论文部分内容阅读
通过4个火灾后型钢混凝土柱-型钢混凝土梁节点试件及2个常温未受火对比试件的低周反复加载试验,研究火灾后该类节点的滞回特性、延性、耗能性能、承载力与刚度退化规律,分析了受火时间、轴压比对火灾后该类节点的抗震性能的影响。结果表明:火灾后试件与常温未受火试件的破坏过程和破坏形态基本一致。经历火灾损伤后,型钢混凝土梁柱节点的滞回曲线仍然饱满,但试件承载力降低、变形增大、延性减弱,受火时间越长,承载力下降程度越高、变形增加程度越大、延性系数越小。反复荷载下型钢混凝土梁柱节点的强度出现衰减,加载初期的衰减系数随位移的增大而减小,加载后期的衰减系数随位移的增大总体保持稳定,体现出良好的抗荷载循环能力。与常温未受火试件相比,高温后试件加载初期的刚度降低、等效阻尼比增大,受火时间越长,刚度降低和等效阻尼比增大的程度越高。随着加载的进程,高温后试件的刚度与常温未受火时间刚度逐渐趋向一致,但等效阻尼比相比常温未受火试件减小,受火时间越长,减小程度越高。轴压比对火灾后节点的抗震性能产生一定影响,随着轴压比的增大,试件强度和刚度有所提高,但延性下降。
Four hysteresis-type steel-reinforced concrete columns-steel reinforced concrete beam joint specimens and two low-temperature cyclic loading tests were conducted to study the hysteresis characteristics, ductility, energy dissipation and bearing capacity of such joints after fire Force and stiffness, and analyzed the influence of fire time and axial compression ratio on the seismic performance of such nodes after fire. The results show that the damage process and the failure mode of the specimen after fire are basically the same as those of the specimen without fire at room temperature. After the fire damage, the hysteretic curves of the beam-column joints of SRC are still full, but the bearing capacity of the specimens decreases, the deformation increases, the ductility decreases, the longer the fire, the higher the bearing capacity decreases, the greater the deformation increase, The ductility coefficient is smaller. The strength of beam-column joints decreases with the increase of displacement, and decreases with the increase of displacement. The attenuation coefficient increases with the increase of displacement at the end of loading, and shows a good capability of anti-load cycle. Compared with the unheated specimen at normal temperature, the initial stiffness of the specimen after the high temperature is reduced, the equivalent damping ratio increases, the longer the exposure time, the lower the stiffness and the higher the equivalent damping ratio. With the process of loading, the stiffness of the specimen after high temperature gradually tends to be consistent with that of the untempered time at room temperature, but the equivalent damping ratio is not reduced by the test specimen at room temperature, the longer the fire, the higher the degree of reduction . The axial compression ratio has a certain impact on the seismic performance of the post-fire node. With the increase of the axial compression ratio, the strength and rigidity of the specimen are improved, but the ductility is decreased.