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Study of the approximate approaches to the POD based spectral representation method

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Science China(Technological Sciences) 2013年第4期56卷 970-979页

作者： WU YongXin GAO YuFeng LI DaYong XU ChangJie MAHFOUZ Ali Hasson Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai University Institute of Engineering Safety and Disaster Prevention Hohai University Geotechnical Research Institute Hohai University Department of Civil Engineering Shandong University of Science and Technology Research Center of Coastal and Urban Geotechnical Engineering Zhejiang University College of Engineering Jazan UniversityJazanSaudi Arabia

The spectral representation method (SRM) is most widely used in simulating the stochastic *** proper orthogonal decomposition (POD) based SRM is an important *** paper investigates the approximate approaches to the POD-based SRM in simulating two typical problems,i.e.,the seismic ground motion and wind velocity fields ***,the accuracy resulting from the power spectral density matrix-based POD method (PSRM) is compared to that of the coherency matrix-based POD method (CPSRM).It is concluded that the CPSRM maintains a much higher accuracy than the *** the CPSRM,the linear interpolation of eigenvectors and third-order polynomial interpolation of eigenvalues can be accepted to attain high accuracy;the linearly distributed interpolation nodes are effective in the ground motions simulation;however,the exponentially distributed interpolation nodes are effective in the wind velocity simulation.

关键词： stochastic field simulation coherency matrix based spectral representation method proper orthogonal decomposition approximation

Large eddy simulation study of 3D wind field in a complex mountainous area under different boundary conditions

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第7期25卷 541-556页

作者： Yan LI Lei YAN Xuhui HE School of Civil Engineering Central South UniversityChangsha410075China National Engineering Research Center for High-speed Railway Construction Changsha410075China Hunan Provincial Key Laboratory for Disaster Prevention and Mitigation of Rail Transit Engineering Structures Changsha410075China

Large eddy simulations generally are used to predict 3D wind field characteristics in complex mountainous *** simulation boundary conditions,such as the height and length of the computational domain or the characteristics of inflow turbulence,can significantly impact the quality of *** this study,we examined these boundary conditions within the context of the mountainous terrain around a long-span cable-stayed bridge using a wind tunnel *** sizes of computational domains and turbulent incoming wind velocities were used in large eddy *** results show that when the height of the computational domain is five times greater than the height of the terrain model,there is minimal influence from the top wall on the wind field characteristics in this complex mountainous *** the length of the wake region of the computational domain has negligible effects on the wind *** in the inlet boundary reduces the length of the wake region on a leeward hill with a low slope,but has less impact on the mean wind velocity of steep hills.

关键词： Large eddy simulation(LES) spectral representation method Recycling method High mountainous canyon Wind characteristics Atmospheric boundary layer Computational domain

Digital simulation of 3D turbulence wind field of Sutong Bridge based on measured wind spectra

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第2期13卷 91-104页

作者： Hao WANG Zhou-hong ZONG Ai-qun LI Teng TONG Jie NIU Wen-ping DENG Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education Southeast UniversityNanjing 210096China Key Laboratory of Environmental Impact and Structural Safety in Engineering China University of Mining&TechnologyXuzhou 221116China

Time domain analysis is an essential implement to study the buffeting behavior of long-span bridges for it can consider the non-linear effect which is significant in long-span bridges. The prerequisite of time domain analysis is the accurate description of 3D turbulence winds. In this paper, some hypotheses for simplifying the 3D turbulence simulation of long-span cable-stayed bridges are conducted, considering the structural characteristics. The turbulence wind which is a 3D multivariate stochastic vector process is converted into four independent 1D univariate stochastic processes. Based on recorded wind data from structural health monitoring system (SHMS) of the Sutong Bridge, China, the measured spectra expressions are then presented using the nonlinear least-squares fitting method. Turbulence winds at the Sutong Bridge site are simulated based on the spectral representation method and the Fast Fourier transform (FFT) technique, and the relevant results derived from target spectra including measured spectra and recommended spectra are compared. The reliability and accuracy of the presented turbulence simulation method are validated through comparisons between simulated and target spectra (measured and recommended spectra). The obtained turbulence si-mulations can not only serve further analysis of the buffeting behavior of the Sutong Bridge, but references for structural anti-wind design in adjacent regions.

关键词： Turbulence simulation spectral representation method Fast Fourier transform (FFT) Cable-stayed bridges Struc-tural health monitoring system (SHMS) Power spectral density

Approximation approach to the SRM based on root decomposition in the simulation of spatially varying ground motions

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Earthquake Engineering and Engineering Vibration 2013年第3期12卷 363-372页

作者： Wu Yongxin Gao Yufeng Li Dayong Xu Changjie Ali H Mahfouz Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai University Institute of Engineering Safety and Disaster Prevention Hohai University Geotechnical Research Institute Hohai University Department of Civil Engineering Shandong University of Science and Technology Research Center of Coastal and Urban Geotechnical Engineering Zhejiang University College of Engineering Jazan University

The spectral representation method （SRM） is widely used to simulate spatially varying ground motions. This study focuses on the approximation approach to the SRM based on root decomposition, which can improve the efficiency of the simulation. The accuracy of the approximation approach may be affected by three factors： matrix for decomposition, distribution of frequency interpolation nodes and elements for interpolation. The influence of these factors on the accuracy of this approach is examined and the following conclusions are drawn. The SRM based on the root decomposition of the lagged coherency matrix exhibits greater accuracy than the SRM based on the root decomposition of the cross spectral matrix. The equal energy distribution of frequency interpolation nodes proposed in this study is more effective than the counter pith with an equal spacing. Elements for interpolation do not have much of an effect on the accuracy, so interpolation of the elements of the decomposed matrix is recommended because it is less complicated from a computational efficiency perspective.

关键词： ground motions simulation spectral representation method spatially varying approximation root decomposition