الفهرس 
CHAPTER (1): INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
This study presents a numerical investigation based on finite elements analysis (FEA) to study the shear behavior of rectangular and T-sections of reinforced concrete (RC) beams strengthened with ultra-high-performance fiber reinforced concrete (UHPFRC). The results of literature experimental studies were used to validate the finite element model and the FEA shows acceptable results close to the literature experimental results. Two models were compared to simulate the
concrete beam: the 2D shell element and the 3D solid element. It was observed
that the results obtained from both models are very convergent, although
modelling using 2D shell elements took significantly less central processing unit (CPU) time in the analysis. Furthermore, various strengthening techniques using UHPFRC were investigated. Such techniques include adding two sides plates, one sides plates, vertical strips, U-shaped strips, U-shaped strengthening along the entire length of beam, and near surface mounted (NSM) strengthening technique.
Many variables were considered in the study of the behavior of rectangular RC
beam, i.e., thickness, length, and reinforcement of strengthening plates, strip width to strip spacing ratio, and effect of using steel anchor system.
The numerical studyof rectangular RC beamshowed that the strengthening using
two side plates with a length equals to the shear span resulted in partial debonding
in the lower part of the strengthening plate. However, the overall failure pattern changed from shear in the control beam to flexural. The strengthening using two sides and one side plates along the entire length of beam showed similar values for the ultimate maximum load, in addition to their ability to change the failure
pattern from shear in control beam to flexural, but it was observed a partial
debonding in the case of one side strengthening. The NSM strengthening
technique was able to overcome the debonding. Additionally, the study showed that increasing thickness of the strengthening plates has a minor effect on increasing the ultimate load, while maintains the failure pattern as ductile flexural in all thicknesses.
The study of strengthening RC T-beam showed that the two-sided strengthening
increased the ultimate load, stiffness, and ductility and changed the failure pattern from shear to flexural. However, the one-sided strengthening provides an increase in ultimate load close to two-sided strengthening but could not be able to change the failure pattern of the control beam. U-shaped strengthening was the best technique as it gave the maximum load compared to other strengthening cases in addition to a better increase in stiffness and ductility.