الفهرس | Only 14 pages are availabe for public view |
Abstract Reinforced concrete (RC) columns are considered the most important structural element in the skeleton type structures. The design of RC columns has been developed in the last third of 20 th century through a large number of experimental and theoretical researches all over the world. Previous researchers studied the general behavior of RC columns under various loading types, different reinforcement details, several concrete grades exposure to severe environmental conditions and verifications of code provisions. The objective of this research is to establish a mathematical formula to predict the ultimate load capacity for axially loaded short columns taking into consideration the variation of lateral steel reinforcement represents the confinement effect for both square and circular RC columns. The effect of concrete compressive strength f cu, , the effect of concrete cross section shape ( square – circular – rectangular ) and the concrete cross section area were studied as well. For this purpose, a total number of 12 specimens were prepared and tested experimentally under axial load to study the parameters that correlated to confinement. Tested columns were divided into 2 main groups in which one of them contains 9 specimens with a concrete compressive strength equal to 25 MPa and varying in transverse steel volumetric ratio, concrete cross section shape in addition to cross section area. The second group contains 3 specimens with a concrete compressive strength equal to 40 MPa. to study the effect of concrete compressive strength. The results of all tested specimens (ultimate loads-strainsdeformations…etc) were recorded and discussed. Different gains of strength, stiffness and ductility were recognized. Mathematical formulas to correlate the axial capacity for both square and circular specimens were determined as well. the longitudinal steel for all specimens was kept constant with a ratio of 1.28% of the concrete cross section area. To verify the experimental results, the tested specimens were analyzed numerically using a non linear finite element program and the obtained results were compared to those obtained experimentally. the ultimate loads, deformations and strains were also recorded and comparedAlso, a parametric study was carried out using the non linear finite element program mentioned above. The parameters studied were the concrete compressive strength and transverse steel volumetric ratio for both square and circular columns and the concrete cross section area of square columns. For all of the two phases of the research ( experimental work, numerical analysis) the equations correlating axial capacity of the column to transverse steel volumetric ratio were obtained. For the parametric study, the equations correlating the axial capacity of the column to the transverse steel volumetric ratio and concrete compressive strength were obtained for both square and circular columns. The equation correlating the axial capacity of the square columns to the concrete cross section area of the columns was obtained as well. The overall research conclusions were listed at the end of the research in addition to the future research suggestions. Keywords Axial loads; Confinement; Transverse (Tie) steel; Compressive concrete strength; Volumetric ratio; Short columns; Cross sectional area: Numerical study, Parametric study, Mathematical formula |