Tweet Share

• Send by email

  Send by email

  

  Enhancing the Ductility of Fibre Reinforced Concrete for Tunnel Lining s

  Recent work has shown that hoop thrust in a tunnel lining is potentially useful for enhancing the ductility of fibre reinforced concrete sections in bending. Tests have demonstrated that under the action of an axial compressive stress, an FRC section that ordinarily displays strain-softening behaviour in pure bending can exhibit a form of ‘structural’ deflection-hardening behaviour [1]. This is potentially useful for reducing the minimum amount of reinforcement required in tunnel linings. Previously published work has outlined the requirements for a section analysis approach to the calculation of post-crack performance that is capable of modelling this behaviour based on the principles described in the Model Code 2010 [2].The present study has extended earlier work by conducting a series of parametric analyses to demonstrate the relationship between the magnitude of axial compression, the degree of post-crack residual strength exhibited by FRC in standard beam tests, and the resultant improvement in ductility in flexure at the ultimate strength limit state. The analytical approach adopted utilises concrete characteristics typical of precast tunnel segments and post-crack residual flexural strength parameters obtained from standard beam tests, but is otherwise independent of the material characteristics of the fibres used in the concrete.Present results indicate that flexural toughness parameters obtained in standard beam tests are very conservative and quite unrepresentative of performance likely under even a modest compressive hoop stress in a typical tunnel lining. Given that almost all tunnel linings exist in a state of near permanent compression, this indicates that the minimum ductility requirements necessary for the satisfactory in-place performance of FRC linings can be quite low, and that strain-hardening flexural behaviour in standard beam tests is not required to achieve excellent inplace lining ductility for the majority of underground lining applications. Fibre Reinforced Concrete, Ductility, Segments, Interaction, Design.

  Recipient :

  Name ^* :

  E-mail address ^* :

  ^* Required fields

  Send   or  Cancel

• Print