Loading Methods Effect on Behavior of RC Beam-Column Sub-assemblages to Resist Progressive Collapse

This paper investigated the effect of different loading methods on the collapse mechanism of reinforced concrete (RC) structures by conducting tests on two RC beam-column sub-assemblages. Tests employed two loading methods, i.e., concentrated loading (CL) method and uniformly distributed loading (UDL) method. Failure modes and load-displacement curves of the sub-assemblages were obtained by the tests. The results revealed that the specimens subjected to different loading methods exhibited different failure modes. The CL method would over-estimate the deformation capacity of the sub-assemblages. The ultimate displacement of the specimen subjected to CL was 3.5% higher than that subjected to UDL. The ANSYS/LS-DYNA based finite element (FE) analyses were performed to discuss the effects of different initial uniform loads on UDL specimen beams. The FE results indicated that the deformation capacity decreased with the increase of initial uniform loads. A 200% increase in initial uniform load decreased the ultimate displacement by 10.3%. Moreover, comparison of results under single- and multi-point loading demonstrated that the failure modes of specimens were influenced by the number of loading points.