Amirkabir University of TechnologyAmirkabir Journal of Civil Engineering2588-297X54420220622An Investigation on the Capacity of Membrane Action of Restrained Slender Reinforced Concrete BeamsAn Investigation on the Capacity of Membrane Action of Restrained Slender Reinforced Concrete Beams15331552440410.22060/ceej.2021.19684.7235FAMehdiKoohestaniDepartment of Civil Engineering, Faculty of Engineering, Ferdowsi University of Mashhad. Mashhad. IranJournal Article20210301In recent years, several studies have been conducted on the membrane action of restrained reinforced concrete beams. Several factors and parameters are involved in the analysis and calculation of this phenomenon. Determination of the effect of each parameter on the response of the load-carrying capacity of these beams is the main purpose of this study. An analytical model for the analysis of slender restrained reinforced concrete beams with different span-depth ratios is used to investigate the effect of four parameters of concrete compressive strength, reinforcement ratio, axial stiffness and rotational stiffness of the support. This analytical model is formulated based on a sectional analysis approach to establish equilibrium and compatibility conditions. Programming of the model is carried out with FORTRAN software. The results show that with increasing the span-depth ratio, the effect of membrane action on the capacity of beams decreases. It is also observed that the effect of all four parameters on the load-carrying capacity is greater in short beams. With an increase of 0.75% in the concrete compressive strength with a span-depth ratio of 9, the load-carrying capacity increases to 111 kN, while for the ratio of 31, this value increases only to 26 kN. The load-carrying capacity response is nonlinear with the amount of support stiffnesses. In evaluating the effect of support stiffnesses on the membrane action response, it was observed that membrane action capacity increases with restraint stiffness only in the regime of weak restraints.In recent years, several studies have been conducted on the membrane action of restrained reinforced concrete beams. Several factors and parameters are involved in the analysis and calculation of this phenomenon. Determination of the effect of each parameter on the response of the load-carrying capacity of these beams is the main purpose of this study. An analytical model for the analysis of slender restrained reinforced concrete beams with different span-depth ratios is used to investigate the effect of four parameters of concrete compressive strength, reinforcement ratio, axial stiffness and rotational stiffness of the support. This analytical model is formulated based on a sectional analysis approach to establish equilibrium and compatibility conditions. Programming of the model is carried out with FORTRAN software. The results show that with increasing the span-depth ratio, the effect of membrane action on the capacity of beams decreases. It is also observed that the effect of all four parameters on the load-carrying capacity is greater in short beams. With an increase of 0.75% in the concrete compressive strength with a span-depth ratio of 9, the load-carrying capacity increases to 111 kN, while for the ratio of 31, this value increases only to 26 kN. The load-carrying capacity response is nonlinear with the amount of support stiffnesses. In evaluating the effect of support stiffnesses on the membrane action response, it was observed that membrane action capacity increases with restraint stiffness only in the regime of weak restraints.https://ceej.aut.ac.ir/article_4404_ccde797ccc42911b9d77e9ad9f23f7ce.pdf