Progressive collapse-resisting mechanisms of planar prestressed concrete frame

Abstract

This paper presents the behavior of six tests of planar prestressed concrete frames under the loss of a middle column. The six tests consist of two non-prestressed reinforced concrete (RC) specimens and four prestressed concrete (PC) specimens with bonded post-tensioning tendons (BPT). The structural response of the specimens with different flexural reinforcement ratio, span-depth ratio, and effective prestress level has been reported. In addition, the impact of parabolic BPT on the behavior of RC frames to resist progressive collapse is also evaluated. Experimental results indicated that the BPT cannot only increase the initial stiffness and yielding load of the RC counterparts, but also increase the ultimate load capacity in the catenary action stage. Moreover, it will impact the load-resisting mechanisms and the failure modes. Contrary to the commonly accepted sequential mobilization of compressive arch action and catenary action to resist progressive collapse of RC frames, no effective compressive arch action is developed in PC frames to mitigate progressive collapse risk. Based on experimental observations, it is found that higher effective prestress in BPT results in enhanced initial stiffness and yielding load but less deformation capacity and ultimate load capacity. It is also found that higher non-prestressed flexural tensile reinforcement ratio could improve the behavior of PC specimens to resist progressive collapse.