Seismic Upgrade of a Non-Conforming Steel Braced Frame Hospital Building Using Steel Plate Shear Walls and In-line Friction Dampers

摘要

The 6-story building located in the greater Seattle area was designed and constructed in the 1980's using 1979 UBC. The existing braced frames were constructed with various wide flange sections and non-compact double angles. Due to the current and future hospital function improvements, large capital was raised to invest into the current building usable spaces, which trigged this seismic upgrade to protect the current and future investments. Various seismic upgrade options were studied. The option of using steel plate shear walls converted from the existing angle and/or wide flange braced frames in addition to in-line friction dampers installed on the existing wide flange braces offered substantial cost savings due to its ease of construction and minimum disruptions to the hospital's on-going operation. With the implementation of this upgrade, ASCE-41-06 Structural Immediate-Occupancy performance level was achieved under the site specific 10% 50 year seismic event. The majority of the construction for the upgrade was completed in later March of 2011. The remaining necessary upgrade will be completed in a later date when related spaces are vacated for re-modeling. This paper describes the design implementation and construction of this seismic upgrade.