EXPERIMENTAL AND THEORETICAL ANALYSES ON ENTIRE COURSE OF VERTICAL PROGRESSIVE COLLAPSE OF SPATIAL RC FRAME STRUCTURES

A quasi-static test is carried out to experimentally study the vertical progressive collapse of a two-storey by two-bay spatial RC frame structure. The progressive collapse mechanism and collapse details of the residual structure due to a side column loss are simulated by unloading the jack, replacing the failure column. The experimental results indicate that: the whole vertical-collapse damaged-process of RC spatial frame structures can be divided into three stages, including an extrapolation stage (arch action stage), an adduction stage (catenaries action stage) and a collapse stage; the appearance of plastic hinges, which are relative to the binding effects of slabs on beams, can be put off or even be skipped; RC spatial frame structure has a fine anti-collapse performance, but the influence of cast-in-situ slabs on anti-collapse performance of a structure should be considered seriously; the theoretical method for maximum lateral displacement and the mathematical model and the method for the critical displacement of the slumping column are raised in the combination of an experimental research and a theoretical analysis; what is more, the structure damage indictor model was proposed.