Modified Design Formulas for Structures with Supplemental Viscous Dampers

Modified Design Formulas for Structures with Supplemental Viscous Dampers

Following a previous research(Hwang, J.S. and Yi, SL., 2003), it is the attempt of this study to modify the current design formulas of viscous dampers provided by NEHRP 1997(FEMA273 and FEMA274) and NEHRP 2000(FEMA356, FEMA368 and FEMA369). The dynamic analysis of a model structure is used to investigate the significance of the modified design formulas of viscous dampers. From this study, it is concluded that the proposed design formulas are more rational and accurate compared with the design formulas given in the existing design specifications. Besides, the distribution for the damping coefficients of viscous dampers along the height of building structures is another focus of this study. The distribution formulas for viscous dampers along the height of buildings are derived based on the proportion to(1) the story shear force and(2) the work done by the story shear force. The distribution formulas provide other options to practical engineers for the determination of the viscous damping coefficients of viscous dampers.