Large-scale beam-column tests incorporating Bartec/Fortec and Griptec couplers located at the expected plastic hinge zone, together with un-spliced rebar specimens, have been performed under loading simulating seismic load conditions.
Highlights of the test include:
• Both coupler systems allowed the development of ultimate rotation levels that are likely to be adequate for typical seismic design situations.
• The capacity was largely the same for all non-axially loaded members, suggesting that the use of Bartec/Fortec and Griptec couplers do not notably influence the member capacity.
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The seismic performance of reinforced concrete members incorporating Dextra Bartec/Fortec and Griptec couplers
Ductility is a key performance characteristic for concrete reinforcement used in seismic design. The ductility of mechanical rebar splices, when used in seismic design, is therefore also extremely important and sometimes not sufficiently considered in product standards and testing practices.
Dextra recently collaborated with Imperial College London, in an experimental study and associated numerical assessment, into the performance of mechanical slices in dissipative regions of reinforced concrete members.
Monotonic and cyclic uniaxial ‘in-air’ and ‘in-concrete’ tests on 16mm and 20mm Bartec/Fortec and Griptec mechanical splices, as well as non-spliced reference members, were firstly performed.
After obtaining a detailed insight into the uniaxial behavior of the mechanical splices, large-scale beam-column members of 300×300mm square cross-section and 1,350mm cantilever length were tested.
The specimens were subjected to reversed cyclic lateral deformation, with or without co-existing axial load. Three specimens were provided with couplers in the expected plastic hinge zone while for comparison a fourth specimen had continuous longitudinal reinforcement.
Prior to the large-scale member tests, predictive numerical simulations were performed in order to steer the experimental assessment.
Specimens preparation a) reinforcement cages, b) members after formwork removal
Specimens preparation a) using Bartec/Fortec, b) using Griptec
The load-deformation responses showed that both uniaxial “in air” and “in concrete” Griptec couplers seemed to provide marginally less ductility than Bartec/Fortec splices and non-spliced specimens.
However, it is thought that the ratios between coupler and rebar length considerably influenced the performance of the in-concrete tie members. The comparative assessment between in-air and in-concrete tests show lower ultimate deformations on in-concrete members in comparison with in-air samples.
For the large-scale beam-column tests, the capacity was largely the same for all non-axially loaded members, suggesting that the use of Bartec/Fortec and Griptec couplers does not notably influence the member capacity.
With regards to ductility, both coupler systems allowed the development of ultimate rotation levels that are likely to be adequate for typical seismic design situations, although Bartec/Fortec performed slightly better due to its shorter length.
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संदर्भ
Bompa, D. V., & Elghazouli, A. Y. (2019). Inelastic cyclic behaviour of RC members incorporating threaded reinforcement couplers. Engineering Structures, 180, 468–483. https://doi.org/10.1016/j.engstruct.2018.11.053
Bompa, D. V., & Elghazouli, A. Y. (2018). Monotonic and cyclic performance of threaded reinforcement splices. Structures, 16, 358–372. https://doi.org/10.1016/j.istruc.2018.11.009
