الفهرس 
EXPERIMENTAL WORKOnly 14 pages are availabe for public view
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Abstract
The objective of this research is to asses experimentally the torsional behavior of high strength reinforced concrete beams under the effect of changing three parameters which are: concrete strength, volume of side bars and volume of stirrups. br The experimental program of this research consists of testing 7 specimens divided into six groups. The first and last two groups have concrete strength of 90 MPa, and the third group has concrete strength varying between 25 and 90 MPa. The fourth group has concrete strength varying between 25 and 90 MPa. The variable in the first group is the volume of stirrups, in the second group is the volume of the side bars, in the third group is the concrete strength, in the fourth group is the concrete strength with no stirrups nor side bars, in the fifth group is the side bars with no stirrups and in the sixth group is the stirrups with no side bars. All specimens are fixed at one end and are provided with roller support at the other end where they are loaded with a cantilever by a single concentrated load. The behavior of tested specimens, cracking patterns, cracking loads, failure loads and relations between load and deformations as well as strains in concrete and steel were reported and analyzed. Key test results demonstrated that the use of higher concrete grades represented the most dominant parameter influencing the torsional behavior from both capacity enhancement and ductility points of views. In fact moving from 25 MPa to 50 MPa strength concrete resulted in most of the enhancements associated to higher concrete grades (66.67 % capacity enhancement and 65.71 % ductility increase). However, the further increase to 90 MPa concrete grades (High Strength Concrete) resulted in much lower capacity enhancement (10 % increases) at the price of reduced ductility (21.43 % decrease). This is normally due to the smooth shear crack surfaces in case of High Strength Concrete and the associated loss of aggregate interlock. This was followed by the provisions of stirrups leading to (29.41% increases) capacity enhancement and 83 % ductility increase. Finally the effect of side bars comes at the end as the least influencing parameter on the torsional behavior and capacity (4.76 % capacity enhancement and 84.12 % ductility decrease).