A novel approach to long-term load-carrying capacity assessment of circular reinforced concrete support structures considering hereditary creep

In this study, a multi-step numerical method was suggested for solving the integral constitutive equation for hereditary creep, accounting for the nonlinear characteristics of instantaneous and time-dependent concrete deformations. Numerical verification demonstrates that the method exhibits high computational stability and accuracy, even for relatively large values of time increments in the solution of relaxation problem. By incorporating hereditary creep effects, the long-term loading response of reinforced concrete support structures is practically transferred into a series of incremental short-term static analyses performed at discrete time points. The structural model considers a cantilever circular reinforced concrete member subjected to axial compressive and transverse lateral loads applied at its free end. The proposed computational model enables the determination of the time evolution of the load-carrying capacity and stress–strain state from the initial loading stage to any specific load value. Parametric numerical calculations revealed that low transverse loadings alone caused a considerable loss in the load-carrying capacity. Moreover, through the formulation of a new creep coefficient function from a solution to the relaxation problem, the time-dependent stress–strain behavior and capacity loss were accurately captured using a series of equivalent short-term static analyses. The numerical investigations determined that this creep coefficient function had extremely low sensitivity to load amplitudes, which was predominantly a function of the loading duration. It was quantitatively verified that genetic creep can reduce the load capacity of structural members by a maximum of 30%. Keywords: concrete; reinforcement; hereditary creep; creep coefficient function; load-carrying capacity.