اتصال برشی نوع خرپا برای ستون های کامپوزیتی بتنی فولادی Truss-type shear connector for composite steel-concrete beams

1. Introduction The economic, technical, and scientific developments in the construction industry have brought about a great number of structural systems. Among them, steel-concrete composite structures have proved to be efficient from the structural and constructive points of view. As for the structural aspect, one can emphasize the better usage of materials’ resistance properties, effectively exploring in a better way the potentials of concrete and steel [1]. The resulting combination of steel and concrete in composite beams, for example, provides lighter but more resistant structures. The use of composite structures with all its structural efficiency advantages [2] should be encouraged for bridge construction and even made more popular for medium and small construction too. As for the constructive aspect, steel-concrete beams can be built faster than reinforced concrete beams as the steel beam helps as support along the concrete slab curing process. Therefore, steelconcrete beams use less wood forms to cast the concrete slab. To accelerate even more the constructive process in making composite beams, precast concrete slabs can be associated with steel I-beam sections. Today, with increasing demand for infrastructures and dwelling, steel-concrete beam is a fast and cost effective system that may be well used for multi-story buildings and bridges. The efficiency of steel-concrete beams, as resisting structure, depends highly to the interaction between two key structural elements: (a) steel I-beam and (b) overlaid concrete slab. Effective links between concrete slab and steel profile are required because these two materials have to act as a unique structure. Steel connectors are used as shear connectors, and, generally, they are welded to the steel profile flange and merged into the concrete slab – even though other options are available today [3]. One important characteristic for a shear connector in composite beams is its ductility. Shear connector may be classified in two categories depending of its ductility: rigid or flexible. Rigid connectors do not deform much under service load. They can provide good connection without showing much relative slipping displacement between steel I-beam and concrete slab. However, the collapse of rigid connectors is brittle. In this case, concrete failures for shear or crushing, and brittle failure takes place.