PC箱梁桥斜截面空间应力精细化分析与配筋研究

发布时间：2018-03-22 14:51

本文选题：箱梁空间效应　切入点：腹板斜裂缝　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：经过近几十年大规模的基础设施建设,PC连续箱梁桥因为具备独特的优势已经被广泛采用。随着经济发展、使用功能要求的提高,大跨径宽箱梁桥也越来越多。但是,从工程实践中发生的一些问题来看,箱梁腹板上出现了普遍开裂的现象,其中尤其是腹板斜裂缝比较常见,甚至达到腹板裂缝数量的95%,斜裂缝的存在对桥梁的安全性和耐久性是十分不利的。鉴于该类病害的普遍性,本文分别从箱梁桥的空间效应、当前的设计计算方法、预应力钢筋配筋以及施工工艺等角度对多腹板宽箱梁的腹板斜裂缝的病害成因、开裂机理进行了研究,并从控制主拉应力的角度给出了配筋建议。首先,本文对腹板斜裂缝病害的相关文献进行了统计研究,明确了斜裂缝的性质,阐述了剪切破坏的机理。多腹板宽箱梁桥具有显著地空间效应,常用的简化分析方法和针对简单桥梁的现行规范并不能完全反映箱梁的空间效应,这是引起箱梁腹板开裂的重要原因之一;对预应力损失估计不足、下弯束设计不合理、施工组织管理不善、未能够按照设计要求严格施工等,导致预应力难以起到限制主拉应力的作用引起腹板开裂。其次,本文分别研究了箱梁空间效应以及腹板剪应力的解析分析方法,通过实例分析明确了箱梁腹板的受力规律。依托辽阳河东新城宏伟大桥,运用MIDAS/FEA有限元分析方法分别从施工阶段和成桥阶段进行了斜截面空间应力的精细化分析,并分别与施工监控数据和梁单元计算结果进行了对比;实体单元计算结果表明在L/4跨及边跨支点附近是主拉应力较大的位置,与实际PC箱梁桥腹板产生斜裂缝的位置基本一致。加之现行规范中对腹板的剪力分配并未明确说明,导致腹板主拉应力计算不准确,同样给设计带来了安全隐患。最后,本文在对多腹板宽箱梁桥斜截面空间应力把握的基础上,对现有的预应力配筋方法进行了研究和评价。分别研究了竖向和纵向预应力筋对腹板受力的影响因素,并从控制主拉应力的角度出发,对竖向筋的配筋间距及施工方法以及纵向预应力筋的设置形式分别给出了相关建议。
[Abstract]:PC continuous box girder bridges have been widely used in recent decades because of their unique advantages. With the development of economy and the improvement of function requirements, there are more and more long span and wide box girder bridges. From the point of view of some problems in engineering practice, there is a general cracking on the web of box girder, especially the inclined crack of web. Even reaching 95% of the number of web cracks, the existence of oblique cracks is very unfavorable to the safety and durability of the bridge. In view of the universality of this kind of disease, this paper analyzes the spatial effects of box girder bridges and the current design and calculation methods. In this paper, the causes and mechanism of the diagonal cracks of web plate of multi-web wide box girder are studied from the angles of reinforcement and construction technology, and suggestions are given from the angle of controlling the main tensile stress. This paper makes a statistical study on the diseases of web slant cracks, clarifies the properties of oblique cracks, and expounds the mechanism of shear failure. The commonly used simplified analysis method and the current code for simple bridges can not completely reflect the spatial effect of box girder, which is one of the important reasons for the cracking of box girder web. The construction organization is not well managed and can not be strictly constructed in accordance with the design requirements, which leads to the failure of the prestress to limit the main tensile stress and the cracking of the web plate. In this paper, the spatial effect of box girder and the analytical analysis method of web shear stress are studied respectively, and the force law of box girder web is clarified by examples. The MIDAS/FEA finite element analysis method is used to analyze the spatial stress of the inclined section from the construction stage and the bridge stage respectively, and the results are compared with the construction monitoring data and the calculation results of the beam element. The results of solid element calculation show that the main tensile stress is high near the fulcrum of L / 4 span and side span, which is basically consistent with the actual position of inclined cracks in the web of PC box girder bridge. In addition, the shear distribution of web plate is not clearly stated in the current code. As a result, the calculation of the main tension stress of the web is not accurate, and it also brings the hidden danger of safety to the design. Finally, based on the grasp of the spatial stress of the inclined section of the multi-web wide box girder bridge, The existing prestressed reinforcement methods are studied and evaluated. The influence factors of vertical and longitudinal prestressed tendons on web stress are studied, and the main tension stress is controlled from the point of view of controlling the main tensile stress. The relative suggestions on the spacing and construction methods of vertical tendons and the setting form of longitudinal prestressed tendons are given respectively.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U448.213

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