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AGG TECHNICAL BULLETIN – JULY 2014 Compliant Balustrading Solutions This technical bulletin is set out to clarify use of the balustrading section (7) of the current standard AS1288-2006, including the application of load information from loading standard AS/NZ 1170.1 The Building Code of Australia (BCA) has adopted the Glass Standard AS1288 for glass selection and installation. Glass selected within the parameters of the standard are considered as “deemed to comply” and require no further certification or engineering other that they fall within this standard. Amendments to the selection of glass in buildings code (AS1288) were made in 2006. This affected the use of frameless glass, and limits were introduced for the use of monolithic toughened panels traditionally used for balustrade, roof glazing and structural assemblies. A new section (Section 7) was introduced into the standard covering balustrades, where previously, all balustrades were briefly covered in two paragraphs. AS1288-2006 Glass in Buildings – Selection and installation. Section 7 Balustrades The general section classifies glass balustrade panels into either: (i) Structural, or (ii) Infill panels. Importantly, the design of a balustrade needs to allow for actions and effects arising from the loads as set out in AS/NZ 1170.0, AS/NZ1170.1 and AS/NZ1170.2 AS/NZ1170.1 sets out specific loads to be applied for barriers within defined building occupancy types. Type A – Domestic and Residential Activities Type B and E covers Office and work areas Type C – Areas where people may Congregate These are set out in Table 3.3. This is a key table. (refer Appendix 2) Many of the defined loads appear within the tables of Section 7 of AS1288-2006 and you will need to reference this table to interpret deemed to comply glass choices. It has a number of columns defining “Top Edge”, relating to structural balustrades, and “Infill”. Now armed with our barrier load information, we can approach the basic balustrade definitions and configurations within section 7. Purpose The Australian Glass Group issues technical bulletins to provide clarity on a range of technical aspects of high performance glass, including glass properties, performance , application and other interest areas. agg.com.au AGG VIC Knoxfield, VIC P: (03) 9730 7400 F: (03) 9730 7488 AGG NSW Girraween, NSW P: (02) 9896 0566 F: (02) 9896 0190 AGG QLD Brendale, QLD P: (07) 3205 5033 F: (07) 3881 1565
Transcript

AGG TECHNICAL BULLETIN – JULY 2014

Compliant Balustrading SolutionsThis technical bulletin is set out to clarify use of the balustrading section (7) of the current standard AS1288-2006, including the application of load information from loading standard AS/NZ 1170.1

The Building Code of Australia (BCA) has adopted the Glass Standard AS1288 for glass selection and installation. Glass selected within the parameters of the standard are considered as “deemed to comply” and require no further certification or engineering other that they fall within this standard.

Amendments to the selection of glass in buildings code (AS1288) were made in 2006. This affected the use of frameless glass, and limits were introduced for the use of monolithic toughened panels traditionally used for balustrade, roof glazing and structural assemblies. A new section (Section 7) was introduced into the standard covering balustrades, where previously, all balustrades were briefly covered in two paragraphs.

AS1288-2006 Glass in Buildings – Selection and installation.

Section 7 BalustradesThe general section classifies glass balustrade panels into either: (i) Structural, or (ii) Infill panels.

Importantly, the design of a balustrade needs to allow for actions and effects arising from the loads as set out in AS/NZ 1170.0, AS/NZ1170.1 and AS/NZ1170.2

AS/NZ1170.1 sets out specific loads to be applied for barriers within defined building occupancy types. • Type A – Domestic and Residential Activities • Type B and E covers Office and work areas • Type C – Areas where people may Congregate

These are set out in Table 3.3. This is a key table. (refer Appendix 2)

Many of the defined loads appear within the tables of Section 7 of AS1288-2006 and you will need to reference this table to interpret deemed to comply glass choices. It has a number of columns defining “Top Edge”, relating to structural balustrades, and “Infill”.

Now armed with our barrier load information, we can approach the basic balustrade definitions and configurations within section 7.

PurposeThe Australian Glass Group issues technical bulletins to provide clarity on a range of technical aspects of high performance glass, including glass properties, performance , application and other interest areas.

agg.com.au AGG VICKnoxfield, VICP: (03) 9730 7400F: (03) 9730 7488

AGG NSWGirraween, NSWP: (02) 9896 0566F: (02) 9896 0190

AGG QLDBrendale, QLDP: (07) 3205 5033F: (07) 3881 1565

Firstly, referencing 7.3.1 all glass needs to be A Grade safety.

The rest of Section 7.3 defines balustrade types and references which “deemed to comply” tables apply to each. These are listed as follows:

• 7.3.2 Structural balustrades – Cantilevered glass – Protecting a difference in level of less than 1000mm no handrail, or non-load supporting handrail. (Note requirement is for it to be continuously fixed along it’s base.)

• 7.3.3 Structural balustrades – Two-edge support (opposite edges) – Protecting a difference in level of less than 1000mm, no handrail, or non-load supporting handrail.

• 7.3.4 Structural balustrades – Three-edge support (Bottom and two sides) - Protecting a difference in level of less than 1000mm, no handrail, or non-load supporting handrail.

• 7.3.5 Structural balustrades – All Types – Protecting a difference in level equal or greater than 1000mm, with an interlinking handrail

• 7.3.6 Infill balustrades – Protecting any difference in level. o 7.3.6.1 – Four edge support o 7.3.6.2 – Two edge support (Full edge) o 7.3.6.3 - Two edge support (Mechanical fixings)

All of the above balustrade types, as described, refer you to one of a number of tables, where the load information described earlier will provide the limits of glass types to select.

• For Structural balustrade tables, when considering top edge line loads and point loads, the WORSE case solution is that selected.

• For Infill balustrade tables, when considering distributed or horizontal loads and point loads, the WORSE case solution is that selected.

If your balustrade fits within the definitions above, then the solutions are quite clear. However many balustrade designs fall outside the above

Section 7.3 – Selection of Balustrade Glass

Areas not covered within section 7 (What is missing?)There are no deemed to comply solutions concerning mechanically fixed cantilevered designs, both with and without interlinking and structural handrails. These include point fixing and spigot fixings and dry glazed systems which do not provide continuous fixing to the base of the panel.

There are no deemed to comply solutions concerning structural laminates, which do not rely purely on the glass strength to maintain rigidity. Structural interlayers provide increased strength and rigidity to laminate make-ups and were not considered at the time of the standard being written.

The limited deemed to comply solutions leave some confusion and ambiguity within the balustrade section of the code. There is some uncertainty as to what is legal & what constitutes a load bearing handrail. (ie a simple channel over the top is not a load bearing handrail!)

agg.com.au AGG VICKnoxfield, VICP: (03) 9730 7400F: (03) 9730 7488

AGG NSWGirraween, NSWP: (02) 9896 0566F: (02) 9896 0190

AGG QLDBrendale, QLDP: (07) 3205 5033F: (07) 3881 1565

Toughened glassMaximum glass height (mm)

Laminated toughened safety glassDesign loadkN/m

10mm 12mm 15mm 19mm 10mm 12mm 16mm 20mm

0.35

0.75

1.50

3.00

1100

820

470

250

6700.60kN*

16501330 221013202050 1070 1750

12801030 171010201590 820 1360

930640 13606301260 460 1040

460340 780310680 230 520

13801030 206010201850 640 1490

* Point load

There is provision within both the BCA and AS1288-2006, for alternative solutions to be considered for materials which can be proven to meet the requirements of the standard. In the case of section 7, materials need to satisfy the performance requirement of the standard. (ie withstand the loading standard AS/NZ 1170). However these solutions need to be verified through expert opinion, backed by evidence of compliance. The use of suitably qualified engineers, who can verify through basic finite analysis of materials and compilation of an “Alternate Solution Report”, can verify designs and configurations outside those defined within the code.

This Alternative Solutions Report needs to include a full analysis of each panel, (tensile strength is examined and modelled with fixing types, height of cantilever and obviously the load that requires to be met). It is a comprehensive and site specific report.

There remains some debate amongst some certifiers as to the legality of the handrail free applications due to concerns over the ability of a bottom fixed panel to withstand required loads when one or both components of the panels are broken.

• Firstly, we are not aware of any material that is expected to fully perform when fractured or broken. The intent of the standard was to prevent unimpeded openings to be caused when damage occurred, such as could occur in a monolithic toughened application.

• Secondly we would point out that a broken structural laminated cantilevered panel will leave no unimpeded opening, particularly when compared to a fully compliant toughened and handrail design, where if the toughened fails, it leaves only the handrail to prevent fall, also creating a tremendous risk to small children.

Given the lack of definitive criteria, if considering a cantilevered frameless design, it is important that the certifier is involved in the planning stage to ensure they are accepting of the documentation involved.

I have also attached extracts of the loading standard table 3.3 and Section 7 tables for illustration and example of how the loads applied within the “deemed to comply” context.

Areas not covered within section 7 (What is missing?) Cont’d

Appendix 1 - Table 7.1 – Cantilevered Glass – AS1288-2006 extract

agg.com.au AGG VICKnoxfield, VICP: (03) 9730 7400F: (03) 9730 7488

AGG NSWGirraween, NSWP: (02) 9896 0566F: (02) 9896 0190

AGG QLDBrendale, QLDP: (07) 3205 5033F: (07) 3881 1565

Horizontal VerticalInwards,

outwards ordownwards

Horizontal Anydirection

Type of occupancy for partof the building or structure Specific uses

kN/m kN/m kN kPa kNAll areas within or serving exclusively one dwelling including stairs, landings, etc. but excluding external balconies and edges of roofs (see C3)

0.35 0.35 0.6 0.5 0.25

A Domestic andresidential activities

Other residential, (see also C) 0.75 0.75 0.6 1.0 0.5

Light access stairs and gangways not more than 600

0.22 0.22 0.6 N/A N/A

Fixed platforms, walkways, stairways and ladders for access (see Note)

0.35 0.35 0.6 N/A N/A

B, E Offices and workareas not includedelsewhere includingstorage areas

Areas not susceptible to overcrowding in office and institutional buildings also industrial and storage buildings

0.75 0.75 0.6 1.0 0.5

C Areas where people may congregate

C1/C2 Areas with tables orfixed seating

Areas with fixed seatingadjacent to a balustrade,restaurants, bars, etc.

1.5 0.75 0.6 1.5 1.5

Areas without obstacles for moving people and not susceptible to over-crowding

Stairs, landings, external balconies, edges of roofs, etc.

C5 Areas susceptible toover-crowding

Theatres, cinemas, grand-stands, discotheques, bars, auditoria, shopping malls (see also D), assembly areas, studios, etc.

3.0 0.75 0.6 1.5 1.5

D Retail areas All retail areas including public areas of banks/build-ing societies, (see C5 for areas where overcrowding may occur)

1.5 0.75 0.6 1.5 1.5

C3

Pedestrian areas in car parks including stairs, landings, ramps, edges of internal floors, footways, edges of roofs

1.5 0.75 0.6 1.5 1.5

F/G Vehicular

Horizontal loads imposedby vehicles

See Clause 3.8

NOTE: This usage (under B, E) is for access to and safe working at places normally used by operating, inspection, maintenance and servicing personnel.

5.00.16.057.057.0

Infill Top edge

Appendix 2 - Table 3.3 – Minimum Imposed Actions for Barriers – AS/NZ 1170.1-2002 extract

The Australian Glass Group disclaims any liability for loss or damage arising from the use of this bulletin.This publication is issued as a general guide for information purposes only. Any product information, performance data or recommendations contained within should not be substituted for independent detailed technical advice. AGG provided information on a wide variety of products and makes no representatives concerning a product’s fitness for a particular purpose or merchantability. Persons receiving this information are responsible for obtaining independent advice to determine a products completeness and suitability for a particular application, including but not limited to conformity to the Australian Glass Standard AS1288-2006 and regulatory building codes.

agg.com.au AGG VICKnoxfield, VICP: (03) 9730 7400F: (03) 9730 7488

AGG NSWGirraween, NSWP: (02) 9896 0566F: (02) 9896 0190

AGG QLDBrendale, QLDP: (07) 3205 5033F: (07) 3881 1565


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