Main Article Content


The parameters used to generate IBC (International Building Code) compliant design response spectra are specified only approximately for a given site in most cases and values may even be erroneous. S o, the question arises about the effect of approximation or error in the values of these parameters on the predicted internal forces in the structural elements of a building calculated on the basis of the provisions of IBC. This paper explores this issue and presents the sensitivities of design response spectra and maximum moments induced in the structure to these IBC parameters. Within the critical range of short time periods, the variation in peak acceleration of design response spectra for various site classes is found non-uniform. Only peak acceleration is affected by varying SS. Thus, for buildings with the fundamental time period of around 0.6 sec and greater, the parameter SS of IBC is immaterial. Also, for a given site class, the design response spectra are almost identical in the peak acceleration region for all values of S1. The maximum moment is insensitive to SS except for the site class E. This implies that any error in the evaluation of this parameter will not affect the design of the structure.



Structural modeling IBC Multi-story building Response spectrum Moment capacity

Article Details

How to Cite
Nahhas, T. M. (2009). Sensitivity of Predicted Maximum Bending Moment to IBC Design Response Spectrum Parameters. The Journal of Engineering Research [TJER], 6(1), 66–75.


  1. Anagnostopoulos, S., Demopoulos, A., 2003, "Preliminary Assessment of a Simplified Code Method for Earthquake Design Of Asymmetric Buildings", Proc. Concrete Structures in Seismic Regions: FIB 2003 Symposium.
  2. Chopra, A. K., Goel, R. K, 2001, "A Modal Pushover Analysis Procedure for Estimating Seismic Demands for Buildings", Earthquake Engineering & Structural Dynamics, Vol. 31(3), pp. 561 - 582.
  3. Computer & Structures Inc, 2005, "SAP2000 Software Package",, California,USA Engineering Optimization Software, 2007, "PLAN23D User's Manual",, Georgia, USA.
  4. Hooper, J. D., 2006, "General Seismic Design Requirements For Buildings", Proc. 100th Anniversary Earthquake Conference.
  5. International Code Council Inc., 2003, “International Building Code 2003”, Falls Church, Virginia.
  6. International Conference of Building Officials, 1997, "Uniform Building Code", Whittier, California.
  7. Nahhas, T. M., Imam M. H. 2001, "Three-Dimensional Structural Modeling of Multi-Storey Buildings for Obtaining Moment Envelopes", Proceedings of Eighth International Conference on Civil and Structural Engineering Computing.
  8. Wilkinson S, Thambiratnam D., 2001, "Simplified Procedure for Seismic Analysis of Asymmetric Buildings", Computers and Structures, 79:2833-2845