FRC Tunnel Linings: New Design Perspective

Fiber Reinforced Concrete (FRC) is commonly used in tunnel construction as shotcrete or final lining, both conventional and segmental. Designer usually prescribe a fiber content for obtaining the structural performance required. Since FRC is a composite whose properties depend on both the matrix and fiber content and type, the fiber dosage can not guarantee any minimum FRC performance. The enhanced property of FRC is its toughness that is usually determined by means of fracture tests on notched beams. The new Model Code prepared by fib (Féderation Internationale du Béton), includes FRC among the structural materials and provides material performance classes and design rules for FRC structural elements. This paper aims to briefly explain the main concepts behind the Model Code rules for structural design of FRC tunnel linings and show an alternative test method for material characterization