Veering Towards a Unique Building Structure
September 2020 – by Neb Erakovic
I began my career as an academic at the University of Sarajevo and progressed as an engineer and project manager with major Canadian engineering firms–including Halsall and Yolles. Over the course of my 25+ year career, I’ve been fortunate to cultivate numerous and major market sectors, both locally and internationally, and enjoy delivering complex “first-of-a-kind” structures. One of them being the Veer Towers at CityCentre, on the Las Vegas strip, completed in 2010.
Above: The Veer Towers, situated on Block C of the CityCenter development on the Las Vegas Strip. The design team included both local and Toronto structural engineers.
The Veer Towers are twin high-rise residential buildings that each lean at opposing five-degree angles from the vertical. The leans are the defining architectural characteristic of these 37-storey, 480 feet tall towers and required the sophisticated application of conventionally reinforced concrete to the structural building systems. The towers house a combined total of 670 condominium units, rooftop amenity spaces, and podium lobby spaces.
Challenges
Numerous factors contributed to the leaning effect, demanding the towers to resist veering of its intended geometry. These include:
Overturning effects due to eccentricity of the building mass along the height
Lateral earthquake and wind loads
Differential axial shortening of gravity load carrying structures
Differential foundation settlement
The structural design ensures that the towers remain stable, the leans remain within a controlled range, all building movements within acceptable building code limits, and comparable performance to vertical buildings is achieved at all times.
Left: Veer Towers during construction; Right: Building cross-section
Structural Features
Inclined Lobby Columns
The residential lobbies of both towers are located at the sloping South facades adjacent to the elevated roadway. These 80 ft tall lobbies feature exposed concrete columns that are inclined to follow the leans. Located at the base of the towers the columns have significant axial forces, particularly the West Tower, which has a lobby situated on the down-lean side. To minimize column sizes and enhance slenderness performance due to their height, the composite columns utilized large embedded ‘W’ steel sections encircled with 8% of section with reinforcing bars. Temporary shoring was required to hold the columns in their correct position during construction until the tops of the columns could be tied into the transfer floor level above the podium.
Branch ‘Y’ Shaped Column Transfers