预制节段桥梁钢榫键干接缝抗剪机理及计算方法

Shear Mechanism and Calculation Method of Steel Shear Key Dry Joint of Precast Segmental Bridge

接缝是节段预制拼装桥梁的薄弱部位,为确保节段间的定位和传力,设计了钢榫键接缝。为充分完整掌握钢榫键接缝局部剪切性能,基于试验研究,结合理论分析对钢榫键接缝的抗剪机理和计算方法进行深入研究。研究结果表明:在侧限压力的作用下钢榫键接缝借助榫键和混凝土的接触受压来传递接缝间的剪力,接缝具有较高的抗剪承载力和良好的延性。结合钢榫键接缝的传力机制,构建了适用于钢榫键接缝的力学模型,揭示了钢榫键接缝的抗剪机理及破坏模式,包括:榫键剪切破坏、混凝土局部受压破坏(接触面压碎、接触面端部膨胀、劈裂破坏)、混凝土撕裂破坏。最后,建议采用钢榫键剪切破坏作为钢榫键接缝抗力设计的依据,同时应对钢榫键周围混凝土强度进行验算。

Joints are the weak parts of segmental precast Bridges.To ensure the positioning and force transmission between segments,steel shear keyed joints are designed.To fully grasp the local shear performance of steel shear keyed joint,the shear mechanism and calculation method of steel shear keyed joint were deeply studied based on the existing experimental research results and theoretical analysis.The results showed that the steel shear keyed joint transmits the shear force between the joint by means of the contact pressure between the steel key and the concrete under the action of confining pressure,and the joint had high shear capacity and good ductility.Combined with the force transfer mechanism of steel shear keyed joint,a mechanical model was constructed,and the shear mechanism and failure mode of steel tenon joint were revealed,including shear failure of steel key、partial compression failure of concrete、tearing failure of concrete.Finally,the paper suggests that the shear failure of steel key should be used as the basis for the resistance design of steel shear keyed joints,and the strength of concrete around the steel key should be checked.