【作者】 马伊硕；

【导师】 王元丰；

【作者基本信息】 北京交通大学 ， 结构工程， 2013， 博士

【摘要】 近年来我国钢管混凝土拱桥建设长足发展。目前其综合时效问题非常突出,长期性能已开始成为影响该种桥型发展的重要因素。混凝土徐变效应对钢管混凝土拱桥的依时行为影响显著,是钢管混凝土拱桥基础理论研究中特别需要深入关注的问题。进一步开展钢管混凝土拱桥徐变静动力效应的理论研究工作,从广度上而言,意味着需从静力范畴拓展到动力范畴去认识徐变对结构的影响,推动徐变相关的静、动力交叉问题研究；从深度上而言,意味着需从确定性问题领域过渡到随机问题领域,从概率角度出发,研究徐变对结构可靠度的影响。基于以上两方面的考虑,取二者交点为主题,本文重点研究了徐变对钢管混凝土拱桥静力可靠性、随机振动响应以及动力可靠性的影响。本文从分析混凝土的变形性能和徐变机理入手,基于现有的徐变试验数据并以混凝土徐变微观本构模型为工具,首先在材料层次研究了混凝土徐变的基本性质,提出了含不同掺和材料的混凝土的徐变数学模型。在材料模型的基础上,利用数值方法分析了钢管高强混凝土、钢管粉煤灰混凝土轴心受压构件的徐变行为,并与试验结果进行对比验证,为后面延续到结构层次的徐变研究打下基础。在徐变对结构的静力行为影响方面,本文引入来自于混凝土徐变模型、材料以及结构几何三方面的不确定性因素,利用基于拉丁超立方体抽样方法的Monte Carlo法对考虑输入变量随机性的结构进行了徐变效应的概率分析,同时给出了徐变对结构时变可靠度影响的评价方法,以及结构徐变效应的敏感性分析方法。在徐变对结构的动力行为影响方面,本文系统地分析了静动力行为、持续荷载与瞬时荷载、长期效应与瞬时响应之间的联系,阐释了徐变对结构动力行为影响的机制,以长期持续荷载作用后混凝土力学性能试验为基础,提出了混凝土徐变后效的预测模型。以此为基础,本文首先分析了徐变对钢管混凝土拱桥动力特性以及不同激励作用下确定性动力响应的影响,然后采用结构随机振动分析的虚拟激励方法,以钢管混凝土拱桥在一致、非一致地震激励作用下的随机振动分析结果为依据,在均方响应的意义上揭示了徐变对其随机地震响应的影响规律,对徐变与结构动力性能关系的研究作了进一步深化。最后,本文以考虑徐变影响的结构随机振动分析结果为基础,依据符合Poisson假设的首次超越破坏准则,分析和评价了徐变对大跨度钢管混凝土拱桥动力可靠性的影响。更多还原

【Abstract】 Rapid development of concrete filled steel tube (CFST) arch bridges is inevitably accompanied by special attention paid to the issue of long-term performance, which is significantly influenced by concrete creep. Further carrying out the theoretical research on creep effects of CFST arch bridges, in terms of breadth, means that the understanding on structural creep effects should be expanded from static area to dynamic area; in terms of deapth, means that the study on creep effects should be extended from deterministic area to probabilistic area, and be from the angle of reliability. In view of the two points mentioned above, this paper focuses on the influence of creep on the static reliability, random vibration response and dynamic reliability of CFST arch bridges.Based on creep test data and a micro constitutive model of concrete creep, this paper proposes creep models for concrete containing silica fume or fly ash. On the basis of the material models, creep of CFST columns is analyzed by numerical method.In the field of creep effect on static behaviors of structures, this paper presents a probability analysis to investigate the creep effect on structural serviceability reliability by Monte Carlo simulation with Latin Hypercube sampling method, considering random variables involved in three aspects:creep model uncertainty and variations of material and geometrical properties.In the field of creep effect on dynamic behaviors of structures, this paper analyzes the relationships between instantenous and sustained loadings, and between instantenous and long-term responses, and explains the mechamism of creep influence on structural dynamic behavior. According to tests on concrete mechamical properties after a sustained loading, this paper develops a model to predict elastic modulus of concrete having subjected to the effect of sustaind loading. Based on this, this paper analyzes the creep influence on structural dynamic properties, deterministic dynamic responses and random dynamic responses. In accordance with first-passage failure criterion, this paper finally assesses the creep influence on the dynamic reliability of CFST arch bridges.更多还原