Flexural Stiffness and Second-Order Effects in FRP-RC Frames

Present ACI guidelines for fiber-reinforced polymer (FRP)-reinforced concrete (RC) structures (ACI 440.1R-15) do not cover axially loaded members. This omission can be partly attributed to the unavailability of certain parameters that influence the analysis and design of FRP-RC frames. Parameters, chief among them the assumed flexural stiffness of columns whether for structural analysis or for slenderness effects, are well established by ACI 318, but only for steel-RC and are not readily available for FRP-RC. In this paper, provisions of ACI 318 on the stiffness of columns and second-order effects in non-sway frames subject to gravity loads are recalculated for FRP-RC columns. Hence, a set of requirements parallel to those of ACI 318 is proposed that ensures: a) smooth transition for designers from the conventional provisions of ACI 318 to those of an envisioned FRP-RC code; and b) performance for FRP-RC structures comparable to that of steel-RC.