薄钢板自攻螺钉连接受剪性能与力学模型研究

对薄钢板自攻螺钉连接开展受剪试验研究，探究了板件厚度与螺钉直径对连接受剪性能的影响。结果表明:自攻螺钉连接常见的失效模式包括板件孔壁承压失效、螺钉拔出失效和螺钉剪切失效三类，且失效模式受螺钉直径与钉帽侧板件厚度之比的影响；连接的受剪承载力与板件厚度和螺钉直径呈正相关关系，连接的初始刚度和延性也与板件厚度和螺钉直径存在规律性相关关系。采用Johnson-Cook损伤本构和线性损伤积累法则定义材料属性，同时考虑螺钉的形貌特征，建立了自攻螺钉连接的精细有限元模型，经试验结果对比验证表明该模型能够比较准确地模拟自攻螺钉连接的受剪性能。采用中国规范GB 50018?2002的自攻螺钉连接受剪承载力计算公式，同时分析了板件压缩刚度和螺钉剪切刚度的影响，并考虑了螺钉的群钉效应修正，提出了三段式的简化力学模型，能较好地预测自攻螺钉连接受剪的荷载-变形关系。

SHEAR BEHAVIOR AND MECHANICAL MODEL FOR SELF-DRILLING SCREW CONNECTIONS BETWEEN THIN STEEL SHEETS

Self-drilling screw connections between thin steel sheets were tested under shearing forces, and the impacts of the sheet thickness and the screw diameter on the shear behavior of the connections were investigated. It has been indicated that: the obtained three typical failure modes including bearing failure of steel sheets, pull-out failure and shear failure of screw, depend on the ratio between the screw diameter and the thickness of the sheet adjacent to the screw head. The shear resistance of each connection is positively correlated with the sheet thickness and the screw diameter, and the initial stiffness and the ductility of the connections are also related to these two parameters. Elaborated finite element (FE) models for the self-drilling screw connections were developed by introducing the Johnson-Cook damage constitutive model and the linear damage accumulation rule, and by considering the geometric characteristics of screw threads. The developed FE models were validated against the obtained test results, which provide accurate simulations of shear behavior of self-drilling screw connections. By using the calculation formulas for the shear resistance of self-drilling screw connections in the Chinese code GB 50018?2002, a new three-stage simplified mechanical model was proposed herein by considering the impacts of the compressive stiffness of steel sheets and of the shear stiffness of screw, as well as of the multi-screws effect, which has been further verified for accurately predicting the shear force versus deformation relationships of self-drilling screw connections.