As a part of a bridge, abutments provide vertical supports to bridge substructures at bridge ends, connect bridges with approach roadways, as well as retain roadway base materials from bridge spans. Although other types of abutments and abutments of important bridges may be pretty complicated, design methods and analysis principles are almost the same. This article will look closely at topics related to design of traditional highway bridge abutments. Unlike bridge abutments, earth-retaining structures are primarily designed to sustain lateral earth pressures.
What are bridge abutments?
These things are substructures that support the terminus of bridge substructures. At the same time, it laterally supports the barrier that serves as the approach to the traverse. For river traverses, this thing also protects embankments from scours of streams. It can be made of reinforced or plain concrete.
Five types of abutments
- Perched or Stub
- Spill-through or Pedestal
- Integral End Bents
This type is a full-height wall with wings on each side that retains the full height of approach embankments. This thing minimizes the needed span length of the structure. But there are significant disadvantages, particularly for embankments on soft or unstable foundations or high embankments.
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It needs to be constructed before adjacent barriers. Proper compaction of backfills and placements are pretty hard in restricted areas between walls and wing walls. If heavy types of machinery are used to compact backfills, walls may be pushed laterally, as well as out of vertical alignment.
The weight of backfills will help with the compression of soft or unstable soils, as well as with the post-construction settlement of abutments and embankments. If the structure is supported on piles, the compression of the ground in the foundation will produce a down drag. It can cause overstress on the banks. This thing needs to be designed for lateral earth pressures applied by whole heights of dams.
Perched or stub
Perched or stub is a pretty short attachment that is constructed after the dam has been completed. The barrier can be compacted without attachment interference, and if needed, the attachment construction can be delayed until the foundation soil compression caused by dam loads is completed.
That is why post-construction settlements may be minimized. That is why post-construction settlements or resolutions may be at least minimized. The connector may be backed on spread footings in the dam, drilled shafts, or piles constructed through the filling.
Lateral earth pressures are pretty small compared to the pressures against full-height closed connectors. But longer bridges may be needed compared to full-height connectors. Stubs also are used on natural grounds in cut slopes. Pile, drilled shaft, or pile foundations may be used.
Want to know more about post-construction settlements? Check out https://www.sciencedirect.com/topics/engineering/postconstruction-settlement for info.
Spill-through or pedestal
Spill-through or pedestal connectors are short stub-type connectors supported on columns or pedestals extending to natural grounds. As with its closed counterparts, the connections need to be constructed before the approach …