Bridge Abutment Types
The abutment of bridge belongs to a support structure. The purpose of abutment is to dispense the weight and attach it to an embankment.
Main Function of Abutment
Bridge abutments attach the deck, or surface of the bridge, to the ground and facilitate supporting its weight both horizontal and vertical directions. On short bridges, one abutment is provided at either end of the bridge and jointed with the embankment, sometimes along with a retaining wall.
Longer bridges comprise of extra abutments which are provided along the length, or extent of the bridge to deliver required support at uniform spaces. They provide support to vertical direction without any retaining wall. The selection of abutment is based on the existing space, geologic features of the bridge site, and existing budget for the project.
Elements of an Abutment
Normally, the abutments are arranged at either end of a bridge along with the components given below :
Bridge Seat: This horizontal shelf provides supports to the bridge deck and is adjacent to or on the top of an abutment. On the embankment, these will retain the end of a span, whereas those provided along a span will give support to minimize expanded stress.
Wing Walls: These are found in abutments which are attached with the embankment. They belong to short retaining walls which can resist corrosion and provide durability.
Also read : SOME VITAL COMPONENTS OF PRE-STRESSED BRIDGE
Backwall: It is contained in embankment abutments, backwalls remain over the seat to arrange a horizontal brace from the bridge deck and minimize corrosion at the connecting point.
Pile: The pile of an abutment can either belong to a vertical wall that joins the seat with the foot or a row of columns to fulfill the same objective. On an embankment, the vertical wall structure produces a retaining wall, whereas mid-span abutments make use of more affordable columns.
Footing: This part of an abutment joins the vertical, load-bearing section of the abutment to the ground and is normally hidden under the soil. It comprises of a horizontal surface, sometimes broader than the bridge, to spread the weight.
Types of Bridge Abutments
The following types of abutments are commonly found :-
Typical Gravity Abutment
The typical gravity abutment is frequently utilized and it comprises of the bridge seat, backwall, footing, and wing walls to retain the bridge deck and at the same time contains a retaining wall for the embankment. Normally, the wing walls are provided parallel to the bridge seat or at a slight, backward angle into the embankment.
This U-abutment is a type of abutment that has dissimilarity with gravity abutment in the angle of the wing walls. These are provided at a perpendicular angle to the bridge seat, expanding around the embankment and far from the bridge.
Spill-through abutments normally support the bridge at intervals through its span. The deck stands on a beam supported with columns or a short wall without any wing walls or a back wall to hold the embankment. Water or roadways can move through the supports. The length of the support structure differs to adjust the distance among the level bridge and the changing terrain underneath.
Pile Bent Abutment
The pile bent abutment stands for a variant on a spill-through abutment that substitutes the wall-like supports with a range of piles, or columns, to retain the support beam.