The 415 St. Helens Apartments project is a 9-story, market-rate multi-family project at the north edge of downtown Tacoma, Washington. The project is structurally supported with 4 levels of below-grade post-tension concrete and 2 levels of above-grade post-tension concrete. Level 2 is an 18” thick post-tension transfer slab topped with 8 levels of a light gauge pre-fabricated bearing walls system called ISSI (Inter-steel Structures, Inc.). The panels consist of the metal tubular frame with furring attached to both side for GWB attachment. More information may be found here: https://ssfengineers.com/project/issi-modular-frame-building-systems/
We were the structural engineer of record for this project. Additional services included using Tekla to model the 8 levels of prefabricated panels. We then worked closely with Alliance Steel, the fabricator and Proxedge, the steel detailer, to create the required shop drawings of each panel for Osborne Construction, the general contractor. Alliance Steel began fabrication of the prefabricated panels in January 2021. Panels for the first floor of the ISSI system will begin being set into place starting in July 2021. All 8 levels of the ISSI system are due to be installed by February 2022.