This research investigates the reinforcement of orthotropic steel bridge decks (OBD) by adding a second steel plate to the existing deck. The main idea is to stiffen the
existing deck plate which will reduce the stresses at the fatigue sensitive details and extend the fatigue life of the orthotropic bridge deck. Two reinforcement systems are
subject of research, bonded steel plates system and sandwich steel plates system. In the bonded steel plates system, the existing OBD is reinforced by adding the second
steel plate using a thin epoxy adhesive layer (approximately 2 mm thick). In the sandwich steel plates system, the existing deck is reinforced by adding a sandwich
overlay which is composed of a polyurethane core (PU-core, from 15 mm to 30 mm thick) and the second steel plate. Both reinforcements are considered lightweight
solutions (between 50 and 80 kg/m2), which is of special importance for application on movable bridges.
The rules described in Eurocode 3 for bolts in bearing are dependent on end-distance, edge-distance and pitch for 8.8 and 10.9 bolt classes and are allowed to be used in plates of steel grade up to S700. However, these rules are based on test data of steel plates in mild steel and not for high strength steel, 8.8 and 10.9 steel classes in plates of steel grade up to S460. In fact “strong” bolts in “weak” steel plates. Steel grades of S690, S960 and even higher are being used in civil engineering structures more and more. So, in these cases “weak” bolts in “strong” steel plates.
In this study, a series of tests were carried out using specimens designed according to the rules of Eurocode 3 Part 1-8 “Design of Joints”, in order to investigate whether or not those rules are adequate to high strength steels. The experimental programme consisted in ten different types of specimens of one bolt joints made with steel grade S690. The end and edge distance varied. In total, thirty test were performed (three tests per each different type of specimens).
The test results showed that the rules given by Eurocode 3 are conservative using steel grade S690, mainly when edge distance is smaller than 1.5 d0. Therefore, a corrected function for the k1 factor of the bearing resistance formula given by EC3 is proposed based on a statistical evaluation according to Annex D of EN1990: Basis of Design (formerly Annex Z of Eurocode 3: Design of Steel Structures). This correction was made in the k1 factor, since the main differences between experimental values and theoretical values were found in tests specimens with different edge distances. The minimum values for the edge and end distances can also be reduced from 1.2d0 to 1.0d0 in case of steel grade S690. Further investigations are necessary to see if this also holds to mild steels (from S235 to S700) as well.