Design of Steel Plate and Box Girders
Expert-defined terms from the Postgraduate Certificate in Structural Steel Design course at LearnUNI. Free to read, free to share, paired with a globally recognised certification pathway.
**AASHTO** #
American Association of State Highway and Transportation Officials, a organization that develops standards and guidelines for transportation infrastructure in the United States, including the design of steel plate and box girders.
**Box girder** #
A type of bridge girder that consists of a hollow box-shaped cross-section, made of steel plates. It is often used in long-span bridges due to its high strength-to-weight ratio and resistance to torsional forces.
**Camber** #
The intentional curvature provided to a steel plate or box girder during construction to counteract the effects of dead load deflection and ensure that the structure is in a level position when it is in service.
**Compression flange** #
The top or bottom horizontal flange of a steel plate or box girder that is designed to resist compressive forces.
**Connections** #
The components and details used to connect steel plate and box girders to each other and to other structural elements, such as bearings, supports, and diaphragms.
**Corrosion** #
The gradual destruction of steel by chemical or electrochemical processes, which can weaken the material and reduce its load-carrying capacity.
**Diaphragm** #
A horizontal or vertical steel plate that is used to transfer lateral forces between steel plate and box girders and to provide stability and rigidity to the structure.
**Fatigue** #
The process of progressive damage and failure of a material under cyclic loading, which can lead to cracking and fracture of steel plate and box girders.
**Flange** #
A horizontal or vertical plate that forms part of the cross-section of a steel plate or box girder and provides additional strength and stiffness to the structure.
**Haunch** #
The portion of a steel plate or box girder that is located between the web and the flange and is designed to resist shear and bending forces.
**Hanger** #
A steel member that is used to support the weight of a steel plate or box girder and transfer it to the substructure.
**Haunch depth** #
The vertical distance between the bottom of the haunch and the bottom of the web of a steel plate or box girder.
**Live load** #
The temporary or moving loads that are placed on a bridge, such as vehicles, pedestrians, and wind.
**Moment of inertia** #
A measure of the resistance of a cross-section to bending, which is calculated as the sum of the products of the areas of each element and the square of its distance from the neutral axis.
**Neutral axis** #
The axis of a cross-section that passes through the centroid of the area and is neither in compression nor in tension under bending.
**Painting** #
The application of protective coatings to steel plate and box girders to prevent corrosion and maintain their structural integrity.
**Plate girder** #
A type of bridge girder that consists of a series of vertical and horizontal steel plates that are connected to each other to form a stiff and strong structural element.
**Shear lag** #
The phenomenon where the distribution of stress in a steel plate or box girder is not uniform and the stress is concentrated near the loaded area, leading to a reduction in the load-carrying capacity of the structure.
**Shear stud** #
A threaded steel rod that is welded to the top or bottom flange of a steel plate or box girder and is used to transfer shear forces between the girder and the concrete deck of a bridge.
**Stiffeners** #
The vertical or horizontal plates that are used to reinforce and strengthen the webs and flanges of a steel plate or box girder, and to prevent local buckling and deformation.
**Strain hardening** #
The process of increasing the strength and hardness of a material by subjecting it to plastic deformation, which can improve the fatigue resistance of steel plate and box girders.
**Tension flange** #
The top or bottom horizontal flange of a steel plate or box girder that is designed to resist tensile forces.
**Transverse stiffener** #
A vertical plate that is used to reinforce and strengthen the web of a steel plate or box girder and to prevent buckling and deformation under transverse loads.
**Ultimate load** #
The maximum load that a steel plate or box girder can carry before it fails or collapses.
**Web** #
The vertical plate that forms the central part of the cross-section of a steel plate or box girder and is designed to resist shear forces.
**Web crippling** #
The local buckling and failure of the web of a steel plate or box girder under concentrated loads, which can reduce the load-carrying capacity of the structure.
**Web post** #
A vertical plate that is used to connect the web and the flange of a steel plate or box girder and to prevent web crippling and deformation under transverse loads.
**Web stiffener** #
A horizontal plate that is used to reinforce and strengthen the web of a steel plate or box girder and to prevent buckling and deformation under longitudinal loads.
**Web thickness** #
The vertical distance between the top and bottom surfaces of the web of a steel plate or box girder, which affects the strength and stiffness of the structure.
**Web yielding** #
The local buckling and deformation of the web of a steel plate or box girder under high loads, which can reduce the load-carrying capacity of the structure.
**Weld** #
The fusion of two or more pieces of steel by melting and joining them together, which can improve the strength and durability of steel plate and box girders.
**Weld access hole** #
A small hole that is provided in the web of a steel plate or box girder to allow access for welding the flange and the web together, which can improve the strength and durability of the structure.
**Weld toe** #
The sharp corner at the intersection of the web and the flange of a steel plate or box girder, which is a critical location for fatigue cracking and failure.
**Yield strength** #
The stress at which a material begins to yield or deform plastically under load, which is an important property for the design and analysis of steel plate and box girders.