Study On Effect Of Fire Mode On Mechanical Behavior Of Rc Stub Column After Exposure To Entire Fire

The current code for fire resistance design and study on fire resistance performance of reinforced concrete(RC)are based on the standard fire test or study under various temperature ratings,and were not to consider the impact of structure type and room function on the fire combustion mode.When fire resistant design was being done,it is usually using the concept of time equivalent to convert to the standard fire from actual fire.However,few experimental study was carried out to investigate the effect of the different fire combustion mode on mechanic behavior of reinforced concrete.Recently,some study found that load action in the entire period of fire exposure have a significant effect on the mechanic behavior of reinforced concrete,but the object of study is only concrete block or reinforced concrete members which size was reduced.In the practical engineering,due to the size of members are clearly larger,size effectin will produce obvious inhomogeneous temperature field in high temperatures,which has the direct affection on the mechanical behavior of reinforced concrete members.Therefore,this paper carried out the following studies:(1)For two common scene of shopping mall and residential,using the way from Eurocode to simulate the corresponding actual fire combustion mode.And using two time equivalent method(equal area and equal energy)converted into the standard fire mode from simulated actual fire.(2)Based on the finite element model of ABAQUS,the temperature field of reinforced concrete short columns after exposure to different simulated fires is analyzed in this paper.The FEA model has been verified by the temperature field test of 4 reinforced concrete stub columns after exposure to fire.(3)An experimental study was carried out to investigate the mechanic behavior of reinforced concrete stub columns after entire fire exposure.The effect of axial load level and fire combustion mode on the residual compressive strength,axial stiffness and load-deformation curves of RC stub columns were discussed.(4)On the basis of analyzing the damaged mechanical models at home and abroad for concrete and steel material after exposure to high temperature.The use of numerical methods was calculated residual compressive strength,axial stiffness and load-deformation curves of RC stub columns after exposure to high temperature,and in-depth analysis of the impact of axial load level,fire combustion mode and large-size specimens on the mechanic behavior of RC short columns.