ABSTRACT
The seismic performance of buildings with three types of 3-D moment-resisting framing systems is investigated. The framing systems include (1) two-way framing in which the global system consists of a 3-D beam-column grid and all elements are designed to resist both seismic and gravity loading, (2) separate one-way framing in which the global system comprises individual unidirectional seismic and gravity frames, and (3) uniform one-way framing in which semi-rigid connections or pins are introduced into the two-way framing system such that individual columns resist lateral loads through flexure mainly in one direction. Three-dimensional non-linear dynamic analyses of 3-story buildings under different levels of earthquake loading are used as a basis for evaluating the different framing systems. It is shown that despite the greater strength and stiffness of the two-way framing system, one- and bi-directional loading may cause column yielding and large inter-story drifts. In the separate one-way framing system, gravity frames provide additional seismic resistance once seismic frames have yielded under large displacement demands and thereby greatly enhance earthquake performance of the system. The uniform one-way framing system capitalizes on the strengths and mitigates the weaknesses of the traditional framing systems; numerical data indicate that the relatively efficient uniform one-way framing system exhibits a high-level of seismic performance.
