NCC 2016 Volume One
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Specification A2.3 Fire-Resistance of Building Elements

Specification A2.3 Fire-Resistance of Building Elements

1. Scope

This Specification sets out the procedures for determining the FRL of building elements.

Deemed-to-Satisfy Provisions often require building elements to have an FRL. explains how these FRLs are to be determined and, in conjunction with Table 1, spells out how FRLs apply to specific building elements and materials.

2. Rating

A building element meets the requirements of this Specification if—

(a)

it is listed in, and complies with Table 1 of this Specification; or

(b)

it is identical with a prototype that has been submitted to the Standard Fire Test, or an equivalent or more severe test, and the FRL achieved by the prototype without the assistance of an active fire suppression system is confirmed in a report from a Registered Testing Authority which—

(i)

describes the method and conditions of the test and the form of construction of the tested prototype in full; and

(ii)

certifies that the application of restraint to the prototype complied with the Standard Fire Test; or

(c)

it differs in only a minor degree from a prototype tested under (b) and the FRL attributed to the building element is confirmed in a report from a Registered Testing Authority which—

(i)

certifies that the building element is capable of achieving the FRL despite the minor departures from the tested prototype; and

(ii)

describes the materials, construction and conditions of restraint which are necessary to achieve the FRL; or

(d)

it is designed to achieve the FRL in accordance with—

(i)

AS 2327.1, AS 4100 and AISC Guidelines for Assessment of Fire Resistance of Structural Steel Members if it is a steel or composite structure; or

(ii)

AS 3600 if it is a concrete structure; or

(iii)

AS 1720.4 if it is a timber element other than fire-protected timber; or

(iv)

AS 3700 if it is a masonry structure; or

(e)

the FRL is determined by calculation based on the performance of a prototype in the Standard Fire Test and confirmed in a report in accordance with Clause 3; or

(f)

for fire-protected timber, it complies with Specification A1.1 where applicable.

An FRL is expressed in terms of figures that cover structural adequacy, integrity and insulation.

Examples

Examples

A loadbearing wall may require an FRL of 120/60/30—meaning that in the Standard Fire Test the wall must retain its:

  • structural adequacy for at least 120 minutes;
  • integrity for at least 60 minutes; and
  • insulation properties for at least 30 minutes.

A non-loadbearing wall, however, may require an FRL of –/120/120—meaning that in a Standard Fire Test the wall is not required to retain any structural adequacy criterion. However, the wall must maintain its:

  • integrity for at least 120 minutes; and
  • insulation properties for at least 120 minutes

3. FRLs determined by calculation

If the FRL of a building element is determined by calculation based on a tested prototype—

(a)

the building element may vary from the prototype in relation to—

(i)

length and height if it is a wall; and

(ii)

height if it is a column; and

(iii)

span if it is a floor, roof or beam; and

(iv)

conditions of support; and

(v)

to a minor degree, cross-section and components; and

(b)

the report must demonstrate by calculation that the building element would achieve the FRL if it is subjected to the regime of the Standard Fire Test in relation to—

(i)

structural adequacy (including deflection); and

(ii)

integrity; and

(iii)

insulation; and

(c)

the calculations must take into account—

(i)

the temperature reached by the components of the prototype and their effects on strength and modulus of elasticity; and

(ii)

appropriate features of the building element such as support, restraint, cross-sectional shape, length, height, span, slenderness ratio, reinforcement, ratio of surface area to mass per unit length, and fire protection; and

(iii)

features of the prototype that influenced its performance in the Standard Fire Test although these features may not have been taken into account in the design for dead and live load; and

(iv)

features of the conditions of test, the manner of support and the position of the prototype during the test, that might not be reproduced in the building element if it is exposed to fire; and

(v)

the design load of the building element in comparison with the tested prototype.

requires that a prototype of an element being tested must be subjected to the Standard Fire Test, ie the Fire-resistance tests of Elements of Building Construction in AS 1530.4. When the Standard Fire Test is used to determine an FRL for the purposes of assessing compliance with the Deemed-to-Satisfy Provisions, the prototype cannot be assisted by fire sprinklers or any other fire suppression system during the Standard Fire Test. This limitation does not prevent the use of tests incorporating assistance by fire suppression systems in Performance Solutions.

4. Interchangeable materials

(a)

Concrete and plaster — An FRL achieved with any material of Group A, B, C, D or E as an ingredient in concrete or plaster, applies equally when any other material of the same group is used in the same proportions:

Group A: Any portland cement.

Group B: Any lime.

Group C: Any dense sand.

Group D: Any dense calcareous aggregate, including any limestone or any calcareous gravel.

Group E: Any dense siliceous aggregate, including any basalt, diorite, dolerite, granite, granodiorite or trachyte.

(b)

Perlite and vermiculite — An FRL achieved with either gypsum-perlite plaster or gypsum-vermiculite plaster applies equally for each plaster.

A non-loadbearing element need not comply with an FRL’s structural adequacy requirement.

5. Columns covered with lightweight construction

If the fire-resisting covering of a steel column is lightweight construction, the construction must comply with C1.8 and C3.17.

Some building elements have been tested and their FRLs calculated. Where these are known, they are included in .

Research results are generally available from the manufacturers who sponsor the tests. These results and other research will form the basis of future amendments to .

In recent years, a number of the Standards Australia structural codes have included provisions for the calculation of FRLs. Some more complicated building elements have many combinations and permutations, and reference to specific Australian Standards is necessary.

6. Non-loadbearing elements

If a non-loadbearing element is able to be used for a purpose where the Deemed-to-Satisfy Provisions prescribe an FRL for structural adequacy, integrity and insulation, that non-loadbearing element need not comply with the structural adequacy criteria.

Table 1 FRLs DEEMED TO BE ACHIEVED BY CERTAIN BUILDING ELEMENT

Building element Minimum thickness (mm) of principal material for FRL’s Annexure reference
Wall
60/60/60 90/90/90 120/120/120 180/180/180 240/240/240 Clause
Masonry
Ashlar - - - - 300 1, 2, 5, 6
Calcium silicate see 2(d)(iv) of this Specification
Concrete see 2(d)(iv) of this Specification
Fired clay (inc terracotta) see 2(d)(iv) of this Specification
Concrete
No-fines - - - 150 170 1, 5, 6
Prestressed see 2(d)(ii) of this Specification
Reinforced see 2(d)(ii) of this Specification
Plain - - - 150 170 1, 5, 6
Solid gypsum blocks 75 90 100 110 125 1, 5, 6
Gypsum — perlite or Gypsum vermiculite - plaster on metal lath and channel (non-loadbearing walls only) 50 50 65 - - 1, 5, 7
CONCRETE COLUMN
60/60/60 90/90/90 120/120/120 180/180/180 240/240/240 Clause
Prestressed see 2(d)(ii) of this Specification
Reinforced see 2(d)(ii) of this Specification
HOT-ROLLED STEEL COLUMN
60/60/60 90/90/90 120/120/120 180/180/180 240/240/240 Clause
(inc a fabricated column) exposed on no more than 3 sides: 8
Fire protection of Concrete — Cast in-situ—
loadbearing 25 30 40 55 75 9, 11, 12
non-loadbearing
unplastered 25 30 40 50 60 9, 11, 12
plastered 13mm— 25 25 30 40 50 1, 6, 9, 11, 12
Gypsum — Cast in-situ— - - - - 50 9, 11, 12
Gypsum — perlite or Gypsum-vermiculite plaster
sprayed to contour 20 25 35 50 55 1, 11
sprayed on metal lath 20 20 25 35 45 1, 7
HOT-ROLLED STEEL COLUMN
60/60/60 90/90/90 120/120/120 180/180/180 240/240/240 Clause
(inc a fabricated column) exposed on no more than 3 sides and with column spaces filled: 8, 9
Fire protection of —
Solid calcium-silicate masonry 50 50 50 50 65 1, 3, 11, 12
Solid clay masonry 50 50 50 65 90 1, 3, 11, 12
Solid concrete masonry 50 50 50 65 90 1, 3, 11, 12
Solid gypsum blocks 50 50 50 50 65 1, 3, 11, 12
Hollow terracotta blocks—
plastered 13mm 50 50 50 65 90 1, 3, 6, 10, 11, 12
HOT-ROLLED STEEL COLUMN
60/60/60 90/90/90 120/120/120 180/180/180 240/240/240 Clause
(inc a fabricated column) exposed on no more than 3 sides and with column spaces unfilled: 8, 9
Fire protection of —
Solid calcium-silicate masonry 50 50 50 - - 1, 3, 11, 12
Solid clay masonry 50 50 65 - - 1, 3, 11, 12
Solid concrete masonry 50 50 65 - - 1, 3, 11, 12
Solid gypsum blocks 50 50 50 - - 1, 3, 11, 12
Hollow terracotta blocks—
plastered 13mm 50 50 65 - - 1, 3, 6, 10, 11, 12
HOT-ROLLED STEEL COLUMN
60/-/- 90/-/- 120/-/- 180/-/- 240/-/- Clause
(inc. a fabricated column) exposed on 4 sides: 8
Fire protection of —
Concrete — Cast in-situ—
loadbearing 25 40 45 65 90 9, 11, 12
non-loadbearing
unplastered 25 30 40 50 65 9, 11, 12
plastered 13mm— 25 25 30 40 50 1, 6, 9, 11, 12
Gypsum — Cast in-situ— - - - - 50 9, 11, 12
Gypsum — perlite or Gypsum-vermiculite plaster
sprayed to contour 25 30 40 55 65 1, 11
sprayed on metal lath 20 20 30 40 50 1, 7
HOT-ROLLED STEEL COLUMN
60/-/- 90/-/- 120/-/- 180/-/- 240/-/- Clause
(inc. a fabricated column) exposed on 4 sides and with column spaces filled: 8, 9
Fire protection of —
Solid calcium-silicate masonry here 50 50 50 65 75 1, 3, 11, 12
Solid clay masonry 50 50 50 75 100 1, 3, 11, 12
Solid concrete masonry 50 50 50 75 100 1, 3, 11, 12
Solid gypsum blocks 50 50 50 65 75 1, 3, 11, 12
Hollow terracotta blocks—
plastered 13mm 50 50 50 75 100 1, 3, 6, 10, 11, 12
HOT-ROLLED STEEL COLUMN
60/-/- 90/-/- 120/-/- 180/-/- 240/-/- Clause
(inc. a fabricated column) exposed on 4 sides and with column spaces unfilled: 8
Fire protection of —
Solid calcium-silicate masonry here 50 50 50 - - 1, 3, 11, 12
Solid clay masonry 50 50 65 - - 1, 3, 11, 12
Solid concrete masonry 50 50 65 - - 1, 3, 11, 12
Solid gypsum blocks 50 50 50 - - 1, 3, 11, 12
Hollow terracotta blocks—
plastered 13mm 50 50 65 - - 1, 3, 6, 10, 11, 12
BEAM
60/-/- 90/-/- 120/-/- 180/-/- 240/-/- Clause
Concrete —
Prestressed see 2(d)(ii) of this Specification
Reinforced see 2(d)(ii) of this Specification
Hot-rolled Steel (inc. an open-web joist girder truss etc) exposed on no more than 3 sides: 8
Fire protection of —
Concrete — Cast in-situ— 25 30 40 50 65 11, 12
Gypsum — perlite or Gypsum-vermiculite plaster
sprayed to contour 20 25 35 50 55 1, 11
sprayed on metal lath 20 20 25 35 45 1, 7
Hot-rolled Steel (inc. an open-web joist girder truss etc) exposed on 4 sides: 8
Fire protection of —
Concrete — Cast in-situ— 25 40 45 60 90 11, 12
Gypsum — perlite or Gypsum-vermiculite plaster
sprayed to contour 25 30 40 55 65 1, 11
sprayed on metal lath 20 20 30 40 50 1, 7
FLOOR, ROOF OR CEILING
60/60/60 90/90/90 120/120/120 180/180/180 240/240/240 Clause
Concrete —
Prestressed see 2(d)(ii) of this Specification
Reinforced see 2(d)(ii) of this Specification