Concrete confining methods have been proven to be an effective means to strengthen concrete structures. A new confining method is introduced in this book, which by applying lateral pre-tensioning force to the concrete to increase the confining efficiency, namely the Steel-strapping tensioning technique (SSTT). It is particularly effective in strengthening high-strength concrete (HSC) due to its pre-tensioning feature. To further extend the scope of existing studies on plain concrete or reinforced concrete short columns, this book incorporates the discussion on the insight of slender reinforced HSC columns. In particular, the structural behaviour of slender SSTT-confined HSC columns subjected to eccentric loading. Furthermore, the development of lower- and upper-bound slenderness limits for the confined columns is presented. A set of equations and design procedures for confined columns have been proposed in this book. The design procedure is simple yet guaranteed high safety and reliability, which can be used as groundwork for the design development of other confining methods such as Fibre-reinforced polymer confinement, steel-jacketing, and concrete jacketing.