Experimental Study On Fire Performances Of Earthquake Damaged RC Columns

The researches about reinforced concrete columns experienced fire coupling with earthquake include two aspects: first,the post-fire seismic performance of reinforced concrete(RC)columns.Second,fire performance of seismic damaged RC columns.There are relatively little researches on seismic performance of fire-damaged RC columns found by far.Moreover,pre-load was not taked into account those researches.In other words,the axis load was not applied during high temperature tests.Therefor,in the paper the hysteretic behavior of full-scale aquare RC columns with sustained axial load after the entire period of fire exposure were experimentally investigated.It can be expected to make a rational fire-damage assessment of RC structures after exposure to fire by considering the effect of sustained axial load and the entire period of fire or high temperature exposure.At the same time,there are few experimental studies on the fire resistance of RC columns after earthquake damage.Moreover,papers are about the mechanical properties of damaged RC columns after fire,and the fire resistance limit is little studied.Therefore,this paper studies the fire resistance performance of RC columns after earthquake damage.The experimental researches also be used as a basis for make a rational repair pol icy.The main works are summarized as follows:(1)Experimental study on the hysteretic behavior of 2 full-scale RC columns at room temperature were carried out.The seismic performance of RC columns under different axial load ratios are studied.It can be taken as a comparative test with the hysteretic behavior test of pre-fire RC columns.Simultaneously,The characteristic points and performsnce points of skeleton curve can be taken as basis for determining the fire test loading system of earthquake damaged RC columns.(2)Experimental study on the hysteretic behavior of 3 full-scale RC columns after exposure to the entire period of fire exposure and cooling phase were carried out.The effect of the axial load ratio on the residual load-bearing capacity,ductility,lexural rigidity dissipated energy of the fire-damaged RC columns were experimentally studied.(3)Fire performance tests on seismic damaged RC columns were carried out.The influence of earthquake-damaged levels and loading ratio on the fire resitence and the temperature fields was discussed especially.