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Go to Editorial ManagerThis experimental investigation evaluates the structural behavior of reinforced concrete slab-column connections incorporating columns with square and circular cross-sectional geometries under gravity and lateral cyclic loading. Four interior slab-column specimens were designed, fabricated, and tested, with identical slab dimensions of 1050×1050×80 mm and a column height of 500 mm. The circular columns were intended to have an equivalent second moment of inertia to the square column, ensuring a fair comparison of geometric effects. One specimen identified as SC-G, incorporating a square column, was tested under a progressively increasing vertical load to determine its maximum gravity load-bearing capacity. The remaining three specimens SC-2 with a square tied column, SC-9 with a circular spirally-reinforced column, and SC-10 with a circular column incorporating a column capital were tested under a constant gravity load equivalent to 60% of SC-G’s ultimate capacity (75 kN), combined with a lateral displacement protocol conforming to ACI 374 guidelines. Results indicated that the shape of the column (circular) and reinforcement (spiral) in SC-9 produces a comparatively higher ultimate load, stiffness, and ductility than SC-2 of the square column and tied reinforcement. The ultimate lateral load increase was +13.3%, -26.1%. Circular spiral columns with column capital in slab-column connections led to a noticeable rise in ultimate lateral load by about +62%, -80%. It was also shown that incorporating a column capital in SC-10 significantly enhanced the punching shear resistance and energy dissipation capacity. Circular columns demonstrated more stable hysteretic behavior and improved ductility compared to the square column specimen.
This study concerns utilization of nonlinear finite element method for to evaluate the role of longitudinal soffit-bonded CFRP strips in elevating the shear behavior of RC beams without stirrups. All beams cross-sections were of 150 mm breadth and 200 mm depth, the overall length was 1500 mm with clear span 1300 mm. One beam was provided by minimum web reinforcement according to the ACI 318M-14, while the other five were without web reinforcement but externally strengthened by a variety of CFRP-strip combinations consisting of longitudinal soffit-bonded strips. The predictions of a proposed ANSYS (version 14.5) model for six of the test beams including modeling of concrete, steel rebars, CFRP strips and supports and loading steel plates, by SOLID65, LINK180, SHELL41 and SOLID185 elements, respectively, show high agreements with experimental evidence, which stands as a definite witness to the efficiency and reliability of the present numerical model.