b'18 19PRECAST CONCRETE LEGOTUNED MASS DAMPER ANDMONTREAL SOIL CONDITIONSBLOCKS PREASSEMBLED CONTROL With the Toronto South Detention Centre, we were faced withTOWER SECTIONS Challenging soil conditions have been experienced on the the challenge of a large complex project with an extremelyPremium Outlets retail centre site in Mirabel, Quebec, and the tight time frame for design and construction. Our solution tonew North Simcoe Secondary School for the Simcoe County meet these demands was a precast concrete framed detentionDistrict School Board. building utilizing precast cells, columns, beams and floors. The precast cells act as an integral part of the building structure. The saturated clay and liquefiable soils were consolidated with a Rapid Impact Compaction method (RIC). To facilitate the repetitive nature of cells in a detentionThis method was proposed to avoid deep foundation systems centre we utilized a precast system for the building structure.and achieve significant savings in structural construction costs. The cells were formed as six sided boxes which were inte-grated into the building and became the buildings lateralConsolidation of the soil condition also improved the seismic and gravity bearing structure. The use of precast cells allowedcategorization from Class F to Class D resulting in cost for greater quality control versus cast-in-place concrete orsavings of the project superstructure.masonry cells. This precast solution allowed for the off-siteDue to the logistics of working within the confines of a fully fabrication of components and significantly accelerated theoperational international airport as well as the massive size construction schedule. Precast cells also have the additionaland weight of the steel structure, off-site prefabrication was benefit of requiring minimum ongoing interior and exteriorimportant in the design and construction of the Lester B. maintenance.Pearson Airport Apron Control Tower. The design of the Toronto South Detention Centre, builtStructural framing and position of the columns were designed entirely from prefabricated pieces, including hundreds ofto accommodate 360 degree visibility of all operational sur-precast cells delivered to site complete with windows, wiringfaces. Located above the roof of the terminal building, 2.5 and plumbing, is a first for Canada.metre deep steel girders were used as a transfer structure. The Tuned Mass Dumper (weighing 30 tonnes) was located in the depth of the roof cornice truss to alleviate horizontal vibrations caused by wind. The preassembled two-storey tower sections (weighing 25 tonnes each) were delivered and erected in one day per segment. This project was completed by Zoran Tanasijevic as Project Engineer (with previous employment).STEPHENSON ENGINEERINGCREATIVE SOLUTIONS 02'