Hot-Dip Galvanizing in Bridge Construction

The research project ``Hot-Dip Galvanizing in Steel and Composite Bridge Construction'' has demonstrated, among other findings, that hot-dip galvanizing of bridge structures can achieve a maintenance-free corrosion protection duration of 100 years. To achieve this protective effect, constructive and manufacturing requirements must be considered. The selection of steel grades is determined by the static requirements of the bridge. In addition to corrosion protection design in accordance with DIN EN ISO 12944-3 and DIN EN ISO 14713-1, additional requirements corresponding to the design for hot-dip galvanizing according to DIN EN ISO 14713-2, Annex A, and DASt Guideline 022, as well as manufacturing suitable for hot-dip galvanizing, must be taken into account. Bridge main beams with component lengths over 16–18 meters must be segmented and joined by weldable assembly joints. The location of the weld joints should be chosen considering possible maintenance work. As part of a research project, the Chair of Metal Structures, in collaboration with the Chair of Concrete and Masonry Structures of the Technical University of Munich and the Bundesanstalt für Materialforschung und -prüfung (BAM), developed a new type of galvanization-compatible grouted joint connection using ultra-high performance, fibre-reinforced concrete. In contrast to existing solution as welding the segments on site or using prestressed slip-resistant bolt connections, the hot dip galvanization of the grouted joint remains undamaged for the whole service life time of the bridge structure. This paper aims to explain the constructive and manufacturing requirements for hot-dip galvanized bridge structures. Additionally, examples of existing hot-dip galvanized bridges were summarized.