RESEARCH PROGRESS ON LOAD-RESISITING MECHNISMS OF CONCRETE STRUCTURES TO RESISIT PROGRESSIVE COLLAPSE

To deepen the understanding of behavior of concrete structures to resist progressive collapse and better guide engineering practice, experimental studies and analytical models for the load-resisting mechanisms of concrete structures to resist progressive collapse are reviewed and summarized. The main conclusions are as follows: Existing experiments have focused mainly on cast-in-place reinforced concrete, precast concrete and flat-plate structures, whereas tests on prestressed concrete and masonry structures remain scarce. The primary collapse-resistant mechanisms of frame structures are flexural action, compressive arch action (CAA), catenary action (CA) of beams, and compressive membrane action (CMA) and tensile membrane action (TMA) of floor slabs. The punching-shear capacity of slab–column connections and the residual capacity after punching failure are closely related to the collapse performance of flat-plate structures. Similar to cast-in-place beams, precast frame beams with wet connections can develop CAA and CA, but precast slabs cannot effectively develop TMA. Traditional precast structures with welded or bolted connections exhibit poor progressive collapse resistance compared with wet-connected systems. Due to the presence of strands, prestressed concrete structures can markedly enhance the development of CA. Masonry infill walls can directly transfer part of the load through diagonal strut action, noticeably increasing the collapse resistance of frame structures. Comparing the calculated results from existing analytical models suggests that existing CAA models can predict the peak load reasonably well, but the calculations are cumbersome; existing CA models still have the problem of large prediction dispersion.