Nordringbrücke Cottbus
Completion of renovation of three-span prestressed concrete bridge

The renovation work to ensure the ongoing strength and performance of the North Ring Bridge (Nordringbrücke) over the River Spree in the city of Cottbus was successfully completed in November 2021 - two weeks ahead of schedule - and the heavily trafficked inner-city bridge is open to traffic again. The three-span structure was built in the 1980s with its approximately 70m-long prestressed concrete superstructure freely supported on its substructures. The two piers in the river showed numerous cracks that can be attributed to an alkali-silica reaction (ASR). Testing showed that the piers had a high residual strain potential. To address the problem, considering the permanent high moisture levels in this river location, a solution involving encasing each of the piers in stainless steel was proposed. This novel approach represents the first time such steel casings have been used for bridge pier renovation in the state of Brandenburg.

As well as strengthening the piers by resisting any outward bulging, this new “armour” also protects them physically against floating debris and ice. The Inros Lackner team was responsible, among other things, for checking the strength and stability of the bridge structure throughout the construction phase, and for developing a renovation plan that would enable the work to be carried out while the bridge remained open to traffic. The services provided included project planning, structural design (including verification of serviceability while the work was going on) and hydraulic calculations. 

Source: Lausitzer Rundschau