Quantifying the effects of long-duration earthquake ground motions on the financial losses of steel moment resisting frame buildings of varying design risk category

Abstract

This paper investigates the effect of ground motion duration on risks to life safety and costs associated with low-to-medium-rise reference steel moment resisting frame buildings classified as risk categories II and IV. The ductile steel resisting frame buildings are designed in the downtown area of Seattle, Washington, where long-duration earthquakes are more likely to occur. For this purpose, two sets of spectrally equivalent long- and short-duration ground motions are employed to perform nonlinear dynamic analyses for two-dimensional nonlinear structural models of the steel frame buildings. It is shown that the consideration of the effects of long-duration ground motion significantly increases the collapse risk of the steel frame buildings, by a factor of about 5 on average, in comparison to the short-duration set. The destabilizing P-Delta effects are found to increasingly aggravate the influence of long-duration earthquakes on the risk to life safety of the medium-rise steel frame buildings. For frequently occurring ground motion intensities, reparable damage to nonstructural components holds most of the total expected economic seismic loss in the reference buildings, regardless of the ground motion set and assigned risk category. The influence of ground motion duration on the economic seismic loss in the steel frame buildings starts to become important for strong ground motions associated with design-level earthquakes or higher.