9504186 Kiousis A fundamental experimental and theoretical study on high- strength (HS) concrete structures is conducted in this project. In the first part of this research, basic triaxial testing will be performed on HS concrete to evaluate its lateral expansion tendencies and ability to gain ductility with increased confinement. A theoretical analysis based on a simple plasticity model and the compatibility of deformations of the concrete core and the transverse reinforcement will compliment the experimental work. The second part of the research will concentrate on the testing of HS concrete structural elements that are subjected to combined axial compression and shear loading. A theoretical analysis, based on the concepts developed will be performed to predict the response of HS concrete structural elements. The research is expected to contribute to the development of reliable code provisions for the design of HS concrete structural elements. ***