( Utility infrastructure is often hung below the deck.)ĭecks are usually constructed of concrete, steel, wood, or a grating system. Cantilever bridges can span relatively long distances while still appearing light and open.ĭeck: The deck (also known as the roadway or surface) of a bridge is the functional area that allows vehicles and pedestrians to cross highways, valleys, and bodies of water. Larger ones use trusses made from structural steel or box girders built from pre-stressed concrete. They are the key components of cantilever bridges. Some types of bridge bearings allow back-and-forth motion, while others can accommodate twisting.Ĭantilever: Cantilevers are structures that project horizontally into space. The types of movement supported include thermal expansion and contraction or seismic shaking. Its purpose is to allow controlled movement between the two surfaces. They’re generally used to move traffic over smaller spans.īent: A bent is a cross-ways structural element used to construct a trestle, a key support element in many bridges.īridge bearing: A bridge bearing provides a resting surface between the piers of a bridge and its deck. Beam bridges are typically the simplest and therefore, least strong and flexible over longer distances. A beam typically responds to forces by bending in reaction to its support points, which are typically the abutments and piers at either end. This gives the structure a greater level of flexibility, allowing it to handle thermal expansion and contraction across greater lengths in more extreme climates.īeam: A beam is a structural component on a bridge that resists loads applied to its axis. A three-hinged arch is not only hinged at its base but also at the middle of the bridge span.A two-hinged arch is generally used on mid-sized bridges because the pinned connection at the base is better able to handle temperature fluctuations.Use of fixed arches is limited because they’re vulnerable to temperature-related expansion and contraction. A fixed arch is most commonly used on shorter, concrete bridges.There are three types of arches: fixed arch, two-hinged arch, and three-hinged arch. To keep an arch bridge standing, the trust is restrained by its abutments. As the height of an arch increases, its outward thrust increases. (This is often referred to as “ arch action.”)Īs the forces within arch bridges are pushed toward the ground, the arch is forced out at its base, which is referred to as thrust. Bridges featuring arches were among the earliest large-scale engineering and construction projects.Īrch bridges can span vast areas because they transform the forces affecting them into compressive stresses, which eliminates tensile stresses. They absorb many of the forces placed on the bridge and act as retaining walls that prevent the earth under the approach to the bridge from moving.Īrch: An arch is a curved structure that spans an open space. That’s why we’ve compiled this glossary of 20 of the most common structural components used on bridges.Ībutment: Abutments are the elements at the ends of a bridge, which provide support for it. It would have helped keep the feet of nomads dry while traveling from one location to another.īridges have gotten much more complicated since then. It was a simple log or boulder placed over a small stream or ravine.
Thousands of years ago, pre-humans built the first bridge. 24, 2017 Bridge Masters Bridge Design, Bridges and Utilities
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