四肢变截面钢管混凝土格构柱恢复力模型计算方法
Calculation method of restoring force model of four-element variable cross-sectional concrete filled steel tubular laced column

提出了四肢变截面钢管混凝土格构柱抗震性能有限元分析方法,应用OpenSEES通用程序对试件进行建模,计算了格构柱荷载-位移滞回曲线与水平峰值荷载; 以柱肢坡度、轴压比、长细比、支主管面积比、柱肢钢材强度、混凝土强度、缀管布置形式等为拓展参数,研究了各参数对变截面平缀管式和斜缀管式钢管混凝土格构柱荷载-位移骨架曲线的影响规律; 借鉴等截面钢管混凝土格构柱骨架曲线统一算法的计算框架,采用等效长度法,拟合得到四肢变截面钢管混凝土格构柱骨架曲线各特征值(弹性刚度、水平峰值荷载、峰值荷载位移与下降段刚度)的计算公式; 结合骨架曲线计算模型,推导了恢复力模型的计算公式,并进行了实例验证。研究结果表明:轴压比、长细比、柱肢坡度、支主管面积比和材料参数是影响变截面格构柱抗震性能的关键参数,且与等截面格构柱影响规律具有共性,数值相差不超过20%; 各试件特征值计算结果与有限元分析结果均吻合良好,两者之比为0.990～1.029,均方差为0.105～0.153,误差基本控制在15%内; 四肢变截面钢管混凝土格构柱恢复力模型计算误差小于12%,计算结果可靠。
The finite element analysis method of seismic performance of four-element variable cross-sectional concrete-filled steel tubular(CFST)laced column was put forward. The specimens were modeled and analyzed by the OpenSEES general program, and the load-displacement hysteretic curves and horizontal peak loads of laced columns were computed. The influence rules of longitudinal slope, axial compression ratio, slenderness ratio, area ratio of lacing tubes to longitudinal tubes, yield strength of steel, concrete strength, arrangement type of lacing tubes, and other extension parameters on the skeleton curves of variable cross-sectional CFST laced columns with flat or inclined tubes were investigated. According to the calculation frame of skeleton curves of equal sectional CFST laced columns, the calculation formulas of skeleton curves characteristic values(including the elastic stiffness, horizontal peak load and its displacement, and fall-period stiffness)of four-element variable cross-sectional CFST laced columns were obtained by the equivalent length method. The calculation formula of restoring force model was deduced resorting to the calculation model of skeleton curve and verified by the engineering example. Research result indicates that the axial compression ratio, slenderness ratio, longitudinal slope, area ratio of lacing tube to longitudinal tube, and material parameters are the main influence parameters on the seismic performance of variable cross-sectional CFST laced columns, the common influence rules are the same as the rules on the equal section laced column, and the numerical difference is within 20%. The calculated results of characteristic values of each specimen are in good agreement with the finite element analysis results, and their ratios are 0.990-1.029, the mean square errors are 0.105-0.153, and the errors are basically controlled within 15%. The errors to calculate the restoring force model of four-element variable cross-sectional CFST laced columns are within 12%, so the computation result is reliable. 2 tabs, 21 figs, 32 refs