Damage indices of steel moment-resisting frames equipped with fluid viscous dampers

Abstract

Deformations, accelerations, shear forces, and energy demands are normally utilized to evaluate the performance of steel frames equipped with fluid viscous dampers (FVDs). This study aims to quantify damage indices (DI) and their distributions along the structural height for steel frames (3, 6, 9, and 20 stories) equipped with FVDs. The damage model incorporating both deformation and hysteretic plastic energy is adopted to quantify damage developed in structures. A set of 20 pairs of ground motions is used to perform nonlinear time history analyses. Influences of structural property and FVD features (supplementary damping ratio $${\xi _{add}}$$ and velocity power $$\alpha $$) on DI are investigated. The results show that FVDs with lower α would reduce DI. However, nonlinear FVDs lead to higher DI compared to linear ones when $${\xi _{add}}$$>30%, particularly for 9- and 20-story structures. Nonlinear FVDs ($$\alpha \lt 1$$) are more effective than linear ones in reducing DI during low-intensity earthquakes. The results further demonstrate that the distribution of DI along the structural height is mostly determined by structural properties, FVD characteristics, ground motion intensity, and the type of damage model used.

Keywords

• fluid viscous damper
• damage index
• supplemental damping ratio
• velocity power