循环荷载下高强度螺栓连接摩擦系数试验研究

Experimental study on friction coefficient of high-strength bolt connections under cyclic loads

高强度螺栓摩擦型连接在承受循环剪力时,螺栓拉力和接触面的摩擦系数会随加载过程发生变化,因此,使用抗滑移系数进行分析和设计不安全。为研究高强度螺栓受剪连接中未处理轧制表面直接接触、轧制表面间垫设紫铜片以及螺栓垫圈与轧制钢板接触的摩擦系数,对不同栓杆直径、不同孔形的4组(12个)高强度螺栓连接试件开展了循环加载试验和有限元数值模拟研究,分析了循环荷载下连接滑移过程中高强度螺栓拉力及摩擦系数的变化情况,以及数值模拟中摩擦系数的取值方法。结果表明:改变螺栓直径或孔型对未处理轧制表面直接接触的摩擦系数影响较小;增大螺栓直径,螺栓垫圈与轧制钢板接触的摩擦系数显著降低;采用大螺栓孔时,轧制表面间垫设紫铜片对摩擦系数有一定幅度提高;有限元模拟中,双剪试件输入摩擦系数结果与试验结果较为吻合,而单剪试件输入抗滑移系数结果与试验结果吻合程度更高。

When the high-strength bolted slip-critical connections bear cyclic shear loads,the tension force in the bolts and the friction coefficient between the contact surfaces will change with the loading process.Therefore,it may be unsafe to use the slip coefficient for analysis and design.In order to study the friction coefficient between the untreated surfaces of rolled steel plates in the high-strength bolted shear connection,between the rolled surfaces filled with a red copper sheet,and between the rolled surface of steel plate and the bolt washer,cyclic loading tests and finite element numerical simulation studies were carried out on 4 groups(12)of high-strength bolt connection specimens with different bolt diameters and bolt hole types.The variations of the bolt tension and the friction coefficients during the sliding process under cyclic loads,as well as the value for friction coefficient in finite element models,were analyzed.The results show that,the change of bolt diameter or bolt hole shape has little effects on the friction coefficient between the untreated surfaces of rolled steel plates.When the diameter of the bolt increases,the friction coefficient between the rolled surface of steel plate and the bolt washer decreases obviously.When large bolt holes are used,the friction coefficient between the rolled surfaces filled with red copper increases.In the finite element simulations,the results input of the friction coefficient show good agreement with the test results for the double-shear specimens,while the results input of the slip coefficient shows better agreement with test results for the single shear specimens.