合理成桥状态是斜拉桥设计的重点和难点, 结合混合梁斜拉桥的受力特点, 总结分析确定合理成桥状态的基本原则, 提出确定混合梁斜拉桥合理成桥状态的分步算法, 基本思路为:根据相关工程经验初拟结构尺寸, 先采用"改进零位移法"初定成桥状态, 再采用"最小二乘法"将索力调均匀;计算活载效应, 综合考虑成桥运营状态主梁弯矩均匀, 正负弯矩大小相当, 主塔弯矩较小, 索力均匀及避免墩顶负反力等要求, 对索力进行调整, 边跨混凝土梁配置钢束;成桥运营状态验算.并以某大跨度混合梁独塔斜拉桥为工程实例进行计算分析, 实践表明该方法简单实用, 思路清晰, 计算精度高, 满足设计要求.%The reasonable completed bridge state is the key points and difficulties in the design of cable-stayed bridge. Combined with the stress characteristics of composite beam cable-stayed bridge, this paper sums up, analyses and determines the basic principle of reasonable completed bridge state, and puts forward and determines the fractional step algorithm of the reasonable completed bridge state of composite beam cable-stayed cable. The basic idea is as follow: according to the relative engineering experience, the structure dimensions are drawn up, the "improved zero displacement method" is firstly used to decide the state of completed bridge, and then the "least square method" is used to adjust the cable force evenly. The live load effect is calculated. It is to comprehensively consider the bending moment uniform of the main beam, equal positive and negative bending moments, smaller bending moment of the main pylon, cable force uniform and avoiding the negative reaction of pier top in the operation state of completed bridge. The cable force is adjusted and the side-span concrete beam is set up with steel tendons. The operation state of completed bridge is checked and calculated. The engineering example of a long-span composite beam single-pylon cable-stayed bridge is calculated and analysed. The practice shows that this method is simple and useful with the clear thinking and high calculation accuracy, and can meet the design requirements.
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