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Lupu Bridge over the Huangpu River in Shanghai is a special feat of engineering, as illustrated by its winning of IABSE’s Outstanding Structure Award in 2008. The main arch structure has a length of 750 m, including a 550-metre main span, making it the second longest steel arch bridge in the world. It also combines cable, suspension, and arch technology in its design and construction, and was the world’s first ultra-large arch bridge using the box-type arch structure.
Unfortunately mageba had not yet established its Shanghai factory at the time of the bridge’s construction – that happened just a few years later. But if it had, and our TENSA®MODULAR expansion joints had been used instead of the ones selected at the time, the installed expansion joints would likely still be only half way through their service life. In fact, very large TENSA®MODULAR joints had already been installed on a number of bridges in China by 2003, such as the Tsing Ma Bridge (25-gap joints), the Ting Kau Bridge (16-gap joints), the 2nd Nanjing Yangtze Bridge (20-gap joints) and the Run Yang – Nan Cha Bridge (27-gap joints), but these had been manufactured in Europe and shipped to China. Had the construction of the Lupu Bridge come just a few years later, perhaps locally fabricated TENSA®MODULAR joints would have been used and the current renovation work would not have been necessary.
The project to replace the bridge’s expansion joints was not a straightforward one due to the structure’s location in the city centre and the huge volumes of traffic it carries every day. This required the replacement work to be carried out at night, and even then traffic flows needed to be maintained at all times so the joints had to be installed in sections, lane by lane. Considering all relevant factors, including the bridge’s current tri-axial movement and rotation requirements – which are better understood now after 18 years of service than they were during the bridge design stage, and potentially reduced due to the diminishing impact of material shrinkage and creep – the decision was made to replace the joints with finger-type joints, large enough to accommodate the longitudinal movements of up to 480 mm. Mageba’s TENSA®FINGER Type GF sliding finger joint was selected for use, and ten of these were supplied, with a total length of 108 m. These joints offer the quietness under traffic that is critically important in such a city environment, and their modular design supports phased installation and makes them the kind of component favoured by modern bridge BIM systems.
On the basis of experience gained in the supply of finger-type joints for an enormous number of bridges around the world over a period of many years, we can have strong confidence in the ability of the newly installed joints, properly maintained, to achieve a service life of forty years or more – thereby saving the effort, expense and traffic disruption that might be associated with a next replacement project if an inferior expansion joint solution was selected.
Bridge designer: Shanghai Municipal Engineering Design Institute (Group) Co., Ltd
Contractor: Shanghai Municipal Maintenance Management Co., Ltd
Owner: China State Shipbuilding Co., Ltd