不同加载方式对双室箱梁剪力滞效应的影响分析

发布时间：2018-03-16 07:45

本文选题：双室箱梁　切入点：剪力滞效应　出处：《兰州交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着我国经济的发展，箱梁的使用更加广泛，，且箱梁的悬臂更加长、翼缘板更加宽。特别是在跨度较大的桥梁的修建中箱梁的使用更加的普遍，在箱梁的逐步发展和实践中，设计人员发现按初等梁理论计算的结果已不能满足结构的实际受力状态，经研究人员长期研究，发现由于剪力滞后引起了应力的不均匀分布，在工程实践中发现诸多由剪力滞引发的破损现象，引起了研究人员的重视，并且进行了大量的研究和修复工作，使得箱梁的受力更加符合实际的受力状态。本文针对单箱双室矩形箱梁对不同的加载方式对箱梁剪力滞效应的影响进行研究，通过理论和有限元数值两种计算方法，对两种计算的结果进行比较，并总结其不同规律，主要进行了以下几个方面研究。在理论计算方面，对单箱双室矩形箱梁的受力机理进行分析，运用能量变分法原理推导在不同的加载方式作用下双室箱梁简支、悬臂两种边界条件的箱梁截面的剪力滞系数表达式和挠度计算公式，在这些公式中有按初等梁理论计算的一部分也有剪力滞影响的附加应力和挠度。在有限元数值计算方面，本文使用结构计算软件Midas/FEA，对双室矩形截面梁进行模拟计算，并将计算结果与理论计算结果进行比较，以验证Midas/FEA软件计算箱梁正应力的准确性。不同的边界条件、加载方式对箱梁剪力滞的影响是不同的。选用简支、悬臂两种不同的边界条件，在双室箱梁上分别施加集中荷载和均布荷载且每种荷载考虑三种荷载工况，用有限元软件建立不同的边界条件、加载方式下的结构模型，计算出截面的正应力值并且与按初等梁理论计算的结果相比，所得的结果就是箱梁剪力滞系数。对剪力滞系数进行系统地分析，总结出不同加载方式对箱梁剪力滞的影响因素，断面正应力的横向分布规律，并且可以找出箱梁危险截面的最不利点和最不利的荷载工况，作为结构设计的控制点。选取跨度为40m的双室矩形截面箱梁作为工程背景，采用通用有限元程序MIDAS/FEA建立箱梁桥梁单元有限元模型，分析其在不同荷载作用下简支、悬臂梁正应力的横向分布规律和挠度的变化规律。
[Abstract]:With the development of our country's economy, the use of box girder is more extensive, and the cantilever of box girder is longer, the flange plate is wider, especially in the construction of long-span bridge, the use of box girder is more widespread, and in the gradual development and practice of box girder, The designer found that the calculation results based on the elementary beam theory could not satisfy the actual stress state of the structure. After a long period of research by the researchers, it was found that the stress distribution was uneven due to the shear lag. In engineering practice, many damage phenomena caused by shear lag have been found, which has attracted the attention of researchers, and has carried out a lot of research and restoration work. In this paper, the influence of single box and double chamber rectangular box girder on the shear lag effect of box girder under different loading modes is studied, and the theoretical and finite element methods are used to calculate the shear lag effect of box girder. The results of the two calculations are compared, and their different laws are summarized. In the aspect of theoretical calculation, the stress mechanism of single box and double chamber rectangular box girder is analyzed, and the simple support of double chamber box girder under different loading modes is deduced by using the principle of energy variation method. The shear lag coefficient expression and deflection calculation formula of box girder section under two kinds of cantilever boundary conditions have some additional stresses and deflections affected by shear lag as well as some of them calculated according to elementary beam theory. In the aspect of finite element numerical calculation, the structure calculation software Midas / FEAA is used to simulate the double-chamber rectangular section beam, and the calculated results are compared with the theoretical results to verify the accuracy of the Midas/FEA software in calculating the normal stress of the box girder. The influence of loading mode on shear lag of box girder is different under different boundary conditions. Two different boundary conditions, simple support and cantilever, are applied to double chamber box girder under concentrated load and uniform load respectively, and three load conditions are considered for each load. The finite element software is used to establish different boundary conditions, and the structural model under loading mode is used to calculate the normal stress value of the section and compare with the results calculated according to the elementary beam theory. The result is the shear lag coefficient of box girder. The influence factors of different loading modes on the shear lag of box girder and the transverse distribution of normal stress of section are summarized. The most unfavorable point and the most unfavorable load condition of the dangerous section of the box girder can be found as the control point of the structural design. Taking the double-chamber rectangular section box girder with span of 40 m as the engineering background, the finite element model of the box girder bridge element is established by using the universal finite element program MIDAS/FEA, and the simple support under different loads is analyzed. The transverse distribution of normal stress and the variation of deflection of cantilever beam.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441;U448.213

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