ISO 834-6 pdf download – Fire-resistance tests- Elementsof building construction – Part 6: Specific requirements for beams

ISO 834-6 pdf download – Fire-resistance tests- Elementsof building construction – Part 6: Specific requirements for beams.
6.3.2 When the proposed test specimen is smaller than the element in practice. it is important that the size of the test specimen, the type and level of loading and the support conditions be selected such that the same type of failure (for instance, a bending failure, a shear failure or a bond or an anchorage failure) will be decisive for the test specimen as for the construction it represents; i.e. the load applaed during the test shall provide the same load level as the real construction, For cases in which the decisive type of failure is difficult to predict, two or more tests. individually designed to cover in total all relevant types of failure, shall be required.
6.3.3 The magnitude and the distribution of the load shall be such that the maximLm’i moments arid shear forces prockiced are representative 04 or higher than those expected in practice.
6.3.4 The loading system shall be capable of applying the required load uniformly distributed or by a point loading system as appropriate. When point loads are used to produce bending moments In a distribution corresponding to a uniformly distributed load, these shall be not less than Iwo in number with a minimum separation of 1 m. When a four-point loading system is used, the points shall be normally located at 1/8, 3.8, 518 and 7)8 of the span (L,) from either end. The load shall be transferred to the beam through distribution plates not wider than 100 mm. The loading system shall not inhibit the tree movement of air above the top surface and, other than at the loading point, no part of the loading apparatus shall be closer than 60 mm from the surface.
6.3.5 The loading system shall be capable of compensating for the maximum allowable deformation 01 the test specimen.
7 Test specimen preparation
7.1 Specimen design
7.1.1 For test constructions with beams intended for lest with a floor or roof assembly rePresentative of actual construction, such an assembly can be an integral part of the test construction forming a ‘Tee’ beam arrangement. With steel beams, the slab is permitted to be of dense or lightweight concrete. The results of the former cannot be applied to the latter.
7.1.2 For test constructions with beams intended for test representative 01 the actual floor or roof that will be supported, the slab thickness shall reflect the design construction. The width of the actual floor shall be at least three times the beam width or at least 600 mm. whichever Is the greater. The actual width selected will depend on the furnace design.
7.1.3 For test constructions that do not indude a representation of the actual floor or roof, the beams shall support a symmetrically placed standardized topping defined as follows: a topping designed and manufactured in discrete sections, with discontinuous reinforcements when used, to avoid any composite action between it and the beam which might give additional strength and stiffness to the beam. The topping shall be made from aerated concrete slabs having a density of (650 ± 200) kgm3, each having a maximum length of 1 m and a thickness of at least (150 ± 25) mm. The width of the topping shall be at least three times the beam width or at least 600 mm. whichever is the greater. The actual width selected will depend on the furnace design.
7.1.4 Beams with hollow encasement shall have their ends blocked to prevent any flow of hot gases away from the beam. The mounting of the test specimen shall be such that the encasement does not terminate in the heating zone or is likely to collapse due to restraint to expansion that is contrary to its use In practice.
7.1.5 When in practice a beam incorporates a mechanical joint along its length, this shall be incorporated as in practice or at mid-span. When joints occur in fire protective claddings. specimens incorporating such protection shall include representative pints.
7.2 SpecImen size
7.2.1 For beams supported on rollers, the exposed length shall not be less than 4 m. The span between supports (t) shal be the exposed length plus up to a maximum of 100 mm at each end. The specimen length shall be the exposed length plus up to a maxrium of 200 mm at each end. A general arrangement of a simply supported bean, in the furnace is shown in Figure 1.