Dimensional Problems of
Conventional Reinforcement
Present-Day Codes
Because of the limitations of the machines used in present-day
technology to fabricate conventional reinforcing steel, codes still allow a
large dimensional tolerance of ± 13mm (± ½).
Bar Confinement Problems
When conventional hoops are installed as shown, the hoops do not
confine the longitudinal rebar when it is resisting axial compressive forces,
Consequently in past earthquakes these unconfined rebars have buckled causing
failures.
Conventional hoop and crosstie transverse reinforcement has
caused many constructability problems for design and construction engineers
since the importance of ductility was first recognized.Hoop and crosstie reinforcement is
fabricated on benders, to very loose dimensional tolerance of ±13 mm (±
1/2").Poor fitting hoops caused
damage in structures during the Loma Prieta earthquake, as shown in the above
photo.