PROGRESSIVE COLLAPSE ANALYSIS OF UNBONDED POST-TENSIONED PRECAST RC FRAME STRUCTURES USING COLUMN REMOVAL METHOD

To study the behavior of beam-column joints and the progressive collapse performance of unbonded post-tensioned precast concrete frame structures, finite element models were established in OpenSEES and compared with experimental results. With the established beam-column joint models, a six-story unbonded post-tensioned precast concrete frame and a cast-in-place concrete frame with similar structural configurations were simulated. Progressive collapse analysis was performed for these two kinds of frames using column removal method. Results of the numerical analysis show that, with the interior column removed, the ultimate load at failure of the post-tensioned precast frame is 24.2% higher than that of the cast-in-place frame; the percentage increased to 35.7% if an exterior column is removed. Removal of an exterior column is more likely to cause a progressive collapse than removal of an interior column. The results also show that with the same reinforcement layout of the column and the same flexural capacity of the beam, the post-tensioned precast RC frame exhibit better collapse-resisting performance than the cast-in-place RC frame.