Civil Engineering Construction and Types of Bridges Assignment - 1

Civil Engineering Construction and Types of Bridges - Assignment Example These are one of the oldest forms of the bridge that were introduced by the Romans. In this method, the total downward weight of the arch bridge is distributed along the arch and the load taken up by abutments kept at the outer end of the bridge. This abutment or a kind of stopper prevents the arch from straightening out and keeps the structure of the bridge intact. The olden day arch bridges were constructed of wedge-shaped stones that were arranged neatly to take the shape of an arch. The Pont du Gard aqueduct built near Nimes in France is an excellent example of an arched construction standing the test of time. (Hill James et al, n.d) The modern-day construction involves the use of concrete in construction. These are also reinforced using steel. These new methods of construction make it possible to construct bridges up to 800 ft spans. (Beniwal Tarun et al, 2007) (iii) Concrete Arch Bridge- In this method precast concrete segments in the form of wedges are arranged in arches that are supported on temporary sections. Sometimes two arches may be used and these are supported in the middle using a vertical support called a spandrel. (Hill James et al, n.d) Beam bridges involve a simple design of a beam that is supported at its ends. The loads that act on the bridges act as reactions at the ends. A single span can usually support a span of 250 ft. Pre-stressed concrete that is adequately reinforced using steel rods are used in construction. The concrete can sustain the compressive loads while the steel can take the tensile loads. (Hill James et al, n.d ) Concrete bridges have the advantage that the raw materials are easily available and skilled labor is not required for laying. Three methods are commonly used for the construction of bridges. (i) Balanced cantilever Method- This method involves the construction of a falsework that supports a counterbalance weight and thus prevents the cantilever from tilting over during  progressive construction.