Effect of the Building Damping Model on the Regional Seismic Risk of Tall Buildings

ABSTRACT

The seismic response of lightly damped structures is strongly affected by the level of damping in their modes of vibration. This investigation assesses the influence of the damping model on the estimated seismic response and damage of a portfolio of 97 tall pre‐Northridge steel moment resisting frame buildings located in the Financial District of the city of San Francisco, California, during the 1989 Loma Prieta earthquake, using an advanced probabilistic regional seismic risk framework previously developed by the authors. Building responses and damages were computed using three different damping models, namely the one used in ASCE 7–22 (ASCE), the one recommended in the 2023 Los Angeles Tall Buildings Structural Design Council (LATBSDC), which is also adopted in the Tall Building Initiative (TBi), and the one recently developed by Cruz and Miranda (CM). Results indicate that the CM damping model predicts seismic responses and damages that, on average, fall between those estimated by the ASCE and TBi models. In particular, peak building responses and damages to gypsum partition walls can change by as much as 30% and 75%, respectively, when using the ASCE or TBi damping models with respect to those computed with the CM damping model. However, responses and damages at different building heights, not just where responses and damages are maximum, can change by much more than 30% and 75%, respectively. Moreover, peak responses and damages to gypsum partition walls can change by nearly 50% and more than 400%, respectively, if the ASCE damping model is used instead of the LATBSDC or TBi damping model. Additionally, changes in peak damages to other building components may be significantly larger than those observed for gypsum partition walls due to a change in the building damping model. Large changes in building responses and damages may also lead to significant changes in expected monetary losses. These findings illustrate the significance of the building damping model on regional seismic risk assessment results. They also highlight some of the limitations of the damping models currently used in ASCE and LATBSDC/TBi.