The principle of the integral bridge has long been known, and used by the Romans. Since then and until the mid-1920s, integral bridges were constructed as arch bridges.
According to Mourad and Tabsh (1999), the use of this kind of structure in the modern era was first considered after analyzing the successful performance of old bridges without joints. Hence, and because conventional bridges suffer from the use of joints and connections, jointless bridges have recently been built in several countries (Mourad & Tabsh, 1999). In 1940, a brief 10-page paper written by Professor Hardy Cross, entitled
Analysis of continuous frames by distributing fixed end moments, led to the widespread
application of framed structures, although it initially The provoked serious discussion among academics Cross had described a simple and quick method for the analysis of a continuous frame or beam structure, and this method has since been widely used by bridge engineers, in what amounts to a revolution in bridge design and construction. Previously, many multiple span bridges were built as a series of simple statically determinate spans. Since the 19th century, engineers have used expansion joints in bridge design as stone, the traditional construction material, was replaced by steel and concrete. Expansion joints and bearings separate the superstructure from the substructure and allow their relative displacement. However, the lifespan of expansion joints and bearings is significantly lower than the lifespan of the structure itself. Hence, the bearings and expansion joints are often thought of as a problem because of their maintenance and cost. The effort to eliminate maintenance and operating costs led back to a structure which no longer used expansion joints and bearings, the integral bridge. Because the superstructure and substructure are usually a framed connection, the integral bridge is also termed a frame bridge.
In the USA, there are currently more than 9,000 fully integral bridges and 4,000 semi- integral bridges. The USA started to apply the use of integral abutments tied to the bridge superstructure in 1930. Burke (2009) said that minimization of movable deck joints at
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piers began in the late 1920s. Tennessee, Missouri, Ohio and Kansas are several of the early states which built this type of bridge. In 1990, 11 states had already constructed continuous integral bridges with lengths of up to 300 feet (91 m), while Tennessee and Missouri had even longer bridges. Most reports state that the bridges exhibit a good and effective performance, since they have remained in service for a long time with only simple maintenance and repairs. By 2001, 35 of the 50 states had built integral bridges. Burke also describes how the Tennessee Department of Transportation appears to be leading the way in the construction of continuous bridges. For example, the Long Island Bridge at Kingsport was constructed in 1980 using 29 continuous spans without a single intermediate movable deck joint. The total length of this bridge is some 2,700 ft. (823 m), centre to centre of abutment bearings. Movable deck joints and movable bearings were furnished, but only at the two abutments.
Virginia has reported more than 10 years of satisfactory performance with their more than 25 integral bridges. California, Kansas, Tennessee, Washington and Wyoming have each constructed over 1,000 integral bridges. All have had at least satisfactory experiences. Kansas and Tennessee rate their best experiences as being very good. Arizona discontinued the use of integral bridges because of the expensive repairs to all the approaches of their more than 50 integral bridges. Alaska also had problems with integral bridges, as frozen soil adhered to integral back walls and caused hairline cracking.
Several Canadian provinces have embraced integral bridge construction. Alberta, Quebec, Nova Scotia and Ontario have jointless bridges, and most have reported from good to satisfactory experiences with their use. Nova Scotia built its first integral bridge in 1986, and Quebec in 1988. Ontario limited its integral bridge span to less than 325 feet (100 m) and a 20-degree skew angle. Ontario’s recommendations for their integral bridges are typical of those adhered to by many US states.
Like the USA, the UK applied this bridge concept at the beginning of its development, and integral bridges have become increasingly popular over recent years. Furthermore, because of the great success in its application, the UK now recommends that any new bridge less than 60 m in length should be constructed as an integral bridge. Overall cost efficiencies and longer life expectancy of integral bridges compared with jointed bridges are the main reason for this recommendation.
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A graph presented by Iles in his 2006 paper and reproduced in Figure II-10 describes the trend for bridge construction in the UK using steel material pre-2000 to 2004.
Figure II-10: Trends of bridge construction in steel material from before 2000 to 2004 in the UK (Iles, 2006)
Figure II-10 also shows that the construction of conventional bridges (non-integral bridges) has decreased since 2002, replaced by integral bridges, fully and semi-integral. The blue line illustrates the proportion of integral bridges, and it is clear that their proportion increased significantly during this period, accounting for about half of the total bridge construction by 2004.
According to a European survey carried out in 2007, only Britain, Finland, Ireland and Sweden were building semi-integral bridges. Although they did not respond to the survey, Norway is reported to be employing semi-integral bridges, but not fully integral bridges. Flener (2004) wrote that in Sweden, integral bridge construction had been in use for over 70 years. He stated that integral bridges are the most common bridge types, representing 8,000 of the 14,000 Swedish Road Administration-owned bridges. Germany also reports the construction of integral bridges throughout the country.
White (2007) believed that the European experience with integral abutments was significantly less, but that the experience gained to date had been positive. Consequently, integral bridges will form a larger proportion of planned and newly constructed bridges across Europe.
The typical Australian practice for most medium to short span bridges is to minimize the use of expansion joints generally by adopting link slabs over piers for simply supported spans. The Australian Bridge Design Code contains no particular reference to integral
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abutment bridges or jointless bridge decks (Connal, 2005). Designers must refer to the general design requirements contained in the code and to relevant specialized literature. In Japan, integral bridges have not been as popular as in the United States, Canada or the United Kingdom. Nevertheless, construction of this type of bridge has started to increase rapidly, because of cost efficiency and ease of maintenance. The first integral bridge, the Naibekoshinai River Bridge, which is 110 m in length, was built in 1996. South Korea started to apply this type of construction in 2002.
To summarize, different countries have different reasons for adopting integral bridges, ranging from earthquake resistance to an urgent need to reduce the cost of maintenance and inspection, even when increased resistance to sudden loads has to be taken into account.