结构预应力综合加固法及其在桥梁工程中的应用研究

发布时间：2018-04-14 06:09

本文选题：桥梁加固 + 结构预应力　；参考：《西南交通大学》2015年博士论文

【摘要】：桥梁加固时,新旧材料的应力差(可能是新材料的应力滞后或应力超前)是最为常见又必须考虑的技术难题。如何让新旧材料均衡、合理地参与结构(或截面)受力,即如何有效、便捷地解决新旧材料的应力差是不少桥梁加固工作者面临的一个关键问题。为解决此问题,桥梁加固逐渐形成由被动加固向主动加固、由单一加固方法向综合加固法(各种单一加固方法的联合使用)发展的趋势。本文以此为出发点,通过模型试验、理论分析、以及现场试验,主要完成了以下五个方面内容：1、在预弯预应力思想的基础上,结合加固桥梁新旧材料分阶段受力的特点,本文分析并定义了“结构预应力”。并在此基础上,系统提出了结构预应力综合加固法的核心思想和内容。同时,基于桥梁加固设计的目的及基本原则,详细分析了该方法的优点和适用性。并基于病危桥梁现状,详细分析了该方法的必要性。2、通过3组钢筋混凝土梁的模型试验以及扩展有限元分析,研究了不同卸载水平下加固混凝土梁的极限荷载、应力变形情况、破坏机理,以及卸载率对加固混凝土梁极限荷载、破坏模式的影响。研究表明：在不同卸载率(意义类似“预应力度”,表征预应力施加大小程度,定义详见第2章)条件下进行加固的钢筋混凝土梁,在受载过程中混凝土与钢筋应力分布差异极大,导致加固钢筋混凝土梁正常使用的承载力存在显著差异,但其极限承载能力差异不大；对加固混凝土梁承载力进行计算时必须分阶段进行计算以考虑卸载率的影响；采用扩展有限元分析能较为准确地模拟钢筋混凝土梁的受力行为与开裂过程,可以作为钢筋混凝土梁力学性能分析的有效手段。3、定义了基于两种不同极限状态考虑的最佳初始弯矩及对应的最佳卸载率；并分析和设定了两种极限状态下最佳初始弯矩应满足的条件。依据设定的条件及相应的假定,推导和建立了基于两种极限状态考虑的最佳初弯矩的求解公式,进而即可确定在适宜的加固参数条件下的最佳卸载率。同时,给出了在初弯矩确定的情况下最佳加固层厚度的求解公式。在此过程中,也详细分析了加固层厚度与最佳初始弯矩的相互关系。同时,提出了受弯构件加固设计流程及应重点关注的问题。4、系统分析并提出了结构预应力综合法需考虑的关键因素,主要是拟加固桥梁现状分析和桥梁结构受力特点分析。在此基础上,分析并提出了结构预应力综合加固法的要点。即应遵循相应的安全原则、选择合理的卸载方向、合理选择加固顺序(需要时)。针对拱桥、简支混凝土梁桥等卸载难度较大的桥梁,提出了一系列简单、有效的卸载(预应力施加方法)工程措施,为结构预应力综合加固法的工程应用提供了相应的技术支撑。5、结合具体维修加固工程实例,对采用影响线原理进行卸载的结构预应力综合加固法的应用进行了研究。研究结果表明：在以本文的研究成果为基础进行桥梁加固工程中,新、旧混凝土应力分布合理、加固后承载力储备较高；加固达到了预期的效果,且该方法加固效果明显,并具有较强的可操作性。
[Abstract]:The bridge reinforcement, the stress difference between the old and new materials (possibly new material stress lag or stress in advance) is the most common technical problem. It must consider how to make new material balance, reasonable in structure (or section) force, namely how to effectively, easily solve the problem of stress of old and new materials the difference is a key problem facing many bridge workers. In order to solve this problem, the bridge reinforcement formed gradually from passive to active reinforcement reinforcement to comprehensive reinforcement method by single reinforcement method (using a combination of various single reinforcement methods) development trend. This article as a starting point, through the model experiment, theoretical analysis well, the field test, the following five aspects: 1, based on the pre bending prestressed idea, combined with the characteristics of stage loading bridge reinforcement of old and new materials, this paper analyzes and defines the structure and prestress. On the basis of this, put forward system structure of prestressed comprehensive strengthening core idea and content of law. At the same time, the bridge reinforcement design objectives and basic principles based on the detailed analysis of the advantages and applicability of the method. And based on the detailed analysis of the present situation of the bridge was dying, the necessity of.2, through the model test of 3 reinforced group concrete beam and extended finite element analysis of the ultimate load of reinforced concrete beams under different unloading stress, deformation, failure mechanism, and the unloading rate of reinforced concrete beams with the ultimate load, the failure mode of the influence. The study shows that under different unloading rate (meaning similar degree of prestress, prestressed characterization applied degree, defined in chapter second) under the condition of reinforced concrete beams, in the loading process of concrete and steel bar stress distribution varies greatly, leading to the reinforcement of reinforced concrete Liang Zheng The bearing capacity of commonly used the existence of significant differences, but the difference of ultimate bearing capacity; reinforcement bearing capacity calculation must be calculated by considering the influence of the unloading rate of concrete beam; using extended finite element analysis can accurately simulate the reinforced concrete beam under stress and cracking behavior of.3 can be used as effective means. Mechanical properties of the reinforced concrete beam analysis, defined the best unloading optimal initial moment and corresponding to two different limit states considered based on the rate; and analysis and set up two kinds of limit state optimal initial moment condition. According to the conditions set and the corresponding assumptions, established and deduced formula two limit consider the best state based on the initial moment, which can be determined in the appropriate reinforcement parameters under the conditions of the best unloading rate. At the same time, are identified in the initial moment The best formula of thickness of reinforcing layer under the circumstances. In this process, also analyzed the relationship between consolidation layer thickness and the best initial moment. At the same time, put forward by strengthening design process and should focus on the problem of.4 bending, system analysis and put forward the key factors influencing the structure of pre stress method should be considered that is mainly intends to analyze the stress characteristics of bridge structure analysis and reinforcement of bridge status. On the basis of analysis, and put forward the structure of prestressed reinforcement method. The comprehensive points should follow the corresponding principle of safety, choose reasonable unloading direction, reasonable choice of reinforcement order (when necessary). For the arch bridge, the bridge simply supported concrete beams bridge unloading difficult, put forward a series of simple and effective unloading (prestressing method) engineering measures for prestressed structure comprehensive reinforcement engineering application method to provide the corresponding technical support.5, Combined with the specific maintenance and reinforcement project, the influence of prestressed structure principle of unloading line comprehensive reinforcement method application are studied. The results show that: in this research as the basis for the bridge reinforcement project, the new and old concrete stress distribution is reasonable, high bearing capacity reserves after reinforcement; reinforcement to the expected effect, and the reinforcement effect is obvious, and has strong operability.

【学位授予单位】：西南交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U445.72

【相似文献】