受火后型钢混凝土框架抗震性能试验研究

Experimental study on seismic performance of SRC frame after exposure to fire

型钢混凝土结构在高层、超高层建筑中得到广泛应用,其受火后的受力性能也备受关注。为此,通过1榀受火后型钢混凝土柱-型钢混凝土梁组合框架的低周反复荷载试验和1榀未受火框架的对比试验,研究受火后型钢混凝土框架的抗震性能。获得了受火后型钢混凝土框架的滞回特性、延性、耗能性能、承载力与刚度退化规律,分析了常温下及受火后型钢混凝土框架的累积损伤过程和P-Δ效应。结果表明:与常温未受火框架相比,受火后型钢混凝土框架的承载力减小、刚度下降、延性降低,反复荷载下的累积损伤增大,P-Δ效应更为明显。但是由于构件中核心型钢的存在,受火后的型钢混凝土框架的滞回曲线依旧饱满,破坏前能保持较高的持载水平,具有良好的耗能性能和抗荷载循环能力,框架的塑性极限转角超过0.03 rad,仍能满足我国GB 50011—2010《建筑抗震设计规范》规定的塑性转角限值要求。

Steel reinforced concrete(SCR)structures are used in high-rise buildings and skyscrapers widely,thus their mechanical properties after exposure to fire have attracted much attention.Based on low-cycle reversed loading tests of one steel reinforced concrete(SRC)frame after being exposure to fire and the other SRC frame without exposed to fire for comparison,the influence of fire on the seismic performance of SRC frame was studied.The hysteresis behavior,ductility,energy dissipation,load bearing capacity and stiffness degeneration were obtained from the tests,and the accumulative damage process and P-Δeffect of the two SRC frames under ambient temperature and after being exposure to fire were analyzed respectively.The test results show that the fire-damaged SRC frame has lower bearing capacity,smaller stiffness,lower ductility,increased accumulative damage and more obvious P-Δeffect compared with undamaged SRC frame.Owing to the existence of the core steel in the section of the column and beam,the hysteresis loops of the fire-damaged SRC frame still keep plump,and a relatively large load bearing capacity is maintained before failure.Moreover,the fire-damaged SRC frame also has good energy dissipation capacity and resistance against cyclic load,and the plastic limit rotation exceeds 0.03 rad,which still meets the requirement of GB 50011—2010‘Code for seismic design building’.