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The specification for the supply of the modular expansion joints required by the New Champlain Bridge in Montreal was particularly demanding in a number of ways
The New Champlain Bridge is currently being constructed in Montreal, Quebec to replace an existing 1962 structure that carries approximately 160,000 vehicles per day across the St. Lawrence River. When completed in the coming months, the bridge will have a length of 3,400 m (11,150 ft), including a cable-stayed structure with a main span of length 240 m (790 ft). The bridge’s design is based on a specified design life of 125 years, and it can be seen in the use of highly durable key components and state-of-the-art technology in the bridge’s construction that the design team has sought to minimize the structure’s life-cycle costs during its long service life. This is illustrated here with respect to the structure’s expansion joints, and we will return to the project in a coming newsletter to report on the structural health monitoring (SHM) system that will optimize bridge inspection and maintenance activities.
It has been established that the total life-cycle costs of a bridge’s expansion joints – including in particular for maintenance and replacement, and impacts such as traffic disruption during replacement works – are typically many times the original supply and installation costs. It is thus very important that adequate attention and expenditure are devoted to the selection of well-designed, high-quality joints. This can be ensured, to a large extent, by evaluating the laboratory testing to which the expansion joint type has been successfully subjected. In the case of the New Champlain Bridge, onerous testing in accordance with Appendix A19 of AASHTO Bridge Construction Specifications was specified, demanding very convincing evidence of an expansion joint’s long-term performance and durability. As required, the selected TENSA® MODULAR expansion joints successfully passed all relevant testing before being selected for use, including:
Opening Movement and Vibration (OMV) testing: This test of long-term opening/closing movements and resistance to traffic-induced vibrations is carried out on a full-scale expansion joint specimen.
Seal Push-out (SPO) testing: This test of long-term seal strength and watertightness is carried out following completion of the OMV test, when the seals are in a somewhat weakened condition.
Fatigue testing: This extensive and very demanding testing of the TENSA® MODULAR expansion joint, carried out at ATLSS Engineering Research Center of Lehigh University, Pennsylvania, was conducted in the “infinite life regime”, with an unprecedented 6,000,000 load cycles applied to each of the fourteen three-beam specimens.
A ROBO®CONTROL structural health monitoring (SHM) system initially based on data from the RESTON®STU devices, enabling STU condition to be checked at any time. The system is also designed to provide immediate notification should pre-defined threshold values be exceeded, enhancing bridge safety and optimising maintenance work
Design and manufacture of the joints, for a design life of at least 30 years and to incorporate a specified seismic performance, is primarily in accordance with CAN/CSA-S6-06 and AASHTO LRFD Bridge Construction Specifications, with welding in accordance with CAN/CSA-W59-13 and galvanizing per ASTM A123 and A153.
Fifteen expansion joints were manufactured by mageba, with up to ten individual movement gaps each, designed for movements of up to 800 mm. Most of the joints have lengths of 16 m or more, which presented a significant challenge for transporting the joints from mageba’s factory in Shanghai to Montreal, considering that the bridge’s design and construction team specified that the joints should be delivered to site in their full length. Although this made transport to site much more challenging, it avoids the need to weld sections together on site, leaving all work on the joints done in factory conditions using the ideal equipment and techniques, and thus maximizing long-term durability.
By specifying and using extensively tested, highly durable expansion joints, and minimizing fabrication/welding work on site, the bridge’s design and construction team is not only helping to minimize the structure’s life-cycle costs and avoid unnecessary disruptions to traffic, but also contributing towards a sustainable, eco-friendly bridge construction and maintenance industry.
Bridge design: SNC-Lavalin, TY Lin International and International Bridge Technologies.
Overall project design, construction, operation, maintenance, etc.: SNC-Lavalin, ACS and Hochtief.
Owner’s Engineer headed by Arup Canada; Independent Engineer services by Stantec and Ramboll.
Seismic testing as carried out per CALTRANS protocols