Experimental Study On Seismic Behavior Of Reinforced Concrete Columns After Different Fire Exposurecases

Existing the research achievements of seismic performance of reinforced concrete column after the fire are carried out on all four faces in fire.The filler wall has influenced the reinforced concrete columns of structure.The columns expose to fire with all four faces in fire,three-face-under-fire columns,two-face-under-fire columns and single face-under-fire.Different ways exposed to fire have different influences to the development of the temperature of the concrete column cross-section and the damage characteristics of RC columns.In order to grasp the seismic performance of reinforced concrete columns with different faces exposed to fire,this paper investigates the seismic behaviorand the calculation analysisof the RC columnswith different faces exposed to fire.The main work and conclusions include as follows:Twelve reinforced concrete columns were tested under cyclic loading,including ten columns which have not been exposed to fire after 120 min,two columns which has not been exposed to fire.The following parameters included the fire exposure different ways,loading direction and stirrup ratio which were examined the influence of the columns failure mode,bearing capacity,ductility ratio,skeleton curve and hysteretic energy.The results indicate that:(1)The highest temperature of columns with all four faces in fire,three-face-under-fire columns,two-face-under-fire columns and single face-under-fire is respectively 341 ℃,267 ℃,191 ℃ and 118 ℃.(2)the maximum bearing capacity of all four faces in fire,three-face-under-fire columns,two-face-under-fire columns and single face-under-fire is not affected by the fire of columnswere decreased by39.6% ~ 40.8%,20.9% ~ 34.3%,21.9% ~24.6% and 10.3%,its cracking load decreased by38.4% ~ 38.9%,13.2% ~ 33.1%,5%~ 18.5% and 11.3%,its initial stiffness decreased by 30.2% ~ 45.84%,30.2% ~40.2%,18.5% ~ 23.60% and 23.4%.(3)Compared with asymmetric load testing column,three-face-under-fire columns,along the direction of symmetrical load bearing capacity of concrete columns increased by 8.8%,the cumulative energy consumption increased by 3.5%;single face-under-fire,along the direction of symmetrical load bearing capacity of concrete columns increased by 6.7%,thecumulative energy consumption increased by 11.7%.(4)Reinforcement volume rate reduced from 0.87% to 0.42%,the fire exposure different ways of the bearing capacity of the concrete column after thefire and increase the influence degree of the cumulative hysteretic energy dissipation.The temperature field numerical analysis modelunder high temperatureand the mechanics analysis model of twelve reinforced concrete columns after fire have been established based on the finite element analysis software ABAQUS.Model analysis parameters have been proposed.The simulation results and the experimental results of the ultimate bearing capacity of the error within 12%.Using the numerical analysis model systematically analyzes the influence law of the columns’ bearing capacity afterthe different ways of exposure to fire when changed in the fire exposure time,stirrup ratio.