宽幅箱梁桥施工监控和剪力滞效应分析

发布时间：2019-06-20 16:16

【摘要】：宽幅箱梁桥施工过程中截面易发生横向变形,线形控制难度增加;主梁截面应力最大状态发生在施工阶段,在剪力滞效应的影响下,施工过程中容易发生安全事故。基于以上考虑,本文以扶沟县东关大桥——宽度为26.5m的单箱五室连续梁桥为背景工程开展施工监控,研究施工过程中剪力滞变化规律。完成的主要工作和取得的主要结论有:(1)以有限元软件Midas/Civil建立单梁模型与梁格模型,以有限元软件Midas/Fea建立空间实体单元模型,为开展扶沟县东关大桥施工监控提供理论数据支持。(2)探讨了扶沟县东关大桥施工过程中浇筑混凝土,张拉预应力,桥梁合龙,体系转换等施工步骤对主梁截面应力及剪力滞效应的影响,提出不同施工步骤产生的主梁应力在顶底板均表现出不同的“整体”与“局部”剪力滞效应,分析悬臂根部箱梁截面在施工全过程中剪力滞变化规律。得出:悬臂施工过程中,浇筑混凝土使顶板受拉,底板受压,浇筑混凝土前后主梁截面顶板剪力滞效应有所增加,底板剪力滞效应有所减弱;张拉预应力束使顶板受压,底板受拉,张拉预应力束前后主梁截面顶板剪力滞效应有所减弱,底板剪力滞效应有所增加;桥梁合龙与体系转换对剪力滞效应的影响与梁位有关;随着施工进行,悬臂根部箱梁截面压应力不断增加,剪力滞效应不断减弱。(3)根据扶沟县东关大桥的特点,制定桥梁施工监控方案,采用自适应控制法对扶沟县东关大桥施工过程实施监控:通过合理设置每一阶段的立模标高控制线形,保证施工过程中主梁线形平顺;通过对比修正后现场实测应力结果和理论应力结果,保证施工过程中主梁受力合理安全。监控结果表明:扶沟县东关大桥成桥后线形较为平顺,达到线形控制目标;施工过程中主梁处于安全可靠的状态,成桥后应力满足规范要求,并有一定的安全储备。
[Abstract]:During the construction of wide box girder bridge, the transverse deformation of the section is easy to occur, and the difficulty of linear control is increased, and the maximum stress state of the main beam section occurs in the construction stage. Under the influence of shear lag effect, safety accidents are easy to occur in the construction process. Based on the above considerations, this paper takes Fugou Dongguan Bridge, a single box and five chamber continuous beam bridge with a width of 26.5m, as the background project to carry out construction monitoring, and studies the variation law of shear lag in the construction process. The main work completed and the main conclusions obtained are as follows: (1) the single beam model and beam model are established by finite element software Midas/Civil, and the spatial entity element model is established by finite element software Midas/Fea, which provides theoretical data support for the construction monitoring of Dongguan Bridge in Fugou County. (2) the pouring concrete, tensioned prestress and bridge closure in the construction process of Dongguan Bridge in Fugou County are discussed. The influence of system transformation and other construction steps on the section stress and shear lag effect of the main beam is put forward. The stress of the main beam produced by different construction steps shows different "whole" and "local" shear lag effects at the top and bottom plate, and the variation law of shear lag of the cantilever root box girder section in the whole construction process is analyzed. It is concluded that in the process of cantilever construction, the shear lag effect of the section of the main beam before and after pouring concrete increases, and the shear lag effect of the section of the main beam increases, and the shear lag effect of the section of the main beam before and after pouring concrete is weakened by pouring concrete, and the shear lag effect of the section of the main beam before and after the tension prestressed beam is weakened, and the shear lag effect of the bottom plate is increased. The influence of bridge closure and system transformation on shear lag effect is related to beam position. With the construction going on, the compression stress of box girder at the root of cantilever increases and the shear lag effect weakens. (3) according to the characteristics of Dongguan Bridge in Fugou County, the bridge construction monitoring scheme is worked out, and the construction process of Dongguan Bridge in Fugou County is monitored by adaptive control method: the alignment of the main beam is controlled by reasonably setting the elevation of vertical formwork in each stage to ensure the alignment of the main beam in the construction process; By comparing the measured stress results with the theoretical stress results, the reasonable and safe stress of the main beam in the construction process is guaranteed. The monitoring results show that the alignment of the Dongguan Bridge in Fugou County is smooth and achieves the goal of alignment control, and the main beam is in a safe and reliable state during the construction process, and the stress after the completion of the bridge meets the requirements of the code and has a certain safety reserve.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U445.4

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