NCC 2019 Volume One
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Specification C1.8 Structural tests for lightweight construction
1. Scope
This Specification describes tests to be applied to and criteria to be satisfied by a wall system of lightweight construction.
This Guide does not address, in detail, every provision in this Specification.
Lightweight construction is more susceptible to damage than other forms of fire protection. It therefore needs protection to preserve its integrity in a fire.
Specification C1.8 describes a number of tests on walls of lightweight construction which can be used to demonstrate their acceptance as a fire protection system under the Deemed-to-Satisfy Provisions.
2. Application
A wall system need not be tested in accordance with this Specification for static pressure or impact if it is designed and constructed in accordance with the Deemed-to-Satisfy Provisions of Section B to resist the appropriate pressures and impacts defined in this Specification.
3. Tests
3.1
Walls of certain Class 9b buildings
Lightweight construction forming—
(b)
an external and internal wall bounding a public corridor, public lobby or the like, including a fire-isolated and non fire-isolated passageway or ramp, in a spectator stand, sports stadium, cinema or theatre, railway or bus station or airport terminal, must be subjected to the following tests and must fulfil the following criteria:
(i)
The materials tests of Clause 5(a) and the criteria of Clause 6(a).
(ii)
A static test by the imposition of a uniformly distributed load of 1.0 kPa (or its equivalent) in accordance with Clause 5(b) and the damage and deflection criteria of Clauses 6(b) and (c) respectively.
(iii)
A dynamic test by the fall of the impact bag through a height of 350 mm in accordance with Clause 5(c) and the damage and deflection criteria of Clauses 6(b) and (d) respectively.
(iv)
The surface indentation test of Clause 5(d) and the surface indentation criterion of Clause 6(e).
3.2
Walls of shafts and fire-isolated exits generally
A wall of lightweight construction that is required to be fire-resisting and which bounds a lift shaft, stair shaft, or service shaft, fire-isolated passageway or fire-isolated ramp must be subjected to the following tests and must fulfil the following criteria:
(a)
The materials tests of Clause 5(a) and the criteria of Clause 6(a).
(b)
A static test by the imposition of a uniformly distributed load of 0.35 kPa (or its equivalent) in accordance with Clause 5(b) and the damage and deflection criteria of Clauses 6(b) and (c) respectively.
(c)
A dynamic test by the fall of the impact bag through a height of 150 mm in accordance with Clause 5(c) and the damage and deflection criteria of Clauses 6(b) and (d) respectively.
(d)
The surface indentation test of Clause 5(d) and the surface indentation criterion of Clause 6(e).
3.3
Additional requirements for lift shafts
(a)
In addition to the requirements of Clauses 3.1 and 3.2, a wall system for use in a lift shaft that is required to be fire-resisting must be subjected to dynamic test by the imposition of—
(i)
where the lift car speed is 7 m/s or less — 106 cycles of a uniformly distributed load between 0 and 0.2 kPa (or its equivalent); or
(ii)
where the lift car speed is greater than 7 m/s — 106 cycles of a uniformly distributed load between 0 and 0.35 kPa (or its equivalent) in accordance with Clause 5(e) and must fulfil the damage criteria of Clause 6(b).
(b)
The wall system must be subjected to the static test in accordance with Clause 3.2(b) after the successful conclusion of the dynamic test specified in (a).
3.4
Walls generally
An external and internal wall of lightweight construction that is required to be fire-resisting, other than one covered by Clauses 3.1, 3.2 or 3.3, must be subjected to the following tests and must fulfil the following criteria:
(a)
The materials tests of Clause 5(a) and the criteria of Clause 6(a).
(b)
A static test by the imposition of a uniformly distributed load of 0.25 kPa (or its equivalent) in accordance with Clause 5(b) and the damage and deflection criteria of Clauses 6(b) and (c) respectively.
(c)
A dynamic test by fall of the impact bag through a height of 100 mm in accordance with Clause 5(c) and the damage and deflection criteria of Clauses 6(b) and (d) respectively.
(d)
The surface indentation test of Clause 5(d) and the surface indentation criterion of Clause 6(e).
4. Test specimens
4.1
General
Testing must be carried out on either—
(a)
construction in-situ; or
(b)
a laboratory specimen of the construction.
4.2
Testing in-situ
If testing is carried out in-situ, it must be done on that part of the construction least likely, because of the particular combination of the height of the walls, the support conditions and other aspects of the construction, to resist the loads.
4.3
Testing of specimens
If a laboratory specimen is tested, the specimen must span only in the direction corresponding to the height of the wall and testing must be done in accordance with either (a) or (b) below:
(a)
The test specimen—
(i)
height (or length, if the specimen is tested horizontally) must be identical with the height between supports in the actual construction; and
(ii)
must be supported at the top and bottom (or at each end if tested horizontally) by components identical with, and in a manner identical with, the actual construction.
(b)
If the distance between supports of the actual construction is more than 3 m, then a smaller specimen may be tested but—
(i)
the distance between supports must be not less than 3 m; and
(ii)
forces, reactions and support conditions must be modelled so as to reproduce the behaviour of the actual construction if it were tested in-situ.
5. Test methods
Tests must be carried out in accordance with the following:
(a)
Material tests — The methods specified for the constituent materials of the construction of the standards adopted by reference in the BCA.
(b)
For resistance to static pressure — The provisions for testing walls under transverse load in ASTM E72-15, except that—
(i)
support conditions must be as specified in Clause 4.3; and
(ii)
equivalent load shall mean the quarter-point load that produces the same deflection or central moment as appropriate; and
(iii)
the timber species nominated in that standard may be substituted with a different species.
(c)
For resistance to impact — The provisions for testing wall systems in ASTM E695-03, except that—
(i)
the point of impact must be set 1.5 m above finished floor level or 1.5 m above the part of the specimen that corresponds to finished floor level; and
(ii)
the impact bag must be not less than 225 mm in diameter and not more than 260 mm in diameter and have a mass of not less than 27.2 or more than 27.3 kg; and
(iii)
the mass must be achieved by putting loose, dry sand into the bag and must be adjusted before each series of impact tests; and
(iv)
where the impact bag and suspension cannot be vertical at the instant of impact on a curved surface or an inclined surface, the height of drop is the net height at the point of impact.
(d)
For resistance to surface indentation — The test for resistance to surface indentation must be carried out at three points on the surface of an undamaged sample sheet as follows:
(i)
A steel ball of 10 mm diameter with a load of 150 N must be placed gently on the surface of the sheet and allowed to remain in position for 5 minutes.
(ii)
The ball and load must then be removed and the diameter of each impression of the ball on the surface measured.
(e)
For resistance of lift shaft construction to repetitive load — As for 5(b) except that—
(i)
it is sufficient to test one specimen with the pressure applied from the side of the construction on which the lift will operate; and
(ii)
the load must be applied dynamically at a frequency not less than 1 Hz and not more than 3 Hz; and
(iii)
equivalent load shall mean the quarter-point load that produces the same central moment as the distributed load.
6. Criteria for compliance
The wall system or the specimen of it must fulfil the following criteria:
(a)
Materials — Materials must comply with the applicable standard adopted by reference in the BCA.
(b)
Damage — There must be no crack, penetration or permanent surface-deformation to a depth of more than 0.5 mm or any other non-elastic deformation or fastener failure.
(c)
(d)
(e)
Surface indentation — No impression must be more than 5 mm in diameter.