Compressive behaviour of stub concrete column strengthened with ultra-high performance concrete jacket

This paper firstly performed compressive tests on 18 stub concrete columns with externally confined ultra-high performance concrete (UHPC) jacket. The studied parameters in this testing programme were the thickness of UHPC jacket and the shapes of specimens. The influences of these parameters on the compressive behaviour of stub concrete columns confined by UHPC jacket were reported and discussed. The test results revealed that increasing the thickness of confining UHPC jacket significantly improved the compressive behaviours of concrete stub columns for cylindrical shaped column. However, this influence on that of square shaped stub columns was less significant. An analytical model was proposed to predict the compressive stress-strain behaviour of stub concrete columns with externally strengthening UHPC jacket. The validations of the predictions against the reported test results confirmed the accuracy of the analytical model. The compressive behaviour of stub concrete columns with UHPC jacket was also simulated by 3D nonlinear finite element model (FEM). Validations against the reported test data proved that the FEM simulated well compressive behaviour of concrete stub columns with UHPC jacket.