型钢混凝土异形柱基于损伤的恢复力模型研究

根据16个实腹式配钢的型钢混凝土异形柱试件在低周反复荷载作用下的试验结果，进行了构件的滞回性能分析及基于损伤的恢复力模型研究。提出了一种弹性段-强化段为双折线、下降段为指数函数曲线的复合骨架曲线模型，采用理论推导与回归拟合相结合的方法给出了构件对应不同截面形式、轴压比及配钢率的骨架曲线特征值计算方法；考虑二阶矩效应、轴压附加抗侧刚度、强度衰减、包辛格效应及加载历程对构件性能退化的影响，并通过引入基于试验结果拟合的损伤模型，定量描述了构件滞回环卸载刚度退化规律，建立了恢复力模型。研究表明:试件的抗震性能良好，滞回曲线基本呈梭形，采用实腹式配钢的异形柱在各级荷载循环下的滞回环大致汇交于2点；所提出的基于损伤的恢复力模型是经过理论推导并考虑了多种因素的影响，计算结果与试验结果拟合度较好，可为该类型结构进行高效非线性地震反应分析提供依据。

STUDY ON DAMAGE-BASED RESTORING FORCE MODEL OF STEEL REINFORCED CONCRETE SPECIAL-SHAPED COLUMNS

Based on the experimental results of 16 solid-web steel reinforced concrete (SRC) special-shaped columns under low cyclic reversed loading, the hysteretic performance and damage-based restoring force model of the column were investigated. A composite skeleton model, including the ascent stage consisting of two straight lines and the decent stage in the form of exponential function, was put forward. The calculating method for the characteristic value of skeleton curve with different section forms, axial compression ratios and steel ratios was proposed by using theoretical derivation and regression fitting. Considering the influence of second-order moment effect, lateral stiffness due to axial compression, strength degradation, Bauschinger effect and loading history, the unloading stiffness degradation law of the hysteresis hoops of special-shaped column was proposed quantitatively by means of introducing the damage model based on experimental results fitting; and then the corresponding restoring force model was established. The results show good seismic performance of specimens with shuttle-shaped hysteresis curves. All hysteretic hoops under different loading cycles roughly pass two common points. According to the theoretical derivation and considering the influences of various parameters, the damage-based restoring force model of SRC special-shaped column was established, of which the calculated results agree well with the experimental results. It can provide basis for the nonlinear seismic response analysis of SRC special-shaped column structures.