Environmental Studies and Researches Institute, University of Sadat City, Egypt | ||
| JES. Journal of Engineering Sciences | ||
| Article 1, Volume 42, No 5, September and October 2014, Pages 1138-1162 PDF (1.17 M) | ||
| Document Type: Research Paper | ||
| DOI: 10.21608/jesaun.2014.115058 | ||
| Authors | ||
| Mohamed M. Rashwan1; Aly Abdel Zaher Elsayed1; Ali Mohamed Abdallah2; Mahmoud Abdou Mahmoud Hassanean3 | ||
| 1staff in Civil Engineering Department, Faculty of Engineering, Assiut University, Assiut, Egypt. | ||
| 2Civil Engineering Department, Faculty of Engineering, Kafrelsheikh University | ||
| 3Civil Engineer, Al- Azhar University. | ||
| Abstract | ||
| Reinforced concrete deep beams may exist in many structural applications such as offshore structures, transfer girders, pile caps, tall buildings and water tanks. The depth of deep beams is much greater than normal in relation to their span. Since the beam is short in this case, shear deformations are more important and special design methods should be applied in this case rather than normal beam theory. Continuous deep beams are defined in the Egyptian Code of Practice (2012) [2]as those beams whose height to effective span ratio greater than 0.4. Deep beams are members with special features. In such beams, plane sections do not remain plane after bending, with significant warping of the crosssections because of high shear stresses. The resulting strain distribution is no longer linear and flexural stresses are not linearly distributed even in the elastic range. Recently, high strength concrete, defined by the American Concrete Institute ACI318-08[3], as concrete with cylinder compressive strength greater than 60Mpa, is being widely used in the construction industry. However, limited research efforts were directed towards the study of the behavior and shear strength of reinforced high strength concrete continuous deep beams. Furthermore, sometimes web openings have to be provided in deep beams for the purpose of access or for providing services. The presence of such openings may affect the shear strength of deep beams. However, limited investigations were directed towards the study of continuous deep beams with openings. Also, strengthening simply supported deep beams using carbon fiber reinforced polymers (CFRP) was investigated by many researchers. However, limited research papers were directed towards CFRP strengthening of continuous deep beams. Experimental tests have been carried out on rectangular reinforced concrete continuous deep beams with a/d=1.17, under static loading up to failure. The study takes into consideration the following parameters: Percentage of web reinforcement (ρh), Positions of openings and number of openings. Also, strengthening of openings in continuous deep beams using glass fiber reinforced polymer (GFRP) was studied in this research. Test results indicated that the presence of web openings within exterior or interior shear spans had great effect on the beam capacity and its behavior. Existence of web openings within exterior or interior shear spans caused a high reduction in the shear capacity of the beams by about 35%. Therefore and whenever should be kept clear of the natural load path joining the loading and reaction points (solid) free from openings. Also, the strengthening of openings contains the cracks and increase the crack and ultimate load. Finally we will compare the test results with the theoretical values for beam A1 which were evaluated using strut and tie analysis according to Egyptian code (2012). The strut–and tie method can be used for the design of Disturbed regions (D- regions) of structures where the basic assumption of flexure theory namely plane sections remaining discontinuities arising from concentrated forces or reactions and near geometric discontinuities such as abrupt changes in cross section etc. The strut – and- tie method of design is based on the assumption that the D-regions in concrete structures can be analyzed and design using hypothetical pin-jointed trusses consisting of struts and ties interconnected at nodes. The usual design practice for continuous deep beams has been to employ empirical equations which are invariably based on simple span deep beams testes. Given the unique behavior pattern of continuous deep beams, this practice is unreliable. Since continuous deep beams contain significant extents of D-regions and they exhibit a marked truss or tied arch actions, the strut- and – tie method offers a rational basis for the analysis and design of such beams. The mechanics and behavior of continuous deep beams are briefly discussed from which a strut–and–tie model for such a beam is developed. | ||
| Keywords | ||
| high performance concrete; deep beams; Percentage of web reinforcement (ρh); Positions of openings and number of openings | ||
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