محمد واقفی

In this paper, a numerical model based on the fiber method is used for nonlinear analysis of three dimensional reinforced concrete moment resisting frames. The bond-slip effect has been considered in the formulation of beam-column and joint elements. Two types of joint and beamcolumn elements are used in the formulations. Biaxial bending and axial force in the cross section of elements assumed to be nonlinear but the torsional behavior remains in elastic range. The theory of numerical calculations is similar to fiber method but the perfect bond assumption between the bars and surrounding concrete has been removed. The reliability of the numerical method has been assessed through the comparison of analytical and experimental cyclic results. Including the ability to use this method is that it takes embedded length of longitudinal bars in the joints into account and also considers nonlinear relation for the bond-slip effect. By definition of bond-slip effect in three cases of weak, normal and strong conditions, analytical behavior in two fields of strength and stiffness have been compared to the corresponding real and experimental values.