Since the beginning of the 20th century, concrete has become the most used construction material. The world production of cement in 2007 was about 2.6 billion tons, compared to just 10 million tons in 1990. Traditionally, concrete was understood as a mixture of cement, water and aggregate but in modern concrete other constituents may also be present such as mineral components, chemical admixtures and fibres. Normal and high strength concretes were developed in the early 1900''s and 1950''s, respectively, whereas the development of ultra-high- performance concrete known as reactive powder concrete (RPC) was originated in the mid 1990''s. RPC is an ultra-high strength cementitious material that contains a high quantity of cement and silica fume, low quantity of water, incorporates large amounts of fibres and exhibits remarkable ductility, durability and strength properties. In this book, the mechanical behaviour of steel fibre reinforced RPC girders is detailed and design models presented. Particular emphasis is placed on non-flexural actions such as shear and bursting where steel fibres are used to replace conventional steel reinforcing bars.