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通过6个不同冻融循环次数和轴压比的RC框架中节点梁柱组合体试件的低周反复加载试验,研究冻融循环次数和轴压比变化对节点核心区和梁柱组合体破坏模式、水平承载力、变形及耗能能力等抗震性能指标的影响。结果表明:随着冻融循环次数的增加,混凝土力学性能劣化,贯穿节点的梁端纵筋与混凝土之间的黏结强度显著退化,使得通过“斜压杆机构”与“桁架机构”传入节点核心区的剪力比例发生变化,导致低周反复荷载作用下节点核心区破坏模式发生转变,承载力降低,组合体耗能能力下降,延性稍有增大;当剪压比较大时,轴压比的增大使经冻融循环后的节点承载力降低,延性和耗能能力均出现不同程度的下降;冻融循环次数增加,由节点核心区剪切变形引起的柱顶水平位移在总柱顶水平位移中所占的比例增大。
Six low-cycle repeated loading tests of RC beam-column assemblies in RC frames with different numbers of freeze-thaw cycles and axial compression ratios were carried out to study the effects of freeze-thaw cycles and axial compression ratio on failure of core and beam- Mode, horizontal bearing capacity, deformation and energy dissipation capacity and other seismic performance indicators. The results show that with the increase of the number of freeze-thaw cycles, the mechanical properties of concrete deteriorate, and the bond strength between the longitudinal reinforcement and the concrete at the end of the beam passing through the joint deteriorates significantly. As a result, The change of the shear force in the core zone of the inflexion node leads to the change of the failure mode in the core zone of the low-cycle repeated load, the decrease of the bearing capacity, the decrease of the energy dissipation capacity of the composite body and the slight increase of the ductility. When the shear- The increase of axial compression ratio reduces the bearing capacity of the joints after freeze-thaw cycles, and the ductility and energy dissipation decrease with different degrees. The number of freeze-thaw cycles increases and the horizontal displacement of the column top caused by the shear deformation in the core zone of the joint increases The proportion of the horizontal displacement of the column increases.