2007 Issue

UTAH ENGINEERS COUNCIL JOURNAL 35 need to work on is the misnomer used frequently of making buildings “earthquake proof”. No building will ever be earthquake proof – it will always shake in an earthquake unless someone discovers a way to make an earthquake bypass the building!) Utah structural engineers are at the forefront of developing and implementing new technologies to make our buildings, new and old, safe during an earthquake. The Salt Lake City County Building is regarded as one of the most important structures in Utah. It is also the first existing building in the world to be retrofitted using base isolation. Base isolation works on the premise that the ground can shake back and forth beneath a building without causing the build- ing to move along with the ground. This technology is being used in the seismic retrofit of the Utah State Capitol Building as well. Both these buildings have additional capacity built inside using new structural members and strengthening of existing structural elements in addition to the base isolation system to prevent damage to weaker areas. Other of our more recognizable buildings that have undergone seismic strengthening are the Cathedral of the Madeline, which has new framework installed and walls strengthened and is ready for base isolation work in a future phase; Kingsbury Hall at the Uni- versity of Utah that underwent a shear wall upgrade; The Kennecott Building in downtown Salt Lake City which had new upgrade work done to existing steel moment frames and connections; the Joseph Smith Building (formerly Hotel Utah) which had old unreinforced masonry removed and new concrete shear walls installed and had column loads transferred to temporary supports while old footings were demolished and replaced with larger footings; the Tabernacle on Temple Square has new deep foundations tied to reinforced piers and positive roof to pier connections installed. Other buildings to which people feel strong emotional attach- ment are on our university campuses. Five of the eight original buildings on Presidents Circle at the University of Utah; Gardner Hall, Kingsbury Hall, Cowles Building, Talmage Building, and Emery Building have undergone full seismic retrofits as have Old Main at Utah State University and the Noyes Building at Southern Utah University. Brigham Young University has upgraded several of its buildings including Jesse Knight Humanities Building, the Marriott Center, the Wilkinson Center, and Harris Fine Arts Center. Sometimes it is just not feasible to save an entire building, but the façade is considered irreplaceable to the historic fabric of the community. The ZCMI storefront has long been part of Main Street in downtown Salt Lake. The Promised Valley Playhouse façade was saved by attaching a new concrete moment frame to its interior face and installing new brace frames and reinforced masonry walls for 20 feet of the existing floor plan to keep it intact. Seismic upgrades are not only used on highly recognized build- ings. They are becoming more common as an economically feasible way for building owners to use old buildings for new functions. Building codes often times trigger mandatory seismic upgrades when building use or occupancy changes. One of the most popular changes of occupancy is renovating older warehouse structures into trendy new loft type residences or into new retail or business estab- lishments. Big D Construction turned the old Fuller Paint Building into its new headquarters building. Alexander Lofts, United Electric Building, Salt Lake City Justice Courts, GSBS Architects, all took old buildings that were originally built for very different uses than that of the present owners and renovated them, including seismic structural upgrades, for new occupancy and use. The Buckling Restrained Brace is the latest innovation in the realm of seismic force resisting system design. The technology was developed in Japan and Utah structural engineers are leaders in the nation in the design and implementation of these new structural elements. Buckling Restrained Braces are elements that have a steel core that can yield under both tensile and compressive stress, confined in a grouted tube thus absorbing tremendous amounts of energy in a seismic event without failing. Even after experiencing a maximum considered earthquake, they have the capacity to perform at near original capacity in a subsequent earthquake – something no other seismic lateral force resisting system can do. There are three manufacturers of Buckling Restrained Braces in the world and two of them are based in Utah. These braces are being used equally in new construction as well as retrofit projects of existing buildings. The Bennett Federal Building used these braces to bring the building into compliance with modern code requirements and the University of Utah Marriott Library is using them in its current renovation. The Intermountain Medical Center campus uses Buck- ling Restrained Braces extensively in several of their new buildings under construction. SEAU is proud of the great work our members perform in the field of structural engineering and their significant contribution to the well being of our state communities and beyond. SEAU is proud to be part of the Utah Engineers Council and fully supports UEC’s endeavor to promote the engineering profession as a whole in our great state. SEAU — continued SOCIETY FORUM