Experimental Study On Seismic Performance Of An Innovative PC Frame With Infilled Walls

Five one-half scaled new type prefabricated precast concrete(PC)infilled frame specimens are subjected to cyclic lateral loads to systematically investigate their behavior to resist seismic loads.These five specimens have identical design details,dimensions,and axial force ratio.The effects of concrete material in post-poured joints,infilled walls,and openings on the behavior of PC frame to resist seismic loads are studied.Based on the observation of crack pattern and failure mode and evaluation of the earthquake resistant index such as load-displacement hysteretic loops,skeleton curve,stiffness degradation,energy dissipation capacity,and ductility coefficient,the load resisting behavior of the PC frames is captured.The general conclusions are drawn as below:(1)Less and thinner cracks and little damage are observed in the beam connection of these five specimens and the column joints are failed flexural,which is characteristically by yielding of longitudinal reinforcements and concrete crushing and no damage occurred in the mechanical couplers.This is indicated that the proposed new type PC frame performed well.It performs similar seismic behavior as the cast-in-place frame.(2)By comparing the behavior of infilled frame with the bare frame,it is indicated that the infilled wall could upgrade the load resisting capacity and initial stiffness of the frame significantly.The two infilled frames with openings are failed first by collapse of the masonry infilled wall.Subsequently,plastic hinges formed in the beam and column ends.The failure mode belongs to "Strong Frame,Weak Infilled Wall",which partially recovers the deficiency of less deformation and dissipation capacity of infilled walls.(3)Comparing to the infilled frames with openings,the infilled frame without openings performed higher load resisting capacity and initial stiffness.However,the upper column ends prone to form shear failure,which may decrease its deformation capacity and reduce its energy dissipation capacity.This is due to the interaction between the infilled wall and surrounding frames,which provide constraints to the surrounding frames and changed its failure mode and detriment its energy dissipation capacity.(4)Comparing the behavior of the specimen with or without using steel fibre reinforced concrete in the post-pouring zone,it is determined that steel fibre reinforced concrete upgrades the ultimate load capacity and initial stiffness of the frame limited.However,as the steel fibre reinforced concrete could delay the crack development at the bottom column joint,which delayed the stiffness degradation and increased its energy dissipation capacity.