This dissertation focuses on developing models for ground motion intensity, to formulate improved design spectra for use in assessing the performance of buildings under earthquakes. Most seismic building codes and design guidelines are based on implicit performance goals that structures should achieve. Despite the significant uncertainty in future ground motion occurrence, building codes commonly check a structure's behavior under a single level of earthquake loading, quantified with a design spectrum. However, this explicit design check is often not defined with respect to the performance goals. The objective of this dissertation is to provide the link between the explicit design check and the implicit performance goals. Models for multivariate distributions of ground motion properties are refined (specifically, spectral accelerations at multiple periods and locations) and tractable methods to utilize those models to assess seismic reliability of systems are developed. Using structural reliability approaches, with environmental contours of spectral accelerations at multiple periods, a justification of the use of multiple conditional mean spectra for design checks is achieved. Performance assessment procedures for the response spectrum method as well as nonlinear response history analysis are proposed based on these conditional mean spectra. Finally, this dissertation provides an original spatial cross-correlation model for spectral accelerations at multiple periods, which allows one to conduct the design checks simultaneously for multiple structures in a region.

Performance-Based Seismic Design (PBSD) is a structural design methodology that has become more common in urban centers around the world, particularly for the design of high-rise buildings. The primary benefit of PBSD is that it substantiates exceptions to prescribed code requirements, such as height limits applied to specific structural systems, and allows project teams to demonstrate higher performance levels for structures during a seismic event.However, the methodology also involves significantly more effort in the analysis and design stages, with verification of building performance required at multiple seismic demand levels using Nonlinear Response History Analysis (NRHA). The design process also requires substantial knowledge of overall building performance and analytical modeling, in order to proportion and detail structural systems to meet specific performance objectives.This CTBUH Technical Guide provides structural engineers, developers, and contractors with a general understanding of the PBSD process by presenting case studies that demonstrate the issues commonly encountered when using the methodology, along with their corresponding solutions. The guide also provides references to the latest industry guidelines, as applied in the western United States, with the goal of disseminating these methods to an international audience for the advancement and expansion of PBSD principles worldwide.

This dissertation is a collection of research studies that address challenges in Performance-based Earthquake Engineering (PBEE) and provides solutions to issues of concern to practicing engineers, researchers, city planners, and the insurance industry alike in implementation of PBEE for building structures. Contributions made within this research are four fold: i) An applied solution is provided to reduce the number of ground motion records required to reliably estimating Intensity Measure-Engineering Demand Parameters (IM-EDP) relationship used for building loss estimation. This solution employs classical linear modal analysis to develop a first estimate (i.e. a priori) of IM-EDP relationships, followed by utilizing Bayesian statistics to update these estimates using a small number of nonlinear response history analyses of a detailed model of the building (i.e., posterior). ii) An applied hazard based Regional Seismic Loss Assessment (RSLA) method for buildings is formulated. In contrast to previous research in this field, the proposed RSLA method utilizes a regional rapid seismic hazard disaggregation tool and is computationally efficient and sufficient. iii) A new seismic design methodology is formulized and presented. A set of preliminary Performance-based Seismic Design (PPBSD) tools are developed for four-story reinforced concrete moment-resisting frame (RC-SMRF) office buildings, located in Los Angeles at 475 year ground motion return period by which stakeholders can make informed decisions with regards to the potential risk they may adopt against future earthquakes. iv) An earthquake loss rating system is provided that maps a building's seismic performance to a rating value/index. This outcome can transfer seismic risk metrics to non-engineers in an effective communicative way.

This dissertation presents a case study seismic analysis for the Pacific Earthquake Engineering Research Center (PEER) Tall Buildings Initiative of three design variations of 40 story buckling restrained brace frames: a code based design and two variations of performance based designs with two primary objectives: (1) to assess emerging performance based procedures and (2) to compare the difference in seismic demands between simulated and recorded ground motions on tall structures. Extensive ground motion suites for a site in downtown Los Angeles and detailed nonlinear models for dynamic analysis are developed to better understand the relation of tall building behavior to design requirements and to assess current performance based design practices for tall buildings. Structural response is seen to be most sensitive to variations in strength parameters, especially at high hazard levels, while damping and inclusion of the vertical ground motion components are not as critical. In terms of maximum drift and acceleration, the performance based designs deliver similar or better performance compared to the code based designs but at a lower initial cost, largely due to the more realistic column axial load demands computed in the design phase. Three comparisons between the seismic demands on tall structures due to simulated ground motions and selected and scaled recorded ground motions are made. The first, between extreme simulated ground motions and high hazard recorded motions, shows that the inelastic demand are significantly larger for the simulated motions. The second, between spectrally matched simulated and recorded hazard level motions, shows that the two motions excite similar behavior in tall buildings but are not quantitatively comparable because of higher mode effects. This is likely due to the ground motion pulse period, Tp, which is smaller and less varied for the simulated ground motions. The Third response comparison is made between simulated and recorded motions for the Northridge event and shows that the drift response is slightly larger for the simulated motions. Peak ground velocity and peak ground displacement are strongly correlated to the structural response. These results may be beneficial to ground motion simulators and tall building designers to validate simulated ground motions for use in seismic design.