An Investigation for the Capacity of Membrane Action of Slender Reinforced Concrete Beam Sub-Assemblages

One of the favorable structural mechanism to mitigate the progressive collapse in reinforced concrete structures and increase the load-carrying capacity is the mechanism of compressive membrane action. In the present study, for predicting the compressive membrane capacity, an analytical model for analysis of reinforced concrete beams is used. This analytical model is formulated based on a sectional analysis approach to establish equilibrium and compatibility conditions at each section along the length of the beam. Programming of the analytical model for analysis of RC beams was carried out with FORTRAN software. In order to investigate the membrane action in slender RC beams, several beam specimens with different span-depth ratio are analyzed in parametric studies. Analyzes are carried out to investigate the effect of four parameters of concrete compressive strength, reinforcement ratio, axial stiffness and rotational stiffness of the support on the membrane action in RC beams. The results show that with increasing the span-depth ratio, the effect of membrane action on beams decreases. It is also observed that the effect of all four parameters on the load-carrying capacity is greater in short beams. In evaluating the effect of support stiffnesses on the membrane action response, it was also observed that membrane action capacity increases with restraint stiffness only in the regime of weak restraints. Axial stiffness and span-depth ratio have the highest effect on axial restraint response, and also it is observed that rotational stiffness of the support and span-depth ratio have the highest effect on the maximum midspan deflection response.