It Isn’t All About Height: Building with a Prefabricated Hybrid Superstructure

Session: Track D: Structural Engineering Award: Part 2 & Innovation Award, Part 1

Dominic LemieuxProject image

Dominic Lemieux
Vice President, North America, Peikko
Philadelphia

The 300 Main Street project in Winnipeg Canada completed in early 2022 is not the tallest building in the world, in North America or even in Canada. It is still tall as a 42-story building at 142 meters. However, what makes this building unique is its true hybrid superstructure approach between steel and concrete that allows a minimal floor-to-floor height, a minimal crew size for construction and the ability to build it during harsh Canadian winters. The lateral stability of this high-rise was ensured by a poured-in-place concrete core and the floors were built using wide flange steel columns and beams on the perimeter and shallow composite beams inside the building to minimize the headroom issues. The design team reported that this decision led to a reduction in the total building height of over 60 feet compared to a conventional steel superstructure.

With a reduction in height, this overall height savings decreases wind loads greatly and the cost of the exterior curtain wall system. Another unusual choice for a building of this height is the use of precast hollow-core slabs which lowered the overall weight of the building and helped reduce the cost of the foundations. The combination of hollow-core slabs and UL rated composite beams eliminated the need for fire-proofing on a significant portion of the structure. The 300 Main Street project shows how different construction methods, while they may reduce the overall height, can provide large benefits in the stability and cost of the building.