Seismic Fragility Assessment of Steel SMRF Structures under Various Types of Near and Far Fault Ground Motions

Document Type: Regular Paper


1 civil engineering faculty of Semnan University

2 Civil engineering faculty of Semnan University

3 Civil engineering faculty of Semnan Semnan Civil engineering faculty of Semnan University

4 M.Sc. Student of Earthquake Engineering, Semnan University, Semnan, Iran


In this paper, the seismic collapse probability of special steel moment-resisting frame (SSMRF) structures, designed to 4th edition of Iranian seismic design code, under near fault pulse-like and far fault ordinary ground motions is evaluated through fragility analysis. For this purpose, five sample frames with 3 to 15 stories are designed and imposed to the ground motion excitations with different characteristics. Fragility curves are derived for the sample frames using the results of incremental dynamic analyses. Three sets of near fault ground motion records with different range of pulse period and one set of far fault ordinary records are used in dynamic analyses. Each record set involves ten acceleration time histories on soil type III. Based on the obtained results, it was found that pulse-like motions with medium- and long-period pulses are significantly more destructive than other types of ground motions. Fragility analysis reveals that the average collapse probability for the case study frames under the far and near fault ground motions at the intensity of 0.35g equals to 4.3% and 10.3%, respectively. These values are 15.9%and 38.6%, for PGA of 0.53g. It is also found that the increase in the height, leads to increase in higher modes effect to transfer drift demands toward upper stories.


[1] Shome, N., Cornell, C.A., Bazzurro, P. and Carballo, J.E. (1998). "Earthquakes, records, and nonlinear responses". Earthquake Spectra, Vol. 14, No. 3, pp.469-500.

[2] Khashaee, P., Mohraz, B., Sadek, F., Lew, H.S., Gross, JL, (2003). "Distribution of earthquake input energy in structures". Research report No. NISTIR 6903. National Institute of Standards and Technology, Gaithersburg, USA.

[3] Sehhati, R., Rodriguez-Marek, A., ElGawady, M., William, F. (2011). "Effects of near-fault ground motions and equivalent pulses on multi-story structures". Engineering Structures, Vol. 33, pp. 767–779.

[4] Soleimani Amiri, F., GhodratiAmiri, G., Razeghi, H. (2013). "Estimation of seismic demands of steel frames subjected to near-fault earthquakes having forward directivity and comparing with pushover analysis results". Struct. Design of Tall Spec. Build, Vol. 22, pp. 975–988.

[5] Soltangharaei, V., Razi, M., Vahdani, R. (2016). "Seismic fragility of lateral force resisting systems under near and far-fault ground motions". International journal of structural engineering, Vol. 7, No. 3, pp. 291-303.

[6] Somerville, P. (2005). "Engineering Characterization of near-fault ground motions". NZSEE Conference, Planning and Engineering for Performance in Earthquake, Taupo, New Zealand.

[7] Gerami, M., Abdollahzadeh, D. (2015). "Vulnerability of steel moment-resisting frames under effects of forward directivity". Struct. Design Tall Spec, Vol. 24, pp. 97–122.

[8] Razi, Morteza, Mohsen Gerami, and Reza Vahdani. "Shear Demands of Steel Moment-Resisting Frames Under Near-and Far-Fault Seismic Excitations." Iranian Journal of Science and Technology, Transactions of Civil Engineering, 1-16, 2017.

[9] Gillie, J.M., Rodriguez-Marek, A., McDaniel, C. (2010). "Strength reduction factors for near-fault forward-directivity ground motions". Engineering Structures, Vol. 32, pp. 273–285.

[10] Federal Emergency Management Agency. FEMA.356. "Prestandard and Commentary for the Seismic Rehabilitation of Buildings", Reston, Virginia, USA.

[11] Shahi, S.K. and Baker, J.W. (2014). "An efficient algorithm to identify strong velocity pulses in multi-component ground motions". Bulletin of the Seismological Society of America, Vol. 104, No. 5, pp. 2456–2466.

[12] Kumar, M., Stafford, P.J., Elghazouli, A.Y. (2013). "Seismic shear demands in multi-storey steel frames designed to Eurocode 8". Engineering Structures,Vol. 52, pp. 69–87.

[13] SeismoStruct. 2015. A computer program for static and dynamic analysis for framed structures. Version 7.0.4, Available from

[14] Scott, M.H. smf Fenvese, G.L. (2006). "Plastic hinge integration method for force-based beam-column elements". ASCE Journal of Structural Engineering, Vol. 132, No. 2, pp. 244-252.

[15] Calvi, G.M., Pinho, R., Magenes, G., Bommer, J. (2006). "Development of seismic vulnerability assessment methodologies over the past 30 years". ISET journal of Earthquake Technology, Vo. 43, No. 3, pp. 75–104.

[16] Kim, S.H. and Shinozuka, M. (2004). "Development of fragility curves of bridges retrofittedby column jacketing". Probabilistic Engineering Mechanics, Vol. 19, No. 1, pp. 105–112/ 2004.

[17] Shafei, B., Zareian, F., and Lignos, D.G. (2011). "A simplified method for collapse capacity assessment of moment-resisting frame and shear wall structural systems". Engineering Structures, Vol. 33, No. 4, pp. 1107–1116.

[18] Vamvatsikos, D. and Cornell, C.A. (2002). "Incremental dynamic analysis". Earthquake Engineering &

[19] Ibrahim, Y.E. and El-Shami, M.M. (2011). "Seismic fragility curves for mid-rise reinforced concrete frames in Kingdom of Saudi Arabia". The IES Journal Part A: Civil & Structural Engineering, Vol. 4, No. 4, pp. 213-223.

[20] Eads, L., Miranda, E., Krawinkler, H., Lignos, D. G. (2013). "An efficient method forestimating the collapse risk of structures in seismic regions". Earthquake Engineering& Structural Dynamics", Vol. 42, No. 1, pp. 25–41.

[21] Baker, J.W. (2015). "Efficient analytical fragility function fitting using dynamic structural analysis". Earthquake Spectra, Vol. 31, No. 1, pp. 579-599.

[22] Gerami, Mohsen, and Abbas Sivandi‐Pour. "Performance‐based seismic rehabilitation of existing steel eccentric braced buildings in near fault ground motions." The Structural Design of Tall and Special Buildings 23.12 881-896, 2014.