Experimental Study On Seismic Behavior Of Fire-Damaged Green High Performance Fiber Reinforced Cementitious Composites Frame

Green High Performance Fiber Reinforced Cementitious Composites(GHPFRCC)is a kind of new building material which developed based on Engineered Cementitious Composite(ECC)by using high-volume fly ash to replace cement.GHPFRCC has better ductility and energy absorption capability than ordinary concrete at normal temperature and shows the characteristics of multi-seam cracking and strain hardening.The PVA fiber in GHPFRCC is fused at high temperature,thus reducing the seismic resistance of the structure to a certain extent.Therefore,the seismic performance of the GHPFRCC framework is urgently needed.In this paper,the seismic performance of fire-damaged GHPFRCC frame is studied through the quasi-static test.The main contents include the following aspects:The first part mainly introduces the static test of GHPFRCC frame.According to the basic principle "strong-column,weak-beam,strong-shear,weak-bending,strong-joint,weakmember",five two-story and two-span 1:2 scale frames made of GHPFRCC with the optimal mixture ratio and C30 concrete are prepared.Each specimen is designated with the same size and reinforcements.Three of them are conducted fire test firstly,then the pseudo-static test,considering some factors like the casting material,fire area.The aseismic performance of GHPFRCC frame is discussed in the second part,the damage characteristics,hysteresis curve,skeleton curve,ductility factor,equivalent viscous damping coefficient,stiffness and strength degradation index,the seismic behavior of the specimens are studied.The test results show that:(1)Fire can affect the redistribution of internal force of concrete and GHPFRCC frame,change the appearance order of plastic hinge of the frame structure,weaken the complete development of the damage mechanism of the beam hinge,and reduce the seismic performance of the frame.(2)The ultimate bearing capacity of the GHPFRCC frame under single-chamber fire condition is still 26% higher than that of unfired ordinary concrete frame,the ultimate bearing capacity of the GHPFRCC frame under double-chamber fire condition is basically the same as that of unfired ordinary concrete frame,indicating that the GHPFRCC framework under local fire still has good bearing capacity and seismic performance.(3)The ductility,energy dissipation and ultimate bearing capacity of the GHPFRCC frame under double-chamber fire condition are higher than those of ordinary concrete frame subjected to the same fire condition,and the stiffness and strength degradation are relatively flat,which indicates that the GHPFRCC frame can effectively improve the seismic performance of frame and the security of the safety of the building structure after the fire.(4)The ductility,energy dissipation and ultimate bearing capacity of the GHPFRCC frame under double-chamber fire condition are lower than those of the GHPFRCC frame under single-chamber fire condition,which indicates that the increase of fire area will affect the seismic performance indexes of GHPFRCC frame and further reduce the seismic performance of building structure.