Abstract: This research aims to investigate the effects of earthquakes on structural buildings, focusing on understanding the causes of building collapse. The study seeks to identify the specific locations and reasons for the initial failure of building members, which subsequently lead to the collapse of the entire structure. The goal is to mitigate or prevent building collapses during or after earthquakes, thereby minimizing loss of life and property damage. Recent events highlight a significant gap in the application and understanding of earthquake resistant methods in the design, monitoring, and investigation of buildings. This deficiency has resulted in loss of life and property damage, placing a burden on the state for repairs and emergency response efforts. It's crucial to address these shortcomings to ensure better resilience against earthquakes and their associated risks. This report outlines the process of designing a building according to the BS8110 code, followed by the application of a performance-based analysis method. Two types of analyses will be employed: fiber modeling and the Plastic Hinge Approach. Firstly, the Fiber Modeling Method will be utilized for reinforced columns and shear walls. This involves categorizing the materials (concrete or reinforcement) into three levels: Immediate Occupancy (IO), Life Safety (LS), and Collapse Prevention (CP). Sections of columns and walls will be subdivided into smaller parts to study the effects of movement on them. Secondly, the Plastic Hinge Approach will be employed for reinforced beam sections. Beams will be divided into smaller parts based on their geometry, following the guidelines of the ASCE41-17 code, and analyzed accordingly. Subsequently, the entire building will undergo nonlinear analysis using two methods: Push-Over Nonlinear Dynamic Analysis and Nonlinear Time History Analysis. The pushover dynamic analysis entails applying horizontal displacement gradually until collapse is reached. The Nonlinear Time History Analysis involves subjecting the building to simulated seismic events. Finally, a comprehensive review of the results obtained from these two analytical processes will be presented. By analyzing the obtained results, the causes of building collapse during earthquakes will be anticipated, on this research two results obtained from two different analysis are going to be presented, compared and studied as it is shown in chapter 4. When the case