What is prestressed concrete girder bridge?
Precast prestressed girders are a type of concrete girder that facilitates the rapid construction of a bridge using girders fabricated off-site and then transported and erected into place at the job site.
What is a girder in a bridge?
Girder bridges are the simplest bridge type in structure and consist of steel beams shaped to an I-section or box section, called a plate girder bridge or a box girder bridge, respectively. Girder bridges are comprised of deck slabs, on which vehicles and people pass, and of main girders supporting the deck slabs.
How does a girder bridge work?
The term “girder” is typically used to refer to a steel beam. In a beam or girder bridge, the beams themselves are the primary support for the deck, and are responsible for transferring the load down to the foundation. Material type, shape, and weight all affect how much weight a beam can hold.
What are concrete girders?
(gûr′dər) n. A beam, as of steel, wood, or reinforced concrete, used as a main horizontal support in a building or bridge.
What are the stages of prestressed concrete?
1) Initial: It can be subdivided into two stages. a) During tensioning of steel b) At transfer of prestress to concrete. 2) Intermediate: This includes the loads during transportation of the prestressed members.
How are girder bridges built?
In order to build a beam bridge (also known as a girder bridge), all you need is a rigid horizontal structure (a beam) and two supports, one at each end, to rest it on. These components directly support the downward weight of the bridge and any traffic traveling over it.
How girders are placed?
A girt is a vertically aligned girder placed to resist shear loads. Small steel girders are rolled into shape. Larger girders (1 m/3 feet deep or more) are made as plate girders, welded or bolted together from separate pieces of steel plate.
Why is prestressed concrete used in bridge?
A properly engineered prestressed-concrete beam can span longer distances than a reinforced-concrete beam and it is thinner, lighter in weight, and uses less concrete without cracking or breaking.
What are the limitation of prestressed concrete?
Disadvantages of Prestressed Concrete
- Prestressed concrete requires high-quality dense concrete of high strength.
- It requires high tensile steel, which is 2.5 to 3.5 times costlier than mild steel.
- Prestressing process requires complicated tensioning equipment and anchoring devices.
What is the length of each girder?
Each girder has a cantilever length of 48 m and an I- shaped cross-section with dimensions shown in the figure. The load on each girder (during construction) is assumed to be 9.5 kN/m, which includes the weight of the girder. Determine the maximum bending stress in a girder due to this load.
What is prestressed concrete principle?
The principle behind prestressed concrete is that compressive stresses induced by high-strength steel tendons in a concrete member before loads are applied will balance the tensile stresses imposed in the member during service.
What are the basic elements of prestressed concrete?
Prestressed concrete is a highly versatile construction material as a result of it being an almost ideal combination of its two main constituents: high-strength steel, pre-stretched to allow its full strength to be easily realised; and modern concrete, pre-compressed to minimise cracking under tensile forces.
Which reinforcement is used in prestressed concrete?
High tensile steel
High tensile steel is used for prestressed concrete.
What is the purpose of prestressed concrete?
Prestressing can reduce the volume of concrete required in construction, lowering the use and transportation of materials, as well as boosting durability and service life. Concrete is intrinsically resistant to compressive stresses, but its resistance to tension is much lower.
How deep is a girder?
The Joist Girders that weigh 150 plf or more are shaded grey in the table and shall have a standard 10 inch minimum bearing seat depth.