Elizabeth,
There are a lot of complexities behind answering your question. Others have pointed out reference to ASCE 7-10 chapter 18 which is important. You should be following one of the procedures outlined there or in another similar standard that gives procedures for using dampening devices in buildings.
Occasionally engineers perform time history analysis including modeling the characteristics of the dampers directly. In this case you should get results from the model for peak velocities and reactions for each damper modeled. These would be the forces you need to use for capacity protection of the connections, connecting members, and columns that are part of the damper bay.
It's possible to use modified response spectrum and equivalent lateral force procedures too. In that case you will still need to know something about the size of the damper you are expecting to use, its effective damping properties, and the velocities that would be expected. In this case you might use the manufacturers test data to determine what the peak forces are for their dampers at an expected velocity. You would use these forces for capacity protection of the connections, connecting members, and columns that are part of the damper bay.
In any case, I would suggest not coming up with a method of adjusting the R value randomly unless you have some other support for that method.
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Brett King P.E., M.ASCE
Senior Structural Engineer
GHD Inc.
Lake Oswego OR
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Original Message:
Sent: 10-28-2017 14:33
From: Elizabeth Davalos
Subject: Wall Viscous Dampers
I am modeling a new building in ETABS, and adding Wall Viscous Dampers ir order to control drift My concern is about the design of the elements that holds the dampers, and the other frames that do not have dampers. My thought is to give capacity to the elements receiving the dampers in the elatstic range with the R=1, and the rest of the elements with the R=8 ( for moment frame design).
I would like to hear your recommendation or experiences in this kind of modeling.
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Elizabeth Davalos A.M.ASCE
Constructora Cautin SA de CV
Zapopan
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