Eccentrically loaded concrete under nonuniform passive confinement

There is no doubt that the strength and ductility of concrete structures can be enhanced significantly by lateral confining with steel or fiber reinforced polymer (FRP). Nevertheless, studying the mechanical response of eccentrically loaded confined concrete has received little attention compared to the study of a concentrically loaded concrete structure. To achieve a better fundamental understanding of the mechanical behavior of eccentrically loaded concrete under nonuniform confinement, an experimental study with analytical modeling was conducted in this work. A total of 100 concrete cubic specimens were tested with eccentric loadings and various lateral confinements from a fabricated apparatus that can simulate and generate passive confining pressure. Furthermore, this study successfully extended a well-established stress-strain model, originally proposed for eccentrically loaded FRP-confined circular concrete columns, to nonuniformly confined concrete cubes. The applicability and modification of this eccentricity-based model are verified and developed with the test results in this work. This paper concluded that there is good accuracy and agreement between the theoretical predictions and test results.