Pushover analysis is a nonlinear static analysis method in which a structure is subjected to a monotonically increasing lateral load pattern until a target displacement or collapse is reached. It provides insight into the structure's sequence of yielding, its lateral capacity, and its failure mechanism.
Pushover analysis is a nonlinear static procedure (NSP) used to evaluate the seismic performance of structures. In a pushover analysis, a lateral load pattern β typically proportional to the structure's mass distribution or its first-mode shape β is applied to a nonlinear model of the structure and increased monotonically. The structure is pushed until it reaches a target displacement (representing the demand from a specified earthquake level) or until it becomes unstable (representing collapse). The result is a pushover curve β a plot of base shear versus roof displacement β that captures the structure's global force-displacement behavior, including its initial stiffness, yield point, post-yield stiffness, and ultimate capacity.
Pushover analysis is one of the most widely used tools in performance-based earthquake engineering, and is codified in standards such as ASCE 41, FEMA 356, and ATC-40. Its main strength is that it makes the sequence of damage explicit: the engineer can observe, step by step, which elements yield first, how the load redistributes, and whether the structure develops a ductile global mechanism (e.g., beam hinging in a strong-column weak-beam frame) or a brittle local mechanism (e.g., column shear failure). This information is invaluable for retrofit design, where the goal is often to convert an existing brittle mechanism into a ductile one. The capacity spectrum method and the displacement coefficient method are two common procedures for interpreting the pushover curve and comparing it to the seismic demand.
Pushover analysis has important limitations. It uses a static load pattern, which does not capture the dynamic amplification, higher-mode effects, or the time-varying nature of real seismic loading. It cannot capture the effects of cumulative damage, cyclic degradation, or the sequence of loading and unloading that occurs during an earthquake. For tall or irregular structures, where higher modes contribute significantly, a single pushover analysis may not accurately represent the response, and modal pushover analysis (MPA) β which performs a separate pushover analysis for each significant mode β is often required. Despite these limitations, pushover analysis remains a powerful and practical tool for evaluating the seismic performance of ordinary structures, particularly for retrofit assessment where the goal is to identify weak links and understand failure mechanisms. In Iranian practice, pushover analysis is widely used for seismic assessment and retrofit design of existing buildings, following the requirements of the Iranian code (Standard 360) and international standards. Modern practice increasingly supplements pushover analysis with nonlinear response history analysis (NRHA) for critical structures.