Chapter 3: Structural types

Apart from overburdened or directly walkable arches or stress-ribbon structures, bridges have always a deck that transfers the load into the supports – piers and abutments (Leonhardt, 1979; Liebenberg, 1992; 1984; Manterola, 2006; Mathivat, 1983; Menn, 1990; Podolny and Muller, 1982; Troyano, 2003). The deck can be supported by bearings situated on the supports, or it can be connected to the supports by a frame or hinge. The deck can be also supported by inclined struts or arches, or can be suspended from arches, stay cables or suspension cables (Figure 3.1).

A deck of typical width (up to 15 m) can be formed by slabs, T-beams or box girders (see Figure 3.5). Depending on the nature of the crossing and the load, all deck types can be part of more complex structural systems. They can be fixed into the outer supports to form frame structures (Figure 3.1(a)), or they can be supported by vertical or inclined supports (Figures 3.1(b) to 3.1(f)). The deck can be supported by bearings (Figures 3.2(a) and 3.3), or it can be a part of an integral structural system in which the deck is connected to the supports by a frame or hinge (Figures 3.2(b) and 3.4). Most concrete bridges are post-tensioned by prestressing tendons located inside the perimeter of the cross-section. The bridges can be also prestressed by external cables situated outside the perimeter of the cross-section, forming more complex structural systems (Figures 3.1(c) and 3.1(k)).