Beam Bridge is the simplest bridge in its construction and its cost. It also can be called Girder Bridge as it consists of one girder and it is the main part of it. The beam bridge rests at its ends on supports called abutment, and if the span is tool long to be covered by one girder, then multiple girders are used and supported by piers in the mid of main span or depending on the piers number.Beam Bridge is the first type man invented, in the old times; they used wood logs as bridges to span the rivers. Now the construction materials have been developed, like steel and reinforced concrete. The steel box girder and the concrete one is very efficient in this type of bridges
The forces on the bridge girder is two types, tension at the lower side and compression at the upper side, the weight of the bridge and of the vehicles on it is transferred through the girder to the abutments to the soil. The limitation of this bridge is represented in its length as it can't support large spans because of the deflection effect. The longest girder bridge is "Lake Pontchartrain Causeway" which is located at Louisiana state in the us, its whole length is 38.35 km divided into single spans of length 17 m each
