الفهرس 
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Abstract
The dissertation aims at investigating the performance of
strengthened and un-strengthened flanged RC composite beams. The
main objective of the study was to asses the behavior of composite RC
flanged beams reinforced with various shear connectors reinforcement
ratio and distribution as well as studying behavior of the strengthened
composite flanged beams that are deficient in transmitting the interfacial
shear stresses.
The research program consisted of experimental and analytical
studies. Based on the results of the experimental, adopted analytical
models, design guide lines and design recommendations were introduced
to enhance the strength and ductility of the RC composite beams. The
variables in the experimental program were shear connectors distribution
along beam span (once concentrating the shear connectors near support
and once by equally distributing shear connectors along the beam span),
connector diameter, ratio of shear transfer reinforcement and
strengthening scheme for the deficient composite beams.
The experimental program consisted of testing seven composite
flanged RC beams. Each beam has a thickness of ٢٤٠-mm web, ١٥٠-
mm web width, ٦٠-mm flange thickness, ٤٥٠mm flange width and
٢٣٥٠-mm span. The beams are simply supported with a clear span of
٢١٠٠-mm. One beam was tested as control and was loaded up to failure load while the other six beams were loaded up to interfacial shear cracks
appearance then unloaded and each was strengthened with one of two
proposed schemes and reloaded up to failure.
The analytical phase of this study included a rational analysis to
predict the behavior of composite RC flanged beams in both cases
strengthened and un-strengthened. Strut-and-tie method was used to
analyze the performance of the strengthened and un-strengthened beams,
strain compatibility approach was used for the analysis of control beam,
and response-٢٠٠٠ program which was used for the calculation of the
capacities of rectangular and flanged monolithic sections.
Based on the experimental results of the tested beams and the
analytical work, Different recommendations and design guidelines for
composite RC flanged Beams were introduced.