When No Perimeter Columns Meet the Ground: 111 South Main, Salt Lake City

摘要

A land ownership agreement of neighboring properties necessitated the insertion of the new Utah Performing Arts Center under the entire southern portion of a proposed 25-story office tower. Based on an air-rights agreement, construction of the tower could exist above the 5-story performing arts center but no permanent support could reach the ground in the area of the facility. With unbalanced loads that would exist in the tower if some columns would reach the ground and the others not, the design team decided to balance all the loads of the tower and have no columns meet the ground. Located in a region of high seismicity, a performance based design of the reinforced concrete core wall and complex foundations define the structural system for the tower. Ductile link beams with high-strength concrete core walls are designed to resist all gravity and lateral loads with a three-dimensional steel roof truss system used to carry suspended perimeter column loads. Six friction pendulum structural bearings are used under the roof truss system to manage lateral and gravity load transfers at the top of the core walls as well as the change in temperature of the steel roof truss system. Advanced non-linear seismic analyses were performed on the structure along with a carefully conceived construction sequence using both permanent and temporary structural systems. The conceptual development of the design and analysis as well as the construction of this complex tower is presented.