Re-Fer

Description
Due to insufficient load carrying capacity and excessive deflections, a steel-concrete composite bridge had to be strengthened in flexure. A re-bar R18 reinforcement, which was fixed to the underside of the steel girders, was chosen for the composite construction. The old steel girders were first sandblasted and then treated with a corrosion protection. In such a case, SikaCor^® EG-1 is a suitable protection measure for the existing structure as well as the reinforcement. Afterwards, the Ø18 mm round bar re-bar R18 was end-anchored to the existing steel girders with a mechanical thread/nut anchorage and coupled with sleeves in the free length. The activation/prestressing of re-bar R18 was done with a gas burner. The prestressed re-bars with a total prestressing force of approx. 360 kN per girder were guided in parallel for this object. Posttensioning allowed an uplift of the bridge by 10 mm on average. The span length was about 15 m.

In the run-up to this project, fatigue tests were carried out on the bars and the couplers (M19.5) at Empa Dübendorf (CH) and at ČVUT University in Prague (Czech Republic). Fatigue resistance over 2 million load cycles at a stress amplitude of 50 N/mm² was demonstrated.

re-fer Product
17 girders were strengthened with 4 re-bar R18 each and a total prestressing force of approx. 360 kN per girder.