预拉力螺栓连接焊接T形件受力性能研究

为研究焊接T形件连接的力学性能，对10个焊接T形件连接进行了静力拉伸试验，采用欧洲规范EN 1993-1-8（EC3）方法预测了T形件连接的初始刚度和塑性承载力，研究了螺栓预拉力对T形件连接初始刚度的影响。研究结果表明：当T形件连接的承载力由螺栓强度控制时，塑性承载力随螺栓直径的增加而增大；提高螺栓强度等级，可以提高试件的初始刚度，最大增幅约为47.8%，但对塑性承载力影响较小；螺栓至腹板边的距离d对T形件连接的初始刚度和塑性承载力影响均较大；当螺栓边距大于1.5d后，可忽略其影响；EC3规范中承载力计算公式低估了T形件连接的塑性承载力，初始刚度计算公式中忽略了螺栓预拉力的贡献，当翼缘板受约束程度接近简支和固接时，计算误差较大；采用Faella模型计算初始刚度预测翼缘板边界条件接近固接约束情况的T形件连接初始刚度精度较高，对于接近简支的情况仍需改进。

Research on mechanical property of welded T-stub connections with high-strength bolts with pretension force

In order to analyze the effect of the main parameters on mechanical property of welded T-stub connections, tensile tests on 10 welded T-stub connections were conducted. The formulas from EN 1993-1-8 (EC3) code were used to predict the initial stiffness and plastic resistance of welded T-stub connections, and the impact of pretension force of high strength bolts on the initial stiffness of T-stub connections was also discussed. The results show that with the increase of bolt diameter, when bearing capacity of T-stub is controlled by the bolt strength, the plastic resistance increases significantly. Improving the strength grade of bolts can increase the initial stiffness of the specimens with the maximum increase up to about 47.8%, but the impact on plastic resistance can be ignored. The impact of bolt distance from web on both initial stiffness and plastic resistance of T-stub is larger. When edge distance of bolts is larger than 1.5 times of the bolt distance from web, the impact on mechanical property can be ignored. The EC3 code formulas underestimate the plastic resistance of specimens, ignoring the contribution of bolt pretension force to the initial stiffness. A rather large error can be introduced when the constraint of flange plate is close to simple support or fixed support. In case of fixed support, the predicted value of Faella formulas is in good agreement with the experimental result. For simple support further improvement is needed. The research results can be reference for the design of the beam-column bolt connections of steel structure.