大跨悬浇钢筋混凝土拱桥施工扣索力优化计算分析

为有效控制钢筋混凝土拱圈在悬臂浇筑过程中出现过大的拉应力,文中以某大跨悬浇钢筋混凝土拱桥为依托,提出一种扣索力优化计算方法。首先,基于“未知荷载系数法”获取拱圈最大悬臂状态扣索力初值;然后,开展正装分析并提取施工过程的索力、应力以及位移影响矩阵,基于优化原理并利用MATLAB软件对扣索力开展进一步优化。最后,分别基于影响线原理和无应力状态法原理确定拱圈合龙前扣索力最优拆除顺序和扣索补张拉值,确保拱圈受力合理、松索成拱后拱圈线形光滑圆顺。算例结果表明,扣索初拉力值较为均匀,所有索力值安全系数均大于2.5;拱圈松索成拱线形合理,未出现“马鞍形”;拱圈施工过程中截面拉应力均小于1.8 MPa,满足设计要求。

Optimum Algorithm for Construction Buckling Force of Long-span Cantilevered Reinforced Concrete Arch Bridge

In order to effectively control the excessive tension stress of reinforced concrete arch ring in cantilever casting process,a new optimization calculation method of buckling force is proposed based on a long-span cantilever cast-in-place reinforced concrete arch bridge.Firstly,the initial value of the maximum cantilever cable force of the arch ring is obtained based on the"unknown load coefficient method".Then,the cable force,stress and displacement influence matrix of the construction process is extracted by the forward analysis.Based on the optimization principle,the cable force is further optimized by using MATLAB software.Finally,based on the principle of influence line and stress-free state method,the optimal dismantling order of the cable force before closure of arch ring and the additional tension value of the cable are determined to ensure that the stress of the arch ring is reasonable and the line shape of the arch ring is smooth and continuous after loosening of the cable.The calculation results show that the initial tension of the cable is relatively uniform,and the safety factor of all the cable forces is greater than 2.5;the arch loosening cable has reasonable arch alignment without saddle shape;and the cross-section tension stress during the construction of the arch ring is less than 1.8 MPa,which meets the design requirements.