BEHAVIOR OF SELF COMPACTED RC. COMPOSITE BEAMS BY BOTTOM STEEL PLATE

Abstract

Recently, reinforced concrete composite beams have a profound importance in the field of structural engineering as they are often used in buildings and bridges owing to their satisfactory provisions to the structural requirements and the economical saving. In the present study, eight rectangular reinforced concrete beams strengthened by bottom steel plates firmly interconnected to it by headed-stud shear connectors are manufactured using self compacting concrete since it is of high performance ,effective compaction ,homogeneous dispersion around shear connectors and steel reinforcing bars thus increasing the degree of interaction of the steel plate-concrete interface zone which controls the performance of composite structures to far extents. The eight fabricated composite beams are thoroughly similar in geometry and reinforcements except in the steel-plate thicknesses and lengths, and the shear-connector distributions. They have been loaded up to failure under the effect of a two- concentrated load where the failure mode observed and the load-deflection relationships have been reported. From which the flexural stiffness at failure and the ductility ratio have been computed. The results show that there are a substantial improvements in the flexural resistance approaching 42.6% accompanied by increasing the flexural stiffness up to 82.45%and decreasing the ductility ratio(about 33%) due to increase of thickness of steel plate. The eight composite beams have also been analyzed by the non-linear three dimensional Finite Element Analysis employing ANSYS package (release 12.1) to determine the load-deflection relations. good agreement between the experimental results and the numerically modeled ones for ultimate load and the mid-span deflection( with difference mean of 9.9% and 8.07% ,respectively) confirms the reliability of that modeling in the analysis of such composite beams loaded till failure.