不同形式螺栓抗剪键的受剪性能对比分析

Comparative study on shear performance of various bolt shear connectors

为进一步提高钢-混凝土组合梁界面的受剪承载力,提出一种具有较大横向约束的U形螺栓抗剪键,并通过推出试验对U形螺栓和直螺栓抗剪键的受剪性能进行了对比分析。试验结果表明:直螺栓和U形螺栓抗剪键破坏特征不同,前者为螺栓根部混凝土压溃脱落,后者为混凝土板开裂,且出现限于U形螺杆内侧的横向大裂缝;螺栓埋置长度增加时,直螺栓的受剪承载力和初始刚度有明显提高,对峰值滑移没有影响;U形螺栓螺杆间距改变后,对于U形螺栓的受剪承载力没有影响,但因为摩擦面积不同,对初始抗剪刚度和峰值滑移有一定影响;在螺杆埋置长度和用钢量相同的条件下,U形螺栓与2个直螺栓相比,承载力分别提高了46%和33.9%,初始抗剪刚度分别提高了39%和30.2%。基于试验数据,采用修正的Ollgaard模型得到U形螺栓抗剪键的受剪承载力和初始抗剪刚度的计算方法及界面剪力-滑移预测模型,试验结果与预测结果吻合较好。研究结果可为U形抗剪键的工程应用和后续研究提供一定参考。

In order further improve the shear resistance in the interface of steel-concrete composite beam,a novel shear connector is proposed,namely U-bolt with a large lateral constraint.The shear performance of U-bolts and straight bolt connectors was compared by the push-out tests.The experimental results show that the failure patterns of straight bolt and U-bolt are different.The former is the crusing of concrete around the bolt,while the latter is the cracking of concrete slab with large transverse cracks restricted between U-bolts.When the embedded depth of the bolt increased,the bearing capacity and initial stiffness of the straight bolt shear connector improved obviously,but there is no effect on the peak slip.When the distance between U-bolts is changed,it does not affect the bearing capacity of the U-bolt shear connector but has a certain effect on the initial stiffness and peak slip due to the different friction areas between concrete slab and H-steel.Compared to two straight bolt connectors under the same embedded depth and steel consumption,the bearing capacity of the U-bolt shear connectors improved by 46%and 33.9%respectively,while their initial stiffness increased by 39%and 30.2%respectively.Based on the test results,the prediction method regarding the shear capacity,initial shear stiffness and load-slip model of U-bolt shear connectors were obtained by modifying the Ollgaard model.The experimental results are in good agreement with the predicted results.The research results can provide a reference for the engineering application and follow-up study of U-bolt shear connectors.