Structural Engineering · 2025
Forty-two storeys on a constrained downtown lot
Atlas Development Group
178 m
Height
18%
Concrete saved
H/500
Drift limit
Overview
Structural design of a 42-storey mixed-use tower on a tight urban site flanked by two heritage facades.
The challenge
The site sat above an active transit tunnel, and lateral drift limits were unusually strict to protect two retained heritage facades on the property line.
Our approach
We adopted a reinforced-concrete core coupled to perimeter outriggers at two levels, with a mat foundation designed to bridge the transit box. A performance-based wind study let us trim column sizes without breaching drift limits.
The outcome
The frame topped out on schedule with 18% less structural concrete than the code-prescriptive baseline. Measured inter-storey drift stayed under H/500 in the design wind event.
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