The structural inadequacies of a large number of wood-frame buildings were demonstrated in both the 1994 Northridge and 1989 Loma Prieta earthquakes, where total failures occurred in some buildings and serious impairments occurred in many others. There was significant loss of life and tremendous loss of property value. An economical approach to upgrading older wood-frame buildings is by installing damper frames that contain viscous dampers. These damper frames fit within the standard height of a wood-framed shear wall. The dampers in the frames significantly reduce wall drift and inter-story shear. In many cases, the installation of damper frames permits an older wood-frame building to meet current code requirements with no modification of the foundation. The damper frames can be designed to provide high levels of protection, allowing a building to withstand a maximum credible event with minimal damage. These damper frames are particularly suitable for soft-story structures. Furthermore, damper frames with viscous dampers are available at a relatively low cost and a simplified analysis technique that meets the requirements of the ASCE 41 standard is under development. Testing was recently completed on three versions of damper frames for application to wood-frame construction. All three versions met the goal of providing significantly increased seismic resistance. This paper describes the three damper frames along with results from both experimental tests and numerical simulations.
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