考虑梁重误差效应的节段拼装混凝土斜拉桥索力调整

Cable Force Adjustment for Segmental Assembled Concrete Cable-Stayed Bridge Considering the Effect of Beam Weight Errors

为了减小节段拼装混凝土斜拉桥梁重误差引起的线形变化,将拉索看作弹性支承,将主梁和桥塔均视为弹性支承悬臂梁,提出混凝土斜拉桥施工阶段索力调整的弹性支承悬臂梁法。该方法将梁重误差作用下主梁的弹性支承力作为拉索的竖向分力,求解拉索的索力调整量初始值,再利用塔偏变形对其进行修正。工程实例分析表明:与出现梁重误差梁段接近的拉索索力调整量大,其值可达到梁重误差值的70%,而远离的拉索索力调整量较小,其值不及梁重误差值的5%;调整后的索力能够有效减小梁重误差产生的线形变化,使得拼装阶段结构线形接近预设线形;主梁支承力产生的初始值在索力调整值中占比大,塔偏修正值占比小,而且修正值随悬臂长度的增加而减小;索力调整量随主梁刚度的增大而减小,但会随着拉索刚度的增大而增大。

In order to reduce the linear variation caused by beam weight error of segmental assembled concrete cable-stayed bridge,the elastically supported cantilever beam method for cable force adjustment of the concrete cable-stayed bridge at construction stage is proposed.By using the method,the cables are taken as elastic supports;the main beam and the bridge tower are both taken as elastically supported cantilever beams.This method takes the elasticity supporting force of the main beam under the beam weight error effect as the vertical component of cable forces and calculates the initial cable force adjustment values of the cables;and then the adjustment is modified using deformation of tower deviation.The engineering case analysis shows that a large volume of cable force adjustment is required for the cables close to the beam segment with beam weight errors,and its value can reach up to 70 percent of the beam weight error value;while a small volume of cable force adjustment is required for the cables away,with its value being less than 5 percent of the value of beam weight error.The adjusted cable force can effectively reduce the linear variation caused by beam weight error,thus enabling the structural line shape close to the default at assembling stage.The initial value produced by the main beam supporting force occupies a large proportion of the adjustment value of cable force;while the modified value of tower deviation takes a small proportion and reduces with the increase of the cantilever length.The volume of adjustment of cable force reduces with the increase of main beam stiffness,but increases with the cable stiffness.