This session examines the seismic performance of an existing wall-frame Air Traffic Control (ATC) tower designed using conventional force-based building codes, including linear static and dynamic analyses. ATC towers are critical airport facilities that must remain safe and functional after earthquakes, yet their behavior can be more complex than conventional buildings due to elevated control rooms, varying lateral stiffness, higher-mode effects, and mixed wall-frame systems.

Using a detailed case study, the session shows why Performance-Based Seismic Design (PBSD) with Nonlinear Time-History Analysis (NTHA) is important for severe earthquake evaluation. It highlights how traditional code-based methods may underestimate seismic demands and why advanced nonlinear assessment is needed to better evaluate safety margins, structural vulnerabilities, and post-earthquake functionality.