悬臂曲线箱梁负剪力滞效应

Negative Shear Lag Effect of Cantilever Curved Box Girder

为研究悬臂曲线箱梁负剪力滞效应,本文基于能量原理,推导了悬臂箱梁剪力滞计算公式,经与ANSYS有限元结果相比较,吻合良好,在此基础上采用有限元程序分析了腹板间距、悬臂板宽度、曲率半径、箱梁高度和厚度对其负剪力滞效应的影响。结果表明:(1)在均布荷载作用下,沿全跨纵向,悬臂曲线箱梁呈现出明显的正、负剪力滞效应,负剪力滞在l/6处出现极值,正剪力滞在悬臂梁根部最显著;(2)与直线梁相比,曲线梁考虑曲率的影响,加剧了正、负剪力滞应力分布的不均衡性;(3)内侧腹板与顶板相接处节点易出现剪滞效应惰性区,而外腹板与顶板相接处节点均未出现惰性区,但有相同的正、负剪力滞临界点;(4)腹板间距和悬臂板宽度对负剪力滞影响较大,曲率半径、箱梁高度和厚度对负剪力滞效应有一定的影响。

In order to investigate the negative shear lag effect of cantilever curved box girder,the shear lag calculating formula of cantilever box girder is deduced based on energy principle in this paper. Then comparing the theoretical result with the finite element of ANSYS,a good agreement is achiered between them. Based on it,the influences of web space,cantilever slab width,curvature radius,box girder height and thickness on negative shear lag effect are analyzed by using finite element program. The results indicate that：（ 1） Under uniform load,there are prominent positive and negative shear lag effects along full-span longitudinal direction. The negative shear lag is most prominent at l/6 cross section,and positive shear lag effect is most prominent at the root of cantilever beam.（ 2） Compared with straight beam,the stress distribution of curved beam which considered the influence of curvature is more non-uniform.（ 3） There are inert areas of shear lag effect at the junction between the inside web and upper flange,while for outside web,there isn＇t inert area,but it has the same critical points of positive and negative shear lag.（ 4） Web space and cantilever slab width have a great influence on negative shear lag effect,while curvature radius,box girder height and thickness have some influence on negative shear lag effect.