土—结构相互作用的混合约束模态综合法的应用

发布时间：2018-11-06 10:00

【摘要】：随着城镇化的快速发展,城市人口的不断增多,城市用地紧张的情况越来越严峻,高层建筑以其能节约城市用地、有效利用空间的特点越来越被人们所接受。加之我国处在地震多发地带,2008年汶川地震以来,结构的抗震问题越来越受到工程界的高度关注。因此,在高层建筑的抗震分析和设计过程中十分有必要考虑土-结构的相互作用问题。在现有的计算方法中,动态子结构法能够降低体系自由度、提高计算效率、节省计算时间,被广泛应用到土-结构相互作用的分析中。但是子结构只能用于线性结构,针对此问题,本文在课题组先前提出的线性-非线性混合的约束模态综合法的基础上,将线性-非线性混合的约束模态综合法的基本理论应用于ANSYS大型通用软件。主要的内容和成果有:1.在约束模态综合法的理论基础上介绍了线性-非线性混合的约束模态综合法,以高层框架结构为例,将线性-非线性混合的约束模态综合法的理论应用于ANSYS分析软件中,验证了该理论在ANSYS分析软件中适用性,为线性-非线性混合的约束模态综合法的应用提供实践依据。2.提出了对基于势能判据的截断准则在ANSYS软件中的实施方法,自编了截断准则程序,运用ANSYS大型通用软件提取每个子结构的刚度、质量、固定界面主模态信息以及边界节点号、内部节点号等,将其导入Matlab中,运用自编程序进行处理,为子结构分析时选取截断主模态数提供实践依据。3.对土体采用粘弹性边界的子结构方法进行了理论推导,以框架结构为例,运用线性-非线性混合的约束模态综合法对采用粘弹性边界的土-结构体系进行地震分析。讨论了粘弹性人工边界的设置对子结构的分析的影响。分析结果表明,由于粘弹性人工边界中土体边界的自由度不能缩减,故其总自由度数并不一定比采用自由边界的自由度数小很多。所以在子结构分析中,土体的边界形式对自由度缩减、计算时间影响不大。4.通过运用线性-非线性混合的约束模态综合法对不考虑土体材料非线性的结构做地震分析,讨论了不考虑土体材料线性对结构地震反应的误差。结果表明,不考虑土体材料线性的结构在土-结构相互作用震分析时会夸大结构的位移与内力,因此土-结构相互作用的分析需充分考虑土体材料非线性。5.将基础与地基的交界面上设置接触对的做法引入到混合约束模态综合法中,运用线性-非线性混合约束模态综合法对高层框架进行考虑基础与地基摩擦作用下的地震分析,并分析了摩擦对相互作用计算结果带来的影响。结果表明摩擦使上部结构的位移加大,并增加土体的塑性变形。
[Abstract]:With the rapid development of urbanization and the increasing of urban population, the tense situation of urban land use is becoming more and more serious. Because of its characteristics of saving urban land and making effective use of space, high-rise buildings are more and more accepted by people. In addition, our country is in the earthquake prone area, since the Wenchuan earthquake in 2008, the seismic problem of the structure has been paid more and more attention by the engineering circles. Therefore, it is necessary to consider the soil-structure interaction in the seismic analysis and design of high-rise buildings. Dynamic substructure method is widely used in the analysis of soil-structure interaction, which can reduce the degree of freedom of the system, improve the computational efficiency and save computing time. However, substructures can only be used in linear structures. In view of this problem, this paper is based on the linear-nonlinear hybrid constrained modal synthesis method previously proposed by the research group. The basic theory of linear-nonlinear hybrid constrained modal synthesis method is applied to ANSYS software. The main contents and results are as follows: 1. Based on the theory of constrained modal synthesis method, the constrained modal synthesis method of linear and nonlinear mixing is introduced. Taking high-rise frame structure as an example, the theory of linear and nonlinear hybrid constrained modal synthesis method is applied to ANSYS analysis software. The applicability of the theory in ANSYS analysis software is verified, which provides a practical basis for the application of the linear-nonlinear hybrid constrained modal synthesis method. 2. In this paper, the implementation method of truncation criterion based on potential energy criterion in ANSYS software is put forward, and the program of truncation criterion is compiled. The stiffness, mass, main mode information of fixed interface and boundary node number are extracted by ANSYS software. The internal node number is imported into Matlab and processed by self-programming, which provides a practical basis for selecting the truncated main modal number in substructure analysis. The substructure method of soil using viscoelastic boundary is theoretically deduced. Taking frame structure as an example, the seismic analysis of soil-structure system with viscoelastic boundary is carried out by using linear and nonlinear hybrid constrained modal synthesis method. The influence of the artificial boundary of viscoelasticity on the analysis of substructures is discussed. The results show that the total number of degrees of freedom is not necessarily much smaller than that of free boundary because the degree of freedom of soil boundary can not be reduced in viscoelastic artificial boundary. Therefore, in the substructure analysis, the boundary form of soil has little effect on the degree of freedom reduction and calculation time. In this paper, the linear and nonlinear constrained modal synthesis method is applied to the seismic analysis of structures without considering the nonlinearity of soil material, and the error of the linear response of soil material to the structure is discussed. The results show that the displacement and internal force of the structure will be exaggerated when the soil material linear interaction is not considered in the earthquake analysis of soil-structure interaction, so the soil material nonlinearity should be fully considered in the soil-structure interaction analysis. The method of setting contact pairs at the interface between foundation and foundation is introduced into the hybrid constrained modal synthesis method. The linear nonlinear hybrid constrained modal synthesis method is applied to the seismic analysis of high-rise frame considering the friction between foundation and foundation. The effect of friction on the calculation results is analyzed. The results show that friction increases the displacement of the superstructure and increases the plastic deformation of the soil.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU435

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