剪力键布置方式对连续组合梁桥受力特性的影响

Influence of the Shear Connector Arrangement on the Mechanical Characteristics of the Continuous Composite Beam Bridge

在连续组合梁桥中,剪力键的类型、布置范围和布置间距的差别将引起结构受力特性的差异。利用通用有限元软件MSC NASTRAN对连续组合梁桥结构进行了数值模拟(主要包括用弹簧单元和MPC单元模拟不同类型和抗剪刚度的剪力键,以及用GAP单元模拟负弯矩区混凝土板的开裂),计算了在不同剪力键布置方式下连续组合梁桥的内力分布和变形。通过对计算结果的分析比较,认为剪力键布置方式的不同导致界面处剪力分布、滑移分布、负弯矩区混凝土板中钢筋应力分布、挠度等的显著变化。尤其在连续组合梁桥负弯矩区配置柔性剪力键,可以大大降低混凝土板中钢筋的拉应力;不过,在柔性剪力键与跨中刚度较大的剪力键相交位置,会在刚性剪力键中产生很大的剪力集中,钢筋中也出现轻微的应力集中。因此,工程人员在连续组合梁桥结构设计过程中可以通过调整剪力键的布置方式,使其结构内力分布和变形更加合理。

In the continuous composite beam bridge, the difference in type, arrangement area and arrangement space of shear connectors will cause variation in mechanical characteristics of the structure. By using the universal finite element software MSC/NASTRAN to simulate one continuous composite beam bridge numerically, which mainly includes simulating shear connectors of different type and shear rigidity by SPRING elements and MPC elements and simulating concrete crack in the negative moment area by GAP elements, the internal force distribution and deflection of the bridge with several different shear connector arrangements have been calculated separately. Through comparing the calculation results, it is considered that different shear connector arrangements result in remarkable changes in the distribution of the shear force and slip at interface, reinforcement stress distribution in the negative moment area and deflection of the bridge. Especially when flexible shear connectors are provided in the negative moment area of the continuous composite beam bridge. Reinforcement tensile stress reduces greatly when the intense shear force concentration exists in the rigid shear connector and slight stress concentration exists in the reinforcement at the joined position between the arrangement area of rigid and flexible shear connectors. Hence, during the design period of the continuous composite bridge, the engineer can rationalize the internal force and deformation by adjusting the shear connector arrangement. 