纵向预应力对箱梁剪力滞效应影响研究
发布时间：2018-08-20 08:00
【摘要】：箱形截面梁由于具有很好的结构特点和受力性能,故在连续梁桥和连续刚构桥中广泛应用。箱梁具有横向悬臂板宽、腹板间距大以及箱壁薄等特点,其翼板在承受荷载时存在不均匀的剪切变形,截面正应力沿截面不再是直线分布,而是呈曲线分布,即剪力滞现象。忽略剪力滞效应的影响将会导致结构设计的不安全,严重时有可能造成桥梁结构的破坏。纵向预应力对梁体的作用本质上与轴向力存在着密切的关系,而目前针对轴向力作用下的剪力滞效应研究较少。本文基于剪力滞效应的原理,指出轴向力及纵向预应力作用下箱梁将产生剪力滞效应,运用有限元软件ANSYS对薄壁箱梁剪力滞效应影响进行数值分析,得到并总结剪力滞效应沿梁纵向分布的规律。目的在于研究轴向力及预应力作用下箱梁剪力滞效应及箱梁剪力滞的变化规律,可以为工程实践提供一定参考。主要的研究工作包括:数值分析探讨轴向力所引起的纵向应力的分布规律,选取简支、悬臂两种基本边界条件下的薄壁箱梁作为研究对象,区分对称荷载和偏心压力荷载两种不同荷载类型,以及箱梁顶板有悬臂和无悬臂两种情况,进行计算比较分析,从而反映不同荷载作用下各控制截面顶板、底板正应力值横向分布的变化差异,以及剪力滞效应沿纵向的变化情况,以便在结构设计和理论研究时作为参考。此外,本文以某16+2?20+16m的实际连续箱梁桥为工程背景,研究施工阶段施加纵向预应力导致的梁体截面上的剪力滞效应。采用理论计算和有限元程序对预应力混凝土连续梁桥的各控制截面的截面正应力进行了计算分析,探讨了后张法构件曲线布筋情况下预加力对连续箱梁桥各控制截面剪力滞效应的影响,以及剪力滞效应沿桥梁纵向的变化情况;依据规范计算施工阶段的预应力损失并在有限元程序中予以实现,对比分析了考虑预应力损失和未考虑预应力损失的情况下,纵向预应力产生的剪力滞效应,并计算考虑自重后的剪力滞效应变化,可为实际工程设计及施工提供参考。
[Abstract]:Box section beams are widely used in continuous beam bridges and continuous rigid frame bridges because of their good structural characteristics and mechanical properties. Box girder has the characteristics of transverse cantilever plate width, large web spacing and thin box wall. There is uneven shear deformation in the wing plate under load, and the normal stress distribution along the section is no longer linear, but curve distribution, that is, shear lag phenomenon. Ignoring the effect of shear lag will lead to the unsafe design of the structure, which may lead to the destruction of the bridge structure. The action of longitudinal prestress on beam body is essentially closely related to axial force, but there is little research on shear lag effect under axial force at present. Based on the principle of shear lag effect, this paper points out that the box girder will produce shear lag effect under axial force and longitudinal prestressing force. The influence of shear lag effect on thin-walled box girder is analyzed numerically by finite element software ANSYS. The law of longitudinal distribution of shear lag effect along the beam is obtained and summarized. The purpose of this paper is to study the shear lag effect of box girder and the variation law of box girder shear lag under the action of axial force and prestress, which can provide a certain reference for engineering practice. The main research work is as follows: the distribution of longitudinal stress caused by axial force is analyzed numerically, and thin wall box girder with simple support and cantilever is selected as the object of study. Two different load types, symmetrical load and eccentric pressure load, and cantilever and no cantilever on the roof of box girder are distinguished, and calculated and analyzed, so as to reflect the control section roof under different loads. The variation of the transverse distribution of the normal stress and the variation of the shear lag along the longitudinal direction are used as references for the structural design and theoretical study. In addition, the shear lag effect on beam section caused by longitudinal prestressing in construction stage is studied in this paper, which is based on a practical continuous box girder bridge with 162m and 2016m. The normal stress of each control section of prestressed concrete continuous beam bridge is calculated and analyzed by theoretical calculation and finite element program. The influence of prestress on the shear lag effect of each control section of continuous box girder bridge and the variation of shear lag effect along the longitudinal direction of continuous box girder bridge are discussed. The prestress loss in construction stage is calculated according to the code and realized in the finite element program. The shear lag effect caused by longitudinal prestress is compared and analyzed when the prestress loss is taken into account and the prestress loss is not taken into account. The change of shear lag effect considering deadweight can be used as a reference for practical engineering design and construction.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441
本文编号：2192948
[Abstract]:Box section beams are widely used in continuous beam bridges and continuous rigid frame bridges because of their good structural characteristics and mechanical properties. Box girder has the characteristics of transverse cantilever plate width, large web spacing and thin box wall. There is uneven shear deformation in the wing plate under load, and the normal stress distribution along the section is no longer linear, but curve distribution, that is, shear lag phenomenon. Ignoring the effect of shear lag will lead to the unsafe design of the structure, which may lead to the destruction of the bridge structure. The action of longitudinal prestress on beam body is essentially closely related to axial force, but there is little research on shear lag effect under axial force at present. Based on the principle of shear lag effect, this paper points out that the box girder will produce shear lag effect under axial force and longitudinal prestressing force. The influence of shear lag effect on thin-walled box girder is analyzed numerically by finite element software ANSYS. The law of longitudinal distribution of shear lag effect along the beam is obtained and summarized. The purpose of this paper is to study the shear lag effect of box girder and the variation law of box girder shear lag under the action of axial force and prestress, which can provide a certain reference for engineering practice. The main research work is as follows: the distribution of longitudinal stress caused by axial force is analyzed numerically, and thin wall box girder with simple support and cantilever is selected as the object of study. Two different load types, symmetrical load and eccentric pressure load, and cantilever and no cantilever on the roof of box girder are distinguished, and calculated and analyzed, so as to reflect the control section roof under different loads. The variation of the transverse distribution of the normal stress and the variation of the shear lag along the longitudinal direction are used as references for the structural design and theoretical study. In addition, the shear lag effect on beam section caused by longitudinal prestressing in construction stage is studied in this paper, which is based on a practical continuous box girder bridge with 162m and 2016m. The normal stress of each control section of prestressed concrete continuous beam bridge is calculated and analyzed by theoretical calculation and finite element program. The influence of prestress on the shear lag effect of each control section of continuous box girder bridge and the variation of shear lag effect along the longitudinal direction of continuous box girder bridge are discussed. The prestress loss in construction stage is calculated according to the code and realized in the finite element program. The shear lag effect caused by longitudinal prestress is compared and analyzed when the prestress loss is taken into account and the prestress loss is not taken into account. The change of shear lag effect considering deadweight can be used as a reference for practical engineering design and construction.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441
【参考文献】
相关期刊论文 前1条
1 祝明桥;魏启智;曾垂军;蒋伟忠;;混凝土薄壁连续箱梁剪力滞效应分析与对比[J];湘潭大学自然科学学报;2009年03期
，本文编号：2192948
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