自锚式悬索桥钢混组合主梁施工预拱度分析

摘要

对自锚式悬索桥的主梁施工方法进行了总结与评价，指出顶推施工的钢混组合主梁即使在均匀成桥吊杆的作用下，其成桥线形仍会在最大跨临时墩范围内发生局部凹陷的情况，而主梁施工预拱度也不能采取圆曲线或二次抛物线在各跨径内统一布置。鉴于此，本文基于有限单元法对一座自锚式悬索桥的施工过程进行正装模拟分析，计算结果表明，钢混组合梁截面性质改变是引起主梁成桥线形存在凹陷的本质原因；同时将成桥状态的主梁简化为承受竖向均布荷载和梁端集中水平力作用的三跨连续梁结构，并采用力法推导了各跨跨中位置竖向位移的简化计算公式；经算例验证，本文提出的施工预拱度简化计算公式能够有效计入主梁截面性质改变对主梁成桥线形的影响，较准确地预测出主梁累计竖向位移，其计算精度满足工程需求，而本文的研究结论将对同类桥型的主梁施工预拱度设计有较强的指导意义和参考价值。%This paper summarized and evaluated the main beam construction methods of self‐anchored suspension bridge ,pointed out that the main‐beam line would have a local depression between the largest span temporary pier when the steel‐concrete composite beams were constructed by the incremental launching construction method ,even if the main beam were withstand uniform boom‐forces ,moreover , the construction pre‐camber curve of the main girder could not be arranged as a circle curve or quadratic parabola within the entire span .In view of this ,the entire construction process of a self‐anchored suspen‐sion bridge was analyzed by the finite element method ,The results showed that the cross‐section proper‐ty changes of steel‐concrete composite beam were the nature reason of the local depression on the main‐beam line;T he completed main beam w as simplified into a three‐span continuous beam w hich suffered vertical uniform distributing loads and horizontal forces at the two ends ,and the simplified formulas of calculating the vertical displacement of each span were derived by the force method ;The numerical exam‐ple show ed that ,the proposed simplified formulas could effectively solve the affection by the cross‐section property changes ,accurately predicted the main beam cumulative vertical displacement ,and the calculation accuracy could meet the engineering requirements .T he conclusions of this paper had a strong guiding significance and reference value on the construction pre‐camber design of the bridge with the similar structural type .