Date of Award

Spring 1999

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


Fully-restrained connection failures resulting from the 1994 Northridge earthquake caused increased interest in the use of partially-restrained connections in seismic resistant design of steel structures. When a building structure is subjected to ground motion, its base tends to move with the ground on which it is supported while the floor levels move in or out of phase with the ground. The relative motion causes stresses and deformations in the structure. If the building is very stiff, it tends to move in synch with the motion of its base, and the dynamic forces acting on it are nearly proportional (through mass) to the base acceleration. However, if a structure is flexible, large relative motions between the floor masses and the base can occur. ln order to survive seismic excitation, the structure must be sufficiently strong as well as sufficiently ductile. Since stiffness and ductility are opposing goals, it is desirable to devise a structural system that combines these properties in the most effective manner without an increase in cost. The objective of this thesis is to propose a dual system comprised of fully- and partially-restrained moment resisting frames to aid in limiting seismic design forces and dissipating seismic energy. To achieve this, an understanding of seismic design and analysis will be addressed. Furthermore, behavior of elastic and inelastic FR and PR frames will be quantified. Understanding the response of a dual system to seismic loading and the effect of connection yielding on the energy dissipation characteristics of the framework will be sought. An optimum PR frame's strength ratio will also be determined. The overalI goal is to understand the response of a dual FR/PR system to seismic loading and to understand the effect of connection yielding on the energy dissipation characteristics of the system.



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