Experimental Research On Seismic Performance Of Heat-damaged Reinforced Concrete Shear Walls Strengthened With BFRP

The mechanical properties of the reinforced concrete structures after fire has a significant decrease,and it is also a deadly threat to people's life safety and property.At present,a series of research results on the mechanical properties of reinforced concrete structures under high temperature have been obtained.A large number of experimental research on behavior of strengthened reinforced concrete(RC)elements have been carried out.However,most of them are focused on beams,slabs and columns.In many existing buildings,shear walls constitute the seismic force resisting system.Existing research shows that: the seismic performance of post-fire shear wall in high-rise building is markedly worse.In order to ensure that the shear wall structure strengthened meet the goal of the region seismic fortification requirements,it is necessary to research the seismic behavior of heat-damaged shear wall strengthened.In this paper,with the support of project of National Natural Scientific Foundation? Experimental study on strengthening post-fire seismic behavior of reinforced concrete shear walls?(51308213)for the following research:1.Six reinforced concrete shear wall specimens were exposed to one side by the fire and then make it natural cooling.The test factors included axial load ratio and fire exposure time.The results show that: fire exposure time affects the cracks form and quantity to a small extent,but the axial load ratio is greater.Vertical cracks extended downward trend is more and more obvious with the increase of axial load ratio.Axial load ratio of 0.2 compared with 0.1 the diagonal cracks grow in quantity,but it has a decreasing trend when the axial load ratio is 0.3 and become neat.2.The test under cyclic reverse loading of post-fire reinforced concrete shear wall which are strengthened by BFRP.The effects of fire exposure time and axial load ratio on the failure mechanism,hysteresis characteristic,skeleton curve,bearing capacity,ductility ratio and hysteretic energy of reinforced concrete shear wall were investigated.The results show that:(1)Compared with normal temperature,the bearing capacity of post-fire 90 minutes of component is declined 10%.The ductility of shear wall is declined within 15%,and the energy dissipation is fell more than 15%;The bearing capacity and ductility coefficient of shear wall is increased significantly when it strengthened with BFRP sheet.The energy dissipation capacity of RC shear wall strengthened can be increased by 3 times.(2)The shear wall strengthened has obvious warning before destruction,and it showed better ductility failure characteristics.(3)Compare with unreinforced specimens,the increase of axial load ratio led to the decrease of the ductility and energy dissipation capacity of shear wall,and it can improve the bearing capacity of the specimen.Finally the Seismic performance of shear walls is degraded.