High Temperature Performance Research On Seismic-damaged Reinforced Concrete Columns Under Post-earthquake Fire

Post-earthquake fire(PEF)is one of the most dangerous disasters in the secondary disaster after the earthquake,the loss caused by PEF is also unusually large,and sometimes even greater than the direct loss caused by the earthquake.Compared with the study of the high temperature performance of the structures or components without damage,there is little research on the fire resistance of damaged structures or components at home and abroad.Reinforced concrete columns are the main load-bearing components in concrete building structures,its fire performance directly affects the overall structure of the safety performance.Based on the domestic and foreign literatures,this paper explores the high temperature performance of the damaged concrete columns under the secondary fire.Therefore,the main work done in this paper is as follows:(1)Reference to domestic and foreign literature,the parameters of thermal performance and high temperature mechanical properties of reinforced concrete and concrete are summarized,and the parameters required in this paper are determined.(2)Based on the existing seismic hazard data and experimental data,the main geometric damage forms of the reinforced concrete columns after the earthquake are summarized: cracks,concrete peeling and residual deformation,and the main geometric characteristic parameters corresponding to the damage form are determined.(3)The finite element software ABAQUS is used to establish the threedimensional prestressed concrete column model,and the influence of cracks,concrete peeling and co-existence on the temperature field of reinforced concrete columns isanalyzed.(4)The effects of geometrical parameters such as relative depth of cracks,thickness of concrete peeling,relative height of dewatering and residual deformation on the fire resistance of reinforced concrete columns are studied,and the quantitative relationship between the refractory limit reduction coefficient and the geometric characteristic parameters of the earthquake is fitted;The influence of mechanical properties such as axial compression ratio,reinforcement ratio and eccentricity on the fire resistance of reinforced concrete columns is analyzed.The influence of axial compression ratio and eccentricity on fire resistance limit are also analyzed.(5)The high-temperature bearing capacity of damaged reinforced concrete columns is calculated,the influence of the geometric characteristic parameters on the bearing capacity of the prestressed reinforced concrete column is analyzed.According to the relationship lines of high-temperature bearing capacity reduction factor and damage index of the reinforced concrete column,the reduction coefficient of high temperature compressive bearing capacity and the seismic damage index of the reinforced concrete column are established.