Experimental Study On Shear Bearing Capacity Of Reinforced Concrete Simple Supported Beams With Web Bar Under Fire

With the help of four parameters such as the shear span ratio,the reinforcement ratio of the stirrup,the load ratio and the reinforcement ratio of the longitudinal reinforcement,the experimental study on the diagonal section bearing capacity of nine full-scale reinforced concrete beams with full scale under the fire temperature and constant load coupling was carried out with the help of the large scale fire simulation test system.The test is based on the ISO834 international standard temperature rise curve.During the test,the temperature field distribution and the vertical deflection deformation of the beam are measured during the whole process of rising and lowering temperature.The failure full appearance,the whole deformation,the crack distribution and the oblique section of the simple beam specimen after the fire resistance are observed.Features and forms of surface damage.On the basis of this,the mechanism of the effect of fire high temperature on the inclined section bearing capacity of reinforced concrete simple beam with abdominal tendons is studied and analyzed,and the formula for calculating the shear capacity of the simple supported beam of reinforced concrete with abdominal tendons at high temperature is preliminarily proposed.The main research results in this paper are as follows:(1)the test results show that the failure mode of reinforced concrete beams with reinforced concrete under the principle of "strong bending and weak shear" is the standard shear failure under the condition of normal temperature,and the bending failure may occur under the effect of high temperature and constant load coupling.(2)the test results show that the larger the shear span ratio of reinforced concrete simply supported beams with stirrups is,the smaller the fire resistance limits are.(3)the test results show that,under the interaction of high temperature and constant load offire,about 40 minutes before the fire limit damage is reached,the vertical deformation of the test piece begins to accelerate,indicating that the test beam begins to enter the stage of failure.(4)the test results show that when the load ratio is fixed,the reinforcement ratio of stirrup has no obvious influence on the fire resistance of the reinforced concrete simple beam with abdominal tendons under fire,but the disposition of the abdominal tendons will effectively reduce the sudden change of the vertical displacement after the member enters the failure stage.(5)the test results show that the greater the load ratio is,the smaller the fire resistance limit of the reinforced concrete simple beam with abdominal tendons is,and the relationship between the fire resistance limit and the load ratio is basically linear when the load ratio is between0.4P~0.6P.(6)the test results show that the greater the reinforcement ratio of the longitudinal reinforcement,the greater the fire resistance of the reinforced concrete simply supported beams with abdominal tendons in the fire,and the effect of the pin on the longitudinal reinforced bar can obviously improve the shear performance of the reinforced concrete simple beam under the fire.(7)the formula of shear bearing capacity of reinforced concrete beams with abdominal tendons at high temperature is proposed based on the formula of shear bearing capacity and test results of bending members at normal temperature.The correctness and effectiveness of the formula are verified by examples.