位于“V”型峡谷桥址的连续刚构桥风冲击模型与抗风设计

Wind Impacting Model and Wind-Resistant Design of Continuous Rigid-Frame Bridge at V-Shape Valley

风荷载作用效应的精确分析是对"V"型峡谷桥址处平衡悬臂工法施工的高墩大跨连续刚构桥的结构安全性的重要保证。以1座最高主墩153 m,跨径组合85 m+4×160 m+85 m的连续刚构桥为例,依据其桥址处的风环境确定了上、下部结构的风冲击模型,并在最大悬臂工况下与静风荷载进行对比分析后对桥的抗风构造进行了优化。结果表明:高墩的位移与应力,构造的动风载模型效应比静力风载的大3倍以上;增加的风撑横系梁构造可最大减小墩顶的应力与位移的73.9%;墩顶在最大悬臂阶段出现侧向最大位移11.9 cm,桥墩墩底截面拉应力1.65 MPa,虽未超过容许值,但应考虑采取适当的抗风措施。

Long-span and high-pier continuous rigid-frame bridges constructed by balanced cantilever method at V-shape valley,detailed analysis on response of wind impacting is the key to ensure structural safety during constructional stage.A dynamic wind loading model is built for a continuous rigid-frame bridge with the highest pier up to 153 m and the combination of span is 85 m＋4×160 m＋85 m,with different superstructure and substructure in accordance with wind environment.Comparative analysis is made between static wind loading model and dynamic one in the key constructional stage-maximum cantilever stage and optimized wind-resistant structure is designed.The result shows that the displacement and stress of dynamic wind loading model for super high-pier are three times larger than that of static one.The straining beam of wind bracing may reduce the displacement of super high-pier top under wind loading evidently up to 73.9%.The lateral displacement at the top of the pier is 11.9 cm and the stress is 1.65 MPa at the bottom in the largest cantilever stage.Within permitted ones,however appropriate wind resistant ways may be adopted.