Comparing seismic performance of using pipe damper in toggle and diagonal braces

Soil type of building site is one the most effective parameters on the buildings seismic behavior. Site effect, which occurs mostly is softer soils fortifies the influence of earthquakes and apply greater seismic forces to the buildings. Therefore, the buildings in soft soils should be designed for greater lateral seismic forces, based on the codes such as Iranian Standard 2800. In the present research, performance of viscous dampers in buildings is investigated in all soil types from very stiff, type I to very soft soil, type IV. The main purpose of this paper is to find where viscous dampers have the most performance regarding different soil types. For this, some building frames having 5, 10 or 15 stories are designed on different soil types. It is assumed that the buildings have steel moment resisting structures. Each building on every soil type is designed twice: with and without viscous dampers, and their seismic behaviors are calculated under some earthquake records and compared. ASCE7-16 is based for designing the buildings having viscous dampers. The assumed buildings were analyzed for earthquake acceleration records of the corresponding soil type, with return period of 475 years, having PGA of 0.35g.. Nonlinear time history analyses of the buildings under 24 far-field records and 10 near-field records show that: regular buildings, without viscous dampers, on softer soils are more vulnerable, and equipping them with viscous dampers is a good method to protect them in earthquakes and decreasing their responses and damages. Viscouse dampers are more effective in buildings on softer soils. In summary, viscous dampers are always effective in decreasing the structural seismic responses and damages, and they are more effective in buildings on soft soils.