超限径厚比下高强薄壁钢管混凝土柱抗震性能研究

Seismic Behavior of High-Strength Concrete-Filled Thin-Walled Steel Tubular Columns with Out-of-Code Diameter-to-Thickness Ratios

为了深入研究低周往复荷载下高强薄壁钢管混凝土柱抗震性能,对8根超限径厚比的Q690高强薄壁钢管混凝土柱开展拟静力加载试验,分析了该类柱破坏模式、滞回与骨架曲线、延性系数、滞回耗能、刚度退化与荷载衰减,揭示了轴压比、径厚比和混凝土强度对关键性能指标的影响程度,对横向受剪承载力进行分析,提出了基于桁架机制的抗剪承载力计算公式。结果表明:超限径厚比下高强薄壁钢管混凝土柱可分为耗能能力强的弯曲主导和耗能能力弱的剪切主导的两类破坏模式;该类柱延性系数介于1.99~2.89之间,侧移率为1%~6%,加载时,荷载比维持在0.9以上,表现出良好的滞回性能与塑性变形能力;超限径厚比下高强薄壁钢管搭配高强混凝土时需适当提高轴压比增加试件延性、侧向刚度和耗能能力;基于桁架机制的抗剪承载力公式计算结果与试验值吻合良好。该方法可用于强度破坏控制下高强薄壁钢管混凝土柱横向受剪承载力的分析与评估。

Aiming at the seismic behavior of high-strength concrete-filled thin-walled steel tubular(HCFTST)columns under low cycle reciprocating loading,a quasi-static test was conducted on eight Q690 HCFTST columns with out-of-code diameter-to-thickness(D/t)ratios.The failure mode,hysteretic and skeleton curves,ductility coefficients,energy dissipation,stiffness and load degradation were analyzed in detail to reflect the influences of axial compression ratios,D/t ratios and concrete strengths on the key performance indicators.Subsequently,the lateral shear-resistant capacity was examined to develop a simplified calculation formula based on the truss mechanism.The result indicates that:the failure modes of the tested Q690 HCFTST columns can be generally divided into flexure-dominated or shear-dominated failure,and the former performs a plumper hysteretic behavior than the latter;the ductility coefficients are in the range of 1.99-2.89 while the degradation ratios of bearing capacity maintain above 0.9 in the drifts of 1%-6%,moreover,the tested out-of-code HCFTST columns exhibit a reasonable hysteretic performance and plastic deformation capacity;the axial compression ratio ought to be reasonably improved to heighten the ductility,lateral stiffness and energy dissipation;the prediction results of the proposed shear-resistant calculation model based on truss mechanism coincide well with the test values,implying this method can serve as a practical tool in evaluating the lateral shear-resistant capacity for the HCFTST columns suffered from the strength-controlled failure.