Concrete in Biaxial Cyclic Compression

An experimental program was conducted to study the behavior of concrete under low‐cycle high amplitude biaxial cyclic compression. Biaxial loading was achieved by subjecting square concrete plates to in‐plane loading where compressive stress was applied in one direction while confining the deformation of the specimen in the orthogonal direction. Three main types of tests were performed: Monotonic loading to failure; cycling of compressive stresses to a limiting envelope curve; and cycling of compressive stresses to prescribed values. In each category, tests were performed on specimens under different levels of strain confinement, and for comparison, on unconhned specimens. Complete stress‐strain histories were recorded and analyzed to assess the effect of confinement on concrete behavior under different nonproportional load conditions. A simple predictive model for the constitutive behavior of concrete in biaxial cyclic compression is proposed. Predicted behavior from the model which does not require any a priori information from experiments is found to be in good agreement with the measured response.