Structural engineering : Pasquin St-Jean & Associés

Three pavilions compose Phase 1 of this hospital complex built in two phases. The first is the 21-storey Diagnostic and Treatment Center (Building D), followed by the 19-storey Ambulatory Center (Building B1) and finally, the 9-storey Logistics Center (Building A). The entire project aims for a LEED Silver Certification. This phase of the project includes more than a 1,000 underground parking stalls, two pedestrian tunnels, a historic façade belonging to a mansion, a church bell tower rebuilt in the new project, and a footbridge located on the 5th level above Sanguinet Street connecting buildings B1 and A.

* The following members from ELEMA had the opportunity to work on this project while employed for the engineering firm Pasquin St-Jean et associés. The function of each member for this particular project is in parentheses: 

• Dominic Miron (Technical Lead)
• Félix Bédard (Seismic Designer)
• Jake Estok (Project Manager Block A + Lead Designer for Blocks D and B)
• Ricardo Segantini (Senior Technician and BIM Manager)
• Martin Houle (Project Coordinator)
• Thomas Labrie (Junior Engineer)

Technical challenges :

• Meticulous re-use of historic buildings with a high degree of public attention. These are:
• Reconstruction of the historic façade of the Garth House originally built in 1871;
• Reconstruction of the Saint-Sauveur church bell tower originally built in 1865;
• Permanent construction joint required in the floor diaphragm at the junction of the D and B1 towers;
• Multiple lateral analyses using linear response spectrum analysis, non-linear pushover analysis, and time-history analysis, taking the staged construction sequencing into account;
• Particular attention to the floor slab flatness was required for Automated Guided Vehicle (AGV) traffic in certain zones of the hospital;
• Perimeter columns of the building were supported on the 610 mm (24 in) wide concrete slurry wall which served as the foundation wall of the building;
• Overall floor diaphragms of the D and B1 towers were tied together without any permanent expansion joints;
• Specialized analyses were required for floor vibration control to ensure the performance of medical equipment and ultramodern operating rooms;
• Post-tensioned transfer beams;
• Challenging construction site logistics in a dense urban environment.

Notable solutions and innovations :

• Maison Garth : Each stone from the masonry façade was dismantled, numbered, and archived during the construction phase and was reassembled on a new back-up structure located inside the atrium of the new hospital;
• Maison Garth : The back-up structure had to be meticulously coordinated with the heritage architect and was supported at the base and at the top of the façade, integrated in the design of the concrete frame of the new building and providing protection against seismic forces.
• Maison Garth : The structural system required for support of the reassembled stone façade included major reinforced concrete transfer beams, allowing the stone walls to be rebuilt directly above the underground parking garage. Precast concrete back-up walls were chosen to support the heritage stone masonry, providing full seismic resistance in the hospital context and allowing a rapid installation without the need for formwork.
• Clocher de l’église Saint-Sauveur : The same procedure employed for the dismantling of the Garth House facade was also used for the stone masonry components of the church bell tower.  The existing spire was a rebuilt model since the original spire had been destroyed by fire in 1923;
• Clocher de l’église Saint-Sauveur : The major difference with the bell tower was that it had to be entirely reconstructed as an independent structure at the exterior of the hospital;
• Clocher de l’église Saint-Sauveur : A mixed system using concrete and structural steel was developed: the lower portion of the bell tower consisted of the outer layer of historic stone attached to a new concrete core, all of which was transferred on a massive concrete slab.  The structural steel frame of the new spire was fabricated off-site and erected in three prefinished sections using two mobile cranes, with a total weight of 100 tonnes;
• Clocher de l’église Saint-Sauveur : The concrete core of the bell tower supports the spire above and provides lateral stability to the hybrid structure, and its design responds to the post-disaster requirements of the NBCC. Using an integrated design method, the exterior shape of the core was developed using BIM in order to match the exact contours of the historic façade, and reinforcing steel zones were hidden in the concrete core walls providing resistance to earthquakes and matching the original form of the buttresses of the bell tower;
• Clocher de l’église Saint-Sauveur : The project architect chose to use the concrete core as a feature, leaving the interior concrete surfaces exposed to view.

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