What Is A Box Culvert Bridge?
What Is A Box Culvert Bridge?
A box culvert bridge is a tunnel-like structure built under roadways or railways to provide cross drainage from one side to the other. It is a monolithically cast, rigid framed structure suitable for non-perennial streams where the soil is weak.
Box culverts are box-shaped and are popular in road design because the shape provides a rigid structure that is appropriate in areas with poor soil conditions.
They are manufactured off-site and delivered to where they will be installed. Precast concrete box culvert bridges are installed quickly with less labor and deliver a long service life.
Box Culvert Bridge Design
Box culverts are structures used to convey water and are often used for pedestrian or cattle underpasses. Box culverts can be provided in both precast concrete and cast-in-place concrete forms. Designing box culverts requires following the AASHTO LRFD Bridge Design Specifications.
The design of box culverts is based on the application of live loads, which will be based on the design fill height. Reinforced concrete box culvert designs should consider crack control, hydraulic design, waterproofing, and material properties.
The use of glass FRP (GFRP) bars has been explored as an alternative to steel reinforcement for box culvert bridges. In one example, two specimens were tested in a lab and designed for maximum forces determined in accordance with AASHTO design guidelines.
The box culvert units were selected to be 1.5 by 1.5 m with a wall thickness of 150 mm and reinforced entirely with GFRP bars pre-bent and cut to size by the manufacturer.
Special designs for sizes and conditions other than as specified by ASTM C 789 or ASTM C 850 may also be considered when designing box culvert bridges.
Box Culvert Bridge Construction
Box culverts are tunnel-like structures built under roadways or railways to provide cross-drainage from one side to the other.
They are different from bridges in terms of structural design, components, load-carrying capacity, costs, etc. Box culverts are popular in road design because they provide a rigid structure that is appropriate in areas with poor soil conditions.
Box culverts can be made of reinforced concrete, corrugated steel or aluminum and other materials. Most box culverts are manufactured off-site and delivered to where they will be installed.
Structural analysis and design of buried single cell reinforced concrete box culverts can be achieved using BOXCAR software developed by the Federal Highway Administration (FHWA).
In July 2001, a concrete box culvert bridge was constructed and reinforced entirely with glass FRP (GFRP) bars to replace a bridge that was built in the early 1980s and consisted of three concrete-incased corrugated steel pipes due to excessive corrosion. The bridge was 4.9 m wide with box culvert units 1.5 by 1.5 m with a wall thickness of 150 mm.
Advantages Of Bridge Culvert
Bridge culverts are an important form of river crossings as they provide a strong and reliable connection allowing traffic to pass with ease. They are highly expensive but deliver the assurance of a safe passage over the body of water.
They also extend the reach of the transportation network by acting as repeaters between two points. These structures require strong foundations and are renowned for their sturdy construction and durability.
All in all, bridge culverts offer an efficient solution for river crossings with assurance of safety and security.