Date of Award
Master of Science (MS)
Foley, Christopher M.
Heinrich, Stephen M.
ELASTIC AND INELASTIC STABILITY OF TWO-PANEL TIERED CONCENTRICALLY BRACED FRAMES
Michael H. Bloom, B.S.
Marquette University, 2013
Multi-panel, tiered concentrically braced frames are commonly used in the lateral resisting systems of industrial facilities for loads resulting from wind and earthquake. To date, minimal investigation has been performed on the effect of gravity and lateral loads on the local and global (system) stability of these framing systems.
Recent research has evaluated the effects of in-plane and out-of-plane bending moments induced by inelastic brace deformation and transverse notional loads on the stability of columns in a two-panel concentrically braced frame with an x-bracing arrangement. Other recent research efforts have studied the effect that differential tier drifts resulting in weak-axis flexural yielding have on the strong-axis buckling strength of columns in a four-tier concentrically braced frame. A three-dimensional finite element analysis was used to impart varying levels of weak-axis flexural yielding onto various wide flange sections and the strong-axis buckling strength was analyzed. That study, however, consisted of analyzing columns isolated from the rest of the frame.
This research effort utilizes the structural analysis program MASTAN2 to conduct multiple elastic and inelastic critical load analyses and nonlinear inelastic analyses on a two-panel, tiered concentrically braced frame. Multiple lateral loading conditions, frame height, frame slenderness, and column orientation scenarios are considered to determine the effects of these variables on the stability behavior of the frame. The results of this research effort indicate that the ratio of applied lateral load to applied gravity load and the frame aspect ratio have a profound effect on whether frame stability behavior is controlled by local member behavior or global (system) behavior.