Behavior of circular steel tube confined UHPC and UHPFRC columns under axial compression

This dissertation reported primarily an assessment of the axially compressive behavior of circular STCC stub columns based on the previous test results and a developed finite element model (FEM) in ATENA-3D software for these columns with various concrete strengths. This provides the starting point for the main experimental investigations presented in this dissertation. Then the constitutive behavior of UHPC without fiber and with steel fibers (UHPFRC) was investigated by the compression tests on cylindrical specimens and direct tension tests on notched prisms, thereby determining the influence of steel fiber content and aspect ratio on the uniaxial compressive and tensile responses.