基于线性规划的连续刚构桥合龙段顶推力研究

发布时间：2019-01-30 10:15

【摘要】：为了确定多跨连续刚构桥合龙顶推力的最优解,以1座多跨混凝土连续刚构桥为工程背景,取各合龙段顶推力为设计变量,以各墩顶和墩底截面应力为目标函数,以顶推过程中桥墩截面应力为约束条件,基于多目标线性规划方法对合龙段顶推力进行求解。计算时忽略顶推力对主梁混凝土徐变的影响,考虑其对桥墩混凝土徐变的影响,通过线性迭代计算获得非线性最优解,同时对比2种顶推方案(方案1为3个顶推力;方案2为2个顶推力)的优劣。研究结果表明:采用提出的方法经过4次迭代即可收敛,计算方便快捷;考虑合龙顶推力产生的徐变效应时,主梁应力变化幅度相对较小,而桥墩应力变化幅度很大;合龙前施加顶推力对主梁内力影响相对较小,且可以有效调整桥墩受力,使得桥墩在成桥状态荷载组合作用下截面上下缘应力分布均匀;当实际合龙温度与设计合龙温度存在差异时,也可以通过调整顶推力使桥墩受力达到理想状态;采用方案2顶推时结构形成3个独立的框架结构,具有较大的整体刚度,便于保持顶推过程中的稳定性,虽然其增大了顶推力,但减少了顶推次数,总体而言优于方案1。
[Abstract]:In order to determine the optimal solution of the roof thrust of a multi-span continuous rigid frame bridge, a multi-span concrete continuous rigid frame bridge is used as the engineering background, the top thrust of each segment of the bridge is taken as the design variable, and the stress at the top of each pier and the cross-section of the pier bottom is taken as the objective function. Based on the multi-objective linear programming method, the top thrust of the closure segment is solved by taking the cross-section stress of the pier as the constraint condition during the jacking process. The influence of top thrust on creep of main beam concrete is ignored, and the nonlinear optimal solution is obtained by linear iterative calculation considering its influence on creep of concrete of bridge piers. At the same time, two kinds of jacking schemes are compared (scheme 1 is three jacking thrust). Scheme 2 is the superiority and inferiority of 2 thrust. The results show that the proposed method can converge after four iterations, and the calculation is convenient and quick, and the stress variation range of the main beam is relatively small and the stress change range of the bridge pier is very large when considering the creep effect caused by the top thrust of the closure. The influence of the top thrust on the internal force of the main beam is relatively small before closing, and the force of the pier can be adjusted effectively, so that the stress distribution of the upper and lower edge of the section is uniform under the action of the load combination of the bridge under the state of the bridge. When the actual closure temperature is different from the designed closure temperature, it is also possible to adjust the top thrust to make the pier force reach the ideal state. Three independent frame structures are formed when scheme 2 is used, which has large overall stiffness and is convenient to maintain stability in the process of pushing. Although it increases the thrust, it reduces the times of pushing, which is better than that of scheme 1.
【作者单位】：潍坊市市政工程设计研究院有限公司;中南大学土木工程学院;湖南省交通规划勘察设计院;
【基金】：国家自然科学基金项目(51378503) 中国博士后科学基金项目(2014M552158)
【分类号】：U445.4

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