Strengthening and Widening of Steel Single Box Girder Bridge in Warsaw

Grota-Roweckiego Bridge is the busiest bridge in Poland with average daily traffic over 185 000 vehicles in 2017. The 646-m long bridge with main spans of 120m was built in 1977-1981. The paper presents the design and realisation of the rebuild done in 2013-2015. Modernisation involved widening of two independent decks with braced cantilevers by total of more than 9m and strengthening the structure by external prestressing. The design included increasing the load capacity of the bridge by using over 100 straight prestressed tendons on each of two superstructures. Special attention was paid to the estimation of the remaining fatigue life of the orthotropic deck. The procedure according to JRC-ECCS recommendations was applied, including fatigue tests of selected parts of the existing deck. The paper also presents technological aspects such as methods of assembling of steel structure, prestressing of the bridge and order of works. Particular attention has been devoted to unexpected behaviour of the structure, that is vibrations of the deck cantilevers near dilatation joints and pot bearing damage during laying of the asphalt pavement.