预应力混凝土箱梁剪力滞效应纵向影响长度分析

Longitudinal Influence Length of Shear Lag Effect of Prestressed Concrete Box Girder

为研究预应力混凝土箱梁剪力滞效应在纵向梁长方向上的影响长度,采用通用有限元分析软件ANSYS,建立有限元分析模型,讨论了剪力滞系数沿梁纵向分布规律,重点分析了宽跨比、跨高比、预应力大小以及集中荷载等参数对箱梁剪力滞效应纵向影响长度的影响。研究结果表明,无论箱梁顶板还是底板,其剪力滞系数最大值均在荷载施加的截面,远离荷载施加的截面最大剪力滞系数迅速减小。荷载引起的剪力滞效应纵向影响长度较小,仅在荷载施加位置附近影响较大。随着宽跨比增大,箱梁剪力滞效应纵向影响长度均越来越明显,且越来越剧烈;跨高比的改变对箱梁顶板剪力滞效应影响较为剧烈,但其给箱梁造成的纵向影响不太明显。预应力以及集中荷载的改变对箱梁剪力滞效应影响较小,对箱梁剪力滞效应纵向影响长度的改变程度也较微弱。

In order to study the effect of shear lag effect of prestressed concrete box girder in the longitudinal direction,the finite element analysis software ANSYS is used to establish the finite element analysis model,and the longitudinal distribution of shear lag coefficient along the longitudinal beam is also discussed.The change of length of shear lag effect of the box girder is mainly analyzed by using the parameters such as the ratio of span to width,the ratio of span to height,the size of the prestress and the concentrated load and so on.The results show that the maximum shear lag coefficient of the box girder is always on the section of load,regardless of the roof of the box girder or the bottom plate.When the shear lag coefficient of the cross section is far from the load,it decreases rapidly,and the shear lag effect caused by the load has a little influence on the length,only in the vicinity of the load exerted strongly.With the increase of wide span ratio,the longitudinal effect of the length of shear lag effect of box girder is more and more obvious and fierce.The effect of the change of the span depth ratio on the shear lag effect of the box girder is also severe,but the vertical influence is not obvious.The changes of the prestress and concentrated load have a little effect on the shear lag effect of box girder,and also it is weak on the change of the longitudinal effect of the shear lag effect of box girder.