Integral Bridge

What is an integral bridge?

Integral bridges are single span or multiple-span bridges with a continuous deck and a movement system composed primarily of abutments supported on flexible piles.

Typical integral bridge is shown below;

In these types of bridges, the road surfaces are continuous from one approach embankment to the other and the abutments are cast integral with the deck. The effect of forces parallel to the bridge longitudinal direction is minimized by designing the abutments and their foundations flexible and less resistant to longitudinal movements of the structure.

Accordingly, the abutments are built shorter to reduce the restraint provided by the backfill soil to the longitudinal movement of the bridge. Only a single row of steel H piles is generally used to provide vertical support to abutments and minor resistance to longitudinal forces.

The connection between the bridge deck and the abutment can be rigid or semi-rigid depending on the detailing of joint reinforcement. Elastomeric bearings are used under each girder at intermediate supports. The reinforced concrete columns at intermediate supports may either be free standing or rigidly connected to a reinforced concrete cap-beam supporting the superstructure. The columns are assumed to be supported either by shallow foundations or deep foundations with two or more rows of piles.