Design procedure and experimental study on fibre reinforced concrete segmental rings for vertical shafts

Abstract

Structural fibres are used to replace partially or totally the passive reinforcement in precast concrete segments for tunnel linings constructed with TBM, showing several advantages. Fibre reinforced concrete (FRC) could also be applied with similar benefits to vertical shafts. However, to the author's knowledge, this material has not been used in such application yet. The Model Code 2010 gathers an approach for the design of FRC structural elements. This approach should be adapted according to the structural needs of precast segment, for which the transient load stages are often the most critical and specific ductility requirements should be established. The objective of this paper is twofold: propose a general analytical formulation to assess the minimum mechanical requirements that FRC must fulfil in case of partial or complete substitution of the steel rebars and confirm that it is possible to replace the rebars by using fibres in vertical shaft linings. First, the general analytical formulation is proposed. Then, the segments of the Montcada vertical shaft (Barcelona) are redesigned considering the total substitution of the traditional reinforcement by fibres. Finally, two full-scale tests of the FRC precast segments were performed to verify the suitability of the analytical formulation proposed.