Table of Contents
In this article, we will discuss wing walls in bridges.
The major aim of wing walls on an abutment is to maintain backfill material behind the abutment wall and decrease carriageway settlement. High lateral earth pressures could outcome from the backfill material being compacted and the soil being contained.
In nature, the retaining walls close to the abutment are known as wing walls. The walls may be distinct from or a portion of the abutment wall. The wing walls, which can be recreated at different angles or at a right angle to the abutment, maintain the soil and fill that supports the roadway and near the embankment. The wing walls are usually built at the exact time as the abutments and from the same materials.
1. Types of Wings Walls
The types of wings walls are as follows:
a. Free Standing Wing Walls
The foundation for free-standing wing walls is independent of the main abutment and is designed as a nominal cantilever retaining wall. In the Us case, it is very possible for the abutment and wing walls to settle and tilt independently (differential settlement).
Therefore, it is essential to carefully plan the construction joints between the two structures in order to both permit and cover the relative movements. The wing walls can be arranged parallel to the abutment wall to adjust the local topography, which drives compacting the backfill easily and eradicates any design issues, regardless of the deck’s skew angle.
As a choice, the wing walls can be formed to follow the path of the over-road and hold both the backfill and the parapet fencing. With this structural configuration, positioning the backfill material will be more difficult, and higher earth pressures will outcome from the restriction against sideways movement. Asa result, building this type of design would be more costly. Rather, wing walls tapered in height and spread out at 45 degrees to the abutment can be utilised.
b. Cantilevered Wing Walls
The usage of horizontally cantilevered wings is another method for making wing walls parallel to the over-road. For lengths, up to 12 m from the abutment, this sort of construction is workable, although care must be employed while planning the intersection of the wing and abutment wall.
Although the building’s base provides that it settles as a single unit, it may be contesting to pack the backfill around the wings. This sort of rigid construction sustains high earth pressures, therefore at the most negligible, “at-rest” earth pressures should be carried into account when bringing out the design.
A 2D structure is made employing this style of abutment and wing wall structure. Although the typical metre-strip assumption is often utilised, it may not be the most suitable foundation for a design.
The existence of the wing walls significantly changes the vertical and horizontal bending movements in the abutment, and if the wings are utilised to their full potential, an overall decrease in steel needs is probable.
Since the wing wall’s self-weight greatly influences the stability and bending moments of the abutment wall, it is necessary to take this into performance. Horizontal stresses on the wing walls are transferred across the abutment wall and into the abutment, corners.
To keep the high torsional moments made by the wing wall loading, the corner splays between the abutments and wing walls can be developed as vertical torsion blocks.
2. Design Consideration of Wing Walls
The following loads must be taken into account in the design of wing walls;
• Earth pressures from the backfill
• Surcharge from live loading or compacting plant
• Hydrostatic Loads from Saturated Sod Conditions
The structural elements of the wall are generally prepared to withstand “at rest” earth pressures (Ko), whereas the stability of the wings wall is generally prepared to withstand “active” earth pressures (Ka). The idea k that initial “at rest” pressures set, the force method and structural elements should be constructed to resist these loads without failing.
However, as the wall shifts either by rotating or sliding-the loads will be decreased to “active” pressure. Therefore, if the wall is built to resist “active” earth pressure, it will stabilise if it moves under “At rest” pressures.
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