Earthquakes have led to extensive loss of human life, destruction of the built environment, displacement of residents from their homes, and high economic costs in many parts of the world. These impacts largely stem from building collapse and damage, and reinforced concrete (RC) structures are a significant contributor. The behavior of RC buildings in earthquakes is highly uncertain, particularly when a building has been damaged or built informally. The goal of this research is to develop improved assessment techniques of RC buildings that increase the understanding of the seismic performance of RC structures in order to improve community outcomes in major earthquakes. This dissertation is a compilation of two studies that each present a new methodology for assessing seismic performance. In each, the methodology is also exercised for a set of archetype structures. These frameworks employ nonlinear simulation models and computationally efficient analysis methods.

In a post-earthquake environment, repair and demolition decision making play a significant role in community recovery. These decisions are made based on a number of factors, including the future seismic performance of buildings. The connection between the extent of damage---and how best to evaluate damage---and the change in performance is not well understood. Chapter 2 of this dissertation presents a new computationally-efficient framework for evaluating future seismic performance based on damage. This relationship is affected by building characteristics: short period buildings are more sensitive to damage and highly ductile buildings are capable of withstanding higher levels of damage. The framework and the findings in this study can be used in conjunction with component-level assessments and visual inspection to guide post-earthquake decision making about repair and demolition.

Informally-constructed houses have had devastating consequences in recent earthquakes. Informally constructed homes are those that are built without explicit engineering design or code-compliance, and may be built with low-quality materials. Despite the ubiquity of this type of construction, few seismic performance assessments have been conducted. Chapter 3 presents a methodology for evaluating the collapse risk of informally-built RC houses. This framework is exercised for houses in Puerto Rico, where informal construction is prevalent. This work revealed which building components and characteristics are most critical for seismic safety. Open-ground-story houses are most vulnerable to collapse, but can be improved through improved column detailing or retrofit. One-story houses are generally safer than two-story houses, heavier buildings generate larger seismic forces on building components. Confined masonry construction is safer than infilled masonry. These findings are used to provide recommendations for homeowners, builders, and local organizations that will improve seismic safety. The methods outlined in this study can be applied more broadly to areas where informal construction is common and seismic hazard is high.