Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Civil and Environmental Engineering


Dr. Youssef M.A.

Second Advisor

Dr. El Naggar H.E.


Modular Steel Buildings (MSBs) have unconventional detailing requirements, compared to traditional onsite steel buildings. This may affect their design and performance. Currently, traditional design procedures are followed in their design. This thesis evaluates the performance of MSBs under gravity and seismic loads. It documents for the first time a detailed description of this unique steel building system and its detailing requirements and provides the first analytical experimental investigation that aims at improving its design methodology. The effect of directly welded stringer-to-beam connections used in MSBs on behaviour and design of MSBs floors is investigated using the finite element method. The results obtained revealed that this unique connection type affects the design of the floor stringers and welded connections but has little effect on the floor beams. Empirical relations and a simplified model were developed to predict the forces and moments likely to develop in MSB floor stringers. Nonlinear seismic performance and characteristics of braced frames of a typical MSB were studied using cyclic tests, nonlinear static pushover analysis, and incremental dynamic analyses. These studies consist of (i) an experimental investigation of the hysteretic behaviour of a scaled one-bay one-storey MSB braced frame; (ii) the strength and ductility design of braced frames of a typical MSB dormitory; (iii) the development of analytical models of selected braced frames of MSBs accounting for their unique detailing requirements and the hysteresis of steel bracing members; (iv) a study of the effect of design philosophy on the nonlinear behaviour of MSB braced frames using pushover analyses; (v) the evaluation of structural overstrength and displacement ductility of the braced frames using pushover analyses; and (vi) the assessment of seismic inelastic drift and ductility demands and capacities of the braced frames using an incremental dynamic analysis. It is concluded that while the MSB frame configuration may not significantly affect certain design and behavioural characteristics, in some others its unique detailing requirements need to be considered during design to eliminate undesirable seismic response.



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