大跨桥梁结构损伤诊断与安全评估的多尺度有限元模拟研究   总被引：6，自引：0，他引：6  

丁幼亮  李爱群  缪长青  李兆霞  韩晓林 《地震工程与工程振动》2006,26(2):66-72

探讨了以结构损伤诊断与安全评估为目标的大跨桥梁结构多尺度有限元模拟的策略与方案。在有限元模型误差来源分析的基础上,提出了大跨桥梁结构模型误差的分层次修正方法。通过对润扬长江大桥斜拉桥的有限元建模和模型修正过程,提出了大跨斜拉桥结构以损伤诊断与安全评估为目标的多尺度有限元模拟方法。研究表明,大跨桥梁结构的多尺度有限元模拟必须建立在模型误差分析的基础上,并采用模型误差的分层次修正方法才能较好的满足多尺度有限元模拟的技术要求。  相似文献   

辽西医巫闾山海蚀地貌遗迹的发现及其意义     

商翎  高飞  张立东  郑月娟  张志斌 《地质与资源》2006,15(4):253-255,271

简要介绍医巫山闾山山区海蚀地貌遗迹的发现及其形态类型、形成的可能时代和机制.这不仅为定性及定量研究中国东部地区新构造运动上升和海平面变化幅度和速率提供科学依据,同时为医巫闾山风景区申报世界自然与文化遗产提供新的条件.  相似文献   

Online numerical simulation: A hybrid simulation method for incomplete boundary conditions          下载免费PDF全文

《地震工程与结构动力学》2018,47(4):889-905

Hybrid simulation is a powerful and cost‐effective simulation technique to evaluate structural dynamic performance. However, it is sometimes rather difficult to guarantee all the boundaries on the physical substructures, especially when the boundary conditions are very complex, due to limited laboratory resources. Lacking of boundary conditions is bound to change the stress state of the structure and eventually result in an inaccurate evaluation of structural performance. A model updating‐based online numerical simulation method is proposed in this paper to tackle the problem of incomplete boundary conditions. In the proposed method, 2 sets of finite element models with the same constitutive model are set up for the overall analysis of the whole structure and the constitutive model parameter estimation of the physical substructure, respectively. The boundary conditions are naturally satisfied because the response is calculated from the overall structural model, and the accuracy is improved as the material constitutive parameters are updated. The effectiveness of the proposed method is validated via numerical simulations and actual hybrid tests on a RC frame structure, and the results show that the negative effect of incomplete boundary conditions is almost eliminated and the accuracy of hybrid simulation is very much improved.  相似文献   

基于面平均雨量误差修正的实时洪水预报修正方法     

司伟  包为民  瞿思敏  石朋 《湖泊科学》2018,30(2):533-541

空间集总式水文模型的洪水预报精度会受到面平均雨量估计误差的严重影响.点雨量监测值的误差类型、误差大小以及流域的雨量站点密度和站点的空间分布都会影响到面平均雨量的计算.为提高实时洪水预报精度,本文提出了一种基于降雨系统响应曲线洪水预报误差修正方法.通过此方法估计降雨输入项的误差,从而提高洪水预报精度.此方法将水文模型做为输入和输出之间的响应系统,用实测流量和计算流量之间的差值做为信息,通过降雨系统响应曲线,使用最小二乘估计原理,对面平均雨量进行修正,再用修正后的面平均雨量重新计算出流过程.将此修正方法结合新安江模型使用理想案例进行检验,并应用于王家坝流域的16场历史洪水以及此流域不同雨量站密度的情况下,结果证明均有明显修正效果,且在雨量站密度较低时修正效果更加明显.该方法是一种结构简单且不增加模型参数和复杂度的实时洪水修正的新方法.  相似文献   

基于洪水预报系统误差反演的多河段联合校正方法     

黄一昕  梁忠民  胡义明  李彬权  王军 《湖泊科学》2021,33(6):1914-1924

提出一种基于洪水预报误差系统反演的多河段联合校正方法.采用马斯京根法矩阵方程描述多河段多区间入流的河道汇流过程,基于动力系统反演理论建立洪水预报误差的递推方程,最后利用修正后的多河段状态变量经演算得到预报断面的洪水过程,进而达到多河段联合校正目的.对大渡河上游的应用示例结果表明：多河段联合校正方法考虑了河系中断面间的水力联系及预报误差在时程上的传递规律,可充分利用上游多断面实测和校正信息进行下游预报断面的误差修正,因此具有更高的校正精度和稳定性.  相似文献   

Model-data fusion for seismic performance evaluation of an instrumented highway bridge     

Siddharth S. Parida  Alexandros Nikellis  Kallol Sett  Puneet Singla 《地震工程与结构动力学》2020,49(14):1559-1578

The paper presents a computationally efficient algorithm to integrate a probabilistic, non-Gaussian parameter estimation approach for nonlinear finite element models with the performance-based earthquake engineering (PBEE) framework for accurate performance evaluations of instrumented civil infrastructures. The algorithm first utilizes a minimum variance framework to fuse predictions from a numerical model of a civil infrastructure with its measured behavior during a past earthquake to update the parameters of the numerical model that is, then, used for performance prediction of the civil infrastructure during future earthquakes. A nonproduct quadrature rule, based on the conjugate unscented transformation, forms an enabling tool to drive the computationally efficient model prediction, model-data fusion, and performance evaluation. The algorithm is illustrated and validated on Meloland Road overpass, a heavily instrumented highway bridge in El Centro, CA, which experienced three moderate earthquake events in the past. The benefits of integrating measurement data into the PBEE framework are highlighted by comparing damage fragilities of and annual probabilities of damages to the bridge estimated using the presented algorithm with that estimated using the conventional PBEE approach.  相似文献   

干旱区沙漠与河流复合地貌过程研究进展   总被引：1，自引：1，他引：0  

李小妹  严平 《中国沙漠》2019,39(5):97-104

沙漠-河流过渡带是独特的地理单元,在世界主要沙漠中普遍存在,河岸沙丘地貌发育过程是其独特性的突出表现。一方面,河流通过提供物源和场所控制河岸沙丘地貌的发育过程与格局,另一方面,沙丘发育过程改变河道。本文回顾了沙漠与河流复合地貌过程研究取得的重要进展,包括沙漠与河流交互关系、沙漠和河流交互尺度以及河岸沙丘地貌形成与发育过程等。但水系变迁与沙漠演化、沙丘复杂性与河谷形态之间的关系,以及如何建构沙漠河岸风水复合地貌过程模型等问题,将是未来需要突破的难题,这有助于促进风沙地貌与流水地貌的高度融合,丰富沙漠科学和干旱区水文的理论体系。  相似文献   

基于服务驱动的“天地图·黑龙江”数据快速更新关键技术研究     

张庆全  王同琛  吴迪  覃婷婷  周艳  关显明 《测绘与空间地理信息》2020,(3):148-152

在分析"天地图·黑龙江"应用需求服务的基础上,本文重点阐述了"天地图·黑龙江"数据快速更新的总体技术路线,并详细描述了多源数据获取与分析整理、遥感影像批量快速更新、基于"天地图·黑龙江"母库的数据动态更新、两期影像变化检测的数据快速更新、地名地址数据快速更新等关键技术。本文提出的基于服务驱动的数据动态快速更新思路,进一步加强了"天地图·黑龙江"地理信息保障服务能力建设。  相似文献   

亚毫米波天线有限元模型参数修正复合优化方法     

张明珠  王海仁  左营喜 《天文学报》2019,60(4):39-56

天线有限元模型与实际天线往往存在结构参数误差和材料参数误差等,使有限元模型不能真实反映实际天线结构在各种载荷下的变形特性.针对亚毫米波天线,提出了亚毫米波天线有限元模型参数修正复合优化方法.该方法包括3步,第1步建立天线参数化有限元模型,并进行参数灵敏度分析;第2步,以第1步中得到的高灵敏度参数为优化变量建立优化函数,以初始模型与假想实际天线变形特性的差值最小为目标进行优化;第3步,基于零阶优化法和一阶优化法对天线有限元模型进行复合优化,使天线有限元模型逐渐逼近实际天线.为验证所提出参数修正优化方法的可行性,针对一台1.2 m亚毫米波天线,将对其进行假想实验获得的变形特性作为优化目标,分别对多个材料参数在不同的载荷工况下进行优化,结果表明天线有限元模型经过参数优化后与假想实际天线一致,证明了所提出的亚毫米波天线有限元模型参数优化修正方法可行,并在重力载荷下对修正优化后的天线模型的变形规律进行分析.这种优化方法可以推广应用到大口径亚毫米波天线的有限元模型修正中.  相似文献   

Application of tank,NAM, ARMA and neural network models to flood forecasting     

Tawatchai Tingsanchali  Mahesh Raj Gautam 《水文研究》2000,14(14):2473-2487

Two lumped conceptual hydrological models, namely tank and NAM and a neural network model are applied to flood forecasting in two river basins in Thailand, the Wichianburi on the Pasak River and the Tha Wang Pha on the Nan River using the flood forecasting procedure developed in this study. The tank and NAM models were calibrated and verified and found to give similar results. The results were found to improve significantly by coupling stochastic and deterministic models (tank and NAM) for updating forecast output. The neural network (NN) model was compared with the tank and NAM models. The NN model does not require knowledge of catchment characteristics and internal hydrological processes. The training process or calibration is relatively simple and less time consuming compared with the extensive calibration effort required by the tank and NAM models. The NN model gives good forecasts based on available rainfall, evaporation and runoff data. The black‐box nature of the NN model and the need for selecting parameters based on trial and error or rule‐of‐thumb, however, characterizes its inherent weakness. The performance of the three models was evaluated statistically. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献