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Keywords: spatial structures, cladding, wind tunnel experiment, aerodynamic database, artificial neural network, time-history simulation, load evaluation system.

Summary

The authors have proposed a computer-assisted wind load evaluation system for the design of roof cladding of spatial structures, using an aerodynamic database, artificial neural network and time-series simulation technique. Focus is on spherical domes and vaulted roofs in the present paper. The system consists of the following four procedures:

(1): Database of wind pressures
A series of wind tunnel experiments are carried out in two kinds of turbulent boundary layers corresponding to open-country and urban exposures. Wind pressures are measured simultaneously at several hundred points on spherical domes and vaulted roofs with various rise/span and eaves-height/span ratios. The statistics of wind pressures, e.g. mean, standard deviation, skewness and kurtosis are computed. The data are stored in a database, together with the coordinates of the measuring points. The power spectrum of pressure fluctuations is approximated by an exponential function of the reduced frequency. The values of the parameters included in the function are stored in the database.
(2): Artificial neural network for predicting the statistics of wind pressures
Artificial neural networks based on a Cascade Correlation Learning Network are constructed for predicting the statistics of wind pressures at arbitrary points on the roof. The input vector consists of several parameters, including the geometric parameters of the roof, the coordinates of evaluating point and the turbulence intensity of approach flow at the mean roof height; the wind direction is also considered in the vaulted roof case. Similarly one output node is used, because the expected output vector has a single component. That is, each network is constructed for each of the statistics.
(3): Time series simulation of wind pressures
The approach is based on an FFT Algorithm. The Fourier amplitude is constructed from the power spectrum of pressure fluctuations. The spike features inducing the non-Gaussian character to the pressure fluctuations are achieved by preserving the target skewness and kurtosis of pressure fluctuations.
(4): Application of the wind load evaluation system to wind resistant design
The wind load evaluation system can provide peak pressure coefficients according to a predetermined risk level by combining the extreme value analysis. Simulating the wind pressure time series many times, we can calculate the probability of non-exceedence for the peak pressure coefficients precisely. Furthermore, by introducing a load cycle counting method, e.g. the rainflow count method, the system can provide the wind load cycles for fatigue design.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 86 PROCEEDINGS OF THE ELEVENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING Edited by: B.H.V. Topping Paper 140 A Computer-Assisted Wind Load Evaluation System for the Design of Cladding of Spatial Structures Y. Uematsu¹, R. Tsuruishi², T. Hongo³ and H. Kikuchi⁴ ¹New Industry Creation Hatchery Centre, ²Department of Architecture and Building Science Tohoku University, Sendai, Japan ³Kajima Technical Research Institute, Chofu, Japan ⁴Institute of Technology, Shimizu Corporation, Tokyo, Japan doi:10.4203/ccp.86.140 purchase the full-text of this paper Full Bibliographic Reference for this paper Y. Uematsu, R. Tsuruishi, T. Hongo, H. Kikuchi, "A Computer-Assisted Wind Load Evaluation System for the Design of Cladding of Spatial Structures", in B.H.V. Topping, (Editor), "Proceedings of the Eleventh International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 140, 2007. doi:10.4203/ccp.86.140 Keywords: spatial structures, cladding, wind tunnel experiment, aerodynamic database, artificial neural network, time-history simulation, load evaluation system. Summary The authors have proposed a computer-assisted wind load evaluation system for the design of roof cladding of spatial structures, using an aerodynamic database, artificial neural network and time-series simulation technique. Focus is on spherical domes and vaulted roofs in the present paper. The system consists of the following four procedures: (1) Database of wind pressures A series of wind tunnel experiments are carried out in two kinds of turbulent boundary layers corresponding to open-country and urban exposures. Wind pressures are measured simultaneously at several hundred points on spherical domes and vaulted roofs with various rise/span and eaves-height/span ratios. The statistics of wind pressures, e.g. mean, standard deviation, skewness and kurtosis are computed. The data are stored in a database, together with the coordinates of the measuring points. The power spectrum of pressure fluctuations is approximated by an exponential function of the reduced frequency. The values of the parameters included in the function are stored in the database. (2) Artificial neural network for predicting the statistics of wind pressures Artificial neural networks based on a Cascade Correlation Learning Network are constructed for predicting the statistics of wind pressures at arbitrary points on the roof. The input vector consists of several parameters, including the geometric parameters of the roof, the coordinates of evaluating point and the turbulence intensity of approach flow at the mean roof height; the wind direction is also considered in the vaulted roof case. Similarly one output node is used, because the expected output vector has a single component. That is, each network is constructed for each of the statistics. (3) Time series simulation of wind pressures The approach is based on an FFT Algorithm. The Fourier amplitude is constructed from the power spectrum of pressure fluctuations. The spike features inducing the non-Gaussian character to the pressure fluctuations are achieved by preserving the target skewness and kurtosis of pressure fluctuations. (4) Application of the wind load evaluation system to wind resistant design The wind load evaluation system can provide peak pressure coefficients according to a predetermined risk level by combining the extreme value analysis. Simulating the wind pressure time series many times, we can calculate the probability of non-exceedence for the peak pressure coefficients precisely. Furthermore, by introducing a load cycle counting method, e.g. the rainflow count method, the system can provide the wind load cycles for fatigue design. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £120 +P&P)
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