Prof Dr. Tariq M. Nahhas, Professor of Structural Engineering, Civil engineering department, College of Engineering and Islamic Architecture, Umm AlQura University. Makkah, Saudi Arabia

Professional Experience at Umm AlQura University:
Professor of Civil Engineering( Structural Engineering)
Chairman of The Review committee- Saudi Building Code: (2017-2018)
Chairman of The Consultative committee- Saudi Building Code: (2015-2018)
Saudi Building Code National Committee- Member: (2001-2018)
Vice President – for women students - Umm Al-Qura University: (2007 –2011)
Dean of College of Engineering and Islamic Architecture- Umm Al-Qura University: (2000 –2006)

Research Interest:Seismic analysis of structures, Modal and Design Response Spectra, Evaluation of Existing using Building Code, Appling Codes, Retrofitting of Reinforced Concrete Beams, Behavior Reinforced Lightweight Concrete Beams.

Speech Title: A comparison of IBC with 1997 UBC for modal response spectrum analysis in standard-occupancy buildings*

Abstract: This paper presents a comparison of the seismic forces generated from the Modal Response Spectrum Analysis (MRSA) by applying the provisions of two building codes, 1997 Uniform Building Code (UBC) and 2000-2009 International Building Code (IBC) to most common ordinary residential buildings of standard-occupancy. Considering IBC as the state of the art benchmark code, the question that is targeted is about the safety of the buildings designed using UBC as compared to those designed using IBC. A sample of four buildings of different layouts and heights was used for this comparison. Each of these buildings was assumed to be located at four different geographical sample locations arbitrarily selected to represent various earthquake zones on the map of USA, and was subjected to code-compliant response spectrum analyses for all sample locations and for five different soil types at each location. Response spectrum analysis was performed using ETABS software package. For all the cases investigated, UBC was found significantly more conservative than IBC. UBC design response spectra have higher spectral accelerations, and as a result the response spectrum analysis gives much higher base shear and moment in the structural members as compared to IBC. The conclusion is that the ordinary office and residential buildings designed using UBC 1997 will be considered overdesigned and therefore such buildings are quite safe even according to IBC provisions.

Keywords: response spectrum analysis; seismic forces; multi-story buildings; seismic design; building codes; IBC; UBC