This study investigates the vertical dynamic response of a 52‐story high‐rise building in downtown Los Angeles using small‐magnitude earthquake data recorded by the Community Seismic Network. While seismic design traditionally emphasizes horizontal ground motion, vertical accelerations can have a significant impact on tall structures, leading to amplification effects and complex wave propagation. Using data‐driven techniques, such as subspace system identification, spectral analysis, and transfer function (TF) estimation, we identify a global vertical mode at approximately 1.86 Hz, along with a potential secondary mode and beating phenomena. Results indicate that vertical‐component motions can influence structural response and design considerations, particularly in buildings with dual lateral systems. Our findings contribute to a deeper understanding of vertical seismic effects on high‐rise buildings, emphasizing the need for a more sophisticated treatment of these effects in earthquake engineering.
Vela et al. (Wed,) studied this question.