Q: What do you do when an owner wants to change the design of an office tower after the 6-story underground parking has been built?
A: Start calculating transfers.
Structural Design Changes Under Pressure
Bentall 5, Vancouver, BC
The Bentall Centre, located in the heart of downtown Vancouver’s business district, is Western Canada's largest office complex. Bentall 5, a class-A office tower, is the latest addition.
When the owners came to RJC for help, they envisioned a 34-story building of striking appearance and efficient design. A building that would offer tenants premium amenities and services.
Due to the uncertain demand for office space at the time, the project was completed in vertical phases. One of the challenges facing our engineers was the six-level underground parking structure underneath the building that had already been constructed. However, when the time came to build the tower, the owner had a new idea for the design.
To match this new tower grid design to the parkade structure, numerous columns had to be transferred. By using two or three overlapping columns, RJC engineers were able to effect the transfers and deliver the client's new vision.
Another requirement of the design was that floor spaces be free of interior columns for maximum flexibility. The resulting large floor plates (some 19,000 sq.ft.) required very long spans. By using a 9" thick post-tensioned flat slab structure to minimize the floor-to-floor height and achieve the required spans, we solved the problem and reduced construction costs.
The vertical phasing meant that the lower 24 levels were built first, with the remaining 10 added on years later – an ingenious way to deal with an uncertain market.
The curved east and west facades of transparent glass with metal mullions and spandrels, provide high-energy efficiency and make for a unique and distinctive addition to the Vancouver skyline.