Strength experimental studies of multi-cavity floor slabs support sections in platform joints, taking into account partial pinching

Domestic standards for large-panel buildings design contain a methodology for calculating multi-cavity floor slabs in platform joints support sections, considering the effect of their partial pinching in walls. The calculation method is based on empirical relationships and does not take into account various factors that can significantly affect the stress-strain state of a join in general and a slab support section in particular. These include joint compression level, as well as the slab support depth. Since the specified features of the existing methodology can lead to incorrect assessment of the multi-cavity slabs supporting sections bearing capacity, experimental studies of platform joints with multi-cavity slabs at various compression levels, as well as sealing depths, have been carried out. When analyzing the test results, it was found that bearing capacity theoretical values calculated according to standard methods do not exceed the actual cracking moment values for most samples. This fact indicates that the methods under consideration assume sufficiently large safety margins. It is established that the magnitude of experimental negative bending moment that occurs on the slab support sections under load at the stage of a crack appearance on the support, considering the free support actual reaction, can reach the values of the theoretical moment obtained according to elastic scheme for support rigid pinching.