The $1.15-billion transformation of Seattle’s iconic KeyArena into the Climate Pledge Arena required keeping its 45-million-lb roof in place during construction and removing and replacing its curtain wall. As a result, the project posed challenges that were as difficult as they were unique, including supporting the roof in place with steel shoring because the excavation undermined its foundations.
The temporary steel, which also had to resist seismic loads and limit roof movement to ¼ in., cost $35 million and weighed 4,400 tons—also complicating the top-down construction.