Q2. What have the authors stated for future works in "Design procedure and experimental study on fibre reinforced concrete segmental rings for vertical shafts" ?
The replacement of this reinforcement by an adequate quantity of structural fibres ( Cf ) is a possibility that may bring technical as well as economic advantages.
Q3. What is the classical design philosophy of reinforced concrete structures?
The classical design philosophy of reinforced concrete structures (also for prestressed structures) aims to guarantee ductile behaviour close to failure.
Q4. What is the construction of the highspeed line?
The construction of several vertical ventilation shafts is included in the project of the highspeed line that will connect Madrid, Barcelona and the border of France.
Q5. What test was used to determine the consistency of the concrete in the fresh state?
In the fresh state, the consistency was characterized with the slump flow test [44] for the CSFRC and with the flow extent test [45] for the SCSFRC.
Q6. What tests are used to characterize the residual strength of the precast concrete?
Examples are the bending test on prismatic notched beams [21] or the Barcelona test [38] on cylindrical specimens, which has been reported in numerous scientific papers [39–40] and recently included in guidelines for the design of precast concrete segments [41].
Q7. What is the design of the segment?
It simulates a concentrated load pattern that might occur during transient stages or due to non-symmetric loading in service, both of which tend to be critical in terms of the design of the segment.
Q8. How many Cf values were used to estimate the minimum required to comply with the performance parameters?
For each concrete type, three Cf values (30, 45, and 60 kg/m3)were used to estimate the minimum needed to comply with the performance parameters obtained in Section 4 (Cf,min).
Q9. How many specimens were moulded to evaluate the compressive strength of each concrete?
To characterize the mechanical behaviour of each mixture in the hardened state, nine cylindrical specimens were moulded (Φ150 × 150 in mm) to evaluate the compressive strength fc according with [48] at 1, 7, and 28 days of age.
Q10. What is the purpose of this study?
This study addressed the design and the characterization of fibre- reinforced concrete segments to be used in the vertical shafts constructed with VSM.
Q11. What is the way to assess the ductility of a section of a reinforced?
This would respond to a section of an FRC segment withlocalised reinforcement to confine the concrete during the jack thrust phase and to control possible cracking due to bursting and splitting [31-37].
Q12. How many prisms were cast to perform the notched three-point test?
In addition to that, three prisms (150 × 150 × 600 in mm) were cast to perform the notched three-point test [28] and evaluate fL and fRi at 28days.
Q13. What tests are required to determine the residual strength of the fibre?
Once the fibre type has been chosen, the Cf required must be evaluated through standardized tests that characterize the residual strength of FRC.