Optimal Placement of Viscous Dampers for Seismic Building Design

While the use of supplemental damping for improving the seismic performance of buildings has gained acceptance in recent years, there remains a lack of consensus over how dampers should be optimally arranged within a structure. The authors review recent advances in damper placement methodology based on optimisation theory, and present a detailed comparative study of five selected methods: two using simple empirical rules – uniform and stiffness-proportional damping distributions; and three more advanced, iterative methods – the simplified sequential search algorithm (SSSA), Takewaki’s method based on minimising transfer function drifts, and Lavan’s fully-stressed analysis/redesign approach. The comparison of the selected methods is based on the performance enhancement of a ten-story, steel moment-resisting frame. It is shown that even very crude placement techniques can achieve substantial improvements in building performance. The three advanced optimisation methods show the potential to reduce interstory drifts beyond the level that can be achieved using uniform or stiffness-proportional methods, though the influence on floor accelerations is less marked. The optimisation methods studied show broadly comparable performance, so ease of use becomes a significant factor in choosing between them. In this respect, Lavan’s approach offers some advantages over the others.