The structural behavior of composite steel concrete beams with long term deflection was investigated, taking in considerations several variables including degree of shear connectors 50%, 75%, 100%, and type of connectors including headed and hooked studs smooth or deformed. Five composite steel-concrete beams were tested each consist of steel section W12x35 and 300x100 concrete slabs. The composite beams were tested under uniformly distributed loads for different time interval up to 180 days. The results showed that the degree of interaction have significant influence on the long- term behavior of the composite steel concrete beam . When the degree of interaction decreased from 100% to 75% then to 50% the maximum long-term mid span deflection increased about 35.1% and 65.9% respectively at 180 days after loading. Also, the end slip increased about 67.5% and 112.4% respectively at 180 days after loading. The results showed that the type of the used shear connectors has slight influence on the long-term behavior of the composite steel concrete beams. For certain degree of interaction (75%)with using headed and hooked studs smooth or deformed the maximum long-term mid span deflection decreased about 7.1% and 11.7%at 180 days after loading, and the end slip decreased about 4.8% and 12.5% at 180 days after loading.
Composite beams, made up of a concrete slab and steel in the IPE steel section, are commonly used in bridges and buildings. Their main function is to enhance structural efficiency by merging the compressive strength of concrete with the tensile resistance of steel, thereby improving overall stiffness, ductility, and load-bearing capacity. This study offers an extensive review of the flexural behavior of steel-concrete composite beams, focusing on the interplay of concrete strength, shear connector types, and interaction levels in determining structural performance. It integrates experimental and numerical research to analyze critical parameters, including load-deflection behavior, shear transfer efficiency, and crack propagation at the steel-concrete interface. The study emphasizes the effect of concrete compressive strength, particularly in ultra-high-performance concrete (UHPC) and lightweight concrete, on stiffness, ductility, and load-bearing capacity while reducing self-weight and enhancing sustainability. The study revealed that fully bonded shear connectors, using CFRP sheets and welded plates, enhance flexural capacity and stiffness. In contrast, partial bonding or pre-debonding reduces performance due to crack propagation. Indented and hot-rolled U-section connectors enhance interaction and minimize slip, while uniform distribution of shear connectors optimizes load capacity and stiffness. Lightweight concrete decreases slab weight without compromising performance, and high-performance materials such as ECC, SFRC, and UHPFRC improve strength and ductility. Numerical modeling, particularly finite element methods, and higher-order beam theories validate experimental results, providing accurate tools for predicting structural behavior under various loading and environmental conditions.
In this study, eight rectangular reinforced concrete beams strengthened by bottom steel plates firmly interconnected to them by headed-stud shear connectors are manufactured using self compacting concrete and tested up to failure under two point loads to demonstrate the effect of steel-plate thicknesses, lengths, and the shear-connector distributions on the behavior, ductility and strength of this type of beams. A trial mix conforming to the EFNARC Constraints had been successfully carried out to satisfy the three fresh tests of SCC, these tests are flowability, passing ability and segregation resistance. The results show that there is a substantial improvement in the flexural resistance, increasing the flexural stiffness and decreasing the ductility ratio due to thickening steel plate, On contrary, increasing the spacing between shear connectors to 50% had slight effect on the flexural resistance, but subsequent increase of their spacing to 100% had seriously lowered that resistance, The spacing between shear connectors has a primary effect on the average flexural stiffness and ductility ratio. In regard to the steel plate length, its shortening has reduced the flexural resistance significantly, decreased the average flexural stiffness and had increased the ductility ratio. The experimentally determined ultimate flexural strength had been compared with its corresponding one computed by the "Strength Method" using ACI requirements where high agreement gained between them due to the nearly perfect interaction provided by SCC. The eight composite beams had also been analyzed by the non-linear three dimensional Finite Element Analysis employing ANSYS program (release 12.1),where high agreement is achieved compared with experimental results.