The first aluminum bridge
The first aluminum bridge deck was installed in the city of Pittsburgh (USA) in 1933 year.
However, the first all-aluminum bridge was built near Massena city in the US state of New York 1946 year. This railroad bridge was originally built as a twin-track steel bridge. V 1946 year long span 30,5 m was replaced by a riveted plate-girder structure of the aluminum alloy 2014. It should be noted, that the railway was not a trunk, and served as a local plant for the smelting of aluminum.
Total North America between 1946 and 1963 year was built 9 bridges, 8 of which still stand.
Aluminum bridges in Europe
In Europe, the first aluminum bridge dates from 1949 year (Sutherland, Great Britain). Yet 35 Bridges have been built between 1949 and 1986 year, most of them - between 1950 and 1970 years.
In the Netherlands, the first aluminum bridge was built in Amsterdam in 1955 year and another one near Anna Paulowna in 1961 year. Moreover, two bridges old flooring was replaced with aluminum, one in Amsterdam 1958 year and one in Rotterdam 1985 year.
1995 - the year of the revival of aluminum bridges
History shows aluminum bridges, that worldwide only a few aluminum bridges were built between 1970 and 1995 years. However, beginning with 1995 in the United States, as well as in Europe and Japan, New initiatives have been taken to develop and promote the construction of aluminum bridges. In Europe, in particular, in Norway and Sweden, It was found near 80 aluminum bridge decks, which replaced the old wooden or concrete floorings.
Advantages of aluminum bridges
causes, which caused increased interest in aluminum bridges, They are as follows.
1) Commercial benefits of using lighter structures, to:
- increase the variable load on the bridge, it is important to update the existing bridges, for example, such, like a bridge near the city of Lyon (France) (figure 2);
- reducing the cost of mechanized (for example, lifting) bridges and bridges with long spans, in which the weight of the structure is the main load;
- expansion of existing bridges by adding lightweight structures;
- simplification of assembly and construction;
- lower transport costs.
2) Benefits in terms of sustainable development:
- minimization of material consumption;
- reducing costs and environmental impact of maintenance operations.
3) Possibility of supplying extruded aluminum profiles with a wide variety of cross-sections, usually up to 600 mm and a width of 400 mm.
4) Significant growth in the understanding of aluminum as a material of construction, which occurred over the past decade.
5) Competitive cost of aluminum structures. With proper design of the initial cost of aluminum constructions can compete with steel, whereas the complete lifecycle analysis usually shows benefit of using aluminum structures due to lower maintenance costs and longer life.
Eurocodes for aluminum bridges
In Europe, the design of aluminum bridges based on the following regulations – Eurocodes:
- Design loads for aluminum bridges:
EN 1991-1-3 (Eurocode 1): Effects on structures, part 1-3: Designs, prone to fatigue stresses.
- Calculation of the static strength of aluminum bridges:
EN 1999-1-1, (Eurocode 9), part 1-1: General design rules.
- Calculation of the fatigue strength of aluminum bridges:
EN 1999-1-3 (Eurocode 9), part 1-3: Designs, prone to fatigue stresses.
aluminum alloys, which are currently used for bridges, 5xxx series alloys are, for example, 5083, and 6xxx, for example, 6061 and 6082. These alloys have sufficient strength, as a static, and fatigue, good weldability and good corrosion resistance.
Important features of aluminum bridges
1) Low modulus of elasticity of aluminum:
- increased deflections,
- increase the risk of vibration and
- tendency to buckling.
2) Fatigue tendency:
- variable loads have high values compared to constant loads;
- the fatigue strength of aluminum is approximately two times lower, than steel.
3) Risk of galvanic corrosion due to direct contact between aluminum and steel.
- Aluminium Bridges – Past, Present and Future /T. Siwowski – Structural Engineering International 4/2006