The Hambro Composite Girder is composed of a top and bottom chord, each made of two angle sections.
Developed for the multi-residential and commercial markets, the Hambro composite girder offers greater spans than the conventional steel girder while maintaining a minimum depth to adapt to the Hambro joists.
- The web system consists of vertical and diagonal members.
- The top chord S connector closes the opening between the two angle sections.
- In addition to the S connector and where necessary for shear requirements, U-shaped channels developed specially by Hambro can be shop-installed on the girder between the Hambro joists.
- Composite Action
- Utilizing a concrete slab in the overall design of the Hambro girder allows a better span-to-depth ratio than that of a conventional girder. Although a ratio between 24 and 27 generally represents an efficient and economical solution, a composite product can reach a ratio of up to 30.
For example, in the case of a 30-foot girder, the optimum depth is approximately 14 inches while the minimum depth is 12 inches.
- Duct openings
- Due to the composite design of the Hambro girder, the top and bottom chord members are smaller than those of a conventional girder. This provides for wider openings between the members.
The vertical members of the Hambro girder are aligned with the joists bearing on the top chord, maximizing the size of the openings between the diagonal members and the bottom chord.
- Fire Resistance
- Composite Hambro girders form an integral part of the composite Hambro floor system and therefore can reach a fire resistance rating of up to 2 hours, depending on the type of ceiling used.
- Fewer Structural Members
- Composite Hambro girders are ideal for floors requiring long spans since fewer columns are utilized. The optimum span of a composite Hambro girder ranges between 25 and 35 feet.
- Hambro girders and joists, designed with a camber according to the dead load of wet concrete, become level after the pour. This provides the flexibility to install the ceiling directly beneath the bottom chord in accordance with ULC and UL specifications.
- Mulitple Floor Loading
- With a concrete slab and steel members incorporated into its design, the composite Hambro girder can be designed to carry multiple floor loads. Contact us for more information.
The longitudinal shear that occurs between the concrete slab and the steel girder is due to the action of the following four elements:
- The joist shoes welded at regular intervals to the girder. This concept, patented under the name Shear Shoe, utilizes a secondary structural element (joist) to create the longitudinal shear of a primary structural element (girder).
- The anchorage created by the end plate welded at each end of the girder. The horizontal force is associated with the resistance of the concrete.
- The bond friction that occurs between the joist top chord S and the concrete slab.
- The additional connectors used to support heavy loads (U-shaped steel channels welded to the girder at regular intervals). These U-shaped channels were developed in collaboration with the Centre de recherche industrielle du Québec (CRIQ) and are always installed in pairs (one welded on the top of each angle of the top chord member).
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