Incorporation of Rate-Dependent Fracture Properties in the Design of Precast Concrete Tunnel Segment with Hybrid Reinforcement

The design of precast tunnel segment under service load condition is mostly based on the axial force and bending moment (P-M) interaction diagram. This diagram is usually derived using flexural or tensile parameters obtained from short-term testing procedure. Considering the fact that the tunnel segments are subjected to prolonged loading, the effect of the long-term loading rate on these structures needs to be incorporated. In this paper, the assumption and model used for deriving the P-M diagram is discussed and then the procedure to include the rate-dependent tensile constitutive model in the design is presented. The rate-dependence of the P-M interaction diagram of the tunnel segment with conventional reinforcement and different type and dosage of fibres is discussed.