网壳结构设计临界荷载及安全系数

本文简要地分析了影响确定临界荷载理论值的因素，比较分析了钢筋混凝土薄壳设计临界荷载的各个公式及其特点，在此基础上提出了基于线性和非线性理论的设计临界荷载和安全系数的计算公式。文中还强调了基于经典线性理论的计算公式的适用范围。一些工程实例表明本文提出的设计临界荷载及安全系数的取值是先进合理的，可为网壳结构的设计提供参考。     

悬索结构动力分析理论及参数研究

本文充分考虑了悬索结构大挠度变形几何非线性反应特征,在动力反应有限元理论分析中完善了索单元刚度和拟荷载项表达式,优化了计算方法.对与动力分析直接相关的索网阻尼特性及其对地震反应影响做了深入研究,并给出了常见索网屋盖结构地震反应及主要参数影响规律.在以上研究基础上,对悬索结构地震反应分析与设计提出几点新建议.     

考虑剪力墙连梁刚度折减的设计模型研究

基于混凝土材料刚度退化和能量等效的原则,提出了考虑剪力墙连梁刚度折减设计模型的确定方法,并将本文方法在非线性分析软件SAUSAGE和结构设计软件SATWE中完成开发实现。结合某超高层剪力墙结构在小震、中震、大震作用下的非线性时程分析结果,得到了此结构考虑连梁刚度折减的设计模型。通过结构设计软件SATWE完成此设计模型的等效线性时程分析;通过与非线性结果对比,验证了本文方法的合理性。     

桅杆结构动态设计研究

基于非线性时程分析理论 ,提出了桅杆结构在动力荷载下的设计方法 ,以保证结构动态下的强度、变形和稳定性符合使用要求。给出并分析了桅杆结构动态设计实例 ,结果表明本方法直观、可靠 ,可应用于工程设计     

脉动风作用下电视塔桅杆结构TMD控制的惯性质量与位置优化

本文以深圳市梧桐山电视塔桅杆结构风振控制项目为背景,分析了风荷载的动力特性,给出了脉动风荷载的模拟方法;采用调谐质量阻尼控制方法和线性吸振、非线性耗能的结构控制策略,对控制装置进行了系统设计,分析了装置的惯性质量效应并提出了装置的优化布置方法;在模拟脉动风荷载作用下采用振型分解和时程分析相结合的方法,对结构进行动力分析和振动控制效果计算,为TMD高耸结构抗风设计提供了依据。     

钢框架平面内高等分析方法的应用

基于改进塑性铰法,讨论了构件的计算单元,二阶效应,截面的塑性扩展、构件残余应力、初始几何缺陷等各种非线性因素的处理方法,采用改进塑性铰法可以保证结构较高的计算精度,比较真实地反映结构在荷载作用下的内力和变形状态,可用于工程分析和设计。     

单层正交索网结构有限分析计算方法及实验研究

建立了幕墙正交索网结构的计算力学模型,研究单层索网在网点分配荷载及预张力作用下的平衡方程、位移协调和变形体位能驻值方程,构成多变元的非线性耦合方程组。采用有限分析法将非线性耦合方程组解耦,寻求局部解析解再转化为全局数值解,设计小尺度实际模型在多点荷载作用下的内力和变形的实验,最后给出相关算例。     

温度变化对正交索网结构非线性振动的影响

正交索网结构作为屋盖支承体系有着广泛的应用,属于一种柔性结构,对外荷载的作用比较敏感.非线性自振特性的研究对于正交索网结构在风荷载作用下的响应分析具有重要意义.本文考虑温度变化及几何非线性影响,采用连续化理论导出了正交索网结构非线性振动方程.通过Galerkin原理,将偏微分方程转化为常微分方程,并采用改进的L-P法对常微分方程进行了求解.结合算例讨论分析了温度变化、振幅等因素对正交索网结构非线性振动的影响.算例表明,正交索网结构固有频率随着温度的升高而减小,自振频率密集,具有较强的非线性,其自振频率随着振幅发生变化,其非线性振动呈现"硬弹簧"特性,正交索网结构的非线性自振频率高于线性频率.     

低周反复荷载作用下钢管混凝土框架非线性有限元分析

本文根据本课题组所完成的一榀两跨三层钢管高强混凝土框架在低周反复荷载作用下的模型试验的结果,建立了按钢管混凝土统一理论中钢管混凝土材料的本构方程和考虑约束效应的核心混凝土的本构方程.分别基于钢管混凝土的统一模量理论和分离模量理论,采用APDL(ANSYS Parametric Design Language)参数化程序设计语言编制的命令流,对模型框架在低周反复荷载作用下的滞回性能进行了非线性有限元分析,经与模型试验结果相比较,二者吻合较好,从而验证了基于统一模量理论的钢管混凝土结构设计方法是可行的、适用的.     

钢桥面防滑耐磨新结构分析

提出局部冲击荷载作用下的桥面板的弹塑性变形是影响桥面防滑性能重要因素的观点,在此基础上设计了压筋橡胶条形式的桥面防滑结构形式,运用板壳理论和非线性有限元方法,分析改进形式钢质桥面结构的弹塑性变形,证明了改进形式的有效性和合理性。     

Practical advanced analysis software for nonlinear inelastic dynamic analysis of steel structures

This paper presents a practical advanced analysis software which can be used for nonlinear inelastic dynamic analysis of space steel structures. The proposed software can predict accurately the nonlinear response of a steel structure by using only one element per member in structural modeling. Three types of element including both geometric and material nonlinearities are implemented in the proposed software: (1) catenary cable element; (2) truss element; and (2) beam-column element. An incremental-iterative solution scheme based on the Newmark method and the Newton-Raphson method is adopted for solving the nonlinear equations of motion. Several numerical examples are presented to verify the accuracy and efficiency of the proposed software in predicting the nonlinear response of steel structures. The proposed program is shown to be an efficient and reliable tool for daily use in design.     

杆系结构的高精度非线性分析

在严格的材料、几何非线性分析的基础上,建立一套完整的对钢筋混凝土杆系结构进行高精度分析的非线性有限元法。该方法充分考虑材料非线性的作用,分别建立了面内分层法和面外分块法的计算模型。算例分析表明:与几何非线性相比,材料非线性对钢筋混凝土杆系结构的非线性分析起着更为关键的作用。只考虑几何非线性或对材料非线性做粗略处理会导致计算结果精度不够。     

基于等效线性化的土–地下结构整体动力时程分析方法研究

地下结构抗震设计简化分析方法离不开场地地震反应分析,而频域内的等效线性化方法是一维土层地震反应分析的主流方法。在一维土层地震反应分析的等效线性化方法的基础上,提出了一种地下结构抗震设计的等效线性化分析方法,并给出场地材料参数的确定方法。将该方法应用于地铁车站的横断面抗震分析中,并与土体直接采用非线性的Davidenkov模型进行的动力时程分析方法对比,两者计算误差满足工程需要的精度要求。此方法兼具场地等效线性化方法和地下结构动力时程分析方法的双重优势,可以作为一种动力时程分析方法运用于地铁车站等地下结构的抗震设计中。     

基于Morgenstern-Price法边坡三维稳定性分析

 工程中边坡滑裂面通常都是三维空间上的一个曲面,采用传统的二维稳定性分析方法对其进行分析与实际不符。Morgenstern-Price极限平衡条分法(M-P法)是最严密的边坡二维稳定性分析方法,将其拓展并引入边坡三维稳定性分析中。通过类似于M-P法的条间力假定,建立一种新的边坡三维稳定性分析方法—基于M-P法边坡三维极限平衡分析法。给出2个验证算例,与现有几种方法对比计算结果表明：该法不仅计算结果更可靠,而且力学模型更为严谨,计算公式简便且易于编程,可在边坡工程设计及滑坡治理中推广应用。     

A semi-analytical approach for linear and non-linear analysis of unstiffened laminated composite cylinders and cones under axial,torsion and pressure loads

A semi-analytical model for the non-linear analysis of simply supported, unstiffened laminated composite cylinders and cones using the Ritz method and the Classical Laminated Plate Theory is proposed. A matrix notation is used to formulate the problem using Donnell׳s and Sanders׳ non-linear equations. The approximation functions proposed are capable to simulate the elephant׳s foot effect, a common phenomenon and a common failure mode for cylindrical and conical structures under axial compression. Axial, torsion and pressure loads can be applied individually or combined, and solutions for linear static, linear buckling and non-linear buckling analyses are presented and verified using a commercial finite element software. The presented non-linear buckling analyses used perturbation loads to create the initial geometric imperfections, showing the capability of the method for arbitrary imperfection patterns. The linear stiffness matrices are integrated analytically and for the conical structures an approximation is proposed to overcome the non-integrable expressions.     

The finite element method for thin-walled members—basic principles

The application of the finite element method to thin-walled structures often requires non-linear analysis. Whereas in linear finite element analyses errors are easily made, this is even more so in the non-linear analyses. This paper focuses on possible sources of error in linear and non-linear finite element solutions, and gives suggestions how to check and prevent these errors.     

变电站高架柱与人字柱连接节点受力性能有限元研究

对变电站中高架柱与人字柱连接节点的受力性能进行了有限元研究。在对有限元分析结果验证后,通过改变节点处各类加劲板件的参数,对大量模型进行了非线性有限元分析,分析结果表明:高架柱与人字柱连接节点处加劲板及顶板厚度对节点性能影响很小;主要受力加劲板是否插入人字柱对节点性能影响很小,设计该节点时,可仅从人字柱局部变形要求考虑是否需要将主要受力加劲板插入人字柱。分析计算过程及结果可供实际工程参考。     

Application of cubic spline on large deformation analysis of structures

This paper presents a new method for non-linear analysis of structures using an iterative method originated from quadrature rule based on spline function. At first, the above-mentioned method is developed for solving systems of non-linear algebraic equations and then it is implemented on structural problems. In this procedure like many other state of the art methods, the non-linear equations are linearized by evaluating the non-linear terms with the known solution from the preceding iteration. The proposed method is constructed as a predictor-corrector one, must frequently taking Newton’s method in the first iteration. For this method, a simple step-by-step algorithm was implemented and presented to calculate non-linear analysis of structures. It should be noted that currently, the proposed method is incapable of tracing the equilibrium curve after passing the limit points. The presented method incorporates the known information at each stage of the loading process to determine the subsequent unknown variables. Compared with the classic Newton-Raphson algorithm and a recently proposed two-point method, it offers a strategy that can be deployed to reduce the number of the iterations to trace the equilibrium path in non-linear analysis of structures.     

Analysis of steel storage rack columns

Storage rack systems are structures composed of cold-formed steel structural members that are used as columns, beams and bracing. The rack columns present peculiar features in their design because they have perforations to facilitate assemblage of the system, which makes them more difficult to analyze by cold-formed steel structures design codes. There are several design codes proposed by the manufacturers associations, as the specifications of Rack Manufacturers Institute (RMI), applied in the USA along with the specification of the American Iron and Steel Institute (AISI). These codes propose experimental stub columns tests for the determination of their resistance. In this work, the commercial software, ANSYS, is used for material and geometric non-linear analysis of these columns, and the results are compared with experimental data obtained by stub column tests, for a typical section of racks manufactured in Brazil.     

Reliability based optimization of laminated composite structures using genetic algorithms and Artificial Neural Networks

The design of anisotropic laminated composite structures is very susceptible to changes in loading, angle of fiber orientation and ply thickness. Thus, optimization of such structures, using a reliability index as a constraint, is an important problem to be dealt. This paper addresses the problem of structural optimization of laminated composite materials with reliability constraint using a genetic algorithm and two types of neural networks. The reliability analysis is performed using one of the following methods: FORM, modified FORM (FORM with multiple checkpoints), the Standard or Direct Monte Carlo and Monte Carlo with Importance Sampling. The optimization process is performed using a genetic algorithm. To overcome high computational cost it is used Multilayer Perceptron or Radial Basis Artificial Neural Networks. It is shown, presenting two examples, that this methodology can be used without loss of accuracy and large computational time savings, even when dealing with non-linear behavior.