Featured image: The Triangle Square in Chicago, Illinois (Courtesy of Google Maps). Project profile provided courtesy of CFSEI. All photos courtesy of McClure, except where indicated.
Triangle Square – a 298-unit residential apartment building – is located in the Bucktown neighborhood, just west of downtown Chicago. The east-facing luxury apartment units have a spectacular view of the skyline from their uncovered terraces.
The structure consists of six stories of cold-formed steel (CFS) framing above a single-story concrete podium. The upper levels are framed with C-stud joists spanning between demising walls with a gypcrete over metal deck floor system. The building is accented by its sloped roof structure that highlights the ingenuity required to create this complex architectural masterpiece.
Dana Hennis (left), P.E., S.E. and CFSEI vice chair presents the first place award to Jesse Barnes of McClure.
McClure, an engineering service firm with of 200 professionals in eleven offices, has been recognized by the Cold-Formed Steel Engineers Institute (CFSEI) with the 2023 CFSEI Design Excellence Award — first place in the competition’s residential/hospitality award category.
Lauren Gutknecht of McClure submitted the Triangle Square project to the CFSEI Awards competition. Jesse Barnes of McClure accepted the award for the firm’s work on the building at the 2023 CFSEI Expo held recently in New Orleans.
The building’s unique geometry with nonorthogonal angles in both horizontal and vertical planes created some difficulties and challenges during design.
Coordination with Design Team Key to Success
As CFS-framed buildings continue to grow taller and larger, more coordination between the engineer for the delegated CFS system and the design team is required. McClure’s role on this project was classified as a specialty engineering service, meaning McClure was involved early in the design process and helped coordinate items with the design team throughout the development of the construction documents.
This figure provides a creative design detail of the oversized rim track capping the floor joists used to maintain the continuous diaphragm.
McClure provided loads to the podium for the engineer of record to use in the superstructure design, helped develop details for structural steel components, and coordinated placement of columns and beams above the podium.
Additionally, McClure provided the embed layout for the CFS strap-braced wall end post attachments and went as far as to provide drag strut connections to embed plates in the CMU walls for transfer of lateral forces from the diaphragms to those walls. They were responsible for making the structural design decisions for nearly everything above the podium level. This included services well beyond those provided by the typical delegated design professional and went further than the typical CFS delegated design would usually require.
A 3D renderings of some of the non-stacking elements in the sloped ends of the building.
3D Software Used for Structural Design
Within the sloped section of the building there is a single staircase that runs essentially continuously from Level 1 to Level 5 along the exterior wall of the building. Since the stairs had to align with floors while maintaining a consistent tread riser stair ratio, several of the landings did not align with any structures below. This required McClure to provide a lot of coordination for non-stacking headers and posts tracking down the building from top to bottom.
This would have been very difficult to achieve without the use of 3D structural design software and BIM modeling software.
This figure represents a typical detail used for the sloped roof joist support condition.
Apart from the global lateral issues created by the sloped geometry, local stability issues were also a concern. Bearing conditions as well as thrust from the sloped roof members had to be carefully considered in the detailing of the connections.
Read more about McClure’s CFS details for Triangle Square in Chicago, Illinois, and see more diagrams of the bridge, here.
Triangle Square
2115 N Elston Avenue
Chicago, IL 60614Completion Date
2021PEOPLE
Owner:
LMC A Lennar CompanyArchitect of Record:
Michael Hanley, AIA, LEED AP BD+C, Lamar Johnson CollaborativeEngineer of Record for Structural Work:
Anthony Wolanski, P.E., WSPCold-Formed Steel Specialty Engineer:
Marcus Himmelberg, P.E., McClureCold-Formed Steel Specialty Contractor:
Sean Flynn, Eisen Group, Steve Klomfar, Denk and Roche
Additional Resources