Vibration Testing at Meazza Stadium: Reliability of Operational Modal Analysis to Health Monitoring Purposes
This article has a reply.
VIEW THE REPLYPublication: Journal of Performance of Constructed Facilities
Volume 22, Issue 4
Abstract
In the last years an increasing interest has been devoted to all the topics related to the security and safety of people. Particular attention has been paid to health monitoring of large civil structures hosting many people, such as high-rise buildings and stadiums. Some extraordinary events, such as the Millennium Bridge oscillations in London, excited by pedestrians, or the Bruce Springsteen concert at the Ullevi Stadium in which coordinated jumps from the crowd caused serious damage to the structure, and drew attention toward a deeper and more careful study of all those problems related to the dynamic behavior of civil structures and their interaction with crowds. Research on these topics is also aimed, among others, at developing techniques allowing for a continuous monitoring of the structure, starting from a set of measurements that can be performed continuously, a day, without the need to stop the structure's functionality. The vast scientific literature confirms the possibility of relating structural health to the evolution of modal parameters, often reaching the aim of localizing any eventual damage, a task otherwise impossible with different techniques. This paper shows part of a long lasting project involving Politecnico di Milano in the setting up of a permanent health monitoring system at the G. Meazza Stadium in Milan. The aim of this project was the evaluation of the actual health state of the structures constituting the stands of the stadium and the deployment of a permanent monitoring system to record the vibration levels reached in all substructures during each event. Evaluation of the actual structure condition was performed by the use of ambient vibration, which was also checked against traditional experimental modal analysis, performed by using an inertial force given by a hydraulic actuator and a detailed measurement mesh. This offered the chance to exploit all possible information concerning natural frequencies, modal shapes, and damping factors. This task is extremely time consuming and expensive, therefore, it cannot be repeated very often. The possibility of using the data coming from the permanent monitoring system, which is about to be installed, is then an attractive perspective to improve structural diagnosis. It is expected that using operational modal analysis techniques will mean knowledge of the excitation applied to the structure will not be required. The parameter estimation obtained by this technique is usually affected by a spread, given both by the uncertainty of the adopted identification techniques and the influence of external parameters, such as crowd loading or temperature. As damage identification is related to changes of the modal parameters, the evaluation of their normal spread is fundamental to fix a threshold in order to identify possible worrysome situations. This paper deals with the identification of the spread in the modal parameter estimation of one of the grandstands of the so-called ring of the G. Meazza Stadium in Milan, performed analyzing data collected over more than one year. Vibration data have been recorded during different events, such as soccer matches and concerts. The considered data came from a set of sensors similar to that which is to be installed for the permanent monitoring system, to check about the possibility to use the monitoring system as a diagnostic tool for the structure. A study was also carried out to identify critical aspects in the sensors’ choice and their placement, in order to provide useful information about the design of the permanent monitoring system. The presented results can be used to determine confidence intervals out of which changes in the modal properties can be considered anomalous, and so, worthy of being deeply investigated to assess structural integrity.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The writers gratefully acknowledge the Municipality of Milan for the funding received for this research and Professor Giulio Ballio and Professor Giorgio Diana for their precious opinions in the development of the present work.
References
Agu, E., and Kaspersky, M. (2005). “A random load model for loads induced by coordinated movements of crowds.” Proc., Eurodyn, Parigi, France.
Brownjohn, J. M. W., Hao, H., and Pan, T. C. (2001). “Assessment of structural condition of bridges by dynamic measurements.” Applied Research ProjectRG 5/97, School of Civil and Structural Engineering, Nanyang Technological Univ., Singapore.
Caprioli, A., Castellani, A., Cigada, A., and Vanali, M. (2005). “Vibration monitoring of the G. Meazza Stadium during concerts and soccer matches.” Proc., Int. Modal Analysis Conf., Orlando, Fla.
Caprioli, A., Cigada, A., and Vanali, M. (2006). “Comparison between different operational modal analysis techniques for the identification of large civil structure modal parameters.” Proc., Int. Modal Analysis Conf., St. Louis.
Cigada, A., and Moschioni, G. (2007). “The system for structural measurement diagnosis and surveillance in Meazza Stadium in Milan.” Proc., Int. Modal Analysis Conf., Orlando, Fla.
Cornwell, P. J., Farrar, C. R., Doebling, S. W., and Sohn, H. (1999). “Environmental variability of modal properties.” Exp. Tech., 23(6), 45–48.
De Roeck, G. (2003). “The state-of-the-art of damage detection by vibration monitoring: The SIMCES experience.” J. Struct. Control, 10, 127–134.
Doebling, W., Farrar, C. R., Prime, M. B., and Shevitz, D. W. (1996). “Damage identification and health monitoring of structural and mechanical systems from changes in their vibration characteristics: A literature review.” Technical Rep. LA-13070-MS, Los Alamos National Laboratory, Los Alamos, N.M.
Ewins, D. J. (2001). Modal testing: Theory, practice, and application, 2nd Ed., Taylor and Francis, London.
Farrar, C. R. (1997). “System identification from ambient vibration measurements on a bridge.” J. Sound Vib., 205(1), 1–18.
Farrar, C. R., and Doebling, S. W. (1997). “An overview of modal-based damage identification methods.” Proc., Los Alamos National Laboratory Int. Conf. on Damage Assessment of Structures, Sheffield, U.K.
Farrar, C. R., Doebling, S. W., Cornwell, P. J., and Straser, E. G. (1997). “Variability of modal parameters measured on the Alamosa Canyon Bridge.” Proc., 15th Int. Modal Analysis Conf., Orlando, Fla., 257–263.
Farrar, C. R., Sohn, H., and Doebling, S. W. (2000). “Structural health monitoring at Los Alamos National Laboratory.” Proc., 13th Int. Congress and Exhibition on Condition Monitoring an Diagnostic Engineering Management, Houston.
Huth, O., Feltrin, G., Maeck, J., Kilic, N., and Motavalli, M. (2005). “Damage identification using modal data: Experiences on a prestressed concrete bridge.” J. Struct. Eng., 131(12), 1898–1910.
Kim, J. T., and Stubbs, N. (2002). “Improved damage identification method based on modal information.” J. Sound Vib., 252(2), 223–238.
Maeck, J., Peeters, B., and De Roeck, G. (2001). “Damage identification on the Z24 Bridge using vibration monitoring.” Smart Mater. Struct., 3(3), 512–517.
Mohanty, P., and Rixen, D. J. (2004). “Operational modal analysis in the presence of harmonic excitation.” J. Sound Vib., 270(1-2), 93–109.
Peeters, B. (2001). “Stochastic system identification for operational modal analysis: A review.” J. Dyn. Syst., Meas., Control, 123(4), 659–667.
Peeters, B. (2004). “The PolyMAX frequency-domain method: A new standard for modal parameter estimation?” Shock Vib., 11(3-4), 395–409.
Peeters, B., and De Roeck, G. (2001). “One-year monitoring of the Z24-Bridge: Environmental effects versus damage events.” Earthquake Eng. Struct. Dyn., 30(2), 149–171.
Peeters, B., Vanhollebeke, F., and Van der Auweraer, H. (2005). “Operational PolyMAX for estimating the dynamic properties of a stadium structure during a soccer game.” Proc., Int. Modal Analysis Conf., Orlando, Fla.
Reynolds, P., Pavic, A., and Ibrahim, Z. (2004). “Changes of modal properties of a stadium structure occupied by a crowd.” Proc., Int. Modal Analysis Conf., Orlando, Fla.
Sampaio, R. P. C., Maia, N. M. M., and Silva, J. M. M. (1999). “Damage detection using the frequency–response–function curvature method.” J. Sound Vib., 226(5), 1029–1042.
Sohn, H., Dzwonczyk, M., Straser, E. G., Kiremidjian, A. S., Law, K. H., and Meng, T. (1999). “An experimental study of temperature effect on modal parameters of the Alamosa Canyon Bridge.” Earthquake Eng. Struct. Dyn., 28(8), 879–897.
Strogatz, S. H., Abrams, D. M., McRobie, A., Eckhardt, B., and Ott, E. (2005). “Theoretical mechanics: Crowd synchrony on the Millennium Bridge.” Nature (London), 438(3), 43–44.
Tuan, C. Y. (2004). “Sympathetic vibration due to coordinated crowd jumping.” J. Sound Vib., 269(3-5), 1083–1098.
Yao, S., Wright, J. R., Pavic, A., and Reynolds, P. (2002). “Forces generated when bouncing or jumping on a flexible structure.” Proc., Int. Conf. on Noise and Vibration Engineering, Leuven, Belgium, 563–572.
Information & Authors
Information
Published In
Journal of Performance of Constructed Facilities
Volume 22 • Issue 4 • August 2008
Pages: 228 - 237
Copyright
© 2008 ASCE.
History
Received: Jul 27, 2007
Accepted: Nov 19, 2007
Published online: Aug 1, 2008
Published in print: Aug 2008
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.