Identifying Dynamic Structural Parameters of Soil-Structure System Based on Data Recorded during Strong Earthquakes

Authors: Vahidreza Mahmoudabadi, Omid Bahar, Mohammad Kazem Jafari

Abstract:

In many applied engineering problems, structural analysis is usually conducted by assuming a rigid bed, while imposing the effect of structure bed flexibility can affect significantly on the structure response. This article focuses on investigation and evaluation of the effects arising from considering a soil-structure system in evaluation of dynamic characteristics of a steel structure with respect to elastic and inelastic behaviors. The recorded structure acceleration during Taiwan’s strong Chi-Chi earthquake on different floors of the structure was our evaluation criteria. The respective structure is an eight-story steel bending frame structure designed using a displacement-based direct method assuring weak beam - strong column function. The results indicated that different identification methods i.e. reverse Fourier transform or transfer functions, is capable to determine some of the dynamic parameters of the structure precisely, rather than evaluating all of them at once (mode frequencies, mode shapes, structure damping, structure rigidity, etc.). Response evaluation based on the input and output data elucidated that the structure first mode is not significantly affected, even considering the soil-structure interaction effect, but the upper modes have been changed. Also, it was found that the response transfer function of the different stories, in which plastic hinges have occurred in the structure components, provides similar results.

Keywords: System identification, dynamic characteristics, soil-structure system, bending steel frame structure, displacement-based design.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1130475

References:

[1] Ljung. L. “System Identification — Theory for the User." Prentice-Hall, Englewood Cliffs, N.J., 1987.
[2] Mottershead, J. E. and M. I. Friswell, 1993, “Model Updating in Structural Dynamics: A Survey,” Journal of Sound and Vibration, 167(2), 347–375.
[3] Teughels A., Roeck G. D. (2005) “Damage detection and parameter identification by finite element model updating.” Arch Comput Method E, 12 (12), pp. 123–164.
[4] Ebrahimian, H. (2015). “Nonlinear finite element model updating for nonlinear system and damage identification of civil structures.” ProQuest Dissertations & Theses, 448 pp.
[5] Crawford, R., Ward, H. S. (1964). “Determination of the normal periods of building” Bull. Of the Seis. Of Am., Vol. 54, No. 6, pp.1743-1756.
[6] Luco, J. E. Trifunac, M. D., Long, H. L. (1988). “Isolation of Soil-Structure Interaction effects by full-scale forced vibration tests.” Earthquake Engineering and Structural Dynamics, 116(1), 1-21.
[7] Safak, E. (1995). “Detection and identification of soil structure interaction in buildings from vibration recordings.” Journal of Structural Engineering, Vol. 121, No.5; 899-906.
[8] Snieder, R., Safak, E (2006). “Extracting the building Response using seismic interferometry: theory and application to the Millikan Library in Pasadena, California.” Bulletin of the seismological society of America. 96, No.2, 586-598.
[9] Todorovska, M. I. (2009). “Seismic Interferometry of a soil-structure Interaction model with coupled horizontal and rocking response.” Bulletin of the seismological society of America, Vol. 99, No. 2A, 611-625.
[10] Todorovska, M. I. (2009). “Soil-structure identification of Milikan Library north-south response during four earthquakes (1970-2002): what caused the observed wandering of the system frequencies” Bulletin of the seismological society of America, Vol. 99, No.2A, 626-635.
[11] Wolf, J. P. (1994). “Cone Model as a strength-of-materials approach to foundation vibration.” 10th European Conference on Earthquake Engineering, Vienna, Austria, A. A. Balkema, Invited paper, pp. 1-10.
[12] Wolf, J. P. (1985).”Dynamic soil-structure interaction.” Prentice-Hall, Englewood Cliffs, New Jersey.
[13] Ghahari, S. F., Abazarsa, F., Avci, O., Çelebi, M., Taciroglu, E. (2016). “Blind identification of the Millikan Library from earthquake data considering soil-structure interaction.” Journal of Structural Control and Health Monitoring, v 23, n 4, p 684-706.
[14] Chen, Z., Trombetta, N. W., Hutchinson, T. C., Mason, H. B., Bray, J. D., Kutter, B. L. (2013). “Seismic system identification using centrifuge-based soil-structure interaction test data.” Journal of Earthquake Engineering, v 17, n 4, p 469-496.
[15] Wolf, J. P. and Meek W. (1993) “Cone models for a soil layer on a flexible rock half-space.” Earthquake Engineering and Structural Dynamics, v 22, n 3, p 185-193.
[16] Lu Y., Hajirasouliha I., Marshall A. M. (2016) “Performance-based seismic design of flexible-base multi-storey buildings considering soil–structure interaction.” Engineering Structures, Volume 108, Pages 90–103.
[17] Wolf, J. P. and Meek W. (1992). “Cone models for homogenous soil.” ASCE, Journal of Geotechnical Engineering, Vol. 118, No. 5, pp. 667-685.