The State of Utah undertook a complete historic preservation and base isolation retrofit to their historic capitol. To protect the massive, yet ornate building in an earthquake, the building was strengthened using 256 state-of-the-art seismic isolators placed under the building. VSL supplied and installed a bonded post-tensioning system as part of the seismic isolation of the dome.

One of the main challenges was supporting the structure while the isolators were inserted. Creating an integrated final support system, which in the case of this project was intensified by the 7,000 kip dead load carried by each of the four large piers/footings that support the main dome, was another challenge.

For safety and economy, the designers developed a method of permanently re-supporting the rotunda of the capitol with a unique circumferential post-tensioned concrete load transfer scheme. The plan required temporary support of the existing footings, eliminated the risk of settlement, minimized the need for demolition, and avoided cutting or damaging the existing footing reinforcement.

The rotunda load-transfer and isolation system consisted of large post-tensioned concrete beams and girders that wrap completely around the "stem" of the existing pier footing. At each rotunda footing, the new composite beam section supports the design loads through the use of 16 37-0.6" bonded tendons. These tendons are both vertically and horizontally draped on a skewed plane so that the tendons simultaneously "hug" the existing concrete tower base and balance the high vertical loads.

The high strength and stiffness of the bonded multistrand post-tensioning, produced an innovative, safe and economical load transfer system to protect the historic fabric of the rotunda.