denotes the effect of loading from more than one track.

Values of λ are given in the design codes.



General remarks concerning the fatigue of railwaybridges

General:It cannot be stressed often enough that railway bridges must bedesigned and constructed in a fatigue-resistant way. For havingoptimal Life Cycle Costs (LCC) and for reaching the intendeddesign life of minimum 100 years, all important structural members shall be designed for fatigue!

Rules for steel bridges:Constructional details have to be chosen and found which givethe maximum possible fatigue detail categories ∆σc, e.g.:

Composite girders: detail category 71Welded plate girders: detail category 71Truss bridges: detail category 71 at sites

where fatigue is a risk /detail category 36 at sites where fatigue is no risk.

6




Rules for reinforced bridges:

• For reinforced railway bridges the fatigue strength categories ∆σs must of course beobserved.

• Welded joints of reinforcing bars should beavoided in principle in regions with highstress variation.

• The bending radii of reinforcing bars must be big enough to avoid too much loss offatigue strength.




Rules for presteressed bridges:

• Fully prestressed bridges under service loads have no fatigue problems. For not fully prestressedbridges under servic loads the permissible stress ∆σs must be observed as well for the prestressingsteel as for the reinforcing bars.

• Plastic ducts can increase fatigue resistance ofprestressing steel and electrically isolated tendons permit to assure the quality with long termmonitoring.

• Anchorages and couplers for prestressing tendons have to be placed such that they are in a region oflow stress variation.


EUROCODESBackground and Applications Practical note for bridge competitions

Personal advice:

Bridge competitions should be carried out in twophases. The first phase should be anonymous withonly few calculations and plans called for. Thesecond phase should however not be anonymous. In this phase it is essential, from the owner’s point of view, that recommendations for the importent aspects of the design are provided. These includeavoiding, where ever possible, expansion joints in the rails near the bridge and, very important, excluding poor constructional details which willlead to fatigue problems.


EUROCODESBackground and Applications Permissible deflections

In EN 1990, Annex A2 [2] only minimum conditions for bridge deformationsare given. The rule does not take into account track maintenance. A simplifiedrule for permissible deflections is given below for trains and speeds up to200km/h, to avoid the need for excessive track maintenance. In addition, thissimplified rule has the advantage, that no dynamic analysis is necessary forspeeds less than 200km/h. For all classified lines with α >1,0, that means also if α = 1.33 is adopted for ULS, the following permissible values for deflections arerecommended, always calculated under LM71 “+” SW/O, multiplied by Φ, and with α = 1.0:

V<80 km/h δstat ≤ l / 800*

*Note: Due to what is said in see A.2.4.4.2.3 [2], namely that the maximumtotal deflection measured along any track due to rail traffic actions should not exceed L/600, please note that 600 multiplied with 1,33 gives approximately 800.

80 ≤ V ≤ 200 km/h δstat ≤ l / (15V – 400)**

** Note: The upper limit l/2600 for 200 km/h is the permissible deflection which DB has taken during many years for designing bridges for high speed lines in Germany, with satisfactory results. It is also the formula which you can find in the Swiss Codes (SIA 260).

V > 200 km/h The value determined by the dynamicstudy, but min. δstat ≤ l / 2600


EUROCODESBackground and Applications Flow chart Figure 6.9 of EN 1991-2

For the dynamic analysis use the eigenforms for torsion and for

bending

no

Dynamic analysis required Calculate bridge deck

acceleration and ϕ´dyn etc. in accordance with 6.4.6 (note 4)

v/n0 ≤ (v/n0)lim (2) (3) (7)

START

V ≤ 200 km/h

L ≥ 40 m

nT > 1,2 n0

Use Tables F1 and F2 (2)

n0 within limits of

Figure 6.10 (6)

no

no no

yes

yes

yes

yes no

Dynamic analysis not required.

At resonance acceleration check and fatigue check not

required. Use Φ with static analysis in

accordance

Eigenforms for bending sufficient

Simple structure (1)

no

yes

yes

yes

Continuous bridge (5)

no

(9) X

Flow chart for determiningwhether a

dynamic analysisis required.

(9) If the permissible deformations given just before are respected -taking into account track maintenance -no dynamic study is necessary for speeds ≤ 200 km/h.

.


EUROCODESBackground and Applications Figure A2.3 of EN 1990, Annex2

You can forget the following conditions with the recommended permissible deflections given above:

7


EUROCODESBackground and Applications Risk scenario to avoid:

Collapse of railwaybridge over the river Birs in Münchenstein, Switzerland, the 14th

June 1891, by bucklingof the upper flangeunder an overloadedtrain, 73 persons werekilled, 131 personsmore or less injured.=> Tetmajers law.

EUROCODES - IS-Argebau · 2008-02-29 · 2 EN 1991-1-1: Densities, self-weight, imposed loads for...

Documents

Transcript of EUROCODES - IS-Argebau · 2008-02-29 · 2 EN 1991-1-1: Densities, self-weight, imposed loads for...