BEHAVIOR OF STEEL-NORMAL AND HIGH STRENGTH CONCRETE COMPOSITE BEAMS WITH PARTIAL SHEAR INTERACTION

In this research, aimed to study the behavior of simply supported steel concrete composite beams with normal and high compressive strength of the concrete slab under the action of a span mid-point external load. The steel I-section beam is located at the bottom of reinforced concrete slab and connected with it by stud shear connectors. Eight composite beams were tested under the action of a monotonic load, half of them had a normal strength concrete slab while the others with a high strength concrete slab. Four degrees of shear connection interaction (100%, 80%, 60%, and 40%) were used for both groups of the tested beams. It was noticed that there are no essential differences between the modes of failure that occurred in the tested beams with normal strength concrete and those with high strength concrete. It was also found that there is an increase in the initial stiffness of the beams when the concrete changed from normal to high strength for different degrees of shear connections, but this increment reduced with increasing the degree of the shear connection. It was noted that the ultimate capacity of the tested beams was increased with enhancement of the strength of the adopted concrete from normal to high strength. The results showed that, when the concrete compressive strength was increased from 32.6 MPa to 72.8 MPa, the ultimate moment capacity of the specimens was increased from 28% for 100% shear connection, and it is increased to 38% for specimens with 40% shear connection.