高变形能力螺栓抗剪连接件抗剪承载力理论分析与验证

螺栓抗剪连接件是实现装配式钢-混凝土组合构件的可拆卸功能的基本元素之一。针对螺栓抗剪连接件变形能力不足的问题，提出了一种高变形能力的插块式螺栓抗剪连接件(plug-type bolted shear connector, PTBSC)。试验和有限元分析表明，PTBSC的剪切-滑移关系曲线存在明显的屈服点和极限点，曲线呈现出近似双线性特征。同时，曲线有较大的屈服后刚度(为初始刚度的1/3~1/2)，以及较大的屈服后承载力储备(极限承载力接近2倍的屈服承载力)，其屈服抗剪承载力和极限抗剪承载力的评价方法有待研究。针对PTBSC的屈服抗剪承载力，从PTBSC的受力机理出发，推导了其理论计算公式。为检验所提出PTBSC屈服抗剪承载力的计算公式准确性，将理论计算结果与有限元分析结果进行比较验证。对比发现，PTBSC屈服抗剪承载力的理论计算公式具有较高预测精度，误差在正负20%之内，离散系数不超过13%。对该文提出的屈服抗剪承载力计算公式作参数影响分析，考察其随不同参数的变化规律。增大螺栓直径和螺栓强度等级可显著提高PTBSC的屈服抗剪承载力；增大集中变形段长细比会减小屈服抗剪承载力，增大插块材料抗压强度可提高PTBSC屈服抗剪承载力，当强度大于100 MPa，屈服抗剪承载力基本保持不变。针对PTBSC的极限抗剪承载力，通过对有限元结果进行统计分析标定其经验系数。当PTBSC的螺栓极限抗剪承载力表示为0.7倍的极限抗拉承载力，此时误差在20%之内，可较好地预测PTBSC的极限抗剪承载力且具有一定安全储备。

THEORETICAL ANALYSIS AND VERIFICATION ON SHEAR CAPACITY OF HIGH-DEFORMABILITY BOLTED SHEAR CONNECTOR

Bolted shear connector is one of the basic elements to realize the demountable function of prefabricated steel-concrete composite members. To solve the problem of inadequate deformability of the bolted shear connector, a high-deformability plug-type bolted shear connector (PTBSC) was proposed. The experimental studies and finite element analyses show that the shear-slip relation curve of a PTBSC is bilinear, with significant yield strength and ultimate strength. The development of evaluation methods for yield strength and ultimate strength of a PTBSC is required. A theoretical formula for the PTBSC yield strength was derived and verified by comparing to the corresponding finite element analyses results. The effect of parameters included in the theoretical formula was analyzed. The PTBSC yield strength increases by increasing bolt diameter and bolt strength grade. The yield strength reduces by increasing the slenderness ratio of bolt shank. Increasing the compressive strength of the infilled-plug material can also improve the PTBSC yield strength. When the strength is greater than 100 MPa, the yield strength basically remains unchanged. The PTBSC ultimate strength is proposed by employing a calibrated empirical equation, using the PTBSC finite element analyses results. When the ultimate strength is 0.7 times of the ultimate tensile strength for a PTBSC bolt, the error is within 20%. Therefore, the PTBSC ultimate strength can be well predicted with certain margin of safety.