Parametric study of the strength of reinforced concrete polygonal sections submitted to oblique composite flexion

This work aims to verify the influence of characteristic compressive cylinder strength ( f c k), section geometry and eccentric axial load on the strength of square, cross, “T” and “L” reinforced concrete sections, under oblique composite flexion. A computational algorithm was created to calculate sections interaction diagram of bending strength, taking into account NBR 6118 idealized parabola-rectangle stress-strain relationships for 20 to 90 MPa f c k concretes. The results show that f c k influence is stronger for higher values of axial load and that the failure surface shape in interaction diagrams depends directly on the f c k and on the rebars distribution in the section. Furthermore, under lower compressive axial loads, higher oblique composite flexion strengths are reached when there is more reinforcement area in tension regions but, as the compression increases, the reinforcement presence and larger concrete areas in compression zones provide higher bending moment strengths.

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