矩形空心墩等效塑性铰模型

为准确计算矩形空心墩变形能力，基于弯曲、剪切和纵筋滑移三分量变形模型分析影响有效刚度和等效塑性铰长度的主要因素。通过考虑剪切变形的贡献引入空心率的影响，确定计算有效刚度和等效塑性铰长度的公式形式。通过对48根发生弯曲破坏的矩形空心墩拟静力试验结果进行回归分析，分别标定出有效刚度和等效塑性铰长度计算公式中的参数。利用基于建议公式的等效塑性铰模型计算矩形空心墩荷载-位移骨架曲线，并与另外3根试件的试验结果进行比较。基于48根矩形空心墩拟静力试验结果，对各国规范关于有效刚度和等效塑性铰长度的计算公式进行评估。研究结果表明：矩形空心墩有效刚度随轴压比、纵筋率和剪跨比的增大而增大，随d_bf_y/（L·f_c）和空心率的增大而减小；等效塑性铰长度随墩高、截面高度、纵筋率、空心率及d_bf_y/f_c的增大而增大；利用基于建议公式的等效塑性铰模型得到的矩形空心墩荷载-位移骨架曲线与试验结果吻合较好；各国规范关于有效刚度和等效塑性铰长度的计算公式对矩形空心墩试验结果的估计均偏于不安全，建议公式具有更高的精度和更小的离散性。

Equivalent Plastic Hinge Model of Rectangular Hollow Piers

To calculate the deformation capacity of rectangular hollow piers accurately, a deformation model considering bend, shear, and reinforcement slip was used to analyze the effective stiffness and equivalent plastic hinge length of rectangular hollow piers. The ratio of the rectangular hollow piers was determined based on shear deformation, and formulas were proposed for effective stiffness and the equivalent plastic hinge length. After pseudo-static test results showed that 48 rectangular hollow specimens failed in the flexural mode, regression analysis was conducted to calibrate the coefficients of the above-proposed formulas. A load-deformation skeleton of rectangular hollow piers was obtained based on an equivalent plastic hinge model composed of the proposed formulas, and compared with the experimental results of the other three specimens. The formulas for effective stiffness and equivalent plastic length of various countries were evaluated based on the pseudo-static test results of 48 rectangular hollow specimens. The results show that the effective stiffness of rectangular hollow piers increases with the axial load ratio, the longitudinal reinforcement ratio, and the aspect ratio, and decreases with an increase in the hollow ratio and d_bf_y/(Lf_c). The equivalent plastic hinge length of rectangular hollow piers grows longer with the specimen length, the section height, the longitudinal reinforcement ratio, the hollow ratio and d_bf_y/f_c. The formulas proposed by various countries for effective stiffness and equivalent plastic length are not conservative for experimental results of rectangular hollow piers, but have higher accuracy and less discreteness. Based on the proposed formulas, the equivalent plastic hinge model can provide a load-deformation skeleton curve close to the experimental results.