连续刚构桥宽箱梁裂缝分析与防治措施研究
发布时间：2018-10-08 16:26
【摘要】：连续刚构桥具有跨越能力大、施工简便、造价经济、行车舒适等优点,受到工程师所青睐。通过对大量连续刚构桥的检测发现这种桥型在施工和运营阶段出现了相当数量的裂缝,裂缝对于桥梁的安全性和耐久性都有不利的影响。连续刚构桥具有广阔的前景,连续刚构桥的开裂研究对桥梁施工、设计和养护都有利。本文主要以赶水大桥为工程背景,计算大桥在施工阶段和成桥阶段箱梁应力,分析宽箱梁结构裂缝。用Midas civil分析了赶水大桥的施工过程,重点分析了桥梁体系转换过程梁段内力变化,比较了不同施工阶段合拢段底板应力变化。用ANSYS壳单元SHELL63建立全桥模型,分析宽箱梁的剪力滞和畸变,将壳单元计算结果与杆件单元计算结果进行比较,从而得到剪力滞系数。分析了三向预应力对空间箱梁的力学行为。主要工作有:比较分析设置顶板横向预应力和没有设置顶板横向预应力下宽箱梁顶板应力横向分布;分析竖向预应力对腹板主应力的控制效应,计算比较腹板在不同竖向预应力损失情况下的主应力,分析比较各个梁段腹板受拉区。对赶水大桥成桥状态箱梁结构进行分析。分析预应力损失对跨中梁段挠度和底板应力的影响。通过空间有限元模型分析局部梁段,提出一些预防开裂的措施。在赶水大桥的设计基础上,分别作了以下工作:计算了不同底板线形箱梁底板的径向力。计算了宽箱梁施加横向肋和未加横向肋箱梁的应力。建立了不同腹板厚度的箱梁模型,比较了不同腹板厚度的腹板主应力分布。以径向力公式计算出合拢段底板径向力,建立了合拢段底板有限元模型。计算了不同厚度保护层底板的应力,比较孔道壁的应力分布。通过对前面的计算分析,知道桥梁体系转换过程中合拢段底板受到较大的径向力。径向力大的梁段底板由于箱梁变形和混凝土泊松效应产生横向弯矩,容易产生纵向裂缝。合拢段附近梁段采用高幂次底板线形,更不容易产生纵向裂缝。径向力大的梁段增加横向肋可以增加底板横向刚度,减小横向拉应力,防止结构裂缝。底板保护层厚度增加对孔道壁附近应力影响不大,对改善底板下缘受拉作用有限。顶板横向预应力使得顶板具有一定的压力储备,但是产生的横向弯矩使得翼缘板下缘受拉,特别是翼缘板下缘容易产生纵向裂缝。竖向预应力和剪力控制腹板主应力,当竖向预应力损失到一定值对控制腹板主应力不起控制作用。
[Abstract]:Continuous rigid frame bridge is favored by engineers for its advantages of large span capacity, simple construction, economical cost and comfortable driving. Through the detection of a large number of continuous rigid frame bridges, it is found that there are quite a number of cracks in the construction and operation stages of the bridges, which have adverse effects on the safety and durability of the bridges. Continuous rigid frame bridge has a broad prospect. The research on crack of continuous rigid frame bridge is beneficial to bridge construction, design and maintenance. In this paper, the stress of box girder in the construction stage and the completion stage of the bridge is calculated, and the cracks of the wide box girder structure are analyzed. The construction process of Shuishui Bridge is analyzed by Midas civil. The variation of internal force of beam section during the transition of bridge system is emphatically analyzed and the stress changes of bottom slab of closed section in different construction stages are compared. The full bridge model is established by using ANSYS shell element SHELL63, and the shear lag and distortion of wide box girder are analyzed. The calculated results of shell element are compared with those of member element, and the shear lag coefficient is obtained. The mechanical behavior of three-dimensional prestressing on space box girder is analyzed. The main works are as follows: comparing and analyzing the transverse stress distribution of the wide box girder roof with and without the transverse prestress of the roof, analyzing the control effect of the vertical prestress on the principal stress of the web plate, and analyzing the control effect of the vertical prestress on the main stress of the web plate. The principal stresses of webs under different vertical prestress losses are calculated and compared. The box girder structure of Shuishui Bridge is analyzed. The effect of prestress loss on deflection and bottom stress of mid-span beam is analyzed. Based on the spatial finite element model, the local beam section is analyzed, and some measures to prevent the crack are put forward. Based on the design of Shuihui Bridge, the following works are done: the radial force of different bottom plate linear box girder is calculated. The stress of wide box girder with and without transverse rib is calculated. The box girder model with different web thickness is established and the principal stress distribution of web with different web thickness is compared. The radial force of the bottom plate of the closed section is calculated by the formula of radial force, and the finite element model of the bottom plate of the closure section is established. The stress distribution of the hole wall is compared by calculating the stress of the bottom plate with different thickness of the protective layer. Through the calculation and analysis of the front, it is known that the bottom plate of the closing section is subjected to a large radial force during the transition of the bridge system. Due to box girder deformation and concrete Poisson effect, transverse bending moment of beam bottom plate with large radial force is easy to produce longitudinal cracks. The beam section near the closure section adopts the linear form of high power bottom plate, which makes it less easy to produce longitudinal cracks. The transverse stiffness of the bottom plate can be increased and the transverse tensile stress can be reduced by increasing the transverse rib in the beam section with large radial force and preventing the structural cracks. The thickness of the protective layer of the bottom plate has little effect on the stress near the hole wall, but it has limited effect on the improvement of the lower edge of the bottom plate. The transverse prestressing makes the roof have a certain pressure reserve, but the transverse bending moment makes the flange plate lower edge tension, especially the flange plate lower edge easy to produce longitudinal cracks. The main stress of web plate is controlled by vertical prestress and shear force. When the loss of vertical prestress reaches a certain value, it can not control the principal stress of web plate.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441;U445.4
本文编号：2257449
[Abstract]:Continuous rigid frame bridge is favored by engineers for its advantages of large span capacity, simple construction, economical cost and comfortable driving. Through the detection of a large number of continuous rigid frame bridges, it is found that there are quite a number of cracks in the construction and operation stages of the bridges, which have adverse effects on the safety and durability of the bridges. Continuous rigid frame bridge has a broad prospect. The research on crack of continuous rigid frame bridge is beneficial to bridge construction, design and maintenance. In this paper, the stress of box girder in the construction stage and the completion stage of the bridge is calculated, and the cracks of the wide box girder structure are analyzed. The construction process of Shuishui Bridge is analyzed by Midas civil. The variation of internal force of beam section during the transition of bridge system is emphatically analyzed and the stress changes of bottom slab of closed section in different construction stages are compared. The full bridge model is established by using ANSYS shell element SHELL63, and the shear lag and distortion of wide box girder are analyzed. The calculated results of shell element are compared with those of member element, and the shear lag coefficient is obtained. The mechanical behavior of three-dimensional prestressing on space box girder is analyzed. The main works are as follows: comparing and analyzing the transverse stress distribution of the wide box girder roof with and without the transverse prestress of the roof, analyzing the control effect of the vertical prestress on the principal stress of the web plate, and analyzing the control effect of the vertical prestress on the main stress of the web plate. The principal stresses of webs under different vertical prestress losses are calculated and compared. The box girder structure of Shuishui Bridge is analyzed. The effect of prestress loss on deflection and bottom stress of mid-span beam is analyzed. Based on the spatial finite element model, the local beam section is analyzed, and some measures to prevent the crack are put forward. Based on the design of Shuihui Bridge, the following works are done: the radial force of different bottom plate linear box girder is calculated. The stress of wide box girder with and without transverse rib is calculated. The box girder model with different web thickness is established and the principal stress distribution of web with different web thickness is compared. The radial force of the bottom plate of the closed section is calculated by the formula of radial force, and the finite element model of the bottom plate of the closure section is established. The stress distribution of the hole wall is compared by calculating the stress of the bottom plate with different thickness of the protective layer. Through the calculation and analysis of the front, it is known that the bottom plate of the closing section is subjected to a large radial force during the transition of the bridge system. Due to box girder deformation and concrete Poisson effect, transverse bending moment of beam bottom plate with large radial force is easy to produce longitudinal cracks. The beam section near the closure section adopts the linear form of high power bottom plate, which makes it less easy to produce longitudinal cracks. The transverse stiffness of the bottom plate can be increased and the transverse tensile stress can be reduced by increasing the transverse rib in the beam section with large radial force and preventing the structural cracks. The thickness of the protective layer of the bottom plate has little effect on the stress near the hole wall, but it has limited effect on the improvement of the lower edge of the bottom plate. The transverse prestressing makes the roof have a certain pressure reserve, but the transverse bending moment makes the flange plate lower edge tension, especially the flange plate lower edge easy to produce longitudinal cracks. The main stress of web plate is controlled by vertical prestress and shear force. When the loss of vertical prestress reaches a certain value, it can not control the principal stress of web plate.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441;U445.4
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