基于性能的隔震加固结构设计探讨

在国内外有关隔震加固和基于性能设计方法研究的基础上,提出了基于性能的隔震加固设计的理论框架.其中包括加固结构的性能目标、加固结构的性能评估、设计方法等环节,较为清晰的展现了设计的基本过程,明确了下一步研究的方向及需要解决的问题.     

基于ANSYS的某大桥挂篮有限元分析与加固

以某特大桥施工时的挂篮为研究对象,建立其有限元模型,进行静力分析、动力分析和稳定性分析,并对贝雷桁架的关键部位进行细部分析,提出加固方案并对比加固前后效果,最后提出了ANSYS模拟挂篮设备过程中存在的问题,以及得出的结论 。     

基于ANSYS的湿式外包钢加固梁有限元分析

采用有限元分析软件ANSYS对湿式外包钢加固梁进行非线性分析,将分析结果与现有试验结果进行对比,得出了外包钢混凝土构件受力行为的特点,并对外包钢加固法的应用提出了合理化建议.     

基于ANSYS的碳纤维薄板加固RC梁的有限元分析

基于实验数据的CFRP加固混凝土构件的计算方法,其经验公式得出结果较为粗糙。基于ANSYS有限元软件中的Solid65单元对钢筋混凝土简支梁建模,对CFRP加固RC梁的开裂性状、极限承载力及破坏规律进行分析。本文建立了碳纤维薄板加固RC梁的有限元模型,分析了碳纤维加固后的混凝土构件特性,并与三点弯实验结果进行了对比分析,结果表明:基于ANSYS有限元分析方法可以较好地表征出碳纤维薄板加固RC梁的非线性力学特征;CFRP薄板加固RC梁可以有效抑制裂缝的发展,并提高RC梁的极限承载力。     

基于ANSYS的碳纤维布加固混凝土梁有限元分析

碳纤维布具有耐腐蚀、施工简便快速等诸多的优点,在土木工程中得到了较为广泛的应用。应用ANSYS软件对未加固梁和5根碳纤维布混凝土梁梁体受弯进行了仿真研究,并给出了相应的荷载挠度曲线。与试验结果对比表明,建立的有限元模型能较好地模拟碳纤维布混凝土梁的力学性能,非线性有限元模拟结果与试验结果基本吻合。     

基于ANSYS的斜拉索加固T型刚构桥的有限元分析

基于大型通用有限元计算软件ANSYS建立某T型刚构桥实体模型,研究了利用斜拉索加固T型刚构桥的可行性与加固效果。分析结果表明:斜拉索加固T型刚构桥能够有效改善T构箱梁应力状态,阻止箱梁顶板横向裂缝的发展;斜拉索加固T型刚构桥能够有效纠正T构悬臂下挠,恢复桥面线形;斜拉索加固T型刚构桥能够很好的解决T构箱梁腹板抗剪能力不足的问题。     

基于区间理论的挡土墙稳定性非概率可靠性分析

针对现有可靠性分析方法的局限性与不足,首先,根据挡土墙岩土力学参数取值的区间性特征,引入区间分析理论,视挡土墙岩土力学参数为区间变量,在确定出挡土墙稳定可靠性分析的合理功能函数基础上,建立出基于区间理论的挡土墙结构稳定非概率可靠性计算模型;其次,针对区间运算结果扩张问题,引入区间组合法和改进区间截断法,建立出挡土墙稳定性非概率可靠性分析的区间运算方法,进而建立出基于区间理论的挡土墙稳定性非概率可靠性分析方法;最后,将该方法应用于工程实例,结果表明了本文方法的合理性与可行性,并探讨了岩土力学参数对挡土墙稳定性非概率可靠性指标的影响规律,具有一定的工程参考价值.     

基于性能的耗能减震加固设计理论框架

本文在国内外有关耗能减震加固与基于性能的设计方法研究的基础上,提出了基于性能的耗能减震加固设计的理论框架,并给出了设计过程中加固结构的性能目标、待加固结构的性能评估、减震概念设计、附加耗能器的设计、分析方法、加固结构的抗震安全性评价和社会经济综合评价各关键环节的子框图,较为清晰的展现了设计的基本过程,明确了下一步研究的方向及着重解决的问题。     

基于ANSYS的可靠性分析

介绍了结构可靠性的基本原理和基本分析方法，利用ANSYS中的可靠性分析工具——Probabilistic DEesign，对框架结构的可靠性进行了分析，实例证明：该方法可得到比较精确的可靠度指标和失效概率，但是其效率不高，需要对其抽样方法进行改进。     

基于性能的抗震设计发展及研究现状

针对现行基于承载力(强度)的抗震设计思想的不足之处,提出基于性能的抗震设计的优势,同时对国内外基于性能的抗震设计的研究现状进行了概括分析,阐述了基于性能抗震设计的主要思想,即结构在其设计使用期内,在遭受不同水平的地震作用下,应该有明确的性能水平,并使得结构在整个生命周期中费用达到最小,并提出了目前基于性能的抗震设计理念应用到实际工程设计中所面临的问题。     

Probabilistic finite element analysis using ANSYS

Driven by stiff competition, industrial manufacturers find themselves under growing pressure to optimize apparently conflicting technical and financial goals in an environment of ever increasing product complexity. In addition, this challenge is to be met under the existence of randomness and uncertainty, which the products are subjected to. Consequently, finding the right balance between conflicting goals under the existence of uncertainties requires the use of probabilistic tools. To achieve this, ANSYS Inc. has released two tools, namely the ANSYS Probabilistic Design System and the ANSYS DesignXplorer. This paper describes the problems that can be addressed, the underlying algorithms implemented and methodologies of these methods in both tools. A special topic of the paper is the discussion and explanation of the Variational Technology, which is offered in both tools. Variational Technology is a highly efficient method to provide accurate, high-order response surfaces based on a single finite element analysis. The capabilities, strengths and weaknesses of these methods are discussed. The possibility to reduce the execution time using parallel computing is discussed. Different measures to assess the accuracy and validity of the results obtained with the different probabilistic methods are given special attention. Various capabilities to post-process the probabilistic results are mentioned. The methods and the capabilities to optimize multiple and possibly conflicting goals are highlighted. Finally, the application of the software is illustrated using various industrial example problems.     

Transforming reliability limit-state constraints into deterministic limit-state constraints

This research proposes an efficient methodology that can transform a reliability limit-state constraint into a deterministic limit-state constraint. This new method may have broad applications in reliability-based design and optimization. The method is based on subset simulation and is applicable to general systems, e.g. linear or nonlinear systems and static and dynamical systems with high-dimensional uncertainties. Once the reliability constraint is transformed into a deterministic one, it is no longer necessary to conduct reliability analyses to verify the former. This can potentially save lots of computational time during the process of reliability-based design and optimization. The main idea of the new method is the introduction of the limit-state factor and nominal limit-state function, from which a deterministic nominal limit-state constraint is established. We propose two methods of establishing this nominal constraint, and they are verified with several simulated examples, showing that the established nominal constraint is indeed a satisfactory approximation of the target reliability constraint. Finally, we propose a simplified procedure requiring only two reliability analyses that can effectively transform reliability constraints into deterministic nominal constraints.     

Investigation of reliability method formulations in DAKOTA/UQ

Reliability methods are probabilistic algorithms for quantifying the effect of simulation input uncertainties on response metrics of interest. In particular, they compute approximate response function distribution statistics (probability, reliability and response levels) based on specified input random variable probability distributions. In this paper, a number of algorithmic variations are explored for both the forward reliability analysis of computing probabilities for specified response levels (the reliability index approach (RIA)) and the inverse reliability analysis of computing response levels for specified probabilities (the performance measure approach (PMA)). These variations include limit state linearizations, probability integrations, warm starting and optimization algorithm selections. The resulting RIA/PMA reliability algorithms for uncertainty quantification are then employed within bi-level and sequential reliability-based design optimization approaches. Relative performance of these uncertainty quantification and reliability-based design optimization algorithms are presented for a number of computational experiments performed using the DAKOTA/UQ software.     

基于ANSYS的带加强层结构的空间有限元分析

利用ANSYS建立的6个空间有限元模型分析了带加强层框筒结构的侧向位移。通过对不同假设下建立的有限元模型的计算得到了框架柱弯曲刚度,普通框架梁等因素在带加强层高层结构抗侧移的贡献情况。讨论了各种计算模型的特点及分析结果的精确性。从三维有限元分析结果看出,在设计带加强层的高层建筑结构时必须用考虑楼层梁和框架柱抗弯作用的计算模型来控制侧向位移。     

吊锚架的有限元分析及优化设计

吊锚架是电液桩机的关键部件,安装于桅杆的最高端,质量大,为主、副卷扬钢丝绳的运动进行导向.分析吊锚架的结构,依据电液桩机的工作特点,采用有限元分析软件ANSYS Workbench直接建立吊锚架的实体模型,对吊锚架的结构进行应力和安全系数分析,得出吊锚架结构的应力分布云图和安全系数分布图,发现结构的薄弱环节和过剩部位....     

Reliability-based design optimization with discrete design variables and non-smooth performance functions: AB-PSO algorithm

The purpose of reliability-based design optimization (RBDO) is to find a balanced design that is not only economical but also reliable in the presence of uncertainty. Practical applications of RBDO involve discrete design variables, which are selected from commercially available lists, and non-smooth (non-differentiable) performance functions. In these cases, the problem becomes an NP-complete combinatorial optimization problem, which is intractable for discrete optimization methods. Moreover, the non-smooth performance functions would hinder the use of gradient-based optimizers as gradient information is of questionable accuracy. A framework is presented in this paper whereby subset simulation is integrated with a new particle swarm optimization (PSO) algorithm to solve the discrete and non-smooth RBDO problem. Subset simulation overcomes the inefficiency of direct Monte Carlo simulation (MCS) in estimating small failure probabilities, while being robust against the presence of non-smooth performance functions. The proposed PSO algorithm extends standard PSO to include two new features: auto-tuning and boundary-approaching. The former feature allows the proposed algorithm to automatically fine tune its control parameters without tedious trial-and-error procedures. The latter feature substantially increases the computational efficiency by encouraging movement toward the boundary of the safe region. The proposed auto-tuning boundary-approaching PSO algorithm (AB-PSO) is used to find the optimal design of a ten-bar truss, whose component sizes are selected from commercial standards, while reliability constraints are imposed by the current design code. In multiple trials, the AB-PSO algorithm is able to deliver competitive solutions with consistency. The superiority of the AB-PSO algorithm over standard PSO and GA (genetic algorithm) is statistically supported by non-parametric Mann-Whitney U tests with the p-value less than 0.01.     

基于有限元法的加筋路堤影响因素分析

在综合考虑加筋路堤各种分析方法的基础上,利用ANSYS的APDL语言,建立了基于有限元法的加筋路堤参数化模型,编写了对加筋路堤进行稳定性分析的非线性有限元程序,并且综合各种影响因素对加筋路堤结构进行优化设计。ANSYS建模简单,使用方便,从计算实例看,计算结果较准确,取得了较好的效果,在工程实践中有一定的参考价值。     

On the reliability-based design of structures including passive energy dissipation systems

This contribution presents a methodology for stochastic design of structures including vibration protection systems. The approach is then used to investigate the effect of uncertain model parameters on the reliability-based optimal design of structures with a class of passive energy dissipation systems. The uncertainty of structural parameters as well as the variability of future excitations are characterized in a probabilistic manner. The optimal design problem is formulated as a non-linear constrained minimization problem involving multiple design requirements, including reliability constraints related to the structural performance. Failure events defined by a large number of random variables are used to characterize the reliability measures. A sequential optimization approach based on global conservative, convex and separable approximations is implemented for solving the optimization problem. The effects of uncertain model parameters on the performance, robustness and reliability of protected systems is illustrated by two example problems that consider multi-story buildings under stochastic ground excitation.     

基于ANSYS的结构优化设计有限元分析

为验证ANSYS对结构优化设计的有效性，从理论上说明了结构优化设计的数学过程，介绍了ANSYS优化的相关概念、过程，结合某设计优化实例，为使用者提供了一套系统的思维模式，创造了良好的条件和方法。     

铁路钢波纹管涵洞的计算分析

柔性、高强度的钢波纹管涵洞不仅具有适应地基与基础变形的能力,而且由于轴向波纹的存在,使其更具有优良的受力特征.波纹管涵造价低、设计简单、施工简单、施工工期短等优点,作为新型的涵洞类型具有广泛的应用前景.通过对铁路钢波纹管涵洞的力学性能进行有限元受力分析,对波纹管涵洞的设计提出了建议.