Behaviour of exterior precast concrete frames subject to column removal

This paper describes the behaviour of exterior precast concrete frames subject to column removal scenarios. Two frames, with 90° bend and lap-splice of bottom reinforcement in the joint, were tested under quasi-statie loading condition. Experimental results show that significant compressive arch action developed in the beam. However, the enhancement of compressive arch action to the nexural resistance of the frame was limited due to insufficient horizontal restraints provided by the side columns. At the catenary action stage, horizontal tension force acting on the side column resulted in crushing of concrete in the vicinity of the joint, and nexural failure of the side column occurred under combined axial compression force and bending moment. Conclusions are obtained from the experimental results that the side column and the beam-column joint have to be protected from nexural and shear failure to mobilise effective alternate load path in the bridging beam.