U CONDOMINIUMS ST. MICHAEL’S COLLEGE

Developer: Pemberton SMC Bay Inc.
Architect: Architects Alliance

This residential complex, composed of three, three storey townhouse blocks, with private elevators, and roof terraces, a forty-six storey west tower, and a fifty-six storey east tower is located at the west side of Bay Street, south of St. Mary Street. The buildings are grouped to enclose a landscaped courtyard, with granite cobble paving, all of which is over five levels of subgrade parking.

The columns of the two towers, and the core walls in each tower, are founded on 2000 mm deep raft footing mats with nine or sixteen additional 1200 mm diameter caissons positioned uniformly below the central cores of each tower, below the tower mat footings. All footings bear on natural undisturbed soil, with a safe bearing capacity of 600 kilopascals,
(ie. 12,528 pounds or 6.26 tons per square foot).

For the most part, the subgrade parking level slabs, P1 through P4, are 200 mm thick reinforced concrete flat slabs, with 150 mm deep drop panels, over the columns. On the P1 level, below the three townhouse blocks, where the slab acts as a transfer slab, to pick up the townhouses’ walls, above, and redirect the loads onto the parking garage columns below, the slab thickness is increased to 500 mm, and the drop panels are replaced with 300 mm deep capitals on the columns below.

The ground floor slab, beyond the high-rise towers, and the townhouse blocks, is a 250 mm thick reinforced concrete flat slab with 150 mm deep drop panels, and 300 mm deep capitals, over the columns.

The superstructure floors in the west tower are 200 mm thick reinforced concrete, one-way reinforced between shear walls, with flat plate reinforcing at the bays in the four corners. The east, taller, tower has similarly reinforced concrete slabs, except that the thicknesses are 225 mm. All of the floor slabs are cast with concrete with a specified twenty-eight days strength of 25 megapascals, except that for the balconies and terraces, the concrete strength at twenty-eight days was specified to be 30 megapascals, and to have 6 to 8 percent of entrained air.

Lateral forces resulting from wind and seismic effects are resisted by the interaction of the reinforced concrete shear walls and the central, reinforced concrete cores. The core in the east tower accommodates five elevators and a scissor stair, and the core in the west tower accommodates four elevators and a scissor stair.

The shear walls in the east tower, above the fourth level, are generally 350 mm thick, up to the forty-third level, where they reduce to a thickness of 300 mm up to the fifty-fifth level. Similarly, in the west tower, the shear walls at the fourth level are generally 350 mm thick, however, from the fifth level up the thirty-fourth level, the thickness is, generally, reduced to 300 mm, and is further reduced, generally, to 250 mm from the thirty-fourth level up to the forty-fifth level.