Seismic Analysis and Design for Enhanced Performance of Nonstructural Components in Steel Buildings

Abstract

Large economic losses and downtime due to nonstructural damage in recent earthquakes have highlighted the need for improving the seismic performance of nonstructural components (NSCs). Recognizing this, many studies have focused on evaluating the seismic demands of NSCs supported on structures of various types. However, previous studies considered the supporting structure as a single-degree-of-freedom (SDOF) system or as a simplified multi-DOF frame. More advanced nonlinear modeling techniques able to capture damage-induced deterioration must be considered to arrive at more realistic estimates of the response of various structural system types. In addition, demand estimation methods must be complemented with appropriate design procedures that enable the reduction of seismic losses associated with NSCs. The first main objective of this thesis is to better quantify the seismic demands imposed on acceleration-sensitive components mounted in steel buildings with common lateral force resisting systems, including Special Concentrically Braced Frame (SCBF) and Special Moment Frame (SMF) structures. The second main objective focuses on developing a simplified performance-based design procedure centered on NSC losses. To achieve the first objective, eleven archetypes with varying heights and vibration properties are numerically modeled using state-of-the-art validated methods. Then, the absolute floor acceleration responses are used to generate floor acceleration spectra for various NSC damping and ductility levels. The thesis presents qualitative and quantitative aspects of the NSC demands, as well as practical formulas for relevant design parameters, including the ratio of peak floor acceleration (PFA) to peak ground acceleration (PGA), and the ratio of peak component acceleration (PCA) to PFA. The thesis proceeds with using FEMA P-58 procedures to develop a simplified NSC-loss-based design approach for SCBF structures. This approach is based on NSC loss spectra that allow in-advance selection of the design base shear coefficient so that acceptable exceedance probabilities can be met for multiple loss levels.