This paper is concerned with the finite element modeling of strengthened interior slab-column connections in the existing continuous flat slab structural system by employing steel angle plates at the slab-column junctions and fastened by shear bolts. This technique utilizes the advantage of combined action between the angle plates and bolts in resisting shear particularly at the slabcolumn edges. Three-dimensional analysis was carried out on such slabs employing concrete damaged plasticity model in ABAQUS to investigate their performance in terms of punching shear resistance, load-displacement response, and crack pattern at failure. The numerical models were first validated against the experimental results reported by other researchers. The proposed strengthening technique results in a substantial increase of loadcarrying capacity ranging from about 59 to 79% compared to the unstrengthened slab, and has also provided better stiffness, ductility and energy absorption in the slab system that change the mode of failure from a pure punching shear to flexural failure. The finite element results are compared with the calculated values according to provisions in the current design codes for evaluation purposes. A simple but reliable approach which is based on yield line theory to estimate the flexural capacity of the strengthened slabs is also outlined in this paper.
Reinforced concrete deep beams are a vital member of infrastructures such as bridges, shear walls, and foundation pile caps. Thousands of dollars and human lives are seriously threatened due to shear failure, which have developed in deep beams containing web openings. This paper investigates numerically the overall behavior of simply supported concrete deep beams reinforced with carbon fiber-reinforced polymer (CFRP) sheets through forty specimens grouped in four groups. The numerical analysis results agreed well with the experimental results in the literature, particularly the visual failure initiation with a failure load difference of nearly 7%. Finite element analyses indicated that the presence of an opening with considerable width reduced the failure load by about 71% compared to the corresponding solid specimens. In addition, the reinforced concrete deep beam samples started to behave differently when the (b/h) ratio increased more than (2.0). The findings showed that the compression stress strut pathway had been disrupted by the web opening leading to stress redistribution, and the structure will behave as two separate members. Thus, the upper web-opening part sustained the most stress, while the part under the web-opening did not show any stress concentration. The numerical stress distribution results showed that the attributed reason is that rebars and openings helped redirect the stresses to the compression strut. Using CFRP sheets with a width of more than 160 mm significantly improved the reinforced concrete deep beam with web-opening due to the increasing confinement to the upper part of the reinforced concrete deep beams with the opening.
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