Structural Behavior of Reinforced Self- Compacted Concrete Box Beams

Abstract

Abstract Box beams are very commonly used structural members due to their high performance, their ability to minimize the dead load and the number of supports which lead to reduce cost. Accordingly, it became a major requirement to focus on studying the structural behavior of this type of structural members. In this thesis, an experimental study was conducted in order to investigate and improve the structural behavior of reinforced self-compacted concrete box beams by using different number of cells with the same cross-section dimensions as well as studying the effect of using longitudinal shear steel plates that contain vertical and inclined rectangular spacings as shear reinforcement instead of using traditional reinforcement bars (stirrups). Also, the study focused on the effect of using vertical and horizontal corrugated steel plates in strengthening the cells and studying the effect of using circular-shape cell instead of rectangular-shape one with the same web width and strengthening the circular cell with steel plate in the shape of steel pipe. The experimental program consisted of casting and testing ten reinforced self-compacted concrete box beam specimens with identical cross-section of overall depth of (320mm), top flange width of (420mm), bottom flange width of (270mm), web width of (60mm) and overall length of (1500mm). The specimens were divided into five groups according to the number of cells, reinforcement type, strengthening and the shape of cell. All the specimens IV were tested under four-point monotonic-static load to obtain the ultimate load capacity, crack pattern, mode of failure, crack width, central vertical deflection, ductility and strain in concrete and steel. The test results showed that increasing the number of cells from one cell into two and four cells has increased the ultimate load capacity by (20.12% and 23.37%) respectively and has increased the ultimate deflection by (30.65% and 13.82%) respectively. Also, the use of longitudinal shear steel plates that contain vertical and inclined rectangular spacings instead of vertical stirrups has increased the ultimate load capacity by (7.14% and 20.12%) respectively and has increased the ultimate deflection by (20.73% and 38.23%) respectively. It was found that using corrugated steel plates strengthening with vertical and horizontal corrugation has increased the ultimate load by (7.14% and 11.03%) respectively and has increased the ultimate deflection by (10.92% and 2.67%) respectively. Also, the use of circular cell without and with steel strengthening instead of rectangular cell has increased the ultimate load capacity by (17.85% and 29.22%) respectively and has increased the ultimate deflection by (63.54% and 33.77%) respectively. Finally, the use of horizontally corrugated steel plate strengthening and circular cell with steel plate strengthening has increased the ultimate load by (3.63% and 20.60%) respectively, with a decrement in the ultimate deflection for the use of horizontally corrugated steel plate strengthening by (7.43%) and an increment in the ultimate deflection by (20.60%) for the use of circular cell with steel plate strengthening compared with the use of vertical corrugated steel plate strengthening