Seismic fragility of a reinforced concrete structure
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D. Kurmann
Abstract
Structures can be exposed to seismic loading. For structures of major importance, extreme seismic loadings have to be considered. The proof of safety for such loadings requires sophisticated analysis. This paper introduces an analysis method which of course still includes simplifications, but yields to a far more realistic estimation of the seismic load bearing capacity of reinforced concrete structures compared to common methods. It is based on the development of pushover curves and the application of time-histories for the dynamic model to a representative harmonic oscillator. Dynamic parameters of the oscillator, such as modal mass and damping are computed using a soil-structure-interaction analysis. Based on the pushover-curve nonlinear force-deformation-capacities are applied to the oscillator including hysteresis behaviour characteristics. The oscillator is then exposed to time-histories of several earthquakes. Based on this computation the ductility is computed. The ductility can be scaled based upon the scaling of the time-histories. Since both, the uncertainty of the earthquake by using different time-histories and the uncertainty of the structure by using characteristic and mean material values, are considered, the uncertainty of the structure under seismic loading can be explicitly represented by a fragility.
Kurzfassung
Für Bauwerke in Regionen mit hoher Seismizität und hohem Risikopotential besteht der Bedarf einer möglichst realistischen Ermittlung der seismischen Robustheit (Grenztragfestigkeit). Der vorliegende Artikel erläutert die Berechnung einer solchen seismischen Grenztragfestigkeit eines bestehenden Stahlbetontragwerks. Dazu wird relativ aufwendig mittels einer Pushover-Analyse das nichtlineare Kraft-Verformungs-Verhalten der Struktur erfasst. Anschließend wird die daraus ermittelte Kraft-Verformungslinie für einen äquivalenten Einmassenschwinger verwendet. Für die Umwandlung des Systems in einen äquivalenten Einmassenschwinger mit gleichen dynamischen Eigenschaften werden die modalen Parameter mit Hilfe von Boden-Bauwerk-Interaktionsberechnungen bestimmt. Der Einmassenschwinger wird mit verschiedenen Beschleunigungszeitverläufen beaufschlagt. Dabei wird ein plastischer Verformungsbedarf ermittelt. Dieser kann in Abhängigkeit von skalierten Beschleunigungszeitverläufen für die jeweilige Erdbeben-Intensität berechnet werden. Außerdem können die Widerstände mit charakteristischen Werten und Mittelwerten bestimmt werden, so dass unter Berücksichtigung der Streuung der verschiedenen Zeitverläufe eine Gesamtstreuung am Bauwerk bestimmt werden kann. Als Ergebnis wird eine Fragility für seismische Einwirkungen mit ihren Parametern erstellt.
References
1 Proske, D.: Zur Zukunft der Sicherheitskonzepte im Bauwesen. Bautechnik88 (2011) 217–22410.1002/bate.201110022Search in Google Scholar
2 EPRI: Methodology for developing seismic fragilities, prepared by J. R. Benjamin and Associates, Inc and RPK Structural Mechanics Consulting, TR-103959, Project 2722-23, June 1994Search in Google Scholar
3 Zentner, A.; Nadjarian, N.; Humbert & Viallet, E.: Estimation of fragility curves for seismic probabilistic risk assessment by means of numerical experiments. C.-A.Graubner, H.Schmidt & D.Proske (Eds.): 6th International Probabilistic Workshop, 26–27 November 2008, Darmstadt, Germany 2008, Technische Universität Darmstadt, pp. 305–316Search in Google Scholar
4 Cervenka, J.; Cervenka, V.; PuklR & Janda, Z.: Assessment of remaining structural capacity by computer simulation, Tailor Made Concrete Structures-Walraven & Stoelhorst (eds), 2008Taylor & Francis Group, London, ISBN 978-0-415-47535-8, pp 665–671Search in Google Scholar
5 FEMA 356: Prestandard and commentary for the seismic rehabilitation of buildings. Federal emergency management agency, American Society of Civil Engineers, Reston, Virginia, November 2000Search in Google Scholar
6 Meskouris, K.; Hinzen, K.-G.; Butenweg, C.; Mistler, M.: Bauwerke und Erdbeben: Grundlagen-Anwendung-Beispiele, Vieweg + Teubner Verlag; 2. Auflage, 2007Search in Google Scholar
7 Cervenka, J.; Pappanikolaou, V.: Three dimensional combined fracture-plastic material model for concrete, International Journal of Plasticity, Vol. 24, 2008, 12, pp. 2192–222010.1016/j.ijplas.2008.01.004Search in Google Scholar
8 Červenka, J.; Jendele, L.; Červenka, V.: ATENA Program documentation, Cervenka Consulting, www.cervenka.cz, 2010Search in Google Scholar
9 Renault, P.: PEGASOS Refinement Project: New Findings and Challenges from a PSHA for Swiss Nuclear Power Plants. In: Dutta, B. K., Singh, R. K. & Durgaprasad, O. V. (editors), SMIRT 21-International Conference on Structural Mechanics in Reactor Technology, New Delhi, India, 2011Search in Google Scholar
10 APA Consulting: Development of Acceleration Time Histories for the Intermediate PRP Uniform Hazard Spectra, Walnut Creek, 2011Search in Google Scholar
11 Sadegh-Azar, H.; Hartmann, H.-G.: Grundlagen der seismischen Auslegung von Kernkraftwerken und Einfluss der Boden-Bauwerk Wechselwirkung. Bauingenieur (D-A-CH-Mitteilungsblatt), Band 86, März 2011, pp. S3–10Search in Google Scholar
12 Kurmann, D.: Seismic Analysis of Existing Bridges with Detailing Deficiencies, ROSE School Master Thesis, Istituto Universitario di Studi Superiori di Pavia, Università degli Studi di Pavia, February 2009, PaviaSearch in Google Scholar
13 Bimschas, M.; DazioA.: Large Scale Quasi-Static Cyclic Tests of, Proceedings 14th World Conference on Earthquake Engineering, Beijing, China, 2008Search in Google Scholar
14 Carr, A. J.: RUAUMOKO-Volume 2; User Manual for the 2D-Version, Ruaumoko 2D, Department of Civil Engineering, University of Canterbury, Christchurch, New Zealand, 2004Search in Google Scholar
© 2013, Carl Hanser Verlag, München
Articles in the same Issue
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Editorial
- External hazards – new threats to be assessed?
- Technical Contributions/Fachbeiträge
- External hazards – in focus after the Fukushima accident
- Reassessment of external events in view of the Fukushima accident
- On-site power system reliability of a nuclear power plant after the earthquake
- How to construct a seismic risk model?
- Seismic fragility of a reinforced concrete structure
- Probabilistic safety analysis of external floods – method and application
- Frequency of damage by external explosion hazards based on geographical information
- Case studies for evaluating conditional probabilities of external explosions
Articles in the same Issue
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Editorial
- External hazards – new threats to be assessed?
- Technical Contributions/Fachbeiträge
- External hazards – in focus after the Fukushima accident
- Reassessment of external events in view of the Fukushima accident
- On-site power system reliability of a nuclear power plant after the earthquake
- How to construct a seismic risk model?
- Seismic fragility of a reinforced concrete structure
- Probabilistic safety analysis of external floods – method and application
- Frequency of damage by external explosion hazards based on geographical information
- Case studies for evaluating conditional probabilities of external explosions
