Figure 11.6. Verification of Eq. 11.16 for the punching shear capacity of slabs with test results modification

Multiaxial states of stress

A short review of the major points on this subject, as treated in [1] and [2], is given by Faust in [30]. The text is cited here:

Major differences between LWAC and NDC arise from differences in transversal behaviour, strength under multiaxial state of stress, local compression and efficiency of confinement. All of these aspects are connected with each other and attributed to various LWAC phenomena. First, the transversal strain of LWAC at the maximum compressive load is in part considerably lower, although Poissons ratio in the elastic region is almost the same as for NDC. This is valid in particular for LWAC with lightweight sand, because of the minimum microcracking. The second reson is the lesser resistance of LWA to lateral pressure in comparison to dense aggregates. This leads to a higher compressibility under multiaxial loads due to the porous nature of LWA. Hence, increasing effects of lateral pressure on confined concrete sections are generally reduced in LWAC, Fig. 11.7.

Finally, the lower ratio between the tensile and the compressive strengths reduces the compressive bearing capacity of locally loaded LWAC (Fig. 11.8).

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