混凝土箱梁的横向内力分析

发布时间：2018-09-06 06:53

【摘要】：混凝土箱梁因其众多优点而被广泛应用于现代桥梁工程中。由于箱梁截面挖空率及腹板间距大,箱壁薄,在荷载作用下往往会产生较大的横向内力,从而导致部分混凝土箱梁在运营阶段出现了明显的纵向裂缝。因此,混凝土箱梁的横向内力计算已成为桥梁设计人员所关心的问题。本文在总结和完善传统框架分析的基础上,针对目前混凝土箱梁横向内力研究中存在的主要问题,从以下几个方面对单箱单室斜腹板箱梁的横向内力分析进行了研究。(1)通过对箱梁横向内力的计算方法进行对比分析,进一步完善箱梁横向内力分析理论。本文以承受偏心荷载作用的箱梁为模型,基于推广的“TYL”框架分析理论,提出了一种改进的框架分析方法。该方法将箱梁畸变理论与框架分析原理相结合,通过建立箱梁的畸变位移与框架位移之间的协调关系,推导出计算横向内力所需的基本公式,并将按本文公式求得的横向内力与有限元软件ANSYS壳单元的分析结果进行了对比,从而验证了本文方法的适用性及可靠性。通过对比分析本文改进的框架法和已有的推广“TYL”框架法表明,两种方法的本质区别在于对框架位移的处理方式不同,而本文改进的框架法对横向内力的计算结果明显优于推广的“TYL”框架法。(2)仅按刚性支承框架分析法计算箱梁的横向内力时不能客观反映箱梁的实际受力情况,虽然本文改进的框架分析法具有良好的精度,但由于考虑了箱梁的畸变效应,使得计算相当繁琐。为了便于工程应用,本文引入了横向内力修正系数,通过这一修正系数对刚性支承框架法的计算结果进行修正。结合数值算例,详细分析了竖向偏心荷载位置、箱梁高度、斜腹板倾斜程度以及悬臂板长度等参数变化对横向内力及其修正系数的影响规律。在本文方法与有限元法的横向内力计算结果的基础上,给出了箱梁在计算截面上各控制点处横向修正系数的合理取值。(3)通过对国内几座已建的混凝土连续箱梁桥面板横向内力的分析表明,在计算大跨度预应力混凝土箱梁的横向内力时采用现行公路桥梁设计规范尚难满足安全要求,需要通过提高现行规范中的弹性约束系数来实现大跨度预应力箱梁桥的安全设计。
[Abstract]:Concrete box girder is widely used in modern bridge engineering because of its many advantages. Due to the large hollowing rate of the box girder section and the spacing of the web, and the thin wall of the box girder, the transverse internal force is often produced under the action of load, which leads to obvious longitudinal cracks in some concrete box girders in the operation stage. Therefore, the calculation of transverse internal force of concrete box girder has become a concern of bridge designers. On the basis of summarizing and perfecting the analysis of traditional frame, this paper aims at the main problems existing in the research of transverse internal force of concrete box girder. The transverse internal force analysis of single box girder with single box and single chamber inclined web plate is studied from the following aspects. (1) the theory of transverse internal force analysis of box girder is further improved by comparing and analyzing the calculation method of transverse internal force of box girder. In this paper, based on the extended "TYL" frame analysis theory, an improved frame analysis method is proposed based on the model of box girder subjected to eccentric loads. In this method, the distortion theory of box girder is combined with the principle of frame analysis. By establishing the harmonious relation between the distortion displacement of box girder and the displacement of frame, the basic formula for calculating the transverse internal force is derived. The transverse internal force obtained by the formula is compared with the analysis results of the finite element software ANSYS shell element, which verifies the applicability and reliability of this method. By comparing and analyzing the improved frame method and the existing extended "TYL" frame method, it is shown that the essential difference between the two methods lies in the different ways of dealing with the displacement of the frame. The result of the improved frame method is obviously better than that of the extended "TYL" frame method. (2) when calculating the transverse internal force of the box girder only according to the rigid support frame analysis method, it can not objectively reflect the actual force situation of the box girder. Although the improved frame analysis method in this paper has good precision, but the distortion effect of box girder is taken into account, the calculation is rather complicated. In order to facilitate engineering application, the transverse internal force correction coefficient is introduced in this paper, through which the calculation results of rigid support frame method are modified. Combined with numerical examples, the influence of the position of vertical eccentric load, the height of box girder, the inclined degree of inclined web and the length of cantilever plate on the lateral internal force and its correction coefficient are analyzed in detail. Based on the results of the method and the finite element method, The reasonable value of the transverse correction coefficient at each control point of the box girder is given. (3) through the analysis of the transverse internal forces of several concrete continuous box girder bridges built in China, it is shown that, When calculating the transverse internal force of long-span prestressed concrete box girder, it is difficult to meet the safety requirements by using the existing highway bridge design code. It is necessary to achieve the safety design of the long-span prestressed box girder bridge by increasing the elastic constraint coefficient in the current code.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441

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