Loading and Unloading Stress‐Strain Curves for Brick Masonry

Abstract

Reloading and unloading stress‐strain curves of brick masonry tested under uniaxial cyclic compressive loadings perpendicular and parallel to the bed joint are discussed. A simple mathematical model is proposed to predict these curves at different values of plastic strain. An exponential relationship involving the axial stress, the axial strain, and the plastic (residual) strain is found to be appropriate to represent the reloading and unloading curves. It is shown that the reloading curves can be mathematically represented by a family of parabolas and the unloading curves can be similarly represented by a family of straight lines. The equations of a parent parabola and a parent straight line are used to generate the family of parabolas and the family of straight lines respectively. The families of parabolas and straight lines can then be used to compute the reloading and unloading curves respectively. Comparisons of the model predictions with the experimental reloading and unloading curves show very good agreement.