Experimental Study On The Axial Compression Performance Of Solid Web Steel Reinforced Concrete T-shaped Columns After High Temperature

The high frequency of fire makes the structural damage of buildings more serious,causing huge casualties and economic losses.In contrast,the Steel Reinforced Concrete special-shaped Column(SRC shaped Column),with its thin legs,small thickness and large surface area,is apt to be damaged in case of fire.At present,the research on the mechanical properties of SRC special-shaped column after high temperature is limited to the hollow type steel component,and the research on the solid belly type steel component is very few,which limits the application and popularization of this new type of composite structure.Therefore,experimental research and numerical simulation are used in this paper to deeply study the high temperature rear axial compression performance of the tshaped steel concrete column with solid abdomen.A high temperature test was carried out on 8 short Steel-concrete T-shaped columns.The color change and crack of the specimen after high temperature were observed,and the temperature-time relation curve of the cross section was obtained.The results show that the concrete color of the column body mainly goes through three stages:dark gray,dark red to gray white with the increase of temperature.With the increase of temperature,the transverse crack of web and flange gradually increased,and the longitudinal crack gradually became coherent from discontinuity and irregularity.The temperature curve in the furnace is basically consistent with the rising trend of the theoretical temperature rise curve.The temperature rise trend of each measuring point in the same specimen is basically consistent.The temperature rise rate of measuring points at different depths in the same section is different.Axial compression test was carried out on 8 high-temperature test specimens and 1normal temperature comparative specimen,and the axial compression performance(failure form,load-vertical displacement curve,bearing capacity,shaft Compression stiffness and deformability).The test results show that temperature and constant temperature have an effect on the bearing capacity,axial compression stiffness and deformability of the specimen.With the increase of temperature and the extension of constant temperature time,the residual bearing capacity and axial compression stiffness of the specimen will decrease.The degradation of axial compression stiffness is more significant than the loss of bearing capacity.The residual bearing capacity of the specimen decreases by an average of 10.9%,and the axial compressive stiffness decreases by an average of 46.3%,but the deformation capacity of the specimen increases.The remaining bearing capacity of the test piece also has an effect.The greater the high-temperature loss rate,the more the bearing capacity decreases.Based on the reasonable selection of constitutive relations and thermal parameters of steel and concrete,the ABAQUS finite element software was used to carry out temperature field simulation and axial compression performance simulation of the steel reinforced concrete T-shaped column consistent with the test,simulation results and tests The results agree well,proving the effectiveness of the model.On this basis,the parameters analysis of the bearing capacity,stiffness and deformability of the axiallycompressed bearing capacity of steel reinforced concrete T-shaped columns with different steel protective layer thicknesses,different steel ratios and different limb height to thickness ratios are carried out.The analysis results show that: the greater the height-tolimb-thickness ratio,the smaller the deformation capacity of the member and the little change in bearing capacity and stiffness;the greater the ratio of steel distribution,the higher the bearing capacity of the member,the greater the stiffness,the better the ductility,and the temperature The higher,the more obvious the effect;The protective layer of steel reinforced concrete has little influence on the rigidity and bearing capacity of T-shaped columns after high temperature,and has a great influence on the deformation capacity,which is related to the temperature.When When the temperature is higher than 600℃,the deformation capacity of T-shaped column increases with the thickness of protective layer.