TRANSPORTATION
2020 CANADIAN CONSULTING ENGINEERING AWARDS
• A single mounting system--with a mobile lifting beam, transport carts and lifting equipment—to lift the main span of the cable-stayed bridge without impeding commercial shipping traffic in the St. Lawrence Seaway, a vital economic corridor for Canada. In parallel to the on-site fabrication of the concrete elements, SSLC opted for off-site manufacturing of oversized parts, which were to be transported to the site mostly by road. The deteriorating condition of the old Champlain Bridge and the ring road network, however, led to more restrictive weight limits, forcing the consortium to review its logistics plan, so as not to jeopardize the timely arrival of parts critical to the successful completion of the project. Consequently, SNC-Lavalin revised the plan to deliver more than 10,000 components—mostly of non-conventional sizes and weights—through different modes of transportation, with a mix of seaway, rail and road shipments. The initially planned method of construction for the erection of the main span over the seaway was to lift 15 main span segments from the pylon. A major change was made, however, to accelerate construction and complete the infrastructure in a timely manner: a temporary tower was installed east of the seaway to allow for the erection of segments, in parallel, on either side of it. Vehicular and marine traffic was maintained throughout construction by undertaking various provisions for trade and transit routes for the general population along this key transportation corridor. A concrete vision The consortium used reference designs, three-dimensional (3-D) visualization and animation in collaboration with an architectural review committee to ensure it could deliver a project as envisaged by the federal 18
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Temporary jetties were built to help maximize on-site prefabrication and assembly.
government. It was important for this client that the design be consistent with the general principles of the International Federation for Structural Concrete’s fib Bulletin 34 – Model Code for Service Life Design. This bulletin addresses service life design (SLD) for plain, reinforced and pre-stressed concrete structures, with a special focus on design provisions for managing the adverse effects of degradation. SNC-Lavalin’s experience in geotechnical matters helped SSLC achieve this objective. For example, corrosion time for the concrete was modelled using Software for Transport and
Degradation In Unsaturated Materials (STADIUM), which was developed within Quebec. Other measures to ensure concrete quality included the use of thermal probes, infrared (IR) thermography and numerical analysis, all of which helped assess thermal behaviour and, thus, the risk of the concrete cracking. Further, to prevent the danger of ice falling from the cables, the consortium conducted new research and designed a custom sheath for the cables. CERTIFIED
CERTIFIED PLANT Ensuring sustainability CERTIFIED PLANT PLANT Working in partnership with Infra-
October/November 2020
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