Prediction of Structural Behavior of Continuous Reinforced Concrete Beams with Hybrid CFRP-Steel Bars

The present investigation aims to identify the flexural performance of two-span concrete beams reinforced with hybrid carbon fiber reinforced polymer (CFRP) and steel bars. By applying a finite element analysis, a comprehensive numerical assessment is performed. The investigated variables are A(f)/A(r) (A(f) = area of CFRP bars; A(r) = total area of CFRP/steel bars), load pattern (symmetrical and unsymmetrical loading) and load type (center-point, third-point and uniform loading). The results show that beams with A(f)/A(r) of 0.25 show 16.0% and 11.3% higher ultimate load at symmetrical and unsymmetrical loading, respectively, than beams with A(f)/A(r) of 0.0 (i.e., beams with steel bars), but the change in ultimate load is not apparent when varying A(f)/A(r) between 0.25 and 1.0. Unsymmetrical loading causes 6.0–15.0% greater deflection capacities than the symmetrical one. When A(f)/A(r) increases from 0.0 to 1.0, moment redistribution at symmetrical loading is decreased significantly by 62%, while the redistribution variation is marginal at unsymmetrical loading. In addition, the applicability of two equations based on the ultimate strain in tensile bars for predicting moment redistribution is evaluated. It is generally shown that these equations can account for the influence of A(f)/A(r) and load type.