Collapse Safety Margin in Iranian Seismic Design Code: Case Studies of RC Frame Structures

Document Type : Technical Note


Urmia University, Urmia


According to the modern seismic design codes, the structural collapse is a catastrophic state which is not acceptable, even under very rare earthquakes. Hence, evaluation of collapse safety margin for structures design based on code requirements is very important. The paper tackles this issue considering RC frame structures designed according to Iranian seismic standard (Standard 2800). Incremental Dynamic Analysis (IDA) is carried out using 22 natural ground motion records. The study includes RC moment resisting frames with 3, 6 and 10 stories considering two types of soil classifications (Type II and III) and two alternatives of ductility levels (intermediate and high), as defined in standard 2800. It is concluded that while all structures on the sites with soil class II demonstrate sufficient margin against collapse, taller structures on soil class III show lower than acceptable collapse margin. It is also noted that the collapse margin is generally reduced with the increased height of the structure.


FEMA (2009) Quantification of Building Seismic Performance Factors. FEMA P-695, prepared by Applied Technology Council for the Federal Emergency Management Agency, Washington, D.C.
May, A. (2011) Assessment of seismic design response factors of concrete wall buildings. Earthquake Engineering and Engineering
Vibrations, 10, 115-127.
Haselton, C.B., Liel, A.B., and Deierlein, G.G. (2010) Example application of the FEMA P695 (ATC-63) methodology for the collapse perfor-
mance evaluation of reinforced concrete special moment frame systems. 9th U.S. National and 10th Canadian Conference on Earthquake Engineering, Toronto, Ontario, Canada.
NIST (2010) Evaluation of the FEMA P-695 Methodology for Quantification of Building Seismic Performance Parameters. NIST GCR
-917-8, Gaithersburg, MD.
Mahmoudi, M. and Ghasem Abdi, M. (2012) Evaluating response modification factors of TADAS frames. Constructional Steel Research,
Gogus, A. and Wallace, J. (2015) Seismic safety evaluation of reinforced concrete walls through FEMA P695 methodology. ASCE J. Structural Engineering, 141(10).
Vamvatsikos, D. and Cornell, C.A. (2002) Incremental dynamic analysis. Earthquake Engineering and Structural Dynamics, 31, 491-514.
FEMA (2011) Quantification of Building Seismic Performance Factors: Component Equivalency Methodology. FEMA P-795, prepared by Applied Technology Council for the Federal Emergency Management Agency, Washington, D.C.
Kircher, C.A. and Heintz, J.A (2008) ATC-63-recommended methodology for quantification of building system performance and response
parameters. 14th World Conference on Earthquake Engineering, Beijing, China.
BHRC (2005) Iranian Code of Practice for Seismic Resistance Design of Buildings. Standard No. 2800, Building and Housing Research Center, 3rd Edition.
American Concrete Institute (2011) Building Code Requirements for Structural Concrete and Commentary (ACI 318-11).
Baker, W., Besjak, C., Sarkisian, M., Lee, P., and Doo, C.S. (2010) Proposed methodology to determine seismic performance factors for steel diagrid framed systems. CTBUH (Council on Tall Buildings and Urban Habitat), 13th U.S. Japan Workshop.
Donovan, L. and Memari, A. (2011) Deter-mination of Seismic Performance Factors for Structural Insulated Panel Shear Walls Based on FEMA P695 Methodology. PHRC Research Series Report No. 110.
FEMA (2004) NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Other Structure. FEMA 450-2/2003 Edition. Federal Emergency Management Agency, (Ed.) Washington, D.C, Part 2: Commentary.
Farahi, M. and Mofid, M. (2013) On the quantification of seismic performance factors of Chevron Knee Bracings in steel structures. Engineering Structures, 46, 155-164.
Zsarnoczay, A. (2013) Influence of plastic mechanism development on the seismic performance of buckling restrained braced frames case study. Conference of Junior Researchers in Civil Engineering.
CSI (2011) SAP2000 v-15.0: Integrated Software for Structural Analysis and Design. Computers and Structures Inc., Berkeley,
California, USA.
Tohidian, M. and Manafpour, A.R. (2014) Investigating the behaviour factor of Iranian Seismic Standard 2800 for RC frames based on FEMA P695 procedure. 10th International Congress on Civil Engineering, University of Tabriz, Tabriz, Iran (in Persian).
ASCE (2007) Seismic Rehabilitation of Existing Buildings. ASCE Standard ASCE/SEI 41-06, American Society of Civil Engineers, Reston, Virginia.
Management and Planning Organization (2007) Instruction for Seismic Rehabilitation of Existing Buildings, Guideline 360. Management and Planning Organization, Office of Deputy for Technical Affairs, Technical Criteria Codification & Earthquake Risk Reduction Affairs Bureau, Iran (in Persian).