Response Study of a Tall San Diego, California Building Inferred from the M7.1 July 5, 2019 Ridgecrest, California Earthquake Motions

The shaking of a new 24-story tall building in San Diego, California, was recorded by its seismic monitoring array during the M7.1 Ridgecrest, California earthquake of July 5, 2019. The building is located ~340 km from the epicenter of the event. The building is a special moment framed (SMF) steel structure with reduced beam sections (RBS) and viscous damper systems (DS). Peak accelerations recorded by the array indicate 0.007 g at the basement level and 0.044 g at the roof level. Spectral analyses and system identification methods indicate coupled NS, EW, and torsinal fundamental modes at ~ 0.30 Hz frequency and critical damping percentages < 5%. For the EW and fundamental torsional modes, critical damping percentages are < 2.5%. At the low-level shaking, the computed largest average drift ratio is ~ 0.065%, less than 0.5% of the value considered to be the starting threshold of nonlinear behavior or damage.