考虑损伤效应的钢管转换柱抗震性能试验研究与理论模型

为研究传统风格建筑钢结构转换柱连接的抗震性能及其恢复力特性，对不同上柱长细比（8.9和12.5）与轴压比（0.2和0.4）的4个钢管转换柱连接进行了低周往复加载试验，记录并分析了其受力过程和破坏形态。试验结果表明：随着轴压比和矩形钢管长细比的增大，转换柱连接的P-Δ效应加剧，构件的承载力逐渐降低。通过理论计算提出骨架曲线特征点计算式，得到理想双折线骨架曲线恢复力模型。同时，考虑累积耗能与变形对构件性能退化的影响，引入一个适用于传统风格建筑转换柱连接的损伤模型，确定了柱连接构件在每次滞回循环后的累积损伤指数，基于试验拟合结果定量描述其卸载刚度等力学性能指标的退化规律。最终给出转换柱连接构件在各受力阶段具体的滞回规则，得到考虑损伤效应的传统风格建筑钢转换柱连接的恢复力模型。经比较，所建议的考虑损伤效应的恢复力模型与试验结果吻合程度较高，能够很好地描述传统风格建筑钢转换柱连接在低周反复荷载作用下的受力特征与滞回特性。

Experimental study and theoretical model of seismic behavior of steel transition columns considering damage effect

In order to study the restoring force characteristics and seismic performance of steel transition connections in traditional buildings, the cyclic loading test was carried out on four transition connections with different slenderness ratios (8.9 and 12.5) of upper column and axial compression ratios (0.2 and 0.4) located between the rectangular and circular tubes. The test results show that the P-Δ effect of the transition column aggravates with the increase of the axial compression ratio and the slenderness ratio of the rectangular steel tube, and the ultimate bearing capacity of the test specimens gradually decreases. The formulas of the characteristic points on skeleton curves were presented by theoretical calculation, and the ideal hardening model of skeleton curves was developed. A damage model applied to the transition connections in traditional buildings considering cumulative energy dissipation and deformation on the perfoemance of specimens was introduced. The cumulative damage index in each of the hysteretic loops was defined, the overall seismic behaviors including unloading stiffness and other mechanical performance indexes were described quantitatively. Finally, the hysteretic rules at different loading stages were present, and the restoring force model used for transition connections in traditional buildings considering damage effects was proposed. By comparison, the proposed restoring force model considering damage effects agrees well with the test results, which can appropriately exhibit mechanical characteristics and hysteretic behavior of the traditional buildings under cyclic loads.