Kinematic Structural Glass

The structural glass storefront facade at 111 Main Street in Salt Lake City lends itself as a case study in accommodating large building displacements by utilizing a kinematic assembly of facade elements.

The slender building core that supports all 24 hanging stories of the recently completed tower at 111 Main is set back from the perimeter to allow for an expansive and column-free thirty-five foot tall lobby entrance, and consequently results in significant building movements during seismic events. While all hanging floor plates move together uniformly, a monumental challenge was presented where the lowest hung floor (Level 2) interfaces with the entry facade that is base-supported. This critical interface was identified in the design process and the contractor was engaged early to assist with specialist input to achieve an elegant solution.

As the project architect, SOM was able to work through a collaborative design process with the contractor’s engineer of record for the lobby facade system, EOC. Early engagement and open discussions between the design team and contractor allowed for fluid development of a unique but pragmatic system. The team was informed by contributors ranging from designers, architects, engineers, fabricators, and installers, each with specialist knowledge that uniquely informed the final design.

The critical design challenge was to dissect and understand how the building moves during wind storms and seismic events. A study of deflections, rotations, supports, and rigidity was conducted to define a realistic solution that accommodates the imposed building displacements. A kinematic hinge system was developed to accommodate total building vertical movements of nearly 3 feet (91.4 centimeters) with precision linear slide bearings used to absorb lateral building drifts.

Large cantilever structural steel entry portals are designed integrally with the glazed facade system to create feature entrances. Incorporation of architectural timber fins at the entry portals is accomplished with a novel approach to laminate wood veneer into the glass assemblies.

Detailed analysis of global movements, post-failure behavior, gasket and sealant flexibility, are carried out as part of the delegated design requirements to ensure performance through the building’s design life.