الفهرس 
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Abstract
Expermental and analytical investigation of the shear behavior of High-Strenth concretr(HSC)T-beams was conducted in this research. ten simply supported reinforced concrete beams with web reinforcement in the form of vertical stirrups were experimentally tested under two symmetrically concentrated loads.Nine of the studid beams were mad of HSC with mean compressive strengh 70.0 N/mm, five of them were reinforced by high tensile steel (HTS)bars as main reinforcement, and the other four specimens were reinforced by glass fiber reinforced plastics (GFRP)bars.
Thelast beam was a control beam made of normal strengt concrete (NSC)with compressive strength 30.0 N/mm and reinforced by HTS bar.The studied parameters were the amount of web reinforcement (u), the shear span to depth ratio (a/d) and the type of main reinforcement (G,FRPand HTS).The actual shear strength of each beam was compared with the predicted strength for HSC beam using different codes of practice such as JSCE-1997, CHBDC-Draft/1998, and ACi 318-99, ECCS203-2001 and others.
In addition, an attempt was mad to compare the experimental results with the predicted strength of NSC beams.Based on such comparisons, empirical formulae were developed for the analysis and design of HSC beams reinforced by GFRP bar. Based on the test results of this research it was found that, increasing a/d from 1.5 to 3.5 led to ae reduction in the ultimate load capacity,the maximum defelectin, and the flexural cracks wiidth of the test beams. Moreover, changing the type of main reinforcement from HTS to GFRP, while keeping the main reinforcement ratio constant u=0.58u, resulted in changing the mode of failure from giagonal tension shear failure to flexural failure.Lower stiffiness and low modulus of elasticity of GFRP bars related to HTS bars resulted in higher flexural cracks width; the flexural cracks windth in beams reinforced by GFRP was found to be six to nin times that of beams reinforced by HTS.
The proposed design formulae showed a reasonable accuracy.