Plate Girder | Elements and Types of Plate Girders

A plate girder is a steel beam that is widely used in bridge construction. Girder is required to carry heavy loads on relatively long spans. Plate girders are commonly used as long-span floor girders in buildings. Girder is a flexural x-section made up of a number of elements.

Let us know in detail see about plate girders and elements of plate girders.

Plate Girders

A plate girder is a bridge supported by two or more plate girders. The primary aim of this structure is to resist SF and BM like any other steel structure. When the span becomes large and the load becomes heavy, we have the following options in the design of steel structures.

• Designing as a compound section: This is not preferred as it’s uneconomical.

• Designing as plate girders with cover plates

• Designing as a plate girder

• Designing as steel truss: The fabrication cost is high, but if the span is very high this one is preferred.

Benefits of using

The benefits of using Plate girders are

• The designer has the freedom to choose components of convenient size.

• Flexibility in fabrication, a cross-section can be uniform and non-uniform (based on the BM variation).

• The shape can be proportioned to match the requirement of the BM curve.

Types

There are various types of plate girders based on the fabrication of cover plates. They are-

1. Bolted without cover plates

2. Bolted with cover plates

3. Box girder

4. Welded girder

5. Delta girder

Types of Plate Girders

We have seen different types of plate girders, now let us see the elements of plate girder

Elements of plate girder

The plate girder is made up of the following components

1. Web plate

2. Flange plates, with or without a cover plate

3. Bearing stiffeners (End posts)

4. Intermediate transverse stiffeners (ITS)

5. Longitudinal stiffeners (LS)

6. Web splices

7. Flange splices

Elements of Plate Girders

Web plate: It is the vertical plate of the girder. The web carries applied loads on the flange as shear forces.

Flange plates: It is designed to carry the bending action.

Stiffeners: Stiffeners are provided to enhance structural capacity avoiding the local buckling failures. Stiffeners can be Bearing stiffeners, Intermediate transverse stiffeners, Longitudinal stiffeners.

Splices: When the length of the girder is less than the span, we have to have a splice connection. It can be Web splices and flange splices.

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