الفهرس 
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Abstract
In the construction industry, the challenge is always about the speed and cost of the performance. Precast concrete, as a construction method, ensures high quality control, durable, fast and economic buildings compared with cast in situ construction. Therefore, it is widely used as a proper alternative to the latter. In general, precast building systems are more economical when compared to conventional multifamily residential construction (apartment buildings) in many countries.
Torsion in RC beams is usually associated with bending moments and shearing forces, and the interaction among these forces is important. Thus, the behaviour of concrete elements in torsion is primarily governed by the tensile response of the material, particularly its tensile cracking characteristics. When torsion acts on an RC member, it forms two orthogonal diagonal loops in which one of them is in compression, which is generally resisted by concrete, and the other in tension, which is generally resisted by steel or other reinforcements.
This research focused on the study of torsional behaviour of reinforced concrete edge beams carrying precast slabs specifically when the details of reinforcing steel in beams (stirrups and longitudinal steel bars resist torsion) are different. In this study, the torsional behaviour of reinforced concrete edge beams carrying precast slabs under vertical load was studied, where the details of steel reinforcement in beams are different to get the appropriate steel reinforcement ratio that can be used for resisting torsional moment in beams (rectangular and L-shaped beams).
This research consists of three specimens labelled S1, S2 and S3. S1 consists of two precast edge rectangular beams B1 (0% steel ratio) and B2 (50% steel ratio), one precast slab and the RC layer with thickness 5 cm above the slab/beam system. S2 consists of two precast edge rectangular beams B3 (100% steel ratio) and B4 (50% steel ratio), one precast slab and the RC layer with thickness 5 cm above the slab/beam system. S3 consist of two precast edge L-shaped beams B5 (0% steel ratio) and B6 (100% steel ratio), one precast slab and the RC layer with thickness 5 cm above the slab/beam system. The concrete compressive strength for beams (B1, B2, B3, B4, B5 and B6) and slabs having similar concrete compressive strength (40 N/mm2) and the reinforced concrete layer above the slab/beam system have different concrete compressive strength (25 N/mm2).
Using F.E package (ANSYS Ver.14.0), their behaviour were investigated, analysed and verified. This Program has wide varieties of elements, a large library for material properties and several load types which covers almost aspects needed to model the experimental work conducted in this thesis.
Study was implemented depending mainly on static analysis and design regulations of the Egyptian code for the design & construction of reinforced concrete buildings. In recent decades the evolution of computer technology has advanced to the stage where the finite element method (through codes such as ‘ANSYS’) can realistically be used to model full-scale buildings and subject them to a variety of loads, including seismic. Modelling through a detailed finite element discretisation of the structure can provide a more realistic representation of the actual behaviour of RC buildings. Therefore in this research the theoretical models of reinforced concrete edge beams carrying precast slabs were implemented using ANSYS computer package ver.14 (Structural engineering). Test results showed a good match between both experimental tests and the finite element models.