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The Thang Long Bridge, built between 1974 and 1985, was the first bridge connecting Hanoi’s city centre across the Red River to the city’s northern suburbs and its international airport, and remained the only one until 2015. So the steel through-truss bridge of length 3.5 kilometres, which carries cars and trucks on its upper deck and trains, motorcycles and bicycles on its lower deck, is critically important to the local population. But when it became necessary to resurface the upper deck due to serious deterioration of the driving surface, it was decided to close this part of the bridge for several months while the work was carried out. With the upper deck closed to traffic, 27,000 m2 of its surface were renovated using ultra-high performance concrete, with a layer of polymer concrete on top.
While resurfacing the bridge, the opportunity was taken to also replace the expansion joints at six locations along its length – a wise decision, considering how the cost of replacing a bridge’s expansion joints are typically only half as high when carried out at the same time as resurfacing work, and considering also the fact that the indirect costs of traffic disruption etc., which are often many times higher than the direct replacement costs, are already covered by the resurfacing work.
To satisfy the project’s needs, mageba supplied six TENSA®MODULAR expansion joints, each with the four individual movement gaps needed to facilitate movements of up to 320 mm. The joints’ designs were carefully tailored to match the design of the existing steel structures, and the gap between them, at each location – a considerably more onerous task than arises where a replacement joint can be concreted into position in a non-steel deck.
The joints each have a total length of approx. 20m but were delivered in two sections to facilitate easier and safer transport to site in 40-foot shipping containers. This required welding together on site using the specialised “Secheron” welding method, and insertion of rubber sealing profiles in the second part installed.
Fortunately, considering especially the steel-to-steel connections of the new joints to the existing superstructure and the need to weld sections of joint together on site, it was possible – in spite of Covid – to have a mageba-trained installation team on site via local agent Vinh Hung, with technical support from mageba as required. Thanks to this and also the well-proven durability of the TENSA®MODULAR expansion joint, which has been verified in stringent laboratory testing (including fatigue testing and seismic testing) and in real-life applications on thousands of bridges around the world, the bridge’s owner can be confident that the bridge’s new expansion joints will still be performing excellently the next time the bridge needs to be resurfaced.
This is by no means the first major bridge in Vietnam to be equipped with mageba expansion joints (or other products). Much larger TENSA®MODULAR joints with at least 10 gaps each (for maximum movements of 800 mm or more) had already been installed on the Rach Mieu Bridge (in 2007), the Can Tho Bridge (in 2009) and the Bach Dang Bridge (in 2017). And the spectacularly large RESTON®SPHERICAL bearings supplied for the Tran Thi Ly Bridge are always worthy of a special mention, considering the enormous load-bearing capacity of the two bearings that support the bridge’s dramatically sloping pylon – each designed for a load of 250,000 kN (three times the weight of the Eiffel Tower’s steel structure) and also to accommodate significant displacements and rotations.
Contractor for the bridge renovation work: Vinh Hung Trading, Consulting And Construction JSC, in joint venture with Thanh Hung, Thuan An and Phuong Thanh
Owner: Directorate for Roads of Vietnam – Ministry of Transport of Vietnam