Precast Concrete Frames with Emulative Connections Subjected to Progressive Collapse

摘要

This paper documents an experimental study on load-transfer mechanisms of six precast concrete (PC) frames with different emulative connections to resist progressive collapse. Load-transfer mechanisms, such as compressive arch action (CAA) and catenary action (CA), were observed during the loading history, while the CA dominated the ultimate load capacity. The robustness of PC frames assembled by mechanical couplers or U-shaped bars was evaluated experimentally and analytically. To improve the robust-ness of PC frames assembled by U-shaped bars, two refined strat-egies were introduced: 1) adding additional straight bars in the trough connection; and 2) replacing U-shaped deformed bars with plain bars. It was found that, with the additional straight bars in the beam troughs, the CAA capacity, CA capacity, and deforma-tion capacity can be increased. Replacing U-shaped deformed bars with plain bars can improve the CA capacity and deforma-tion capacity effectively, while it may decrease the CAA capacity slightly. To further understand the load-transfer mechanisms of PC frames with different connections, an analytical elaboration was conducted. It was demonstrated that, at the CAA stage, shear force (related to flexural action) dominated the load-transfer mecha-nisms. At the CA stage, shear force still dominated the load-transfer mechanisms of the beam-side column interface, while tensile axial force dominated the load-transfer mechanisms of the beam-middle column interface.

关键词