Horizontal and overhead glazing

Glass Horizontal and Overhead

Competent Person(Glazing)


Glass Floors and Stairs

Roof Lights and Canopies

1. Legal Framework

2. Design Principles

3. Calculation and Testing


1.Legal Framework2. Design Guidelines

3. Calculation and Testing


Regulation - PART B - STRUCTURAL DESIGN

B1 DESIGN REQUIREMENT(1) Any building and any structural element or component thereof shall be designed to provide strength, stability, serviceability and durability under all actions which can reasonably be expected to occur in accordance with accepted principles of structural design, and so that it will not impair the integrity of any other building or property.(2) Any such building shall be so designed that in the event of accidental overloading the structural system will not suffer disastrous or progressive collapse which is disproportionate to the original cause.(3) The requirements of sub-regulations (1) and (2) shall be deemed to be satisfied where such building is designed in accordance with SANS 10400-B.

4.2.1.2 The representative permanent, imposed and seismic loads and impact sources applied to the structure and structural elements shall be in accordance with the requirements of SANS 10160.

SANS 10400 The application of the National Building Regulations

Part B: Structural design4.2.1.1 The design working life of a building other than a category 1 building shall be not less than 30 years in respect of the structural system and non-accessible components, and 15 years for repairable or replaceable components and materials, such as claddings, roofing materials, exterior trims, and integrated components, such as windows and doors.

PART N - GLAZINGN1 TYPE AND FIXING OF GLAZING

(1) Any material used in the glazing of any building shall be of a secure and durable type and shall be fixed in an manner and position that will ensure that it will -(a) safely sustain any wind actions which can reasonably be expected;(b) not allow penetration of water to the interior of the building; and(c) be apparent, in the case of clear glazing, to any person approaching such glazing.

(2) Glass, plastics and organic coated glass shall be selected in order to provide, in the case of human impact, a degree of safety appropriate in relation to -(a) the position of the glazed area; and(b) the number and likely behaviour pattern of persons expected to be in close proximity to such glazed area.

(3) The requirements of sub-regulations (1) and (2) shall be deemed to be satisfied where the glazing material is selected, fixed and marked in accordance with SANS 10400-N.

SANS 10400 N - Glazing4.2.3 The thickness of panes of glass and flat solid polycarbonate sheeting, other than in lifts, shalla) be not less than that given in tables 1 to 6, orb) be determined by a competent person (glazing) in accordance with the requirements of SANS 10137, and be based on wind loads determined in accordance with the requirements of SANS 10400-B.

Table 1 — Dimensions for vertical glass supported by a frame on all sides in external walls in buildings where the height measured from the ground to the top of such wall does not exceed 10 m

SANS 101371 ScopeThis standard covers the design and installation of glazing and glazing materials used in buildings and is for applications described in SANS 10400-N, and for use by a competent person (glazing).NOTE 1 Compliance with this standard does not necessarily grant exemption from the need for compliance with the relevant national legislation (see foreword).NOTE 2 The design methods described in this standard may represent only one of many methods of determining glass thickness and strength requirements for a given situation. A competent person (glazing) may use any method of calculation they deem fit for purpose provided such method represents good engineering design practice, acceptable safety factors and deflections, and can be backed up by reference to reference material or test data.

SANS 10137:2011 Edition 46.6 Glass floors6.6.2 Imposed loads (for example, distributed load and point load) shall be in accordance with SANS 10160-2 which determines that a glass floor for a building classified in accordance with SANS 10400-A, as residential, will not necessarily use the same design floor load as an office.Design shall take into account the post fracture behaviour of the glass and that the design stress for glass declines with an increase in the time that the load is applied (see table 5)

SANS 10400 N - Glazing4.4 Safety glazing4.4.1 The performance of safety glazing material shall be in accordance with the requirements of SANS 1263-1 and the individual panes of safety glazing material shall be permanently marked by the installer in such a manner that the markings are visible after installation.

h) glazing applications are sloped or horizontal;

SANS 204 Energy Efficiency in Buildings

1. Legal Framework

2.Design Principles3. Calculation and Testing


1. Glass is a brittle material.2. It has perfectly elastic behaviour until it is overloaded

and it snaps.3. Normally the overload is on a defect – a scratch or chip

that concentrates the force – so the shape or surface treatment affects the strength.1. Sandblasting2. Frit pattern

Design Principles

4. It does not fatigue like metals - Fatigue depends upon movement of defects in a metal's crystal structure called dislocations. Glass doesn't have a crystal structure or dislocations, so it won't fatigue in the same way. Glass can be loaded an infinite number of times at stresses below the yield point without any reduction in strength.

5. Glass suffers from static fatigue – constant, or static loading, over time reduces the design strength.

Design Principles

Load Duration Factors adapted from ASTM E1300-02

Duration Factor3 s 1.0010 s 0.931 min 0.8310 min 0.7260 min 0.6412 h 0.5524 h 0.531 week 0.471 month 0.431 year 0.36Beyond 1 year 0.31

6. Safety glazing to be used that does not fall or if it falls is safe.

7. People generally do not like to walk on glass. Do not let it deflect too much.

Design Principles

Glass Floors.1. Small deflection – much less than the

glass thickness.2. Use standard design formulas like Roark.3. Four edge support and two edge.4. Design loads from SANS 10160 Part 2.

1. Point load plus self weight2. Distributed load plus self weight

5. If the bottom leaf breaks the rest of the construction must take the load

5.3 Ultimate limit states5.3.1 Ultimate limit states relate to the following:a) the safety of people; andb) the safety of the structure.

5.4 Serviceability limit states5.4.1 Serviceability limit states apply to the following requirements for the structure under normal use:a) the functioning of the structure or structural members;b) the acceptability of the structure by users in terms of perceived safety and wellbeing; (for example deflection) andc) the appearance of the structure. (for example distortion)

3.1.24serviceability limit statesstates that correspond to conditions beyond which specified service requirements for a structure or structural member are no longer met3.1.26ultimate limit statestate associated with collapse or with other similar forms of structural failure

9 Imposed loads on buildings9.1 Actions9.1.1 Imposed loads on buildings arise from occupancies such asa) normal use by persons,(impact loads, point loads on floors and roofs)b) furniture and movable objects (for example, moveable partitions, storage or the contents of containers),c) vehicles,d) anticipated rare events, such as concentrations of persons or of furniture, (point loads on roof lights due to maintenance and cleaning)e) the moving or stacking of objects which may occur during reorganisation or redecoration, andf) storage and industrial use.9.1.2 Imposed loads are modelled by uniformly distributed loads (wind load and self weight), line loads or concentrated loads or combinations of these loads.9.1.3 For the determination of imposed loads, the floor and roof areas of the building shall be subdivided into categories according to their use.9.1.4 Heavy equipment (for example, in communal kitchens, radiology rooms or boiler rooms) is not covered in this part of SANS 10160 and the appropriate floor loads shall be established in accordance with the principles given in SANS 10160-1.

9.3 Characteristic values of imposed loads9.3.1 Residential, social, commercial and administration areas9.3.1.1 Areas in residential, social, commercial and administration buildings shall be divided into categories according to their specific uses as shown in table 1.9.3.1.2 Independent of this classification of areas, dynamic effects shall be considered where it is anticipated that their occupancy will cause significant dynamic effects (see 5.2.3 and 5.2.5).9.3.1.3 The loaded areas for categories, as specified in table 1, shall be designed by using characteristic values, qk (uniformly distributed load) and Qk (concentrated load). The characteristic load, qk, is intended for the determination of general effects and Qk, for the determination of local effects.9.3.1.4 The characteristic values for, qk and Qk, are minimum values and shall be increased in the design where necessary.9.3.1.5 The loads, qk and Qk, shall not be applied simultaneously.9.3.1.6 For concentrated loads which arise from storage racks or from lifting equipment, Qk, shall be determined for the individual case (see 9.3.2).9.3.1.7 The concentrated load shall be considered to act at any point on the floor, balcony or stairs.9.3.1.8 Where floors are subject to multiple use, they shall be designed for the most unfavourable category of loading which produces the highest effects of actions (for example, forces or deflection) in the member under consideration.

1. Design to deflection limit 2. Distributed load plus self weight/thickness.

SANS 10160 Part 2.

Distributed load

Stress MPa

Point Load

StressMPa

Layered

1.5 0.71 1.5 2.73 4.712.0 0.87 1.5 2.73 4.713.0 1.19 1.5 2.73 4.714.0 1.51 3.0 5.44 9.44 (7.70)

Includes self weight.

1 x 1 m simply supported 3 x 10 mm

Distributed load

Stress MPa

Point Load

StressMPa

Layered

2.5 0.71 4.5 8.17 14.153.0 1.19 4.5 8.17 14.153.0 1.19 5.0 9.07 15.735.0 1.83

Includes self weight.

1 x 1 m simply supported 3 x 10 mm

Glass Roofs.

1. Large deflection – much more than the glass thickness.

2. Non-linear behaviour.3. Generation of web stresses

Glass Roofs.1. Large deflection – much more than the glass

thickness.2. Non Linear behaviour.3. Generation of web stresses 4. Use standard design formulas like Roark

will give a conservative design.5. Four edge support and two edge.6. Design loads from SANS 10160 Part 2.

1. Point load2. Distributed load plus self weight.

Distributed load

Stress MPa

Point Load

StressMPa

Layered

0.5 5.1 1.0 45.4 640.75 7.1 1.0 45.4 642.0 17.1 2.0 90.7 128 (26mm)

Suggests 10.38 minimumIncludes self weight.

1 x 1 m simply supported 6.38 mm

Australian Code AS 1288

6.5 SELECTION OF OVERHEAD GLASS6.5.2 Permanent, imposed and other actionsThe design pressure resulting from the weight of the glass (dead loads) shall be determined from Table 6.1. This design pressure shall be used in Clause 6.5.5 to determine the ultimate limit state design pressure for the combined loads.6.5.3 Wind actions – use wind load charts.

6 mm glass

6.5.4 Live Load (concentrated point load) application. Sloped overhead glazing with a live point load applied is deemed to comply with this Section if the glass is selected in accordance with Tables 6.3 to 6.6. When using Tables 6.2 to 6.5, the following limitations apply:(a) The point load shall be applied as a uniformly distributed load over a circular area of 0.01 m2.(b) Glazed panels inclined at less than 30° to the horizontal shall be capable of supporting the actions incidental to maintenance (1.8 kN in street awnings or 1.1 kN in other roofs).(c) Glazed panels, which are not in street awnings and inclined at 30° or more to the horizontal, shall be protected by boards or ladders laid over the glazed panels to support the actions incidental to maintenance (0.5 kN live load).(d) For a glazed panel supported on all edges, the point loading shall be applied at the centre.(e) For free glazing edges, the point load shall be applied adjacent to the centre of the free edge.

6.5.5 Combined loads (dead, wind)The combined design loads for sloped overhead glazing shall be calculated as follows:Case 1 Dead (maximum) + wind (downward)Case 2 Dead (minimum) + wind (upward)

Example:Horizontal Roof Light with a wind load perpendicular vertically downward on the glass supplied by the engineer of 600 Pa and vertically upward of 1200 Pa. Panel size is 1200 x 1200 mm.Aussie Code:1. Take weight of the glass and convert to Pa.

a. 6.38 – 6 x 2.5 x 9.81 = 147 Pab. 8.38 – 8 x 2.5 x 9.81 = 196 Pac. 10.38 – 10 x 2.5 x 9.81 = 245 Pa

2. Factor wind load upa. 6.38 – 6 x 2.5 x 9.81 = 147 – 1200 = - 1053 Pab. 8.38 – 8 x 2.5 x 9.81 = 196 – 1200 = -1004 Pac. 10.38 – 10 x 2.5 x 9.81 = 245 – 1200 = - 954 Pa

3. Factor wind load downa. 6.38 – 6 x 2.5 x 9.81 = 147 + 600 = 747 Pab. 8.38 – 8 x 2.5 x 9.81 = 196 + 600 = 796 Pac. 10.38 – 10 x 2.5 x 9.81 = 245 +600 = 845 Pa

Laminated

1200 x 1200 = 1.44 m2

6.38 is Ok to 3000 Pa

Example:Horizontal Roof Light with a wind load perpendicular vertically downward on the glass supplied by the engineer of 600 Pa and vertically upward of 1200 Pa. Panel size is 1200 x 1200 mm - AR = 1Aussie Code:4. Take point load for horizontal laminated annealed glass:

Gives 12.38 mm - or 8.38 mm if slope is more than 30o

Using Roark gives 10.38 mm using 1kN and 8.38 @ 0.5kN– 1.1kN gives 12.38

1. Legal Framework

2. Design Guidelines

3.Testing


4.2 General pre-requisitesThe general pre-requisites for the application of SANS10160 are as follows:a) the choice of the structural system and the design of the structure shall be made by a competent person;b) execution shall be carried out by personnel having the appropriate skills and experience;c) adequate supervision and quality control shall be provided during the execution of the work, namely, in the design offices, factories, plants, and on site;d) the construction materials and products shall be in accordance with the appropriate materials based structural design standards (see 4.1).e) the structure shall be adequately maintained; andf) the structure shall be used in accordance with the design assumptions.

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Glass Floor – Annealed Glass Supported on All Four EdgesSection of Elevation

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1. 30mm laminated safety glass marked with SABS 1263 Part 1 manufactured from three 10 mm thick (nominal) glass and PVB interlayers with flat ground and arrissed edge work. Non slip surface finish to architect specification. Translucent interlayer.

2. Structural silicone sealant DC 895 or equivalent approved to meet 1MPa tensile. Installed to comply with manufacturers warranty requirements. Minimum size 6 x 12 mm. Site application not allowed.

3. Preformed silicone setting blocks 80 Shore hardness compatible with structural seal, glass interlayer and supporting structure.

4. Fastenings to superstructure, M6 for location only, four per sub frame.

5. 316/304 Grade Stainless Steel non-supporting framework resting on superstructure, 40 x 40 x 4 mm.

6. Weather seal of silicone compatible with glass interlayer, silicone setting blocks and supporting structure.

• Glass to be marked in accordance with SANS 1263 Part 1.

• Not to scale – arrangement only.

• Measures to be taken to prevent galvanic corrosion

• Floor glass mock up to be design load tested prior to approval

Horizontal and overhead glazing

Engineering

Transcript of Horizontal and overhead glazing