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Keywords: structural identification, penalty function, shake table, acceleration time histories, energy.

Summary

In the framework of the analysis of existing structures vibrating under dynamic loading one of the still open issues is the selection of proper and accurate numerical models along with the pertinent structural parameters that have to be assigned.

Experimentally and numerically evaluated responses present unavoidable discrepancies arising from uncertainties in the material properties and, or in the definition of the structural model (e.g. degrees of freedom, static condensation, joint modelling) whose definition has to take into account both accuracy and computational effort. Once defined a feasible structural model taking into account both geometrical and mechanical data as well as the computational effort involved in further analyses, the calibration of the structural parameters is usually performed using model updating techniques [1] by minimizing the difference between some measured and numerically evaluated response parameters. In this paper the bounded least square procedure proposed in [2] has been extended by introducing a new penalty function based on acceleration measurements. The procedure requires:

experimental evaluation of response acceleration through shake table tests;
definition of the structural model along with the parameters to be identified;
numerical evaluation of the response acceleration through the numerical integration of the equation of motion of the finite element model;
evaluation of the sensitivity of the response acceleration through numerical integration; and
evaluation of the vector of the unknown structural parameters through a simple iteration technique.

The procedure is based on the minimization of a penalty function determined using the response accelerations without further data manipulation (i.e. de-noising techniques or Fourier transformation). Numerical results showed that the parameters identified converged to the exact values quickly and without manifesting wild oscillations. The experimental tests conducted using a shaking table on a simple structure are promising since even in presence of noise the procedure converged quickly to feasible parameters.

References

1: M.I. Friswell, J.E. Mottershead, "Finite element model updating in structural dynamics", Kluwer Academic Publishers, 1995.
2: P. Cacciola, N. Maugeri, G. Muscolino, "Structural identification through the measure of deterministic and stochastic time-domain dynamic response", Computes and Structures, in press. doi:10.1016/j.compstruc.2010.10.013

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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: 96 PROCEEDINGS OF THE THIRTEENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING Edited by: B.H.V. Topping and Y. Tsompanakis Paper 181 Time-Domain Identification of Structural Parameters using Shaking Table Tests P. Cacciola and P. Vachaviolos School of Environment and Technology, University of Brighton, United Kingdom doi:10.4203/ccp.96.181 purchase the full-text of this paper Full Bibliographic Reference for this paper P. Cacciola, P. Vachaviolos, "Time-Domain Identification of Structural Parameters using Shaking Table Tests", in B.H.V. Topping, Y. Tsompanakis, (Editors), "Proceedings of the Thirteenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 181, 2011. doi:10.4203/ccp.96.181 Keywords: structural identification, penalty function, shake table, acceleration time histories, energy. Summary In the framework of the analysis of existing structures vibrating under dynamic loading one of the still open issues is the selection of proper and accurate numerical models along with the pertinent structural parameters that have to be assigned. Experimentally and numerically evaluated responses present unavoidable discrepancies arising from uncertainties in the material properties and, or in the definition of the structural model (e.g. degrees of freedom, static condensation, joint modelling) whose definition has to take into account both accuracy and computational effort. Once defined a feasible structural model taking into account both geometrical and mechanical data as well as the computational effort involved in further analyses, the calibration of the structural parameters is usually performed using model updating techniques [1] by minimizing the difference between some measured and numerically evaluated response parameters. In this paper the bounded least square procedure proposed in [2] has been extended by introducing a new penalty function based on acceleration measurements. The procedure requires: experimental evaluation of response acceleration through shake table tests; definition of the structural model along with the parameters to be identified; numerical evaluation of the response acceleration through the numerical integration of the equation of motion of the finite element model; evaluation of the sensitivity of the response acceleration through numerical integration; and evaluation of the vector of the unknown structural parameters through a simple iteration technique. The procedure is based on the minimization of a penalty function determined using the response accelerations without further data manipulation (i.e. de-noising techniques or Fourier transformation). Numerical results showed that the parameters identified converged to the exact values quickly and without manifesting wild oscillations. The experimental tests conducted using a shaking table on a simple structure are promising since even in presence of noise the procedure converged quickly to feasible parameters. References 1 M.I. Friswell, J.E. Mottershead, "Finite element model updating in structural dynamics", Kluwer Academic Publishers, 1995. 2 P. Cacciola, N. Maugeri, G. Muscolino, "Structural identification through the measure of deterministic and stochastic time-domain dynamic response", Computes and Structures, in press. doi:10.1016/j.compstruc.2010.10.013 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 £130 +P&P)
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