【作者】 丁韶峰；

【导师】 钱永久；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2008， 硕士

【摘要】 预应力砼连续刚构桥的发展历史,就是一部技术不断革新的历程。其修建完工后,砼开裂和下挠几乎成为此类桥梁的通病。本文介绍了大跨度预应力混凝土连续刚构桥的常见病害,承载能力不足及混凝土开裂的加固措施,简明地阐述了桥梁结构预应力加固体系的特点,体外预应力混凝土结构的基本组成部分,以及体外预应力加固既有混凝土桥梁的设计原理与方法。考虑到转向块是体外预应力混凝土结构中的最重要、最关键的结构构造之一,它的设计直接关系到结构的使用性能和耐久性,故本文重点对其受力性能开展研究。本文以东圃特大桥为例,对预应力砼连续刚构桥病害成因作了具体分析,探讨了体加预应力加固的合理性,简要介绍了有限元法分析砼结构的原理与方法,选取边跨转向块进行有限元实体分析。计算采用先整体后局部的思路。先由平面软件整体计算,再针对局部位置进行实体分析,有效提高了计算效率。计算表明:体外索对桥梁纵向应力影响最大,且在转向块与底板相交处局部位置出现应力集中现象,加固设计时应该避免转向孔道靠下侧过近而造成施工张拉时交接处出现裂缝。为减小转向块的自重,可以优化设计成上小下大的梯形块。更多还原

【Abstract】 There are many technical innovation and renovation in the prestressed concrete continuous rigid frame bridge’s development history. The familiar deteriorations such as cracks in concrete and large long-term displacement have been happened in a few years after the construction.It is pointed out the deteriorations of long span prestressed concrete continuous rigid frame bridge and the corresponding strengthening measures to the load carrying capability of the structure and cracks in concrete. Then it is briefly summarized the characteristics and the basic structure of external prestressing system, as well as the design principle in strengthening existing concrete bridges by external prestressing. Considering that it is the most important and key part in external prestressing concrete structure, and the design of deviators is directly related to serviceability and durability of structure, the performance of deviator is analyzed in this paper in detail.The Guangzhou Dongpu Bridge has been used in this paper as an example to analyze the cause of deteriorations and the rationality of external prestressing way to strengthen the prestressed concrete continuous rigid frame bridge. It is also briefly introduced the principle and method of Finite Element Method to analyse concrete structure. The deviator in first span is chosen to analyze the stress distributions by finite element method. The calculation is carried out from the whole to the part, that is, at the beginning we use the plane software to calculate the forces, and then use the FEM to analyze the deviator in detail. This way greatly improves the efficiency. The calculation results show that the external prestressing affects the bending stress most efficiently. The stress concentration appears between the deviators and bottom plane. The design to external pretressing strengthening must avoid the hole of deviators close to the bottom board excessively resulting in concrete cracks . In order to reduce the weight of deviator, echelon piece is brought forward whose upper part is small as the result of optimal design.更多还原