新洋港矮塔斜拉桥主梁施工监控及零号块裂缝研究
发布时间：2018-09-14 12:01
【摘要】：随着中国经济的飞速发展,公路桥梁等大型基础设施正在大规模建设,矮塔斜拉桥作为一个较为新型的桥梁形式,凭借它在中小跨径范围内的经济成本优势和良好的景观收益被人们越来越多的接受与采用。本文以新洋港矮塔斜拉桥为工程背景,对主梁施工期标高和应力的控制进行了系统的研究,并分析了箱梁0#块出现开裂的原因,提出预防裂缝发生的施工建议,为今后同类桥梁的施工提供参考。主要研究内容包括:(1)基于Midas/Civil软件,利用梁单元建立新洋港大桥有限元模型,并详细划分施工阶段,分析了主梁在最大悬臂状态下的受力状态,为后期施工监控工作提供理论基础。(2)结合新洋港大桥的施工监控方案,基于桥梁的有限元模型,通过施工现场实测获得各参数的实际值,然后进行理论值与实际值的对比分析;在施工监控过程中,采用自适应控制法对模型中材料的弹性模量和容重这两个参数进行修正;研究结果表明:基于最小二乘法的自适应控制理论可以很好地指导施工监控工作,理论模型与实际结构的误差较小,施工监控收到较理想的效果。(3)考虑到箱梁0#块作为施工期结构主要传递和承受荷载的构件,其应力极大且分布复杂,基于ANSYS软件建立0#块有限元实体模型,考虑普通钢筋和预应力钢绞线对混凝土的作用,通过对模型中的刚性面施加位移荷载,模拟0#块在最大悬臂荷载工况下的应力状态;分析结果表明0#块在横向预应力、纵向预应力和最大悬臂荷载工况下整体基本处于受压状态,压应力值满足混凝土的设计抗压值并合理储存有预压力;通过应力分析结果与裂缝分布的对比得到,最大悬臂结构荷载有可能为裂缝发育提供拉应力,但不是箱梁开裂的主要原因。(4)介绍了混凝土温度场有限元理论和温度场参数的确定方法;基于ANSYS有限元软件,利用SOLID70热单元和SOLID75结构单元建立有限元模型,模拟了0#块在水化热、收缩和日照作用下的应力状态;根据应力大小及分布情况,判断出温度收缩作用是导致裂缝发生的主要原因;通过调整龄期间隔、后浇层厚度和线膨胀系数对顶板应力进行参数分析,得出这三项施工参数对温度应力的大小均有不同程度的影响;研究结果表明,温度裂缝是可以通过调整施工参数来减轻或避免的,本文研究成果可以为其他类似工程施工提供理论参考。
[Abstract]:With the rapid development of China's economy, large scale infrastructure, such as highway bridges, is being built on a large scale. As a relatively new type of bridge, low-tower cable-stayed bridges are being built. By virtue of its economic cost advantage and good landscape income in the medium and small span range, it is accepted and adopted by more and more people. Based on the engineering background of the cable-stayed bridge with low tower in Xinyang Port, this paper systematically studies the control of the elevation and stress during the construction period of the main girder, and analyzes the causes of cracking in the block of box girder 0#, and puts forward some construction suggestions to prevent the cracks. It provides reference for the construction of similar bridges in the future. The main research contents are as follows: (1) based on Midas/Civil software, the finite element model of Xinyanggang Bridge is established by using beam element, and the construction stage is divided in detail, and the stress state of the main beam under the maximum cantilever state is analyzed. (2) combined with the construction monitoring scheme of Xinyang Port Bridge, based on the finite element model of the bridge, the actual values of the parameters are obtained by the field measurement, and then the comparison between the theoretical value and the actual value is carried out. In the process of construction monitoring, adaptive control method is used to modify the elastic modulus and bulk density of materials in the model. The research results show that the adaptive control theory based on least square method can guide the construction monitoring work very well. The error between the theoretical model and the actual structure is small, and the construction monitoring has a better effect. (3) considering that the box girder 0# block is the main member of the structure during the construction period, the stress is very large and the distribution is complex. Based on ANSYS software, the finite element model of 0# block is established. Considering the effect of common steel bar and prestressed steel strand on concrete, the stress state of 0# block under maximum cantilever load is simulated by applying displacement load to the rigid surface of the model. The results show that the whole block is in the state of compression under the condition of transverse prestress, longitudinal prestress and maximum cantilever load, and the compressive stress value meets the design compressive value of concrete and has reasonable storage of pre-pressure. By comparing the stress analysis results with the crack distribution, it is concluded that the maximum cantilever structure load may provide tensile stress for the crack development. But it is not the main reason of box girder cracking. (4) the finite element theory of concrete temperature field and the determination method of temperature field parameters are introduced. Based on ANSYS finite element software, SOLID70 thermal element and SOLID75 structural element are used to establish the finite element model. The stress state of 0# block under the action of hydration heat, shrinkage and sunshine is simulated. According to the stress size and distribution, it is determined that temperature shrinkage is the main cause of cracks. The thickness of the post-pouring layer and the coefficient of linear expansion are analyzed to the roof stress, and the results show that the three construction parameters have different influence on the temperature stress. The temperature crack can be reduced or avoided by adjusting the construction parameters. The research results in this paper can provide a theoretical reference for other similar projects.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445
本文编号：2242653
[Abstract]:With the rapid development of China's economy, large scale infrastructure, such as highway bridges, is being built on a large scale. As a relatively new type of bridge, low-tower cable-stayed bridges are being built. By virtue of its economic cost advantage and good landscape income in the medium and small span range, it is accepted and adopted by more and more people. Based on the engineering background of the cable-stayed bridge with low tower in Xinyang Port, this paper systematically studies the control of the elevation and stress during the construction period of the main girder, and analyzes the causes of cracking in the block of box girder 0#, and puts forward some construction suggestions to prevent the cracks. It provides reference for the construction of similar bridges in the future. The main research contents are as follows: (1) based on Midas/Civil software, the finite element model of Xinyanggang Bridge is established by using beam element, and the construction stage is divided in detail, and the stress state of the main beam under the maximum cantilever state is analyzed. (2) combined with the construction monitoring scheme of Xinyang Port Bridge, based on the finite element model of the bridge, the actual values of the parameters are obtained by the field measurement, and then the comparison between the theoretical value and the actual value is carried out. In the process of construction monitoring, adaptive control method is used to modify the elastic modulus and bulk density of materials in the model. The research results show that the adaptive control theory based on least square method can guide the construction monitoring work very well. The error between the theoretical model and the actual structure is small, and the construction monitoring has a better effect. (3) considering that the box girder 0# block is the main member of the structure during the construction period, the stress is very large and the distribution is complex. Based on ANSYS software, the finite element model of 0# block is established. Considering the effect of common steel bar and prestressed steel strand on concrete, the stress state of 0# block under maximum cantilever load is simulated by applying displacement load to the rigid surface of the model. The results show that the whole block is in the state of compression under the condition of transverse prestress, longitudinal prestress and maximum cantilever load, and the compressive stress value meets the design compressive value of concrete and has reasonable storage of pre-pressure. By comparing the stress analysis results with the crack distribution, it is concluded that the maximum cantilever structure load may provide tensile stress for the crack development. But it is not the main reason of box girder cracking. (4) the finite element theory of concrete temperature field and the determination method of temperature field parameters are introduced. Based on ANSYS finite element software, SOLID70 thermal element and SOLID75 structural element are used to establish the finite element model. The stress state of 0# block under the action of hydration heat, shrinkage and sunshine is simulated. According to the stress size and distribution, it is determined that temperature shrinkage is the main cause of cracks. The thickness of the post-pouring layer and the coefficient of linear expansion are analyzed to the roof stress, and the results show that the three construction parameters have different influence on the temperature stress. The temperature crack can be reduced or avoided by adjusting the construction parameters. The research results in this paper can provide a theoretical reference for other similar projects.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445
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1 吕艳梅;刘立新;徐有邻;;商品混凝土收缩应力试验研究[J];东南大学学报(自然科学版);2005年S1期
2 袁明;刘建伟;颜东煌;;预应力混凝土连续箱梁桥设计的统计分析[J];中外公路;2012年06期
，本文编号：2242653
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