ABSTRACT
On the Romanian road network many reinforced concrete bridges built between 1950 and 1965 are in use. Some of these bridges have the static scheme of a continuous beam with three spans that have a constant or variable height. They were designed according to the admissible stress method and now must be rehabilitated or strengthened.
The proposal for a bridge to be repaired, rehabilitated or strengthened is made after a technical evaluation. First, the technical condition of the bridge is estimated and then a solution is proposed. In Romania the technical condition of a bridge, expressed by the total value of the technical condition index “Ist”, is classified in 5 different classes, from I, very good, to V, critical.
The strengthening and rehabilitation of the superstructure of a concrete bridge with three spans, with a total length of 81.05 m is presented. The bridge superstructure consists of two reinforced concrete continuous beams with variable sections height. The carriageway is 6.50 m wide with two 1.00 m sidewalks. Severe damages and defects were noticed at the main elements so the resulting technical condition index “Ist” is 31. The technical class of the bridge is IV, which is an unsatisfactory technical condition. The carriageway of the bridge must be 7.80 m wide. For these reasons the strengthening of the superstructure with a concrete over slab was proposed (Fig. 1). New cross sections of the bridge: in field (left) and on the piers (right). https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig355_1.tif"/>
The concrete over slab method has the following advantages:
– increases the sections height, so that the beam might take over the excess of positive bending moments resulting from traffic increase;
– ensures the placement of the reinforcement bars for the negative bending moments in the piers’ area for continuous beams and frames;
– increases the bridges carriageway width;
– allows the construction on half of the structure, permitting traffic on the other side.
