Experimental Study Of RC Beam Shear Performance Of Different Concrete Cover Thickness Under High Temperature

In structure,beam is one of the important structural components,the heat generated by the fire can cause different degrees of damage to it,once the beam loses its carrying capacity,partial failure or even integral collapse may occur in the structure,causing loss of life and property.By conducting full scale fire tests,the shear behavior of the simply supported reinforced concrete beams under and after high temperature is studied,the contents are as follows:1)The shear resistance of three full-size reinforced concrete simply supported beams with different thickness of protective layer(10mm,25 mm and 40mm)was tested under fire.The temperature time history along the section,the temperature of the steel bar,the horizontal and vertical deflection and the fire resistance limit of the beam are obtained.The influence of the different thickness of protective layer on the shear performance of reinforced concrete simply supported beams under fire is studied.2)The shear behavior of six full-size reinforced concrete simply supported beams with different protective layer thickness was tested after fire.The load deflection curve,residual shear bearing capacity,residual stiffness and failure mode of the beams were obtained.The influence of different protective layer thickness,fire duration and cooling mode on the shear behavior of reinforced concrete simply supported beams after fire was studied.The experimental results show that the thickness of concrete protective layer has a significant influence on the fire resistance limit of reinforced concrete beams.The bigger the thickness of protective layer is,the lower the temperature of steel bar is,and the greater the shear capacity of reinforced concrete beams under fire is.The thickness of concrete protective layer has a great influence on the residual shear capacity of beams after fire.The bigger the thickness of protective layer is,the smaller the strength damage of steel bar is after high temperature,and the greater the residual shear capacity is.Figure58;Table14;Reference 60...