【作者】 方辉；

【导师】 沈蒲生；

【作者基本信息】 湖南大学 ， 结构工程， 2006， 博士

【摘要】 高层钢框架-混凝土核心筒或高层劲性混凝土框架-混凝土核心筒混合结构,是近年来在我国迅速发展的一种新型结构体系。混合结构的一个突出问题是混凝土有徐变收缩的性质,而钢无此性质。随着时间的发展,相邻的钢与混凝土竖向构件将发生显著的竖向变形差,相应的产生较大的附加内力,影响结构的安全性和适用性。论文以国家自然科学基金项目“高层混合结构基本受力特性的研究”为依托,围绕混合结构竖向变形差的计算方法及工程对策等问题,进行了研究,取得了以下成果。1.首次根据静定结构分别承受常荷载和变荷载时徐变的受力和变形规律,基于力法和龄期调整的有效模量法,提出了超静定结构考虑施工过程和徐变影响的内力分析方法。该法去掉超静定结构中的多余约束,使原结构等效为一个同时承受外荷载、弹性多余力和随时间变化的徐变多余力的静定结构,称为基本结构。对基本结构分别进行承受每种力作用时的徐变分析得到相应的在多余力方向上的位移。根据多余力处的变形协调条件列出并求解力法平衡方程得到徐变多余力。本文还对一个算例进行了徐变分析,得出各相关因素对结构受力的影响。2.首次提出了徐变效应的位移法分析方法。位移法分析超静定结构徐变效应的关键是求单元的徐变固端力。本文根据徐变分析的力法和虚功原理,推导出杆系结构一次加载的单元徐变固端力计算公式,发现单元的徐变固端力是杆件的徐变系数和弹性杆端力的函数。根据推导出的公式,用FORTRAN语言编制了结构徐变分析的位移法计算机程序,并对一个框架算例进行了徐变分析。结果表明,结构各部分的浇筑时间差和持荷时间对结构的受力和变形影响很大。3.分析了目前高层建筑竖向荷载作用效应分析常用方法的缺限。考虑高层建筑结构施工过程中荷载逐层施加和施工平差的实际情况,提出了高层建筑结构较为精确的模拟施工过程的计算方法,并编制了相应的FORTRAN程序。应用该程序对高层框架和高层混合结构算例进行了分析,并与其他分析方法的计算结果进行了比较。4.以精确模拟施工过程法和徐变分析的位移法为基础,推导了高层建筑结构逐层施工逐层加载并考虑混凝土徐变和收缩影响时的有限元计算公式。5.首次根据线性徐变和迭加原理,采用ACI规范推荐的徐变和收缩计算公式,提出了钢筋混凝土轴压构件分批加载的变形计算简化方法。根据龄期调整的有效模量法,推导了配筋率对构件的徐变收缩变形影响的计算公式。6.以上述钢筋混凝土轴压构件分批加载的变形计算方法为基础,考虑实际的更多还原

【Abstract】 In China, tall building hybrid structures, which are composed with steel frames and concrete core-tubes or with composite steel frames and concrete core-tubes, have been widely applied recently. A noticeable problem of this structure system is that concrete has the characteristics of creep and shrinkage while steel hasn’t. Along with the time, obvious different vertical different displacements will produce between neighbor vertical members, which should result in great additional internal forces and have big effects on the structural security and applicability. In this thesis, combined with the research project“Research on the behavior of the tall building hybrid structures”financed by the Natural Science Foundation of China (NSFC), methods to calculate different displacements of hybrid structure and corresponding engineering measures are studied. Productions obtained are as follows.1. According to the creep behaviors of statically determinate structure under constant load and changing load, respectively, the internal analysis method of statically indeterminate structure considering the effects of construction and creep is put forward first. This method is based on the ideas of force method and age-adjusted effective module method. By removing redundant restraints, the initial structure is equivalent to a statically determinate structure, named released structure, which subjected to loads, redundant forces obtained in elastic analysis and creep-redundant force changing with time due to the creep of structure. Displacements on the directions of redundant forces can be obtained by creep analysis of released structure under every force mentioned above. According to conformability of deformation, creep-redundant forces can be attained by resolving equilibrium equations. Effects of relevant factors on the statically indeterminate structure are presented here through a numerical example.2. The displacement method to analyze creep effects of structures is established first. The key problem of displacement method in creep effect analysis of statically indeterminate structures is to determinate fixed-end forces of the element. Based on the ideas of force method and virtual-work principle, calculation formulas of the fixed-end forces in element-system structures are deduced. It is found that the fixed-end forces of element are function of creep coefficient and elastic fixed-end forces of the element. According to the formulas, a computer program of displacement更多还原