Effect of Degradation on Collapse Margin Ratio of Steel Moment Frames

Document Type : Regular Paper


1 Department of Civil Engineering, Islamic Azad University Shahre Kord branch, Shahre Kord, Iran

2 Department of Civil Engineering, College of Engineering, Roudehen Branch, Islamic Azad University, Roudehen, Iran

3 School of Civil Engineering Iran University of Science & Technology


Although several studies have investigated the effect of degradation on the behavior of structures, inspections on collapse margin ratios are rare in the literature. In this study, the effect of strength and stiffness degradation on collapse capacity of steel moment frames is inquired. The aim is to determine margin of safety against collapse applying a probabilistic approach. To this end, 14 moment frames are designed including 4 long period and 3 short period models with 5 and 8m bay length. These buildings are representative of common office and residential buildings built in cities. Also, they are designed in consonance with ASCE7-05 specifications. In the first stage, effective seismic parameters are calculated using a pushover analysis. In the second stage, collapse performance levels are determined using incremental dynamic analysis by considering seismic excitation uncertainties. Results reveal that the overstrength factor that is recommended by ASCE code is not always conservative. Overall, structures designed with common building codes show acceptable margin of safety against collapse.


Main Subjects

[1] Lignos, D., Krawinkler, H., (2012). ”Sidesway collapse of deterioration structural systems under seismic excitations” The John A. Blume Earthquake Engineering Center. Department of Civil and Environmental Engineering Stanford University.
[2] Jennings, P.C., Husid, R., (1968). “Collapse of yielding structures during earthquakes,” Journal ofEngineering Mechanics, ASCE, Vol. 94, Issue 5, pp 1045-1065.
[3] Takizawa, H., Jennings, P., (1980) “Collapse of a model for ductile reinforced concrete frames under extreme earthquake motions,” Earthquake Engineering and Structural Dynamics, Vol. 8, Issue 2, pp: 117-144.
[4] Bernal, D., (1987). “Amplification factors for inelastic dynamic P-Delta effects in earthquake analysis,” Earthquake Engineering & Structural Dynamics, Vol. 15, Issue 5, pp: 635-651.
[5] Bernal, D., (1992). “Instability of buildings subjected to earthquakes,” Journal of Structural Engineering, ASCE, Vol. 118, Issue 8, pp: 2239-2260.
[6] Bernal, D., (1998). “Instability of buildings during seismic response,” Engineering Structures, Vol. 20, Issue 4-6, pp: 496-502.
[7] Rahnama, M. Krawinkler, H., (1993). “Effect of soft soils and hysteresis models on seismic design spectra,” John A. Blume Earthquake Engineering Research Center Report No. 108, Department of Civil Engineering, Stanford University.
[8] Miranda, E., Akkar, D., (2003). “Dynamic instability of simple structural systems.” Journal of Structural Engineering, ASCE, Vol. 129, Issue 12, pp: 1722–1726.
[9] Song, J., Pincheira, J., (2000). “Spectral displacement demands of stiffness and strength degrading systems,” Earthquake Spectra, Vol. 16, Issue 4, pp: 817-851, 2000.
[10] Ibarra, L.F., Medina, R.A., Krawinkler, H., (2002). “Collapse assessment of deteriorating SDOF systems,” Proceedings of the 12th European Conference on Earthquake Engineering, London, UK, Paper 665, Elsevier Science Ltd., September 9-13.
[11] Ibarra L.F., Medina R.A., Krawinkler H., (2005). “Hysteretic models that incorporate strength and stiffness deterioration,” Earthquake Engineering and Structural Dynamics, Vol. 34, Issue 12, pp: 1489-1511.
[12] Ibarra, L.F., Krawinkler, H., (2005). “Global collapse of frame structures under seismic excitations,” Report No. PEER 2005/06, Pacific Earthquake Engineering Research Center, University of California at Berkeley, Berkeley, California, 2005.
[13] FEMA-P695, (2009). “Quantification of building seismic performance factors,” prepared by the Applied Technology Council (ATC) for the Federal Emergency Management Agency (FEMA), Washington, DC.
[14] ASCE/SEI7–05, (2005), “Minimum Design Loads for Buildings and Other Structures”, American Society of Civil Engineers.
[15] BHRC, (2005), “Iranian code of practice for seismic resistance design of buildings: Standard no. 2800”. 3rd ed. Building and Housing Research Center.
[16] McKenna F, Feneves GL. (2009), “Open system for earthquake engineering simulation (OpenSEES)”, Version 2.1.0, Pacific Earthquake Engineering Research Center.
[17] Vamvasikos, D. and Cornell C.A., (2002). “Aplied Incremental Dynamic Analysis”, 12th European Conference on Earthquake Engineering, London.
[18] Federal Emergency Management Agency; (2000). “Prestandard and Commentary for the Seismic Rehabilitation of Buildings”, FEMA356, Washington, D.C.
[17] Ibarra L.F., Medina R.A., Krawinkler H., (2005), “Hysteretic models that incorporate strength and stiffness deterioration”, Earthquake Engineering and Structural Dynamics, Vol. 34, Issue 12, pp: 1489-1511.
[18] Lignos, D.G., Krawinkler, H., (2011), “Deterioration modeling of steel components in support of collapse prediction of steel moment frames under earthquake loading”, Journal of Structural Engineering, ASCE, Vol. 137, Issue 11, pp: 1291-1302.
[19] Steneker P. and Wiebe L., (2016), “Evaluation of THE contribution of panel zones to the global performance of moment resisting frames under seismic load”, in proc. Canadian Society for Civil Engineering, London, 2016.
[20] Gupta, A., Krawinkler, H., (1999), “Prediction of seismic demands for SMRFs with ductileconnections and elements,” SAC Background Document, Report No. SAC/BD-99/06, SAC Joint Venture, Sacramento, CA.
[21] Vamvatsikos D, Cornell CA., (2002). “Incremental dynamic analysis”, Earthquake Engineering and Structural Dynamics; Vol. 31, Issue 3, pp: 491-514.