Experimental study on lateral impact behavior of square steel-reinforced concrete-filled steel tubular members after exposure to fire
To investigate the lateral impact responses of steel-reinforced concrete-filled steel tubular(SRCFST)members after exposure to fire,tests on nine post-fire specimens under lateral impact were carried out.The effects of heating time,impact height and boundary conditions on the failure modes and impact responses were studied.The temperature field,impact process,failure modes,impact force versus time curves,deflection development and energy absorption of post-fire specimens were all investigated.Based on the equivalent plastic hinge models,a simplified method was proposed to predict the maximum mid-span deflection of specimens under lateral impact.Test results show that post-fire SRCFST specimens under lateral impact experience pronounced bending failure and exhibit good impact resistance.The plateau impact force of SRCFST specimens decreases by 23.9％as the heating time increases from 0 min to 60 min,and the maximum mid-span deflection and impact duration increase by 38.2％and 41.5％,respectively.The maximum mid-span deflection of post-fire specimens increases by 114.7％as the impact height increases from 1.0 m to 2.6 m,whereas the plateau impact force improves by 14.2％.In comparison to concrete-filled steel tubular(CFST)specimens,SRCFST members have higher plateau impact force,less damage and smaller mid-span deflection.The improvement in impact resistance caused by inner section steel is more pronounced for post-fire members than for room-temperature specimens.
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