The seismic upgrade of the Wallace F. Bennett Federal Building in Salt Lake City began as a simple repair and alteration task, but later evolved into an elegant exterior replacement and cutting-edge seismic upgrade design project that will proceed while the building is still occupied.

The design includes upgrading the building’s structure to comply with modern standards of seismic resistance. The existing pre-cast exterior concrete panels will be removed and replaced with a new curtain wall system. Additionally, a completely redesigned building entrance and lobby have been added to the project under GSA’s First Impressions program.

The decision to re-skin the building was based on the need to remove the existing pre-cast concrete panels in order to attach the new diagonal seismic bracing to the existing concrete frame. This cross bracing will be added all around the building and set behind the new curtain wall system to read as a shadow line.

The seismic cross bracing uses the latest brace design technology called “ Unbonded Braced Frame (UBF).” The UBF's are dampening members that enhance the structural performance of the building during a major seismic occurrence. Currently there are only a few buildings under construction in the United States that use UBF’s, however, Japan has used this technology for about 15 years. Today, more than two-thirds of the high rise building designs approved by Japanese officials use some form of unbonded brace technology. (Nippon Steel) The Rocky Mountain Region is proud to be the first region to use this progressive technology in a public building.