折线先张法简支T梁施工方案设计及应用研究

发布时间：2018-08-21 13:21

【摘要】：折线先张法是先张法的一种重要形式,通过弯起器将预应力筋弯折并进行张拉,预弯矩图与荷载作用下的弯矩图更接近,同时克服了直线形先张法预应力混凝土构件不能适用较大跨度的缺点,并从根本上解决了后张法预应力混凝土梁孔道压浆不实、预应力失控等质量隐患。近几年在国内外跨海大桥、高速公路和铁路桥梁中已有较多应用,但配套施工工艺尚不完善,已有的研究主要针对双折线布筋形式,即预应力筋弯折两次,而对单折线配筋先张梁的施工建造缺少研究,成为制约折线先张法推广应用的关键问题。本文以遂宁至广安的高速某大桥建设项目的30m单折线先张法预应力混凝土简支T梁预制施工为背景,针对施工中关键内容展开研究,并介绍该项目单折线先张预应力T梁的施工建造、施工方案的应用情况。本文主要完成的工作有:(1)分析了单折线先张法预制标准简支T梁施工中的关键技术问题,基于现有的张拉反力系统台座形式,提出一套传力明确、施工简单、可重复利用适合于单折线和直线预应力筋整体张拉的反力系统方案。(2)按照现行设计规范要求对所提出的反力系统方案各部分构件进行强度、刚度、稳定性设计和验算,并采用通用有限元软件LS-DYNA建立三维数值计算模型,对关键传力部位的整体受力状况进行计算分析。(3)采用本文设计的张拉反力系统对该大桥项目的单折线先张法30m预应力混凝土T梁进行标准梁施工,从施工工艺流程、预应力筋的张拉程序、混凝土的施工技术要点以及预应力筋的放张程序这几个方面介绍了该反力系统的应用情况。
[Abstract]:Zhang Fa is an important form of the first Zhang Fa. The prebending moment diagram is closer to the moment diagram under load by bending and tensioning the prestressed tendons. At the same time, it overcomes the shortcoming that linear pre-Zhang Fa prestressed concrete members can not be applied to large span, and solves the quality hidden trouble of post-Zhang Fa prestressed concrete beams such as unreal grouting and uncontrollable prestress fundamentally. In recent years, there have been many applications in the sea crossing bridges, highways and railway bridges at home and abroad, but the supporting construction technology is still not perfect. The existing research is mainly aimed at the form of double broken lines, that is, the prestressed tendons bend twice. However, the lack of research on the construction of single line reinforced beam becomes the key problem to restrict the popularization and application of Zhang Fa. In this paper, based on the prefabricated construction of Zhang Fa prestressed concrete simply supported T beam in Suining to Guangan high speed bridge construction project, the key contents of the construction are studied. This paper also introduces the construction of pretensioned T beam with single broken line and the application of construction scheme. The main work accomplished in this paper is as follows: (1) the key technical problems in the construction of Zhang Fa prefabricated standard simply supported T-beam are analyzed. Based on the existing pedestal form of tensioning reaction system, a set of explicit transmission force and simple construction are put forward. The reaction system scheme suitable for the integral tension of single broken lines and linear prestressed tendons can be reused. (2) according to the requirements of the current design code, the strength, stiffness, stability design and checking calculation of the components of the proposed reaction system scheme are carried out. The 3D numerical model is established by using the universal finite element software LS-DYNA. The stress condition of the key force transfer site is calculated and analyzed. (3) the Zhang Fa 30m prestressed concrete T beam of the bridge project is constructed by using the tension and reaction system designed in this paper, and the construction process is carried out from the point of view of the construction process. This paper introduces the application of the reaction system from the tensioning program of prestressed tendons, the key points of construction technology of concrete and the tensioning procedure of prestressed tendons.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U445.4

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