Date of Award

Spring 1998

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)


Civil, Construction, and Environmental Engineering

First Advisor

Foley, Christopher M.

Second Advisor

Heinrich, Stephen M.

Third Advisor

Vinnakota, Sriramulu


Overstrength and response modification factors are commonly used in seismic codes/specifications to establish lateral loads that simulate earthquake loading. Overstrength of partially-restrained non-composite steel frames has not been thoroughly studied within the context of seismic design. Therefore, seismic codes do not contain response modification factors for the design of these frames. Overstrength can be defined as the ratio of the lateral loading corresponding to first significant yield to the ultimate lateral load of a structure. The objective of this research is to quantify overstrength factors for several fully- and partially-restrained frames and compare the quantities obtained with those found in the current seismic codes. A series of fully- and partially-restrained steel frames with differing width to height ratios are studied. The design forces and lateral displacement requirements are based on established seismic design provisions. Member design is based on the AISC load and resistance factor design specifications. The partially-restrained frame design uses beam line procedures to determine a linear rotational stiffness for each beam to column connection. The ultimate (collapse) strength of each frame is then determined using inelastic nonlinear analysis. An overstrength factor is recommended for partially-restrained frames. Response modification factors are calculated from the analytical overstrength using several structure ductility magnitudes. Comparisons to existing code provisions are made.



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