共查询到19条相似文献，搜索用时 125 毫秒
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《地震工程与工程振动》2019,(1)
针对钢-混凝土叠合梁自锚式悬索桥的结构特点,在总结以往大跨径桥梁有限元模型的基础上,采用组合有限元法以梁、板、杆、索单元建立邵阳市桂花大桥三维有限元模型,计算分析获得结构的主要频率和振型。通过现场测试获得大桥环境激励和行车激励作用下的响应时程,分析得到结构的主要频率、振型和阻尼比,引入模态置信因子对计算模态信息和实测模态信息进行比较分析,以验证数值模型和实测结果的准确性。研究结果可为全面了解钢-混凝土叠合梁自锚式悬索桥的动力特性、准确预测结构的动力响应以及类似桥梁的抗震、抗风设计提供重要依据。 相似文献
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针对预应力混凝土连续箱梁桥的通扬运河大桥,建立其有限元模型.基于评价模型修正效果的频率指标与振型相关系数指标、柔度矩阵指标和挠度指标,定义三个目标函数,利用环境激励的试验模态参数,通过实数编码加速遗传算法对有限元模型进行了修正.相对于基于频率指标与振型相关系数指标定义的目标函数,基于柔度矩阵指标或挠度指标定义的目标函数修正的有限元模型,能同时较准确地反映其动态和静态特性,也能实现其试验模态振型较精确的质量归一化. 相似文献
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大跨度预应力混凝土连续刚构桥的动力特性分析 总被引：20，自引：0，他引：20
介绍了福建泉州后渚大桥——大跨度预应力混凝土连续刚构桥的现场环境振动实验．并利用频域中的单模态识别法(SDOFI)、峰值法(PP)和时域中的随机子空间识别法(SSI)分别进行桥梁动力特性识别。利用ANSYS建立了全桥三维有限元模型并进行了理论模态分析,基于参数分析和环境振动测试结果对有限元模型进行了标定,建立了该桥的基准有限元模型,该模型可服务于桥梁长期健康监测与状态评估。 相似文献
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根据平行索面悬索桥的结构体系特征,可以将其划分为几个相对独立的子结构。充分利用振动测试得到的子结构局部振动信息和结构整体振动信息,可以分阶段进行有限元模型修正,从而提高优化效率。本文以克拉玛依市龙门桥为例,结合该桥设计的有限元模型和环境激励振动试验结果,进行了整桥模型修正和子结构多阶段模型修正。首先通过振动法计算得到边悬索的索力近似替代主缆索力,将其施加在整桥有限元模型中,运用基于动力特性的响应面法完成传统的模型修正,得到修正后的土-结构相互作用的弹簧刚度系数和吊杆索力;其次利用主塔横向模态相对独立的特点,通过对主塔子结构模型的修正得到合理的弹性支承参数;再将其施加在初始的整体有限元模型中,完成该桥的子结构分阶段有限元模型修正;最后比较子结构多阶段模型修正与传统整桥模型修正方法的效果,可以看出相比传统模型修正,所提方法不仅提高了修正精度,而且大幅度提高了优化效率。 相似文献
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基于振动台试验的RC框架模型修正及模拟损伤识别 总被引：1，自引：0，他引：1
利用有限元模型修正技术综合利用理论建模和实验建模的优点,可以得到更加符合结构实际的基准模型,为结构动力分析、损伤诊断及健康监测提供更可靠的依据。基于一12层钢筋混凝土框架模型振动台试验测点加速度记录,采用特征系统实现算法对该模型结构进行模态参数识别,识别结果与有限元分析结果之间存在明显的差异。采用基于灵敏度分析的参数型有限元模型修正技术,选择识别精度较高的实测模态频率为修正基准,以构件的弹性模量和密度为修正参数,对该框架的初始有限元模型进行了修正,得到基准有限元模型。进一步以基准有限元模型为标准,以构件弹性模量的降低模拟结构的损伤,对两种假设工况下的损伤结构进行修正,得到构件弹性模量的变化值并与假设的降低值对比,验证了有限元模型修正技术在结构损伤识别中应用的可行性。 相似文献
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基于神经网络的大型空间网架结构的有限元模型修正 总被引：1，自引：1，他引：1
本文提出了依据神经网络方法完成大型空间网架结构节点固结系数的识别，实现空间网架结构有限元模型修正的方法。文中，通过有效独立法优化配置有限数量传感器的安放位置。在此基础上，利用从优化位置处的结构时程响应中获取的结构自振频率和局部位移模态信息，本文建立了基于径向基神经网络的空间网架结构有限元模型修正的计算方法。数值仿真的计算结果表明，该方法能有效地用于空间网架结构的有限元模型修正。 相似文献
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为考虑洪水预报误差的空间变化,提出一种基于微分响应的流域产流分单元修正方法.该方法建立了各单元流域产流与流域出口流量之间的微分响应关系,采用正则化最小二乘法结合逐步迫近进行反演求解,将产流误差估计量分配给相应单元流域实现流域产流分单元修正.将构建的方法应用于大坡岭流域和七里街流域进行新安江模型产流修正,比较分析了流域产流分单元修正、流域面平均产流修正和自回归修正的效果.结果表明：流域产流分单元修正效果优于流域面平均产流修正;随着预见期的增大,产流微分响应修正效果优于自回归修正.该方法通过汇流系统将流域出口断面流量信息进行分解用于修正各单元流域产流,有利于提高实时洪水预报精度. 相似文献
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Lin Xiankun~ Zhang Lingmi~ Guo Qintao~ Zhang Yufeng~ .Institute of Vibration Engineering Nanjing University of Aeronautics Astronautics Nanjing China .College of Mechanical Electrical Engineering China .Jiangsu Transportation Research Institute Nanjing China PhD C idate Professor §Associate Professor *Senior Engineer 《地震工程与工程振动(英文版)》2009,8(3):399-407
The dynamic finite element model(FEM) of a prestressed concrete continuous box-girder bridge,called the Tongyang Canal Bridge,is built and updated based on the results of ambient vibration testing(AVT)using a real-coded accelerating genetic algorithm(RAGA).The objective functions are defined based on natural frequency and modal assurance criterion(MAC) metrics to evaluate the updated FEM.Two objective functions are defined to fully account for the relative errors and standard deviations of the natural fr... 相似文献
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In this study, we determine an updated finite element model of a reinforced concrete building—which was damaged from shaking during 1994 Northridge earthquake—using forced‐vibration test data and a novel model‐updating technique. Developed and verified in the companion paper (viz. BVLSrc, Earthquake Eng. Struct. Dyn. 2006; this issue), this iterative technique incorporates novel sensitivity‐based relative constraints to avoid ill conditioning that results from spatial incompleteness of measured data. We used frequency response functions and natural frequencies as input for the model‐updating problem. These data were extracted from measurements obtained during a white‐noise excitation applied at the roof of the building using a linear inertial shaker. Flexural stiffness values of properly grouped structural members, modal damping ratios, and translational and rotational mass values were chosen as the updating parameters, so that the converged results had direct physical interpretations, and thus, comparisons with common parameters used in seismic design and evaluation of buildings could be made. We investigated the veracity of the updated finite element model by comparing the predicted and measured dynamic responses under a second, and different type of forced (sine‐sweep) vibration, test. These results indicate that the updated model replicates the dynamic behaviour of the building reasonably well. Furthermore, the updated stiffness factors appear to be well correlated with the observed building damage patterns (i.e. their location and severity). Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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混凝土的数值计算模型在滞回性能分析中往往比较难收敛，利用有限元软件ADINA提供Drucker-Prager模型的Cap修正屈服准则确立的非协调参数Drucker-Prager模型对预应力节段拼装混凝土桥墩进行数值分析，对预应力节段拼装桥墩在低周往复荷载作用下的滞回性能进行分析。通过比较采用非协调参数Drucker-Prager模型建立的数值模型计算得到的滞回曲线与试验得到的结果，两者吻合程度较高。基于这一成果可以通过数值模拟的方式获得预应力节段拼装桥墩的滞回曲线与相关数据，可应用于预应力节段拼装桥墩抗震计算和设计。 相似文献
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The problem of identification of the modal parameters of a structural model using measured ambient response time histories is addressed. A Bayesian spectral density approach (BSDA) for modal updating is presented which uses the statistical properties of a spectral density estimator to obtain not only the optimal values of the updated modal parameters but also their associated uncertainties by calculating the posterior joint probability distribution of these parameters. Calculation of the uncertainties of the identified modal parameters is very important if one plans to proceed with the updating of a theoretical finite element model based on modal estimates. It is found that the updated PDF of the modal parameters can be well approximated by a Gaussian distribution centred at the optimal parameters at which the posterior PDF is maximized. Examples using simulated data are presented to illustrate the proposed method. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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Ahmet Can Altunişik Alemdar Bayraktar Barış Sevim Şevket Ateş 《Soil Dynamics and Earthquake Engineering》2011
This paper describes ambient vibration based seismic evaluation procedure of an isolated highway bridge. The procedure includes finite element modeling, ambient vibration testing, finite element model updating and time history analysis. Gülburnu Highway Bridge located on the Giresun–Espiye state highway is selected as a case study. Three dimensional finite element model of the bridge is created by SAP2000 software to determine the dynamic characteristics analytically. Since input force is not measured, Operational Modal Analysis is applied to identify dynamic characteristics. Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification methods are used to obtain experimental dynamic characteristics. Analytical and experimental dynamic characteristic are compared with each other and finite element model of the bridge is updated by changing of material properties to reduce the differences between the results. Analytical model of the bridge after model updating is analyzed using 1992 Erzincan earthquake record to determine the seismic behavior. EW, NS and UP components of the ground motion are applied to the bridge at the longitudinal, transverse and vertical directions, respectively. It is demonstrated that the ambient vibration measurements are enough to identify the most significant modes of highway bridges. Maximum differences between the natural frequencies are reduced averagely from 9% to 2% by model updating. It is seen from the earthquake analyses that friction pendulum isolators are very effective in reducing the displacements and internal forces. 相似文献
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为研究不同加固方式对钢筋混凝土(RC)圆截面桥墩抗震性能的影响,利用OpenSees有限元软件建立了普通RC桥墩以及分别采用钢套管、碳纤维增强聚合物(CFRP)、体外预应力筋进行加固的桥墩数值分析模型,对模型输入远断层地震动,进行增量动力分析。以墩顶峰值位移角与震后残余位移角为指标,对比分析了桥墩加固前后的地震响应。结果表明:采用钢套管、体外预应力筋和CFRP加固后,RC桥墩的峰值位移与震后残余位移均减小,钢套管加固方式对桥墩峰值位移的降低幅度最大,体外预应力筋加固方式对抑制桥墩震后残余位移的效果最好;随着剪跨比的增大,3种加固方式对桥墩在地震动作用下位移响应的抑制作用均逐步减小;随着轴压比的增大,3种加固方式对RC桥墩峰值位移的抑制作用逐步降低。 相似文献
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Partial‐strength composite steel–concrete moment‐resisting (MR) frame structures represent an open research field in seismic design from both a theoretical and an experimental standpoint. Among experimental techniques, vibration testing is a well‐known and powerful technique for damage detection, localization and quantification, where actual modal parameters of a structure at different states can be determined from test data by using system identification methods. However, the identification of semi‐rigid connections in framed structures is limited, and hence this paper focuses on a series of vibration experiments that were carried out on a realistic MR frame structure, following the application of pseudo‐dynamic and quasi‐static cyclic loadings at the European laboratory for structural assessment of the Joint Research Centre at Ispra, Italy, with the scope of understanding the structural behaviour and identifying changes in the dynamic response. From the forced vibration response, natural frequencies, damping ratios, modal displacements and rotations were extracted using the circle fitting technique. These modal parameters were used for local and global damage identification by updating a 3D finite element model of the intact structure. The identified results were then correlated with observations performed on the structure to understand further the underlying damage mechanisms. Finally, the latin hypercube sampling technique, a variant of the Monte Carlo method, was employed in order to study the sensitivity of the updated parameters of the 3D model to noise on the modal inputs. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Structural identification of Egnatia Odos bridges based on ambient and earthquake induced vibrations
Evaggelos Ntotsios Christos Karakostas Vasilios Lekidis Panagiotis Panetsos Ioannis Nikolaou Costas Papadimitriou Thomas Salonikos 《Bulletin of Earthquake Engineering》2009,7(2):485-501
The dynamic characteristics of two representative R/C bridges on Egnatia Odos motorway in Greece are estimated based on low
amplitude ambient and earthquake-induced vibrations. The present work outlines the instrumentation details, algorithms for
computing modal characteristics (modal frequencies, damping ratios and modeshapes), modal-based finite element model (FEM)
updating methods for estimating structural parameters, and numerical results for the modal and structural dynamic characteristics
of the two bridges based on ambient and earthquake induced vibrations. Transverse, bending and longitudinal modes are reliably
identified and stiffness-related properties of the piers, deck and elastomeric bearings of the FEMs of the two bridges are
estimated. Results provide qualitative and quantitative information on the dynamic behavior of the bridge systems and their
components under low-amplitude vibrations. Modeling assumptions are discussed based on the differences in the characteristics
identified from ambient and earthquake vibration measurements. The sources of the differences observed between the identified
modal and structural characteristics of the bridges and those predicted by FEMs used for design are investigated and properly
justified. 相似文献
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A reliable computational model is necessary for evaluating the state and predicting the future performance of existing structures, especially after exposure to damaging effects such as an earthquake. A major problem with the existing iterative‐based model updating methods is that the search might be trapped in local optima. The genetic algorithms (GAs) offer a desirable alternative because of their ability in performing a robust search for the global optimal solution. This paper presents a GA‐based model updating approach using a real‐coding scheme for global model updating based on dynamic measurement data. An eigensensitivity method is employed to further fine‐tune the GA updated results in case the sensitivity problem arises due to restricted measurement information. The application on shear‐type frames reveals that with a limited amount of modal data, namely the lowest three natural frequencies and the first mode shape, it is possible to achieve satisfactory updating by the GA alone for cases involving a limited number of parameters (storey stiffness herein). With the incorporation of the eigensensitivity algorithm, the updating capability is extended to a sufficiently large number of parameters. In case the modal data contain errors, the GA is also shown to be able to update the model to a satisfactory accuracy, provided the required amount of modal data is available. An example is given in which a 6‐DOF stick model for an actual six‐storey RC frame is updated using the measured dynamic properties. The effectiveness of the updating is evaluated by comparing the measured and predicted seismic response using the updated model. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献