基于响应面法的钢- 砼混合梁悬索桥有限元模型修正

有限元初始模型往往与实际结构间存在着某些误差,不能准确反映桥梁实际的工作状态。作者建立了某钢-砼混合梁悬索桥的有限元模型,基于桥梁荷载试验所得响应,建立其响应面模型进行优化计算,修正了有限元模型。     

基于健康监测的连续刚构桥有限元模型确认(Ⅰ)——基于响应面法的有限元模型修正

有限元模型修正不能考虑不确定性和进行响应预测,而模型确认是模型修正的发展,该系列论文建立了桥梁有限元模型确认的基本方法。主要讨论模型确认的关键步骤之一——基于响应面的桥梁有限元模型修正方法,包括试验设计、参数筛选、响应面模型选择以及模型检验等;基于下白石大桥的实时健康监测,利用响应面方法成功地对下白石大桥的有限元模型进行修正。结果表明:有限元模型修正后的计算结果与实测结果比较吻合,最大相对误差不超过6%,修正后的有限元模型可以进一步应用于模型确认,对桥梁健康监测和安全评估有益。     

基于响应面的桥梁有限元模型修正

采用试验设计和回归分析方法,以显式的响应面模型逼近特征量与设计参数间复杂的隐式函数关系,得到简化的结构模型(Meta-model),给出有限元模型修正过程。针对复杂的土木工程结构,讨论样本选择、修正参数选取以及如何从众多因素中较合理地建立结构的响应面模型。用数值模拟算例和六跨连续梁桥环境振动试验结果,实现基于响应面模型的土木工程结构有限元模型修正,并与传统的基于灵敏度方法直接对结构有限元模型修正结果进行比较。结果表明,基于响应面方法的有限元模型修正和验证,能显著提高修正的效率,修正过程计算简洁、迭代收敛快,避开每次迭代都需要进行有限元计算,易于工程实际应用。     

基于响应面模型修正的桥梁结构损伤识别方法

及时、准确地发现桥梁结构的早期损伤,避免桥梁结构的突然破坏或倒塌,无疑具有重要的理论意义和重大的社会经济效益。文章提出基于响应面模型修正技术和单元模态应变能损伤指标的结构损伤识别方法,通过简支梁室内模型试验来检验方法的有效性,进而以下白石大桥为背景,通过数值模拟方法基于响应面模型修正和单元模态应变能指标进行下白石大桥支座损伤识别。结果表明:单元模态应变能损伤指标对开裂损伤和支座损伤具有较好的敏感性,可识别出多损伤位置和损伤程度,具有应用到实际工程结构进行损伤识别的潜力。     

结构有限元模型修正综述

结构有限元分析模型计算的结构响应与实测响应之间不可避免地存在一定偏差。利用结构现场实测的响应信息修正其结构有限元分析模型,使得修正后结构有限元模型计算的响应值与试验值趋于一致,此过程即为结构有限元模型修正。本文对结构动力模型修正和静力模型修正的一般理论及其进展进行了综述,讨论了有限元模型修正中的若干重要技术问题。     

结构有限元模型修正的灵敏度分析方法

文章简要介绍了结构有限元修正的灵敏度分析方法的基本原理、研究现状及现存的问题,并对若干改进算法和发展方向进行了展望。     

基于Hopfield 神经网络的有限元模型修正

工程结构的有限元模型对结构的健康监测与可靠性评估有重大意义,但实际工程中测量数据和模型都与结构初始有限元模型有一定的差异,因此有必要对实际结构的有限元模型进行修正。首先建立有限元模型修正方程来表达结构响应与待修正参数之间的关系,再通过Hopfield递归神经网络技术,对模型修正方程进行求解。通过一个数值梁模型对提出的方法进行了验证,结果显示Hopfield神经网络在求解线性模型修正仿真中有较好的效果。     

古塔有限元模型的建立及修正

古塔的动力特性是评价结构抗震性能和损伤状态的重要指标。本文首先根据测绘资料采用有限元软件ANSYS建立秦峰塔的初始有限元模型,然后利用现场环境振动实测数据修正所建立的有限元模型并进行模态分析。结果表明:修正后的有限元模型模态分析计算结果和现场测试数据相比,误差较小,从而说明文中所建立的有限元模型是比较可靠的,可以为古塔的后续动力响应分析提供理论分析模型。     

组合梁桥有限元修正模型的研究

为改善结构有限元模型的精度,减小理论模型计算结果与试验结果之间的误差,采用模型修正技术对建立的初始有限元模型进行修正.针对铁路组合梁桥模型修正的问题,进行了大量的试验和研究,着重对组合梁力学参数和边界条件进行了修正.结果表明,经过修正后的有限元模型计算结果与试验结果更加接近,模型修正是可行的、有效的.     

可靠度响应面有限元及其工程应用

可靠度响应面有限元是可靠度计算与响应面有限元的直接耦合,是采用有限元数值模拟来解决功能函数不能用解析式表示的结构可靠度问题的一类方法,对于大型复杂结构的可靠度分析有重要的意义。本文简述了响应面方法的研究发展,给出了可靠度响应面有限元的几类算法和可靠度计算的两种途径,并介绍了响应面有限元方法在实际工程中的应用情况。     

基于相似模型试验的导管架平台有限元模型修正

根据设计尺寸建立的有限元模型与实际结构之间不可避免地存在一定偏差,须根据试验测量数据对有限元模型进行必要的修正。基于相似原理设计制作完整平台和损伤平台的缩尺模型,开展模态试验;根据模态置信准则(MAC)评价试验模态数据和有限元计算数据的相关性。应用灵敏度分析方法对结构设计变量进行分级,以有效识别出平台结构中的待修正参数。针对含有未知损伤的海洋平台,采用结构参数的优化方法,识别损伤位置并实现损伤平台有限元模型的更新。结果表明:对于完整平台,修正后前六阶固有频率的误差均值由修正前的17.22%降至2.78%,修正后的有限元模型更接近试验结构;平台损伤后MAC显著降低,根据优化方法可准确定位出2个缺失构件的位置,且修正后固有频率的误差均值由25.94%降至4.79%。通过修正可为在役海洋平台安全评估提供一个准确的有限元模型。     

Finite element model updating on small-scale bridge model using the hybrid genetic algorithm

Finite element (FE) model-based dynamic analysis has been widely used to predict the dynamic characteristics of civil structures. FE model updating method based on the hybrid genetic algorithm, by combining genetic algorithm and the modified Nelder–Mead's simplex method, is presented to improve bridge structures' FE model. An objective function is formulated as a linear combination of fitness functions on natural frequencies, mode shapes and static deflections using measurements and analytical results to update both stiffness and mass simultaneously. A commercial FE analysis tool, which can utilise previously developed element library and solution algorithms, is adopted for applications on diversified and complex structures. The validity of the proposed method is verified by using a simply supported bridge model with three I-shaped girders. FE models such as grid, beam-shell and shell model are considered to modify initial FE models on the experimental structure. Experimental results suggest that the proposed method can be applied efficiently to various FE models and is feasible and effective when this method is applied to identify FE modelling errors.     

Finite element model updating of a large structure using multi-setup stochastic subspace identification method and bees optimization algorithm

In the present contribution, operational modal analysis in conjunction with bees optimization algorithm are utilized to update the finite element model of a solar power plant structure. The physical parameters which required to be updated are uncertain parameters including geometry, material properties and boundary conditions of the aforementioned structure. To determine these uncertain parameters, local and global sensitivity analyses are performed to increase the solution accuracy. An objective function is determined using the sum of the squared errors between the natural frequencies calculated by finite element method and operational modal analysis, which is optimized using bees optimization algorithm. The natural frequencies of the solar power plant structure are estimated by multi-setup stochastic subspace identification method which is considered as a strong and efficient method in operational modal analysis. The proposed algorithm is efficiently implemented on the solar power plant structure located in Shahid Chamran university of Ahvaz, Iran, to update parameters of its finite element model. Moreover, computed natural frequencies by numerical method are compared with those of the operational modal analysis. The results indicate that, bees optimization algorithm leads accurate results with fast convergence.     

藏式山地结构有限元模型修正及动力可靠度分析#br#

布达拉宫建筑群山地结构众多,其与平地结构在地震作用下的动力可靠度差异较大。对布达拉宫内典型藏式山地结构占堆康进行基于环境振动的动力特性测试,分析基础约束刚度 频率敏感域曲线,应用实测结果修正有限元模型。基于首超准则及泊松跨越假定提出改进的动力可靠度解法,将占堆康视为串联体系得到其体系可靠度,并得到基础约束刚度的变化对动力可靠度的影响规律。结果表明：动力测试结果为有限元模型的修正提供依据,藏式山地结构的基础约束刚度对结构基频影响显著,且存在敏感影响域。运用基于首超准则改进的动力可靠度方法计算动力可靠度时应合理估计基础约束刚度。     

基于ABAQUS的振动轮-土体模型有限元分析

本文主要探讨了振动压路机振动压实的非线性特点,利用有限元分析软件ABAQUS建立了振动轮-土体系统的有限元模型,对振动轮的振动压实过程进行了仿真和分析.     

Dynamic test and finite element model updating of bridge structures based on ambient vibration

The dynamic characteristics of bridge structures are the basis of structural dynamic response and seismic analysis, and are also an important target of health condition monitoring. In this paper, a three-dimensional finite-element model is first established for a highway bridge over a railroad on No.312 National Highway. Based on design drawings, the dynamic characteristics of the bridge are studied using finite element analysis and ambient vibration measurements. Thus, a set of data is selected based on sensitivity analysis and optimization theory; the finite element model of the bridge is updated. The numerical and experimental results show that the updated method is more simple and effective, the updated finite element model can reflect the dynamic characteristics of the bridge better, and it can be used to predict the dynamic response under complex external forces. It is also helpful for further damage identification and health condition monitoring.     

Dynamic test and finite element model updating of bridge structures based on ambient vibration

The dynamic characteristics of bridge structures are the basis of structural dynamic response and seismic analysis, and are also an important target of health condition monitoring. In this paper, a three-dimensional finite-element model is first established for a highway bridge over a railroad on No.312 National Highway. Based on design drawings, the dynamic characteristics of the bridge are studied using finite element analysis and ambient vibration measurements. Thus, a set of data is selected based on sensitivity analysis and optimization theory; the finite element model of the bridge is updated. The numerical and experimental results show that the updated method is more simple and effective, the updated finite element model can reflect the dynamic characteristics of the bridge better, and it can be used to predict the dynamic response under complex external forces. It is also helpful for further damage identification and health condition monitoring. __________ Translated from Chinese Journal of Huazhong University of Science and Technology (Urban Science Edition), 2006, 23(4): 57–60 [译自: 华 中科技大学学报(城市科学版)]