Robustness Assessment of Exterior Precast Concrete Frames under Column Removal Scenarios

This paper describes an experimental investigation on the resistance and failure mode of four precast concrete frames. Each frame comprised a middle beam-column joint, a double-span beam, and two side columns. Two parameters, namely, reinforcement detailing in the beam-column joint and dimensions of the side columns, were investigated in the experimental program. Frame specimens were loaded on the middle joint by a vertical servohydraulic actuator, and corresponding horizontal reaction forces were recorded through load cells connected to the side columns. Experimental results and observations indicate that precast concrete frames were capable of developing compressive arch action (CAA) at the initial loading stage. However, frames with smaller side columns exhibited shear failure in the side joint. This hindered the development of catenary action in the bridging beam. By increasing the dimensions of the side columns, significant catenary action developed in the frames, and eventually flexural failure of the side columns took place resulting from horizontal tension force from the bridging beam. Experimental results suggest that horizontal forces induced by CAA and catenary action in the bridging beam have to be considered in the design of side columns and beam-column joints against progressive collapse.