悬臂施工连续梁桥顶板预应力束平弯段径向力效应

EFFECT OF RADIAL FORCE CAUSED BY HORIZONTAL BEND OF PRESTRESSING TENDONS IN TOP FLANGE OF CONTINUOUS BOX GIRDER BRIDGE

平面杆系模型无法考虑预应力束平弯效应的影响,三维实体模型的建立又过于复杂。针对此问题,该文以悬臂施工连续箱梁顶板为研究对象,推导了顶板中轴线处平弯束径向力效应引起的拉应力的弹性力学解。基于拉应力最大值往往是设计控制点,提出了等效宽度的概念,对弹性力学解进行进一步简化。最后,借助ANSYS软件进行算例验证。结果表明,随着平弯半径的增大,曲率逐渐减小,级数解推导过程中由平弯束"以直代曲"造成的误差逐渐减小,增加修正项以考虑平弯束斜率改变的影响后,数值解与公式解趋于一致,即简化后的公式是行之有效的。

The influence of radial force caused by horizontal bend of prestressing tendons can＇t be taken into account in planar member models. The solid models, in which the influence could be reflected, are complicated in modeling process. To solve this problem, an elasticity formula on tensile stress at medial axis is proposed in this paper, which can be applied to the top flange of continuous box girder. Then the concept of equivalent width is suggested to further simplify the elasticity formula based on the idea that the maximum tensile stress is always the control point in the design process. Finally, it is verified by numerical experiment with the aid of ANSYS software. The analysis results indicate that the errors caused by ＂Drawing Curves by Straight Lines＂ in the derivation process decrease gradually with the increase of horizontal bend radius. Furthermore, numerical solutions and formula solutions tend to be identical after a correction term is introduced to take the influence of trend change of prestressing tendons into consideration, that is, the simplified calculation formula is practical.