Identification of bending moment in semi-fixed beam

Abstract

Paper presents procedure of identification of supporting moment in the statically indeterminable, partly fixed reinforced concrete beam. Examined beam is a part of reinforced concrete frame, where rate of fixing is subjected variation under influence of continually increasing loading. Bending moment at the fixing end remains the unknown internal force in the beam. This internal force is determined on the basis of identification of theoretical and experimentally measured deflections in the selected sections of element. Theoretical deflections are computed numerically integrated curvature equation of the beam axis under assumption that effects of physical nonlinearity of reinforced concrete reveal in the process of loading. These effects describes quantitatively the Muraszew’s theory of stiffness changes. Boundary problem of partly fixed beam is solved applying iterative procedure characteristic the initial problem applying integration schema ahead with increased accuracy.