钢混组合曲线梁桥混凝土桥面板应力空间分布特性

Stress Distribution Characteristics of Concrete Slabs of Steel-concrete Composite Girder Bridges

目的研究不同荷载形式下钢混组合梁桥混凝土板应力分布特性.方法以大涧沟大桥为工程背景,采用实体有限元模型分析施工过程对混凝土板剪力滞效应的影响,探讨汽车荷载作用下混凝土桥面板剪力滞-轮载局部综合效应和偏载效应.结果考虑施工过程后组合梁桥控制截面的剪力滞系数均有不同程度的增大,且支点截面的剪力滞系数增幅更大;受弯扭耦合效应影响,组合梁桥活载剪力滞效应将更为显著,剪力滞-轮载局部综合影响系数甚至超过2.0,支点截面处桥面板剪力滞-轮载局部效应大于跨中截面,且边跨的剪力滞-轮载局部综合效应明显大于中跨.结论剔除剪力滞-轮载局部效应后,控制截面的偏载系数仍可能超过1.2,大于设计中采用的经验系数1.15,且越靠近中跨汽车活载的偏载效应愈发显著,建议设计中应予以充分考虑.

In order to study the stress distribution characteristics of concrete slab of steel-concrete composite girder bridge under different load forms.Methods taking the Dajiangou bridge as the engineering background,the influence of the construction process on the shear lag effect of concrete slab was analyzed by solid finite element model,and the local comprehensive effect and partial load effect of the shear lag-wheel load of concrete slab under the action of vehicle load were discussed.Results after considering the construction process,the shear lag coefficient of the control section of the composite beam bridge increases to different degrees,and the shear lag coefficient of the fulcrum section increases greatly.Under the influence of bending-torsion coupling effect,the live load shear lag effect of composite girder bridges will be more significant,the local comprehensive influence coefficient of shear lag-wheel load even exceeds 2.0,the local effect of shear lag-wheel load on the bridge deck at the fulcrum section is greater than the mid-span section,and the local effect of shear lag-wheel load on the side span is significantly greater than the middle span.Conclusion after eliminating the local effect of shear lag-wheel load,the eccentric coefficient of the control section may still exceed 1.2,which is greater than the empirical coefficient 1.15 adopted in the design.Moreover,the partial load effect is more significant when the vehicle is closer to the middle span.Therefore,it is suggested that it should be fully considered in the design.