考虑摩擦滑移的普通板式橡胶支座剪切性能研究

普通板式橡胶支座作为中国量大面广的公路钢筋混凝土梁桥结构体系中的重要支承构件,其力学性能对局部和整体结构的刚度分布和受力变形特点具有一定的影响,甚至影响服役公路桥梁结构的安全性和适应性。因此,针对桥梁服役过程中该类支座普遍存在的滑移、脱空等典型病害特征,研究其不同受力状态下的剪切性能。考虑支座界面接触方式、几何尺寸等参数,设计并进行了6个普通板式橡胶支座的剪切性能试验。对不同参数影响下支座的损伤破坏模式、剪应变-剪应力曲线、支座有效剪切应变及抗剪刚度等参数进行对比分析。进一步应用有限元数值模拟方法,对摩擦滑移下的支座剪切性能进行参数分析,并将其有限元分析结果与普通板式橡胶支座的剪切性能试验结果进行对比。研究结果表明,支座上、下表面的接触摩擦条件可明显影响支座的水平侧移和抗侧力。对于界面摩擦因数较小的情况,卸载后支座摩擦滑动位移不能完全恢复,随着循环加载次数的增加,摩擦滑动位移增幅增大,且支座界面摩擦滑移可降低支座有效剪切变形和抗剪刚度的发挥。0.5,0.7,1.0等效剪切变形下支座的抗剪刚度试验结果、模拟结果与理论计算结果对比表明,试验结果与模拟结果吻合较好,而既有抗剪刚度理论计算结果偏大,且未考虑支座界面摩擦滑移、脱空的影响。因此,在进行实际桥梁结构的力学性能计算时,应考虑不同受力阶段支座力学性能指标的取值。

Shear Performance of Common Plate Rubber Bearing with Friction Slipping

The common plate rubber bearing is as an important supporting member of the serviced highway reinforced concrete (RC) girder bridge system. The degree and type of damage on bearings will affect the stiffness and force uniformity of the local system, potentially the entire structure, and can increase the complexity and uncertainty of the safety assessment under accidental load. Therefore, considering the contact modes of the support interface, geometric size and other parameters, the shear performance testing of six ordinary plate rubber bearings was designed and conducted. The experimental results of shear strain-shear stress curves, effective shear strain, and shear stiffness were derived and analyzed. The finite element numerical simulation method was used, and the simulated shear performance was compared with the test results based on parameter analysis. The results show that the contact friction condition of the bearing can noticeably affect the horizontal lateral displacement and lateral force. In the case of the small interfacial friction coefficient, the friction slip of the bearing cannot be fully recovered after unloading. With the increase of the number of cyclic loads, the friction sliding displacement increases significantly. The friction slip can also reduce the effective shear deformation and shear stiffness of the bearing. In addition, the tested shear stiffness was compared with the simulated and theoretical results under the equivalent shear deformation of 0.5, 0.7, and 1.0. This shows that the theoretical results based on the existing shear stiffness calculation model is higher, when the influence of the friction slip of the bearing interface is not taken into account. The results of this study provide quantitative mechanical indexes to calculate the performance of serviced RC girder bridges.