GENERAL REQUIREMENTS FOR FASTENINGS - SWEBOLT · 2012. 2. 27. · that concrete elements subjected...

GENERAL REQUIREMENTS FOR FASTENINGSSORMAT Technical manual 07/2008

1 GENERALREQUIREMENTSFORFASTENINGS1.1BASEMATERIAL

1.2USAGETARGET

1.3LOADSANDRESISTANCES

1.4INSTALLATION

1.5FASTENINGSYSTEMSAND

MODEOFACTIONS

1.6OTHERASPECTS

2 PRODUCTBASEDINFORMATION2.1METALANCHORS

2.2CHEMICALANCHORS

2.3PLASTICANCHORS

3 TRUSTFIX3.1TRUSTFIXGENERALINFORMATION

3.2TRUSTFIXTRAININGGUIDE

4 TECHNICALLITERATURE4.1ETAG001

ANNEXC

SORMAT Technical manual 07/2008

TAble 1.1 SELECTIONOFTHEANCHOR

before you choose an anchoring

method and type of anchor you

have to find out first the properties

of the base material and installa-

tion and service conditions. Table 1

shows the most important aspects

affecting the anchor selection. The

base material has to be studied

carefully, e.g. material, quality and

shape. The usage target determin-

est e.g. the type of construction,

reinforcements, location and ser-

vice temperature. loads have to be

studied carefully. Also the installa-

tion method restricts the mode of

selection.

Of course there are lots of other

aspects which have to be consid-

ered before the selection and the

most important of these are safety,

service life, fire resistance, econo-

my and availability.

SELECTIONOFTHEANCHOR

BASEMATERIAL

CONSTRUCTIONMATERIAL• concrete (compress

or tensile zone)• masonry work• light constructionSHAPEOFTHECONSTRUCTION

CONSTRUCTION• bearing• non- bearingLOCATION• indoor (dry, humid, aggressive)• outdoorTEMPERATURE

VALUECharacter• regular• variableDIRECTION• direct• shear and

inclined pull

SafetyService lifeFire resistanteconomyAvailability

USAGETARGET LOADS INSTALLATIONMETHOD

OTHERASPECTS

1GENERALREQUIREMENTSFORFASTENINGS

THROUGHINSTALLATION

DISTANCEINSTALLATION

PREINSTALLATION


1.1BASEMATERIAL

1.1.1CONCRETE

1.1.1.1MaterialDescription

Concrete is a composite building

material made from a combination

of aggregate and cement binder.

The most common form of con-

crete consists of Portland cement,

mineral aggregates (generally

gravel and sand), and water. Con-

crete is used more than any other

man-made material on the planet.

1.1.1.2 History

The Assyrians and babylonians

used clay as cement in their con-

cretes. The egyptians used lime

and gypsum cement. In the Ro-

man empire, concrete made from

Quicklime, pozzolanic ash / pozzo-

lana and an aggregate made from

pumice was very similar to modern

Portland cement concrete. In 1756,

the british engineer John Smeaton

pioneered the use of Portland ce-

ment in concrete, using pebbles

and powdered brick as aggregate.

In the modern day, the use of re-

cycled materials, such as concrete

ingredients, is gaining popularity

because of increasingly strin-

gent environmental legislation.

The most conspicuous of these is

pulverized fuel ash, recycled from

the fly ash by-products of coal

power plants. This has a significant

impact on reducing the amount of

quarrying and the landfill space

required.

1.1.1.3 Composition

The composition of concrete is

determined initially during mixing

and finally during the placing of

fresh concrete.

1.1.1.3.1 Cement

Portland cement is the most com-

mon type of cement in general

usage, as it is a basic ingredient of

concrete, mortar and plaster. An

english engineer named Joseph

Aspdin patented Portland cement

in 1824, which was named after

the limestone cliffs on the Isle of

Portland in england because of the

similarity of its colour to the stone

quarried from Portland. It consists

of a mixture of oxides of calcium,

silicon and aluminium. Portland

cement and similar materials

are made by heating limestone

(a source of calcium) with clay

and grinding this product (called

clinker) with a source of sulphate

(most commonly gypsum). The

resulting powder, when mixed

with water, will become a hydrated

solid over time.

1.1.1.3.2 Water

Water suitable for human or

animal consumption can be used

in manufacturing concrete. The

ratio of water-to-cement is the key

factor determing the strength of

concrete. It is also a key factor in

the viscosity of wet concrete, which

directly affects its workability

during placement. A lower water-

to-cement ratio will yield a con-

crete which is stronger, but more

difficult to work. A higher water-

to-cement ratio yields a type of

concrete which is easier to work,

but it will have a lower strength.

1.1.1.3.3 Aggregates

The water and cement paste

hardens and develops strength

over time. In order to ensure an

economical and practical solution,

both fine and coarse aggregates are

utilised to make up the bulk of the

concrete mixture (Picture 1.1). Sand

and crushed stone are mainly used

for this purpose. Decorative stones,

such as quartzite or small river

stones, are sometimes added to the

surface for a decorative “exposed

aggregate” finish, popular among

landscape designers. Recycled

crushed glass can also be added

in the production of concrete for

an aesthetic effect (such as in the

construction of walkways).

1.1.1.3.4 Admixtures

Admixtures are organic or non-

organic materials in the form of

solids or fluids that are added

to the concrete to give it certain

PICTURE1.1Coarseandfineaggregates

1.1 bASe MATeRIAl

BACKTOMAINMENU


characteristics, following the lead

of the ancient Romans. In normal

use, the admixtures make up less

than 5 % of the cement weight,

which are added to the concrete at

the time of batching/mixing. The

most common types of admixtures

are:

• Accelerators speed up the

hydration (“hardening”) of the

concrete.

• Retarders slow the hydration of

concrete.

• Air-entrainers add and distribute

tiny air bubbles in the concrete,

which will reduce damage during

freeze-thaw cycles.

Plasticizers can be used to •

increase the “workability” of con-

crete, allowing it be placed more

easily, with less compactive effort.

• Superplasticisers allow a prop-

erly designed concrete to flow

in place even around congested

reinforcing bars. Alternatively,

they can be used to reduce the

water content of concrete (water

reducers) while maintaining

workability. This improves its

strength and durability

• Pigments change the colour of

concrete for aesthetic purposes

1.1.1.3.5Additions

Additions are very fine inorganic

materials that usually have poz-

zolanic or latent-hydraulic prop-

erties, which are added to the

concrete mixer to improve the

properties of concrete. The term

is not used when the materials are

added at the factory as constitu-

ents of blended cements.

• Fly ash: A by-product of coal-

fired electric generating plants

fly ash is used to partially replace

Portland cement by up to 40 %

in weight. experiments have

determined that the use of ash up

to 95 % can produce a structur-

ally sound concrete; however it

is only useful under limited load

pressures.

• Ground granulated blast fur-

nace slag: A by-product of steel

making, it is used to partially

replace Portland cement (by up

to 80% by weight). larger slag is

sometimes used as an aggregate

as well.

• Silica fume: A by-product of the

production of silicon and fer-

rosilicon alloys. Silica fume is

a very reactive pozzolan that is

used to increase strength and

durability of concrete.

1.1.1.4 Characteristics

During hydration and hardening,

concrete needs to develop certain

physical and chemical proper-

ties. Among others, mechanical

strength, low permeability to mois-

ture, and chemical and volumetric

stability are all necessary. Table

1.2 shows the average densities for

different concrete types.

1.1.1.4.1Strength

Concrete has relatively high com-

pressive strength, but significantly

lower tensile strength (varies 7–13 %,

average 10 % of the compressive

strength). As a result, concrete

always fails from tensile stress -

even when loaded in compression.

The practical implication of this is

that concrete elements subjected to

tensile stress must be reinforced.

Concrete is most often constructed

with the addition of steel or fibre re-

inforcement. The reinforcement can

be by bars (rebar), mesh, or fibres,

producing reinforced concrete.

Concrete can also be pre-stressed

(reducing tensile stress) using steel

cables, allowing for beams or slabs

with a longer span than is practi-

cal with reinforced concrete alone.

The ultimate strength of concrete

is primarily influenced by the

water-cement ratio w/c or water-

cementatious materials ratio (w/

cm) and the mixing and placement

methods employed. Concrete with

a lower water-cement ratio makes

a stronger type of concrete than a

higher ratio. The total quantity of

cementatious materials can affect

strength, such as shrinkage cracks,

which develop in the cement paste

while curing, can weaken the final

product. In high-strength concrete,

the strength of the aggregate can be

a limiting factor. In concrete with

a high water/cement ratio, the

shape of the aggregate may affect

the strength: if a weak cement-

aggregate bond zone develops,

cracks will develop much more

easily along smooth aggregate

TYPEWEIGHTKG/m³

Plain concrete, with natural stone aggregate 2 300

Plain concrete, with natural broken brick aggregate 2 000

Reinforced concrete, with dense aggregate 2 400

lightweight aerated concrete 400 - 650

lightweight aggregate structural grade concrete 1 800

Steelshot aggregate concrete 5 300

TAble 1.2 CONCRETEDENSITIES

1.1 bASe MATeRIAl


than along rough aggregate.

experimentation with various

mix designs is generally done by

specifying desired “workability”

as defined by a given slump and

a required 28-day compressive

strength. The characteristics of

the coarse and fine aggregates

determine the water demand of

the mix in order to achieve the

desired workability. The 28-day

compressive strength is obtained

by determing the correct amount

of cement to achieve the required

water-to-cement ratio. Only with a

very high-strength concrete does

the strength and shape of the

coarse aggregate become critical

in determining ultimate compres-

sive strength.

The internal forces in certain

structures, such as arches and

vaults, are predominantly com-

pressive forces, and, therefore,

concrete is the preferred construc-

tion material for such structures.

It is possible to reduce material

usage with high-strength con-

crete (60 - 100 MPa). As a result of

developing high-strength concrete

it was estimated that, for exam-

ple, doubling the strength of the

column will reduce relative costs

approximately 25 %. Also from the

environmental point of view, the

use of high-strength concrete is

beneficial.

The utilization of ultra-strength

concrete (150-250 MPa) is becom-

ing more and more popular in

special structures. Different fibres

are used e.g. steel, glass, carbon

or plastic, to improve the tensile

strength of the structure.

1.1.1.4.2 Consistence

Consistence is the ability of a fresh

(plastic) concrete mix to fill the

form /mould properly with the

desired work (vibration) without re-

ducing the quality of the concrete.

Consistence depends on water

content, chemical admixtures,

aggregate (shape and size distribu-

tion), cementatious content and

age (level of hydration). Raising the

water content or adding chemical

admixtures will increase concrete

workability. excessive water will

lead to increased bleeding (sur-

face water) and/or segregation

of aggregates (when the cement

and aggregates start to separate),

with the resulting concrete hav-

ing a reduced quality. The use of

an aggregate with an undesirable

graduation can result in a very

harsh mix design with a very low

slump, which cannot be readily

made more workable by the ad-

dition of reasonable amounts of

water.

1.1.1.4.3 Curing

because the cement requires time

to fully hydrate before it acquires

strength and hardness, concrete

must be cured once it has been

placed. Curing is the process of

exposing concrete to a specific

environmental condition, until

hydration is relatively complete.

Good curing is typically considered

to require a moist environment

that promotes hydration, since

increased hydration lowers per-

meability and increases strength,

resulting in a higher quality mate-

rial. Allowing the concrete surface

CONCRETE GRADE fck,cyl(N/mm²) fck,cube(N/mm²)

NORMAL

C8/10 8 10

C12/15 12 15

C16/20 16 20

C20/25 20 25

C25/30 25 30

C28/35 28 35

C30/37 30 37

C32/40 32 40

C35/45 35 45

C40/50 40 50

C45/55 45 55HIGHSTR

ENGTH

C50/60 50 60

C55/67 55 67

C57/70 57 70

C60/75 60 75

C65/80 65 80

C70/85 70 85

C75/90 75 90

C80/95 80 95

C85/100 85 100

C90/105 90 105

C100/115 100 115

TAble 1.3 THEMOSTCOMMONCONCRETEGRADES

1.1 bASe MATeRIAl


to dry out excessively can result in

tensile stress, which the still-hy-

drating interior cannot withstand,

causing the concrete to crack.

Also, the amount of heat gener-

ated by the chemical process of

hydration can be problematic for

very large placements. Allowing

the concrete to freeze in cold cli-

mates before the curing is com-

plete will interrupt the hydration

process, reducing the concrete

strength and leading to scaling

and other damage or failure. The

effects of curing are primarily a

function of specimen geometry,

the permeability of the concrete,

curing length and curing history.

Picture 1.2 shows a series of

pictures of different stages of the

curing process. The upper left

corner shows cement particles in

water. The right top corner shows

the situation after a couple of min-

utes of adding water. The bottom

left corner shows the situation

after a couple of hours with hydra-

tion products expanding into the

water chamber. The bottom right

corner shows the situation after

couple of days.

1.1.1.4.4 Expansionandshrinkage

Concrete has a very low coefficient

of thermal expansion. However if

no provision is made for expansion,

very large forces can be created,

causing cracks in parts of the

structure not capable of withstand-

ing the force or the repeated cycles

of expansion and contraction.

As concrete matures, it continues

to shrink, due to the ongoing reac-

tion taking place in the material.

A brickwork of made of clay tends

to expand for some time after the

manufacture of the bricks, and the

relative shrinkage and expansion

of concrete and brickwork require

careful accommodation when the

two forms of construction interface.

Concrete can shrink 0,1–0,5 ‰,

depending on environmental con-

ditions. This means that the higher

the relative humidity is, the lower

the shrinkage is.

1.1.1.4.5 Cracking

Concrete is placed while in a wet

(or plastic) state, and therefore can

be manipulated and moulded, as

needed. The hydration and hard-

ening of concrete during the first

three days is critical and abnor-

mally fast drying and shrinkage

due to factors such as evaporation

from wind during placement may

lead to increased tensile stress at

a time when it has not yet gained

significant strength, resulting

in shrinkage cracks. The early

strength of the concrete can be

increased by keeping it damp for

a longer period during the curing

process.

Minimizing stress prior to curing

minimizes cracking. High early-

strength concrete is designed

to hydrate faster often by the

increased use of cement, which

increases shrinkage and crack-

ing. by its very nature, concrete

shrinks, and therefore cracks.

Plastic-shrinkage cracks are

immediately apparent, i.e. visible

within 0 to 2 days of placement,

while drying-shrinkage cracks de-

velop over time. Precautions such

as mixture selection and joint

spacing can be taken to encourage

cracks to occur within an aesthetic

joint, instead of randomly.

engineers are familiar with the

tendency of concrete to crack,

and, where appropriate, special

design precautions are taken to

ensure crack control. This entails

the incorporation of secondary

reinforcing placed at the desired

spacing to limit the crack width

to an acceptable level. Water

retaining structures and con-

crete highways are examples of

structures where crack control

is exercised. The objective is to

encourage a large number of

very small cracks, rather than a

small number of large, randomly-

occurring cracks. Picture 1.3

shows the principle of cracking,

which means, that cracks occur in

places where concrete is sub-

jected to tension. Reinforcement

bars are located in places where

tension takes place. Reinforce-

ment bars will take up the tension

load, and they also function as a

warning mechanism. That means

that before the construction totally

collapses, correctly designed

reinforcement permit the cracks

to grow visible enough and the

overloading of construction can be

discovered during inspections.

PICTURE 1.2 Differentstagesofthecuringprocess

1.1 bASe MATeRIAl


1.1.1.4.6 Creep

Creep is the term used to de-

scribe the permanent movement

or deformation of a material in

order to relieve stress within the

material. Concrete subjected to

forces is prone to creep. Creep can

sometimes reduce the amount of

cracking that occurs in a concrete

structure or element, however

it also must be controlled. The

amount of primary and secondary

reinforcing in concrete structures

contributes to a reduction in the

amount of shrinkage, creep and

cracking.

1.1.1.4.7 Typesofconcrete

There are many different types

of concrete available. The most

common is regular concrete, which

can be defined according to many

subclasses (Table 1.4).

Self-compacting concrete (SCC)

was first developed in Japan 1988

to reduce labour in the placement

of concrete by eliminating or reduc-

ing the need for vibration to achieve

consolidation. Self-compacting

concrete is often used in complex

or in close space reinforcement bar

structures.

Shotcrete or sprayed mortar is

commonly used e.g. in tunnels to

stabilize the walls of the tunnel.

Shotcrete was already invented in

the early 1900s. Up until the 1950s,

the wet-mix process was known,

with only the dry-mix process being

used. In the 1960s, the alterna-

tive method for gunning by the dry

method was devised with the devel-

opment of the rotary gun.

Pervious Concrete is a special type

of concrete allowing high volumes

of water to run through it. environ-

mentally, it makes good sense to

let rainwater directly recharge our

groundwater. Pervious can miti-

gate “first flush” pollution protect-

ing our streams, water-sheds and

ecosystems. Pervious does not

get as hot as standard cement and

asphalt.

Cellular or aerated concrete is a

light weight concrete, the volume

of which is only 20 % solid mate-

rial and the rest is porous. Aerated

concrete is mainly used in a differ-

ent shape of blocks.

Roller-compacted concrete or RCC

takes its name from the construc-

tion method used to build it. It is

placed with conventional or high-

density asphalt paving equipment,

and then compacted with rollers.

RCC has the same basic ingredient

as conventional concrete: cement,

water, and aggregates, such as

gravel or crushed stone. but unlike

conventional concrete, it is a drier

mix - stiff enough to be compacted

by vibratory rollers. Typically,

RCC is constructed without joints,

requiring neither forms nor finish-

ing, nor containing dowels or steel

reinforcing. These characteristics

make RCC simple, fast, and eco-

nomical.

Asphalt concrete (cement re-

placed with bituminous) is also

one type of concrete. The terms

asphalt concrete, bituminous as-

phalt concrete, etc., are typically

used only in engineering jargon.

Asphalt pavements are often

called asphalt by laypersons, who

tend to associate the term con-

crete only with Portland cement

concrete.

1.1.1.4.8 Concretetesting

engineers usually specify the

required compressive strength of

COMPRESSIONNON-CRACKED CONCRETE

TENSIONCRACKED CONCRETE









PICTURE 1.3 Principleofcracking

1.1 bASe MATeRIAl


concrete, which is normally given

in terms of 28-day compressive

strength in MN/m² or in N/mm².

Twenty eight days is however a

long time to wait to determine

wheter the desired strengths are

going to be obtained, so three-

day and seven-day strengths can

be useful to predict the ultimate

28-day compressive strength of

the concrete. A 25 % strength gain

between 7 and 28 days is often

observed with 100 % OPC (Ordinary

Portland Cement) mixtures, and

frequently a 40 % strength gain

can be realized with the inclusion

of pozzolans and supplementary

cementatious materials (SCM’s)

such as fly ash and/or slag cement.

Strength gain depends on the type

of mixture, including its constitu-

ents and the use of standard curing,

proper testing and care of cylinders

in transport, etc. it becomes imper-

ative to equally rely on testing the

fundamental properties of concrete

in its fresh, plastic state.

Concrete is typically sampled while

being placed with testing protocols

requiring that test samples be cured

under laboratory conditions (stan-

dard cured). Additional samples may

be field cured (non-standard) for the

purpose of early stripping strengths,

i.e. form removal, evaluation of cur-

ing, etc. However the standard cured

cylinders comprise acceptance

criteria. Concrete tests measure the

“plastic” (unhydrated) properties of

concrete prior to, and during place-

ment. As these properties affect the

hardened compressive strength and

durability of concrete (resistance

to freeze-thaw), the properties of

TYPEOFCONCRETE DESCRIPTION

CEMENTCONCRETEThis is the most common type of concrete and is made mostly from Portand cement, sand, aggregate and water. It is used to reinforce and un-reinforce structures, roads and foundation. The compositions of cement, sand and aggregate vary from 1:1:2 (a richest practical mixture) to 1:3 :6 (a lean mixture used for concrete filling).

PLAINMASSCONCRETE Concrete not strengthened by reinforcement. Used for foundations and mass structures such as dam, and gravity retaining walls. Also called non-reinforced concrete.

LEANCONCRETE A plain concrete with a large ratio aggregate to cement than structural concrete. It is used for filling and not structural purposes.

STRUCTURALCONCRETElightweight concrete of such a quality is suitable for load-bearing members of structures. If it is a compact concrete made with stone aggregate, it is of comparatively high density (about 2.4) and great strength. If it is based on lightweight aggregate, then high strengths are available but the design generally requires special considerations.

REINFORCEDCONCRETElightweight concrete of such a quality is suitable for load-bearing members of structures. If it is a compact concrete made with stone aggregate, it is of comparatively high density (about 2.4) and great strength. If it is based on lightweight aggregate, then high strengths are available but the design generally requires special considerations.

PRESTRESSEDCONCRETE Structural concrete which is subjected to compression in those parts which in service are subjecte to tensile forces so that generally, the concrete is nowhere is a state of tension under the working load.

CASTINPLACE/CASTINSITUCONCRETE

This is deposited in its permanent position to harden. This is the most common method of construction and when to concrete is not deposited on the ground, such as for roads and similar purposes, it is generally placed in temporary moulds or is contained within a formwork or shuttering.

PRECASTCONCRETE

This is concrete placed in separate moulds under controlled factory conditions to harden and required to be transferred to a site for final construction. This procedure allow high quality concrete castings to be made at low relative costs. This method is used for the production of paving slabs, bricks, road channels, kerbs lintels, fence posts, bridge beams, etc. Precast units can include re-inforcement and engineered steel inserts.

VACUUMCONCRETE

This is concrete containing high water content to allow sufficient workability to enable it to be placed into complicated moulds or around extensive reinforcement. The concrete is then subject to a vacuum removing significant quantities of water resulting in a stronger concrete on hardening. Pumped concrete needs to include higher water content to improve the flow characteristics. If a high strength concrete is required then special additives are use in place of the additional water. A concrete pumping station may be static or mobile.

PUMPEDCONCRETEConcrete conveyed from the mixer to the point of deposit through pipes. The concrete is discharged from the mixer into a hop-per which feeds it into a pump which forces it through the pipe. The pipe is 100 or 150 mm dia and the method can be used to pump over distances of 650 m horizontally or 50 m vertically, or some combination of these lengths.

SPUNCONCRETE This process used for the production of vessels and pipes involves feeding relatively dry concrete into a rotating cylindrical mould. The concrete is flung against the wall by a centrifugal action to form a dense hard impermeable wall.

READYMIXEDCONCRETEConcrete made at a mixing plant and delivered to the site in special transport vehicles. The transport includes a rotating drum in which the concrete is continuously mixed until it is discharge on site. The mix specification is agreed upon between the sup-plier and the user prior to delivery and generally results in a high quality product.

WATERRESISTANTCONCRETE

Water Resistant concrete can either be water proofed or watertight. • Waterproof concrete is formed with a water resistant layer or surface with the mass of concrete remaining ordinary concrete. The water tight layer can be formed using a spray of lacquer, or applying a coat of asphalt or bitumen or using a wash of soda (water glass) • A watertight concrete can be produced by ensuring and dense product using tight quality control of the production process. The resulting can be sufficiently watertight to enable it to be used for tanks retaining water

HIGHDENSITYCONCRETE High density concrete for use as nuclear shield walls and ballast blocks and sea walls can be produced by using different materials for the aggregate. Candidate materials include barytes, haematite, iron shot, steel shot and lead shot.

FIBREREINFORCEDCONCRETE

High strength high performance concrete can be produced by including short fibres in the mix. A number of reinforcement materials are available including glass, nylon, polypropylene, carbon and steel. Concrete in such a form leads to increased strength, impact resistance and greater strength. This is an area of concrete development which is continuously being devel-oped.

TAble 1.4 TYPESOFCONCRETE

1.1 bASe MATeRIAl


slump (workability), temperature,

density and age are monitored to

ensure the production and place-

ment of ‘quality’ concrete. Tests are

performed according to european

methods and practices. Techni-

cians performing concrete tests

must be certified. Compressive

strength tests are conducted using

an instrumented hydraulic ram to

compress a cylindrical sample to

failure. Tensile strength tests are

conducted either by a three-point

bending of a prismatic beam speci-

men or by compression along the

sides of a cylindrical specimen.

1.1.2 NATURALSTONE

The globe is an amazing and compli-

cated structure (Picture 2.1). The core

of the globe is formed of solid iron

(Fe) and nickel (Ni). This solid core is

surrounded with liquid Fe-Ni-core.

Around this liquid core is a so-called

mantel. Mantel is formed of iron sul-

phates and Fe- and Mg-silicates. The

hard surface of the globe is called

crust. Those stones used for con-

structions are mined from crust.

1.1.2.2 Materialdescription

A rock is an aggregate composed

of grains of minerals which are

cemented. The rocks occurring in

the crust can be divided into three

groups: magmatic rocks, sedimen-

tary rocks and metamorphic rocks.

1.1.2.3 Rocktypes

Magmatic rocks - rocks formed 1.

during the crystallization of

magma (melted rock).

Sedimentary rocks - rocks 2.

formed during the lithification of

sediment.

Metamorphic rocks - rocks forming 3.

during metamorphism (i.e. transfor-

mation) of previously existing rocks.

See the rock types from picture 2

1.1.2.4 Commercialtypesand

geologicalnames

Commercial names for different

types of stones are often different

from geological names. Table 2.1

compares some commercial and

geological names.


1.1.2.5.1 Strength

Different rock types have differ-

ent strengths. Generally speaking,

granites are the most common form

of hard rocks. Slates and marble

are normally slightly softer than

granites. Sand-stones, soapstones

and limestones are significantly

softer than granites. Table 2.2 shows

the typical strengths of different

types of stones.

1.1.2.5.2 Applicationsandsuitability

Stones can be used in different

types of constructions. Table 2.3

shows some constructions where

stones can be used. The usage tar-

gets of different type of stones vary

according to weather conditions

and common habits.

1.1.3 SOLIDANDHOLLOWBRICK

PICTURE2.2 Rocktypes

CRUST AND UPPER PART OF MANTLE FORM

LITHOSPHERE

MANTLE- IRON SULPHATES AND FE- AND MG-SILICATES

- UPPER PART OF MANTLE IS PARTLY MOLTEN- FLOW OF UPPER PART OF MANTLE MOVES

PLATFORMS IN LITHOSPHERE

LIQUID FE-NI-CORE

CRUST- SEA AREAS 6-7 KM

- CONTINENTS 35-40 KM

SOLID FE-NI-CORE

PICTURE2.1Structureoftheglobe

GRANITE-AMAGMATICROCK

SANDSTONE-ASEDIMENTARYROCK

ECLOGITE-AMETAMORPHICROCK

1.1 bASe MATeRIAl


TAble 2.1 COMMERCIALANDGEOLOGICALNAMES

INDUSTRIALTYPE GEOLOGICALNAME

GRANIITTI Syenite, granite, granodiorite, dioriitti, gabro, anortosite, diabase, migmatite, gneiss

SLATE Quartsite, mica schist, fyllite, amfibolite

MARMOR Marmor, limestone, dolomite, travertine

SANDSTONE limestone, sandstone

SOAPSTONE Soapstone, serpentine

LIMESTONE limestone, dolomite, travertine

TAble 2.2 STRENGTHSOFSTONES

ROCKTYPE DENSITY kg/m³

WATERAB-SORBTION

wt%

COMPRESSIVESTRENGHT

N/mm²

FLEXURALSTRENGHT

N/mm²

GRANITE 2 580 - 3 080 0,084 - 0,35 150 - 300 8,25 - 26

SLATE 2 500 - 2 800 0,1 - 0,4 100 - 200 10 - 35

MARMOR 2 600 - 3 000 0,2 - 0,6 80 - 180 6 - 20

SOAPSTONE 2 760 - 2 980 0,1 - 0,24 25 - 135 8 - 12,5

TAble 2.3 DIFFERENTAPPLICATIONS

XXVERYSUITABLE

XSUITABLE

X*NOTINSCANDINAVIA

FLOORSANDSTAIRS(INDOOR)

INDOORWALLS

KITCHENSURFACES

FIRE-PLACES

FACADESFOUNDA-TIONS

WALLSANDENVIROMENTALSTRUCTURES

STAIRS(OUTDOOR)

PAVINGS

GRANITE

cleavage plane x x xx xx xx xx xx

burned x x x xx xx xx xx xx

cut x x xx xx xx xx xx

ground xx xx xx x xx xx x x x

polished xx xx xx x xx xx x x x

SLATE

cleavage plane xx x x xx xx xx xx xx

ground x x x xx xx xx xx x

MARBLE

polished xx xx x x* x* x* x*

SOAPSTONE

cleavage plane x xx x x x

polished xx xx xx x x

1.1.3.1 History

Indications of the earliest use of

brick as a building material go

back about 5,000 to 6,000 years

in the archaeological ruins of our

history. Where, when and by whom

the first bricks were formed and

assembled, no one can say.

The first brick buildings were built in

Ur in Mesopotamia about 4000 bC.

bricks have also been used in egypt

already 3000 bC. At that time clay

was also used as a raw material,

but it was dried rather than burned.

burning bricks has been known

since about 2200 bC in Mesopotamia.


brick is a building material, which

consists of dried and fired clay and

sand. Normally brick has a rectan-

gular shape. The colour of the brick

is dependent on the iron contents

of the clay. The colour can be red or

yellow, for example.

There are sometimes holes added

inserted in the bricks, which in-

crease the compression strength

1.1 bASe MATeRIAl


of the brick. Also sawdust can be

added to make bricks more frost

proof. Sand-lime brick is a product

that uses lime instead of cement.

It is usually a white brick made of

lime and selected sands (quarts

sand), cast in molds and cured

under steam. Some people don’t

even recognize sand-lime brick as

real brick.

1.1.3.3 Production

1.1.3.3.1 Clayextraction

The clay pit is usually nearby the

production plant. This reduces the

transportation distance to a mini-

mum. The clay is extracted from

the clay pit by means of modern

equipment, stored and transported

to the clay preparation unit (Picture

3.1).

1.1.3.3.2Claypreparation

Clay preparation means that the

clay is going to be grinded, milled,

wedded and foreign materials,

such as stones, will be removed

to achieve the right consistency

and homogeneity of the clay for

production (Picture 3.2). In order to

produce special colours, different

types of clay or mineral aggregates

can be added.

1.1.3.3.3 Theshapingprocess

Hand moulded brick: for mechani-

cally produced “hand” moulded

bricks, the raw material is, depend-

ing on the machine producing these

bricks, either rolled in sand or di-

rectly thrown forcefully into already

sanded moulds. The sand acts like

flour in a cake mould. The surplus

material is cut off from the top edge

of the moulds.

Stock bricks: The raw material is

pressed into the moulds already

sanded under high pressure (Pic-

ture 3.3). This results in bricks with

more subdued shapes and surface

structures, and akin to hand-

moulded bricks, five surfaces of

the brick are sand-coated.

extruded bricks are produced by ex-

trusion. Under high pressure, the raw

material is forced through a die. The

produced endless run of clay is cut

into the thickness of the green brick

by a taut wire.

1.1.3.3.4 DryingandFiring

by using the excess heat energy of

the kiln, the green bricks are dried

until nearly all moisture has been

removed after which the unfired

brick is prepared for the following

firing process in the kiln

At a temperature of about 1.050°C,

for pavers over 1.100°C, bricks are

fired in the kiln. Today the fiing pro-

cess usually takes place in modern,

computer controlled tunnel kilns

(Picture 3.4). but there are still some

traditional ring kilns and clamps at

work to produce bricks with a very

special look. by using special firing

methods, such as using a reducing

kiln atmosphere, it is possible to

produce exceptional colours.


As long as humans have made

bricks, the shape and characteris-

tics of bricks have varied. even to-

day most countries have their own

style of bricks which differ from

those of other countries. The fol-

lowing list mentions some principal

characteristics of modern bricks in

europe.

• Compression strength 30 - 45 N/

mm² (could also be 7 - 105 N/mm²)

• Compression strength for hollow

bricks even higher

• Tensile strength about 4-5 % of

compression strength and for

hollow bricks even less

• Resistance to moisture is good

and the coefficient of moisture

expansion is very low

• Coefficient of thermal expansion

is low (3-5 x 10-6)

• Fire resistant

• Splits easily

• Hollow bricks have good resis-

tance to freeze-thaw

PICTURE3.4 Tunnelkiln

PICTURE3.1 Extractedclay

PICTURE3.2 Claypreparationinprogress

PICTURE3.3 Shapingbricks

1.1 bASe MATeRIAl


1.1.4 SAND-LIMEBRICK

1.1.4.1 General

Sand-lime brick is known and used

internationally since it was pro-

duced for the first time in history in

britain in 1886. Some people don’t

even recognize sand-lime brick as

real brick. It distinguishes itself

by its exact geometrical dimen-

sion, nice shape, high strength and

glazed surface.

1.1.4.2 Production

Sand-lime bricks are made of a

mixture of lime, quartz sand and

water. bricks are moulded under

high pressure into meticulous

raw blocks. The final strength is

achieved in an autoclave under

pressure and temperatures of 160

to 200 ºC. In the tempering pro-

cess lime reacts with quartz sand

and forms silicate bonds. Coloured

sand-lime bricks are produced

by adding UV and alkaline re-

sistant pigments (Picture 4.1).

White bricks are made of crushed

quartzite.


Compression strength 15…25 •

MN/m²

Density 1700…1900 kg/m³•

Shrinkage and moisture expan-•

sion about 0,2 mm/m

Water absorbing capacity 10…17 %•

Water absorbing speed 1…2 kg/•

m² min

Coefficient of thermal expansion •

(8 x 10-6)

Good moisture resistance•

Heat resistance up to +600 ºC•

Good resistance to freeze-thaw•

1.1.5 AERATEDCONCRETE

1.1.5.1 History

Finland and Sweden developed

aerated concrete in the 1920s

and 1930s. The Finnish chemist

lennart Forsén and the Swedish

chemist Ivar eklund discovered

a mixture of cement, lime, water

and sand that expands by adding

aluminium powder. Akin to wood

but without the disadvantages of

combustibility, decay, and termite

damage, the material was further

developed to what we know today

as autoclaved aerated concrete

(also called autoclaved cellular

concrete or ACC).


In its manufacture, Portland cement

is mixed with lime, silica sand, or

recycled fly ash (a byproduct from

coal-burning power plants), water,

and aluminium powder or paste and

poured into a mould. Steel bars or

mesh can also be placed into the

mould for reinforcement.

Reinforcing bars must be protected

with anticorrosion paste. The

reaction between aluminium and

concrete causes microscopic hy-

drogen bubbles to form, expanding

the concrete to about five times its

original volume.

After the hydrogen evaporates, the

now highly closed-cell, aerated

concrete is cut to size and form

and steam-cured in a pressurized

chamber (an autoclave, 180 °C and

11 bar). The result is a non-organic,

non-toxic, airtight material that can

be used in non- or load-bearing

exterior or interior wall, floor, and

roof panels, blocks, and lintels. Ac-

cording to the manufacturers, the

production process generates no

pollutants or hazardous waste.


• 400 kg/m³ - 600 kg/m³, see also

table 5.1, (in some countries

even higher)

• light weight: normally 75 %

lighter than normal concrete

• easy to work

• Durable: resists decay and insects

• Fire resistant

• Sound absorptive

• Porous: 20 % solid material, 50 %

macropores 0,5 - 2 mm and 30 %

micropores (500 kg/m3)

• Shear strength about 2 - 3 %

from compression strength

• Creep and shrinkage is low

(hydroexpansivity 0,02 ‰)

PICTURE4.1 Differentcoloursofsand-limebrick

TAble 5.1 MAINCHARACTERISTICS

DENSITYkg/m³

COMPRESSIONSTRENGHT

N/mm²

FLEXURALSTRENGHT

N/mm²

MODULUSOFELASTICITY

N/mm²

400 1,7 0,3 1 000

450 2,3 0,44 1 200

500 3,0 0,58 1 400

1.1 bASe MATeRIAl


1.1.6 LIGHTWEIGHTEXPANDED

CLAYCONCRETEORLIGHT

GRAVELCONCRETE


light gravel is made of clay baked

in a rotating oven over 1 100 °C

degree (Picture 6.1). The rotation

gives clay its round shape and

smooth surface. The grain has a

compact surface, but the inside of

the grain is porous and the grain

size is 1–32 mm. The porosity

makes it light with good thermal

insulation ability. light gravel is

not only used in light gravel blocks,

but also in concrete (Picture 6.3) as

an insulation material.


The nominal density of light gravel

block is 650 kg/m³ or heavier

950 kg/m³. This means that the

compression strength varies from

3 MN/m² to 5 MN/m². The com-

pression strength is high enough

in the normal usage of light gravel

blocks, such as in foundations

and wall construction. For ex-

ample, one 590 x 290 x 190 mm³,

3/650-block can bear 130 kN = a 13

ton uniform load before it breaks.

The hollows in the blocks vary ac-

cording to different block types and

also producers manufacture differ-

ent products (Picture 6.2).

1.1.7 PLASTERBOARD

1.1.7.1 History

Gypsum, the first mortar binder

produced by burning and it was

already used in ancient egypt and

Rome. Gypsum landed in europe in

the 17th century when the French

and the english started to use it as

a building material. It was mainly

used for decorations and for indoor

plastering. Plasterboard was

invented at the end of 19th century.

The modern type of plasterboard

was patented in the USA in 1908.

The first plasterboard factory was

introduced in europe in 1917. Since

then, plasterboard has also been

used in Finland.


Plasterboard (also called wall-

board, gypsum board, GWb, and

drywall) is a building material con-

sisting of gypsum formed into a flat

sheet and sandwiched between two

pieces of heavy paper. 94 % of the

weight is gypsum and 5 % paper.

1 % consists of water, starch and

admixtures. As of 2005, it is the

most commonly used material

globally for constructing interior

walls and ceilings.


Normal gypsum board

• Density 9,0 kg/m²

• bending stiffness 2,0 – 2,5 N/mm²

• When RH > 90 % à strength will

decrease

• Deformation RH 40 % - 90 % à

0,4 mm/m

• Working temperature < 50 ºC

• emission class M1

• Slow down fire

• Capillary rise at least 1 m

• Cardboard works akin to rein-

forcement bars in concrete

1.1.8 Shapeoftheconstruction

The shape of the construction is

limited quit often by the selection of

the anchoring method. Thin slaps

limit anchoring depths and the

same problem also arises with thin

walls. especially narrow beams and

columns pose challenges to an-

choring. In engineering and instal-

lation, it is important to pay atten-

tion to installation depths as well

as to splitting forces. For example,

all ordinary expansion anchors may

be ruled out because of too high

expansion forces.

PICTURE6.1 Expandedclaygrains

PICTURE6.3 TWA-terminal,KennedyAirportN.Y,USA1956-1962,architectEeroSaarinen

PICTURE6.2 Differentsshapesoflightgravelblocks

1.1 bASe MATeRIAl


1.2 USAGETARGET

1.2.1 CONSTRUCTION

Construction can be bearing or

non-bearing. bearing construc-

tions are submitted to loads which

strain construction. This strain can

lead to cracking of the construc-

tion and therefore cracking must

be noticed by the design of the

anchorage. Although non-bearing

construction does not take vertical

loads, it is able to take horizontal

loads, e.g. rigid wall.

1.2.2 CORROSION

ever since metallic materials have

been used in the construction in-

dustry, building and civil engineers

have faced problems of corrosion

and designing protection against

corrosion. As early as the Middle

Ages, fasteners made of iron and

iron alloys were used, e.g. as

staple-like clamps and fasteners,

for securing building components.

They were positioned in such a way

that they remained accessible and

could be maintained. Recently,

however, engineers believed that

corrosion problems could be

overcome by using stainless steel

and covering steel members and

components more carefully with

concrete. During past decades,

there has been a great increase in

the exposure of certain areas to

pollutants, e.g. technical facilities

for traffic. This trend has resulted

in previously used materials reach-

ing the limits of their capabilities.

even today, materials used for

building and structures situated

in corrosive environments have an

unsatisfactory service life in many

cases.

In the field of composite con-

struction, in particular, problems

resulting from corrosion are not

restricted only to zones exposed to

the atmosphere. As a rule, a cor-

rosive medium gains access to a

metal connector or other fastener,

etc. through, for example, cracks

which appear in concrete or gaps

which exist in structure. Gaps of

this kind can be the result of the

structural design, such as those

gaps between the original concrete

and a concrete overlay on repaired

bridges. In the course of time

pollutants, such as chlorides and

corrosive acids, can accumulate,

producing considerably more cor-

rosive conditions in this way.

Corrosion seriously impairs the

functioning and service life of an-

chors as well as of other fasteners,

as a result possibly creating a con-

siderable safety risk. Several field

tests and laboratory tests by differ-

ent manufactures and universities

in different environments, such as

tunnels, indoor swimming pools,

power plant chimneys, have been

conducted proving that it is neces-

sary to pay attention to the right

materials. For example, it was

found that the high-alloyed auste-

nitic steel according to eN 1.4529 or

similar, which has a molybdenum

content greater than 6 % (and nickel

content high over 20 %), is ideal for

use in construction in highly cor-

rosive surroundings (chlorides and

sulphur dioxide).

In addition to conventional corro-

sion, there are also other types of

corrosion that occur on fasteners,

such as galvanic corrosion (contact

corrosion), stress corrosion, pitting

corrosion and crevice corrosion.

1.2.2.1 Galvaniccorrosion

Galvanic corrosion is corrosion

that occurs between two different

grades of metals, where the least

noble (base) metal is corroded

through electrolytic contact with

the nobler metal. This type of cor-

rosion may pose a major risk when

the fitting is made of a less noble

metal and is significantly smaller

than the piece being mounted. This

risk can be avoided by not using

different metals together or by iso-

lating the metals from one another

with, for example, plastic insulat-

ing washers.

1.2.2.2 Stresscorrosion

Stress corrosion is a very difficult

type of corrosion to detect. It oc-

curs in fittings which are under

tension and exposed to chloride in

warm conditions. Fittings used in

the suspended ceilings of indoor

swimming pools are typically sus-

ceptible to this type of corrosion.

In such areas, not even A4 grade

stainless steel provides adequate

corrosion resistance instead eN

1.4529 or similar grade steel

should be used.

1.2.2.3 Pittingcorrosion

Pitting corrosion involves the

corrosion of metal in small areas

on the metal surface, resulting

in localized ‘pits’. Pitting cor-

rosion rarely advances through

solid structures. Generally, the

corrosion stops when the pits

have reached a certain depth. The

passive layer on stainless steel is

a gel-like, hydrated oxide film a

few nanometres in thickness. In

chloride solutions the chloride ions

displace water molecules in the

passive layer. Hydrated metal ions

normally part of the passive layer

1.2 USAGe TARGeT

BACKTOMAINMENU


and found in its flaws, dissolve to

form metal chloride complexes,

which diffuse even further. This

leaves a gap in the passive layer

where the metal continues dis-

solving and pitting corrosion takes

hold. The susceptibility of stain-

less steel to pitting corrosion can

be reduced by means of doping.

The most effective doping agent

is molybdenum, but chrome and

nitrogen doping also have a reduc-

tive effect on the susceptibility of

pitting corrosion.

1.2.2.4 Crevicecorrosion

Crevice corrosion occurs in most

metals, ranging from noble metals,

such as silver and copper, to very

ignoble metals, such as titanium

and aluminium. Crevice corrosion

occurs in very tight cracks, into

which the solution penetrates, but

where it cannot circulate at the

same rate as in other areas of the

metal surface. When corrosion

strains and problems are exam-

ined more closely in the installa-

tion area, they usually lead to an

increase in the need for corrosion

protection. This, of course, re-

duces the risk considerably, while

enhancing the liability protection

of engineers and installers in any

problem case.

Crevice corrosion occurs when:

The geometric form or manufac-1.

turing technique of the struc-

ture is such that approximately

0,0025 - 0,1 mm gaps form in

areas where there is contact with

the solution. These gaps gener-

ally form at various rivets, bolts,

and weld joints.

At contact interfaces between 2.

metals and non-metals, such as

at seal joints, if the seal material

is, for example, water-absorbent

or does not completely cover the

seal surface.

There are various solid particles 3.

on the metal surface, such as

sand, dirt or precipitates formed

by corrosion products.

1.2.3 CORROSIONPROTECTION

1.2.3.1 Electroplating

electroplating (zinc plating) is a

sacrificial coating, which corrodes

instead of the underlying steel and

is normally 5–12 μm (micrometres)

in thickness. In a dry climate an

oxide layer forms on its surface

to protect the zinc from advanc-

ing corrosion. However, if there

is any moisture and air present,

the zinc coating will corrode and

turn into basic zinc carbonate. A

basic zinc carbonate is sometimes

referred to as “white rust”. The

zinc carbonate is sloughed off by

air currents or rain and, over time,

the zinc gradually disappears. Pas-

sivization, which can be yellow or,

nowadays often nearly clear, pro-

tects the zinc coating from chemi-

cals present in the packaging. It

provides protection for the zinc

coating and keeps the fittings in

good condition before their instal-

lation. electroplated products are,

however, only suitable for use with

installations in dry, indoor spaces.

1.2.3.2 Hot-dipgalvanization

Hot-dip galvanization is the next

step up in corrosion protection. It

has a thicker layer of zinc (ap-

prox. 45 μm), which generally lasts

longer, but will corrode over time

in damp or wet conditions. Hot-dip

galvanized products are generally

suitable for use in rural or urban

environments for as long as 10

years, and in industrial and marine

environments for 2–3 years. Regu-

lar inspections are always recom-

mended. It must, however, be kept

in mind that in highly polluted

areas, the zinc can corrode consid-

erably faster, while in leaner areas

it can last significantly longer,

even longer than the specifications

estimate. Always remember that

coatings are sensitive to damage,

particularly during installation.

Zinc is not usually able to repair

major damage by itself, thus mak-

ing the product quickly susceptible

to corrosion and even resulting

in a serious safety hazard. This

is why zinc coated fittings are not

recommended for use in long-term

exterior installations.

1.2.3.3 Stainlesssteel

Stainless steel comes in six differ-

ent grades (A1, A2, A3, A4, A5 and

HCR), but, in practical terms, only

three of these grades are used

in anchors: two standard grades

and one special grade usually only

available upon special order. The

least corrosion-resistant grade

is A2. A2 contains chrome and

nickel and is suitable for use in

long-term exterior installations in

areas where the air is not polluted

and there is no chlorine present.

This primarily covers or applies

to rural and sparsely populated

areas. even though A2 will not rust

in these conditions, it may still lose

its sheen, thus giving decorative

structures a smudgy appearance.

A4 provides better corrosion-re-

sistance. In addition to chrome and

nickel, this grade also contains

molybdenum. Its surface does not

become smudgy in outdoor use

and it can be used in just about any

type of outdoor structure, includ-

1.2 USAGe TARGeT


ing industrial and marine environ-

ments and even underwater instal-

lations, however not in coastal

areas, where saltwater spray can

reach the fittings. Special-grade

stainless steel is recommended

for use in coastal areas. Special-

grade stainless steel (HCR) is a

specialized alloy, containing larger

concentrations of chrome, nickel

and molybdenum than the alloys

mentioned above. Special-grade

stainless steel is identified by its

code, for example, eN 1.4529. The

material can be used in all types

of aggressive climates, including

areas subject to sea spray. Other

aggressive climate areas include

various types of chemical plants,

tunnels, and indoor swimming

pools.

1.2.3.4 Sherardization

Sherardization is more environ-

mental way of galvanizing than

hot-dip galvanizing. Articles, which

are cleaned by etching, are placed

into rotating reel oven with zinc

powder and sand. Oven is warmed

up, close to melting point of zinc,

and after certain time steel and

zinc will react (diffusion), and iron-

zinc coating will be formed on sur-

face of the steel. Coating thickness

is normally 15–40 μm and colour is

dark grey.

1.2.3.5 Mechanicalgalvanizing

Articles, which are degreased, are

placed into a rotating reel oven

with glass balls where acid clean-

ing will be carried out. After the

coppering treatment, zinc powder

and some chemicals are added to

the reel oven. The normal coating

thickness is 12–15 μm. However

thicker layers are also possible

(up to 75 μm). The coating thick-

ness is very even and the colour is

grey. There is no risk of hydrogen

embrittlement, which explains why

hardened steels are also treatable.

1.2.3.6 DeltaCoating

Delta coating is comprised mainly

of overlapping zinc and aluminium

flakes in an inorganic binder. The

applied and cured coating forms

a 97 % zinc-rich structure of

laminated zinc flakes. The coating

thickness varies 15–20 μm and the

colour is silver.

1.2.3.7 DacrometCoating

Dacromet Coating is similar to

Delta Coating.

1.2 USAGe TARGeT


1.3 LOADSANDRESISTANCES

1.3.1 LOADTYPES

1.3.1.1 Staticloads

Static loads refer to for example,

a dead load (own weight), loads of

non-bearing structures and loads

due to temperature changes or

movement of supports. All kind of

equipments and furniture are also

defined as static loads. Nature also

creates static loads, e.g. snow,

wind and temperature. When we

consider anchor design, generally

about 95 % of the cases concen-

trate on static loads.

1.3.1.2 Dynamicloads

A dynamic load is a load associ-

ated with the elastic deformations

of a structure subjected to time-

dependent external forces. The

main difference between static

and dynamic loads is the effective-

ness of inertia and damping force.

Dynamic loads can be classified

into fatigue loads, seismic loads/

pulsate and shock loads.

1.3.1.2.1 Fatigueload

Fatigue loads can be divided into

two main groups:

Vibration (very high repetition •

rate and low amplitude range).

Frequent loading and unloading •

(high loads and frequent repetition).

Fatigue loads create changes in

stress in the anchors. Stress de-

creases the strength of the mate-

rial and this decrease is greater

subject to the change in stress

and the increase in the number of

cycles.

1.3.1.2.2 Shockload

Shock loads are loads with a very

short duration but extremely high

force. loads occur mainly as single

peaks. Shock loads are, generally

speaking, quite rare loading situa-

tions. However sometimes they are

the only loading case a structure is

designed for, e.g. explosions, crash

barriers, falling rocks, etc.

1.3.1.2.3 Seismicload

Seismic loads appear naturally in

seismically active areas. An earth-

quake moves the ground, leading

to the displacement of a founda-

tion. Due to its inertia of mass,

the building is unable to follow the

movements, causing a deformation

of the building. Due to the stiffness

of the building, restoring forces are

set, resulting in vibrations. Due to

the resonance phenomenon, the

larger range of vibrations are often

measured on the upper floors.

1.3.2 LOADCOMBINATIONS

Anchors can be subjected to

different kinds of loads (Picture

3.1). A load can refer to tension,

pressure or even only a share. In

most cases, however, the anchor

is subjected to a combination of

loads. load combinations increase

the complexity of the anchor

design because when we consider

the tension load and the share load

separately, it is possible that the

anchor is able to resist both loads.

A combination of these loads

can at any rate turn the situation

upside down, i.e. anchor will fail

under a combined load. Picture 3.1

shows different loads and combi-

nations.

N

N

N

V

V FR

N

e

VM

FR

e

VM

M

PICTURE3.1 Loadsandcombinations

1.3 lOADS AND ReSISTANCeS

BACKTOMAINMENU


1.3.3 RESISTANCEOFTHEANCHOR

The resistance of the anchor

depens on the type of the anchor.

The anchor can be an expansion

anchor, undercut anchor, screw

anchor or chemical anchor. each

anchor type has its own char-

acteristics in different service

conditions. It is very important

to notice and understand these

characteristics. Different types of

anchors are handled more closely

in chapter 1.5.

The resistance of the anchor is

greatly influenced by the base

material. The type and condition of

the base material is critical. The

base can be concrete (non-cracked

or cracked), masonry, aerated con-

crete or light aggregate concrete.

The softer or porous the mate-

rial, is the lower is the resistance.

Despite this fact the resistance of

the anchor is often strong enough

to overcome the strength of the

material. The situation is often dif-

ferent in non-cracked and cracked

concrete.

If a crack exists, the load bearing

mechanisms are seriously dis-

turbed because no ring-shaped

tensile forces can be taken up

beyond the edge of the crack. This

will reduce the load bearing capac-

ity of the anchor system. The width

of a crack in the concrete has a

major influence on the tensile

loading capacity of anchors. In the

official approvals the crack width is

limited up to 0,3 mm, eliminating

the need to have comprehension

charts between tension forces and

crack widths.

1.3.4 FAILUREMODES

Anchors can fail for different rea-

sons. That’s why it is important to

make a distinction between failure

modes caused by tension load and

share load.

1.3.4.1 Tensionload

The following failure modes are

valid for expansion and undercut

anchors. The same kind of failure

modes can also occur in chemical

anchors (Picture 5.3).

When a pull-out occurs (Picture

3.2a), the anchor is extracted or

removed from the hole without

remarkable damage to the hole.

The shallow surface cone may be

noticed, but it is irrelevant to the

break load. Pull-out failure can

occur in undercut anchors only if

the mechanical interlock is inad-

equate. Curve 4a in picture 3.3

demonstrates a representative

load-displacement relationship for

a drop-in anchor. Pull-out failure

can also occur for torque controlled

expansion anchors when the follow-

up expansion of the anchor does not

develop properly (Picture 3.3 curves

4c and 4d). Curve 4b in picture 3.3

shows the load-displacement be-

haviour for an undercut anchor as a

result of a pull-out.

Pull-through (Picture 3.2b),

where the cone is pulled through

the expansion clip, is unique to

the torque controlled expansion

anchors. It is a failure mode that is

consistent with the correct func-

tion of the anchor. The ultimate

capacity is, however, reduced,

compared with an anchor of equal

embedment failing by concrete

cone failure. The load-displace-

ment behaviour is similar to un-

dercut anchor by pull-out failure

(Picture 3.3 curve 4b).

As a result of concrete cone

failure (Picture 3.2c), the anchor

creates a cone formed concrete

fragment starting through the

expansion or undercut zone of the

anchor. If several closely spaced

anchors are used in the same

base plate, then a combined con-

crete cone failure may occur (Pic-

ture 3.2d). If anchor is installed

near to the edge of concrete, the

breakout cone will resemble pic-

ture 3.2e. The load-displacement

curve for concrete cone failure is

shown in picture 3.3 curve 2.

In general, splitting failure oc-

curs when the dimensions of the

concrete block are limited (Pic-

ture 3.2f). As a result of splitting

failure, the whole concrete block

can split or splitting can oc-

cur between two closely spaced

anchors. Moreover reduced edge

distances can lead to splitting.

The load-displacement curve for

splitting is shown in picture 3.3

curve 3.

The failure of the steel stud, bolt

or nut represents the highest

achievable load bearing capacity

of the anchor (Picture 3.2g). Steel

failure occurs rarely and then only

in high-strength concrete. The

load-displacement curve for steel

failure is shown in picture 3.3

curve 1. Note that this anchor has

a deeper embedment depth than

the anchor associated with curves

2, 3 and 4.



PICTURE3.2 Failuremodesduetothetensionload

A)PULL-OUT B)PULL-THROUGH C)CONEFAILURE,ONEANCHOR D)CONEFAILURE,SEVERALANCHORS

E)CONEFAILURE,EDGE F)SPLITTINGFAILURE G)STEELFAILURE

LOAD F

DISPLACEMENT

1 STEELFAILURE

2 CONCRETEFAILURE

3 SPLITTINGFAILURE

4APULL-OUT,DROP-INANCHOR

4BPULL-OUT/PULL-THROUGH

4CPULL-OUT

4DPULL-OUT

1

2

3

4A

4B

4C

4D

PICTURE3.3 Idealisedload-displacementcurvesfortensionloadedanchors.



1.3.4.2 Shearload

The shear load is resisted first via

friction generated by the preload

in the anchor. When the shear

load exceeds the available friction

resistance, the base plate slips

to engage the anchor in bear-

ing. As the shear load increases,

the bearing stress in the surface

concrete increases until a shallow

spall occurs which will increase

the lever arm and the associated

flexural stress in the anchor. With

a sufficient embedment depth, the

anchor may be capable of resisting

the load avoiding the failure of the

anchor bolt.

Anchors with sufficient edge

distances and embedment depths

can fail as a result of steel failure

(Picture 3.4a). For a given an-

chor, steel failure represents the

ultimate shear capacity. Relatively

large displacements can be de-

tected in anchors made of ductile

steels.

Short and thick anchors with limit-

ed embedment depth can produce

sufficient rotation to cause a pry-

out failure. Anchor groups can also

develop a common pry-out failure.

Pry-out failure is not dependent on

free edges (Picture 3.4b).

An anchor set close to the edge

and loaded in the shear towards

the free edge, may fail as a result

of development of a semi-conical

fracture surface in the concrete

(Picture 3.4c). A group of anchors

loaded in the shear may develop a

common conical fracture surface

(Picture 3.4d). An anchor installed

in the corner of the concrete

member can fracture the entire

corner of the member (Picture

3.4e).

PICTURE3.4 Failuremodesduetotheshareload

A)STEELFAILURE B)PRY-OUTFAILURE

C)EDGEFAILURE,ONEANCHOR D)EDGEFAILURE,SEVERALANCHORS

E)EDGEFAILURE,INTHECORNER



1.4INSTALLATION

1.4.1GENERAL

An anchor can work properly only

if it is correctly installed.

A drill hole has to be in the right

angle to the base material. It

should be observed that reinforce-

ment bars aren’t damaged or

drilled thorough. If reinforcement

bars are damaged, it could be pos-

sible that the load bearing capac-

ity of the construction is reduced

or even the load resistance of the

anchor may be reduced. That’s

why it is recommended accord-

ing to the design of anchorage to

place anchors to avoid contact with

reinforcement bars.

The fixing thickness has to be

chosen so that the thickness of the

non-bearing structure (plaster, in-

sulation, etc.) and the fixture thick-

ness are complied with. The holes

in the fixture should also conform

to the standard (see eTAG AnnexC,

Table 4.1) and these base plate

does not undergo deformation un-

der the load. This means that the

base plate has to be rigid and fully

placed against the base material,

excluding by distance installation.

If the bore holes in the fixture do

not conform to the standard, this

can cause decrease in the capacity

of the anchor.

1.4.2DRILLBITS

Carbide drill bits used for drill-

ing holes for anchors, should be

checked to meet the dimensional

requirements of anchor manu-

factures. This means that espe-

cially the measurements and the

concentricity of the tip need to

be checked. Typically either the

ISO-norm or the national norm are

used as a reference to determine

the suitability of the drill bit. Ap-

proved drill bits are marked with a

special sign (Picture 4.1). Further-

more all additional tools should

conform to the manufacture’s

recommendations. To achieve

the best performance of drill bits

and to avoid possible damage, the

drill should always conform to the

manufacturers’ recommendations

(speed of rotation/impact, frequen-

cy/impact force).

1.4.3 DRILLINGTECHNIQUES

Drilling techniques are often

undervalued, however, the right

drilling technique will even ensure

the proper function of the anchor.

Some base materials are very

sensitive to correct drilling and

they may even break as a result of

improper drilling. Moreover, the

service life of drill bits is affected

by the drilling technique; especial-

ly large drill bits are sensitive to

overheating, if the rotation speed

or impact frequency is too high.

Picture 4.2 shows various drilling

techniques and the recommended

usage targets.

PICTURE4.1 RockDrillAssociation(Prüfgemeinschaft

Mauerbohrere.V)Germany.Approvalforthedrillbit

accordingtoInstituteofConstructionTechnique(Institut

fürBautech-nik,Germany):Approvalsignforcarbide

cuttingtipdrillbits.

DIAMONDDRILLINGOnly rotation. Normally wet drilling, occasionally also dry drilling. Suitable for all base materials.

PICTURE4.2 Variousdrillingtechniques

NODRILLINGThe anchor is hammered or screwed into thebase material. For example light gravel concrete and aerated concrete.

NORMALDRILLINGFor materials with low compression strength.

IMPACTDRILLINGRotation + low impact force with high frequency.Solid base materials (drill bits under ø20 mm).

ROTARYHAMMERRotation + high impact force with low frequency.Solid base materials (all sizes).

1.4 INSTAllATION

BACKTOMAINMENU


1.4.3.1 Faileddrilling

Drilling can be described as failed, if

The drill hole is made in wrong •

position

The drill bit has touches the •

reinforcement bar and the re-

quired drill hole depth is not met

The reinforcement bar is con-•

tacted so that correct installation

of the anchor is not possible

If the drilling is abortive, the an-

chor should not be installed. It is

important to respect minimum dis-

tances between the failed drill hole

and the new drill hole. As a rule

of thumb, the following distances

can be used (Table 4.1). Always

remember to check precise values

from approvals or from product

information, if available.

1.4.4 EDGEDISTANCESANDSPACING

edge distances and spacing have

a significant influence on the ca-

pacities of the anchors. If smaller

distances are used, the capacities

must also be reduced.

The characteristic edge distances

define “critical zones” for the

placement of anchors with respect

to an edge. The critical edge zone

has a width equal to the character-

istic edge distance. The resistance

of anchors falling within the criti-

cal zone are reduced. For clarity,

picture 4.3 includes the prohibited

zone as well as the critical zone.

Characteristic spacing defines

a critical zone around a given

anchor for placing of further

anchors. The critical spacing zone

has a radius equal to the charac-

teristic spacing. The resistance of

anchors falling within the critical

zone are reduced. For the sake of

clarity, the picture 4.4 includes

the prohibited zone as well as the

critical zone.

ANCHORTYPE DISTANCE/ACTIONMetal expansion Anchor > 2 x depth of the failed hole

Chemical Anchor Fill up the failed hole

Plastic Anchor> 1 x depth of the failed hole and> 5 x diameter of the anchor

TAble 4.1 COMMONRULESFORDISTANCESBETWEENFAILEDHOLEANDNEWHOLE

PROHIBITED ZONE

CRITICAL ZONE

FREE ZONE

Ccr

Cmin

C2

C1

PICTURE4.3 Influenceofedgedistance

Scr S

S = Scr Scr > S > Smin

S < Smin

PICTURE4.4 Influenceofspacing

A)NOINFLUENCE B)REDUCTIONOFTHELOADNECESSARY

C)RISKOFCRACKING,INSTALLATIONPROHIBITED

1.4 INSTAllATION


1.4.5 INSTALLATION

CLASSIFICATIONS

There are three different modes

of installation, with respect to

anchoring technique. In pre-

installation (Picture 4.5a) the hole

will be marked, then drilled, the

anchor installed, the fixture fitted

and tightened. In this installation

method the hole of the fixture and

the drill hole of the anchor will be

different.

In through installation (Picture

4.5b) the fixture will be inserted

first into the right position,

through the hole of the fixture

drilled into the base material. The

anchor is then installed through

the fixture and tightened without

displacing the fixture in between.

This type of installation is used

often to fix heavy or complicated

structures or equipment. This

installation method minimizes the

possibility of fault drilling.

Distance installation, also called

stand-off installation, is used

mainly in facades (Picture 4.5c). In

this case the fixture is positioned

apart from the base material.

This is possible for anchors with a

thick maximum fixture thickness

or for threaded rods with female

thread anchors. In this installation

method anchors are subjected to

additional moment.

A)PRE-INSTALLATION B)THROUGHINSTALLATION C)DISTANCEINSTALLATION

PICTURE4.5 Installationmethods

1.4 INSTAllATION


1.5FASTENINGSYSTEMS

ANDMODEOFACTIONS

1.5.1MECHANICALANCHORS

1.5.1.1General

Mechanical anchors can be char-

acterized by transmitting the load

from the anchor to the concrete by

direct contact and are classified

according to their physical prin-

ciples to transfer loads from the

anchor into the concrete (Picture

5.1).

1.5.1.2 ExpansionAnchors

expansion anchors produce

wedge forces and frictional forces

in the base material. With torque

controlled expansion anchors,

a specified installation torque

is applied, with cone or cones is

drawn into the expanding sleeve

segments. Due to the pretension

in the anchor rod or to an external

tensile load, the torque controlled

anchors expand further, however

only if the friction between the

cone and the sleeves is smaller

than between the sleeves and

the concrete. Torque controlled

anchors are mainly used for

group and single fastenings in the

medium and high load ranges.

Displacement controlled anchors

are expanded by driving the cone

into the sleeve (drop-in anchor) or

the sleeve over the cone (out-cone

anchor). These anchors are mainly

used for multiple fastenings in the

medium and low load range.

1.5.1.2.1 Torquesettinganchors

When torque is applied to the bolt

head or the nut of the anchor, the

cone is drawn up into the sleeve

to expand its effective diameter.

The reaction of the concrete to

the expanded sleeve of the anchor

creates a high friction force be-

tween the anchor and the wall of

the drilled hole (Picture 5.2).

Applied tensile loads are resisted

by the following elements:

The anchor bolt or stud.•

The wedge action of the steel •

cone in the sleeve.

Friction between the expanded •

sleeve and the drilled hole.

Shear and tension at the surface •

of the potential concrete cone.

1.5.1.2.2 Displacementsetting

anchors

The anchor is inserted into a

drilled hole and set by displacing

the expander plug (Picture 5.3).



The fixing element (bolt, stud…)•

The steel body of the anchor•

Friction between the expanded •

anchor and the drilled hole.



PICTURE5.1 Classificationofmechanicalanchors

PICTURE5.2 Torquesettinganchor

PICTURE5.3 Displacementsettinganchor

1.5 FASTeNING SYSTeMS AND MODe OF ACTIONS

FRICTION UNDERCUT UNDERCUT+FRICTION

DROP-INANCHOR THROUGHBOLT SHIELDANCHOR UNDERCUTANCHORS SCREWANCHOR

NOFURTHEREXPANSION FURTHEREXPANSION

BACKTOMAINMENU


1.5.1.3 Screwanchors

(Concretescrews)

The thread of the screw anchor

cuts into the concrete, transmit-

ting tensile loads by a threaded

undercut into the wall of the drill

hole (Picture 5.4). Friction avoids

the loosening and unscrewing of

the screw. The working principle

is a mixture of undercut anchors

and chemical anchors. The work-

ing principle can also be associ-

ated with the working principle of

the reinforcement bar. Concrete

screws are used normally for

medium loads.



The body of the anchor•

The thread cuts into the base •

material

The local compression strength •

of concrete in the location of the

thread


of the potential concrete cone

1.5.1.4 Undercutanchors

Undercut anchors are anchors

with parts that spread and me-

chanically interlock with the con-

crete base material. Much lower

expansion forces are produced

during installation and loading

than with expansion anchors. If

the shape of the undercut is well

adapted and its depth is sufficient,

an undercut anchor funktions vir-

tually identically to cast-in fixings,

i.e. both achieve the same ulti-

mate loads, because the undercut

anchor optimally uses the high

resistance to compression forces

of the concrete. Undercut anchors

are used to fix medium and high

loads with an excellent reliability.

1.5.1.4.1 Undercutanchor

With the use of the undercut-

ting tool, the conical shape of the

anchor fits into the conical cut of

the hole, developing the tensile

capacity of the bolt without any

slip or concrete failure (Picture

5.5). The undercut anchor works

like a cast-in anchor.



The stud•

The steel annulus, which fits •

into the conical cut


of the potential concrete cone

1.5.1.4.2 Selfcutting

undercutanchor

The anchor cuts into the concrete

by turning the nut (Picture 5.6).

Self-cutting anchors have at least

1,5 to 2 times higher resistances

than expansion anchors in general.



The stud•

The cutting action into the •

concrete



1.5.1.5 Workingprinciplesofme-

chanicalanchors

Anchors used in walls and on

floors are generally subjected

to shear or combined shear and

tensile loads. One of the few appli-

cations where anchors are sub-

mitted to pure tensile load is the

suspension of ceilings. Although

most of the anchors are sub-

jected to shear loads; the shear

resistance is mainly influenced

by the substrate. edge distances

and the quality of the substrate

more strongly influence the shear

behaviour than the tensile resis-

tance of the anchor. Furthermore,

to introduce the shear load into

the substrate, only the rod and,

if available, the sleeve with the

rod are relevant. The real anchor

mechanism, normally placed

deeply in the hole, only prevent

the anchor from slipping out at

further displacements.

PICTURE5.4 Screwanchors

PICTURE5.5 Undercutanchor

PICTURE5.6 Self-cuttingundercuttinganchor



1.5.1.6 Behaviourofmechanical

anchorsincrackedconcrete

In those areas where a concrete

member is under tensile stress,

the concrete is usually loaded over

its tensile capacity and the cracks

most often run through the anchor

holes. Drop-in anchors lose about

50 % of their bearing capacity in

a crack of 0,3 mm width, and the

capacity of torque controlled an-

chors is reduced 30 % of the value

attained in non-cracked concrete.

Some anchoring systems, which

are not approved for cracked con-

crete, can lose 90 % of their capac-

ity in cracked concrete (Picture 5.7).

Undercut anchors with sufficient

undercut depth may also be used

up to their full steel tensile capac-

ity in cracked concrete. The great

advantage of undercut anchors,

intelligently designed for steel

failure, is that the concrete quality

and the tensile or compression

zone need not be considered in

calculations. However, the de-

tailing rules concerning edge

distances and spacing must be

complied with.

If it is not proven in each case

that under a service condition the

anchor with its entire anchorage

depth is located in non-cracked

concrete, it must be assumed

that the installation will follow in

cracked concrete. (eTAG 001 An-

nex C, Paragraph 4.1)

The above-mentioned case covers

a large number of installations

into concrete. (Note! economical

design of concrete structures.)

1.5.2 CHEMICALANCHORS

1.5.2.1 General

Chemical anchors are character-

ized by the use of a bonding agent

fixing the anchor to the concrete

and are detailed by the applica-

tion method and the chemical

ingredients of the adhesive. The

usual application methods are the

capsule and the injection systems.

The ingredients are divided into

organic and inorganic compounds.

1.5.2.2 Workingprinciplesof

chemicalanchors

Similar to the mechanical anchors

the shear behaviour of the chemi-

cal anchors is mainly influenced

by the base material and the rod.

The mortar provides a very good

behaviour for dynamic loads by

filling the gap between anchor and

substrate completely and pre-

vents the system from displace-

ment. Therefore further expla-

nations focus only on the tensile

loads.

1.5.2.2.1 Chemicalanchors

The mortar penetrates the pores

and irregularities of the base ma-

terial and forms a key around the

threads of the stud. Cured mor-

tar transfers load onto the base

material via a mechanical and

adhesive bond (Picture 5.8).



The stud•

The bond between the stud and •

the mortar shear in the mortar

bond between the mortar and

the concrete.

Shear and tension in the con-•

crete.

TENSION LOAD

NON-CRACKED CRACKED CRACKED

100%

70%

NOT CRACK APPROVED ANCHOR

CRACK APPROVED ANCHOR

PICTURE5.7 Loadbearingcapacityofanchorsinnon-crackedandcrackedconcrete

PICTURE5.8 Thechemicalanchor



1.5.2.2.2 Designofchemical

anchorsfortensileloads

In adhesive anchors different

failure modes can be observed

(Picture 5.9). If the embedment

depth is small, usually a concrete

cone is pulled out. If the embed-

ment depth is deeper, a combined

failure including a shallow con-

crete cone with bond failure below

the cone is typically observed.

The bond failure can be at the

adhesive / concrete interface or

the anchor / adhesive interface or

a mixture of both. If the embed-

ment depth is deep enough, this

may lead to the steel failure in the

anchor. The minimum depth for

steel failure represents the basic

development length of the anchor,

which depends on the steel qual-

ity, the properties of the bonding

agent and the concrete quality.

The bond strength is dependent

on the type of the resin as well the

producer. The given bond strength

is valid only for an appropriate

product. Furthermore the com-

pression strength of the concrete

affects to the bonding. Gener-

ally, resin, approved for concrete

C20/25, can be used up to con-

crete strength C50/60. If the resin

is used for high strength concrete,

> C50/60, the bond strength may

decrease because of the smooth

surface of the bore hole. Given

values are valid typically both in

dry concrete and in hammer drilled

holes. The holes have to be cleaned

properly with an air pump and brush

and the instruction of the manufac-

turer also has to be followed, e.g.

the temperature and curing times

has to be complied with.

The cleanliness of the bore hole is

one of the most important things

to remember in installing chemi-

cal anchors. Depending on the

chemical anchoring system, the

load-displacement features can

dramatically degenerate. Glass

capsule systems are less

vulnerable because broken glass

and the ingredients of the capsule

clean the wall of the hole as a

result of the installation. As a rule

of thumb, the decrease of the bond

strength is ≤ 20 %.

With respect to injection resin

systems, is the bond strength

directly depends on the remaining

dust on the wall of the bore hole.

High quality resins are less sensi-

tive to the dust, but the decrease in

bond strength could be up to 60 %

(Picture 5.10).

PICTURE5.9 Differentfailuremodesofthechemicalanchorundertensionload

CONCRETE RESIN/CONCRETE ANCHOR/RESIN ANCHOR/RESINANDRESIN/ANCHOR

STEEL

TENSION LOAD

1 2 3 4

PICTURE5.10 Impactofintensityofcleaning

1 2XAIRPUMP 2XBRUSH 2XAIRPUMP

2 1XAIRPUMP 1XBRUSH 1XAIRPUMP

3 2XAIRPUMP

4 NOCLEANING



1.5.2.2.3 Behaviourofchemical

anchorsincrackedconcrete

To introduce the load introduc-

tion into substrate, it is neces-

sary to transfer the load from

the rod into the mortar and from

the mortar into the substrate.

The load transfer into the mortar

for anchors suitable in cracks

is normally achieved by a rod

with cones. The cones can be

described as an undercut in the

mortar. The size of the cone has

to be sufficient to transfer the

load in cracks up to 0,3 mm. The

roughness of the substrate is not

sufficient to transfer the load, if

the crack crosses the joint (Pic-

ture 5.11a). Therefore the aim is

to create the crack through the

mortar (Picture 5.11b). To prevent

detaching the mortar from the

substrate,s sometimes a coating

of the rod is used. It is evident that

also with coned rods, cracks open

first in the boundary surface of the

concrete and resin. However after

an increase in loading, cracks will

run through the mortar.

A)THREADEDROD B)SPECIALRODWITHCONES

PICTURE5.11 Pathofthecrack



1.6 OTHERASPECTS

1.6.1 SAFETYOFTHEANCHORAGE

Safety is the most important

aspect of construction. Therefore,

the so-called safety factor con-

cept has been created to compen-

sate for possible human errors or

irregularities in the material. The

safety factors for base materials,

anchor types, and failure modes

are given in valid approvals. Ap-

provals also include characteristic

loads ensured by several tests. A

permissible load is only a fraction

of the break load and that’s why

the variation of the base material,

installation errors and changes in

loading are taken into account.

Anchorage with high safety

requirements always requires

an engineering-based design,

including verifiable calculations

and construction drawings. There

are actually two different safety

factor methods available the

global safety factor method and

the partial safety factor method.

The partial safety factor is more

flexible and has broader utilization

possibilities, because it takes into

account the variation and ambigu-

ity of material or loads (dead load

and live load) as well as installa-

tion risks more effectively than

the global safety factor method.

In the fire design of anchors,

safety factors are considered

differently otherwise, it would

be impossible to reach adequate

results in anchor designing. The

safety factor for the action is

normally ≥ 1, but the resistance of

the anchor should conform to the

approval. In some cases reducing

the resistance may be necessary

for carbon steels to achieve the

desired fire rating.

Picture 6.1 shows the basic idea

of the global safety factor method

and picture 6.2 illustrates the idea

of the partial safety factor meth-

od. Pictures 6.3 and 6.4 exhibits

some special terminology used in

anchor design. The maximum load

shows the highest achieved load

in a test. The average value shows

the average of all measured maxi-

mum loads in a test. 5 %-fractile

is a statistics value, indicating that

only 5 % of the single values with

certain probability i.e. 90 %, are

below this value. The characteris-

tic resistance is the 5 % -fractile

of maximum loads of each failure

mode and load direction. The

design value for the resistance is

a characteristics resistance di-

vided with relevant safety factors

of material and installation. The

permissible load is the maximum

allowble load value in service

conditions

LOAD

MAX. LOAD

DISPLACEMENTPICTURE6.3 Load-displacementcurvewithamaximumload

1.6 OTHeR ASPeCTS

F5%(CHARACTERISTICSVALUE) FR=(F5%/Y)(PERMISSIBLELOAD)

PICTURE6.1 Globalsafetyfactormethod

CHARACTERISTICSVALUE DESIGNVALUE

RESISTANCE Rk Rd=Rk/YMRd≥Sd

ACTION Sk SD=SK*YF

PICTURE6.2 Partialsafetyfactormethod

BACKTOMAINMENU


1.6.2FIRERESISTANCE

OFTHEANCHORS

1.6.2.1 TemperatureCurves

Picture 6.5 shows the actual valid

temperature-time-assumptions

on which the fire tests for anchors

are based. The significant point of

the tunnel temperature curves is

the inordinately rapid increase of

the temperature over 1 000 ºC.

1.6.2.2 FireImpactonAnchors

It is customary, that electrome-

chanical installations, plumbing,

and false ceilings are fixed by an-

chors. These anchors guarantee

the safe access of the emergency

crews for the design fire load. The

anchors have to be designed to

withstand the impact of the rel-

evant temperature/time curve, i.e.

the emergency crews should not

be exposed to falling debris.

Anchors have been exposed to fire

tests under different fire curves

,for example, at the German

Institute IbMb of the Technical

University of brunswick, Germany.

Tensile loads of anchors made

of normal steel and of high-cor-

rosion resistant steel eN 1.4529

in cracks of 0,2 mm and direct

fire impact without protection of

the anchor have been tested. The

tests have shown the following

results:

At high temperatures, the base •

material breaks down (spalling

of concrete). The damaged area

increases with the duration of

the fire according to the tem-

perature exposure. Setting an

anchor deeper therefore, helps

to keep the anchor intact in a

concrete substrate.

Although metal does not burn, •

its loading capacity decreases

with increasing temperature

(especially from about 500 ºC

upwards). This is shown during

the fire test by slipping nuts or

breaking of anchor rods.

As the temperature increases, •

the loading capacity of the

base material and the anchor

decreases. The conclusion is

that the load must be reduced

below the level of the normal

recommended load necessary

for ordinary steel to achieve the

desired fire rating.

Fire tests have proven that the be-

haviour of stainless steel is better

than that of normal carbon steel.

Generally, it can be stated that the

tensile fire loads of stainless steel

are double that of carbon steel.

PICTURE6.4 Relativefrequencyofloads

1.6 OTHeR ASPeCTS

RELATIVE FREQUENCE

LOAD F

AVERAGE5%-FRACTILE


PICTURE6.5 Temperaturecurves

FireinMontBlanctunnel24.3.1999

1.6 OTHeR ASPeCTS

GENERAL REQUIREMENTS FOR FASTENINGS - SWEBOLT · 2012. 2. 27. · that concrete elements subjected...

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