Experimental and numerical investigation on progressive collapse of self-centering precast concrete frame with infill walls

Two 1/2 scaled self-centering precast concrete (PC) frames with and without infill walls were experimentally and numerically investigated under quasi-static pushdown loading regime. The test results showed that the main failure modes of self-centering PC frames were concrete cracking and spalling at the beam ends. Compared with self-centering bare frame, since the infill walls undertook partial vertical loads, the concrete damage at the beam ends of self-centering infilled frame was reduced. Since the lower strength of AAC blocks and mortar, the presence of infill walls did not change the failure mode and failure location of self-centering PC frame. The infill walls with lower strength could still significantly enhance the initial stiffness and collapse resistance of the structure. However, infill walls also reduced the self-centering capacity of the structure. The simulation results indicated that the prestress force of steel strands between beams and columns had a greater effect on the structural resistance of self-centering PC frames. For the self-centering infilled frames, the progressive collapse-resisting capacity of infill walls mainly depended on the strength of bed joints, while the effect of the cross joints was negligible. When the mortar joints had a lower strength, the increase in block strength had limited effect on the increase in structural resistance. With the increase of strength of mortar joints, the effect of variation of block strength on the structural resistance became obvious. Finally, the proposed analytical method had a relatively better accuracy to predict the vertical resistance of self -centering PC frames.