CompositeTräger

A CompositeTräger, or composite beam, is a structural member that combines two or more materials to resist bending and shear. The most common realization pairs steel (or timber) with concrete, so that the materials act together as a single unit through shear connectors that transfer longitudinal forces across the interface. This composite action increases stiffness and load-carrying capacity compared with the individual materials.

In steel-concrete composites, a steel beam carries bending while a concrete slab on top provides compression resistance and works as a deck. The slab can be cast in place or precast and is connected to the steel via shear studs, dowels, or other connectors. Timber-concrete composites use a timber beam with a concrete slab to improve rigidity and fire resistance. Other combinations exist, such as aluminum-concrete or steel with composite decking.

Design and construction rely on ensuring adequate shear transfer at the interface to achieve composite action. Engineers use transformation methods and modular ratios, and follow standards such as Eurocode 4 for steel-concrete structures or equivalent national codes. Long-term effects such as creep and shrinkage, and differential thermal movement, are accounted for in serviceability checks.

Advantages include higher stiffness and strength, potential reductions in material usage, faster construction, and improved fire performance. Disadvantages include more complex detailing, sensitivity to construction tolerances, durability concerns at the steel-concrete interface, and higher initial costs.

Common standards for design include Eurocode 4 and related national implementations, as well as guidelines for composite steel-concrete systems in various jurisdictions.