【作者】 李松；

【导师】 强士中；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2009， 博士

【摘要】 钢筋混凝土拱肋的稳定极限承载力分析问题是大跨径钢筋混凝土拱桥设计和施工中的一个重要问题。针对大跨径钢筋混凝土拱肋的稳定极限承载力分析中存在的问题,本文在总结和吸收前人研究成果的基础上,对大跨径钢筋混凝土拱桥的稳定极限承载力分析问题进行了系统的研究,着重探讨了以下几个方面的问题：系统地归纳和剖析了混凝土的破坏理论以及相关破坏试验结果。结合大跨径钢筋混凝土拱肋稳定极限承载力分析过程中结构的行为特点,确定了大跨径钢筋混凝土拱肋压溃分析中混凝土破坏状态的基本参量和破坏模型。详细分析了现有钢筋和混凝土本构模型的特点和适用范围。确定了大跨径钢筋混凝土拱式结构稳定极限承载力数值仿真分析中钢筋和混凝土的本构模型。剖析了各种钢筋混凝土裂缝模型的特点和适用范围。结合大跨径钢筋混凝土拱肋压溃分析的实际需要,确定了用于模拟压溃分析中钢筋混凝土拱肋力学行为的钢筋混凝土数值模型。归纳分析了桥梁结构极限承载力分析中常用的数值单元模式。论述了在大跨径钢筋混凝土拱肋的稳定极限承载力数值分析中采用具有特殊功能的混凝土实体单元模式的必要性。并对大型通用软件ANSYS中钢筋混凝土实体单元的力学原理进行了剖析。系统地分析了结构分析中各类非线性方程组的求解方法。结合相关的数值计算,确定了大跨径钢筋混凝土拱式结构稳定极限承载力数值仿真分析中结构非线性平衡路径的跟踪策略。将钢筋混凝土拱肋的模型试验结果与文中所采用的基于压溃理论的数值分析结果进行了对比,二者吻合良好。从而验证了本文所采用的基于压溃理论的数值分析方法的可靠性。探讨了大跨径钢筋混凝土拱肋稳定极限承载力分析中一些主要参数的取值问题；借助于大型通用软件ANSYS为大跨径钢筋混凝土拱肋的稳定极限承载力分析创建了与工程实际基本吻合的压溃分析数值模型。以大量系统的数值仿真模型实验为基础,利用数理统计原理,创立了大跨径钢筋混凝土拱肋的稳定极限承载力的参数影响效应方程。这些影响效应方程包含了拱肋的初始几何缺陷、计算跨径、矢跨比、拱轴系数以及荷载作用形式等影响钢筋混凝土拱肋稳定极限承载力的主要因素。提出了一套适用于大跨径钢筋混凝土拱肋稳定极限承载力分析的满足土木工程精度要求的实用计算方法。该实用计算方法考虑了拱肋的初始几何缺陷、计算跨径、矢跨比、拱轴系数以及荷载作用形式等重要参数对钢筋混凝土拱肋稳定极限承载力的影响效应。分别采用本文提出的实用算法、ANSYS有限元法和现行桥梁结构设计规范法对两座实桥进行了对比性计算。得出了一些可供设计、施工和相关研究参考的结论。更多还原

【Abstract】 The evaluation of the ultimate bearing capacity of reinforced concrete arch ribs is a significant issue in the design and construction of long-span reinforced concrete arch bridges. Aiming at the issue of the evaluation of the ultimate bearing capacity of long-span reinforced concrete arch ribs, this dissertation investigated the ultimate bearing capacity of reinforced concrete arch ribs on the basis of summarizing and absorbing the achievements in the pioneer works. The main research work is as follows:The failure criteria and tests of concrete were systematically summarized and dissected. According to the characteristics of the behavior of long-span reinforced concrete arch ribs, the basic parameters and failure models were determined for the collapse analysis of long-span reinforced concrete arch ribs.The characteristics and suitable scope of the constitutional relationship of concrete and reinforcement were analyzed in detail, then, the constitutional relationship of concrete and reinforcement were determined for the simulation analysis of long-span reinforced concrete arch ribs.The characteristics and suitable scope of the cracking models of reinforced concrete were dissected. With the applied demands for the collapse analysis of long-span reinforced concrete arch ribs, the cracking models of reinforced concrete were determined to imitate the behaviour of reinforced concrete arch ribs.The element models which had been used commonly to analyse the ultimate bearing capacity of bridge structures were summarized. The necessity of using special concrete solid element to the numerial analysis of ultimate bearing capacity of long-span reinforced concrete arch ribs was discussed; furthermore, the principles of the reinforced concrete solid element in ANSYS were dissected.The solution procedures for nonlinear equilibrium equations in structural analysis were systematically summarized. With some numerical examples, the policy on tracing the nonlinear equilibrium paths was determined, which was used for evaluating the ultimate bearing capacity of long-span reinforced concrete arch ribs.Comparing the experiment data of the reinforced concrete arch rib model and its numerical anlysis results on the basis of collapse theory, it was found that the numerical anlysis results are very close to the experimental data, and consequently the reliability of the numerical analysis procedures on the basis of collapse theory for evaluating the ultimate bearing capacity of reinforced concrete arch ribs was certified.The values of dominant parameters of long-span reinforced concrete arch rib were discussed. By means of the large-scale general software ANS YS, the collapse analysis models which were similar to the practical arch bridges were built to evaluate the ultimate bearing capacity of reinforced concrete arch ribs.Based on a large number of systematic simulating numerical experiments, this dissertation deduced a series of expressions to describe the effects of the dominant parameters on the ultimate bearing capacity of reinforced concrete arch ribs by means of mathematical statistic theory. The initial geometric imperfection, calculated span, rise span ratio, coefficient of arch axis and load types were included in these expressions.The applied evaluation methods, which are able to meet the precision request of civil engineering, were deduced to evaluate the ultimate bearing capacity of long-span reinforced concrete arch ribs. The initial geometric imperfection, calculated span, rise span ratio, coefficient of arch axis and load types were taken into account in the applied evaluation methods.This dissertation evaluated the ultimate bearing capacity of two practical bridges by means of the evaluation method, the finite element method and the design codes method, and consequenly some conclusions were reached by comparing with these evaluating results. The conclusions herewith can serve as reference to the design, construction and study of the ultimate bearing capacity of long-span reinforced concrete arch bridges.更多还原