The Hérisson® technical concept (rolled thread after cold-upsetting of the rebar, forged coupler in a high-resistant steel, locknuts to eliminate any play on the threaded rebar)* allows to reach a very high level of resistance.
One of the most severe tests of the Hérisson® coupler models an aeroplane crash situation over a reinforced concrete shell. Therefore, the "choc" test is a rapid traction test: the rebar breaks within a few seconds.
The requirement is the rebar breaks, systematically, « before » the mechanical coupler…
* The thread is rolled following cold-upsetting of the end of the rebar which increases its nominal diameter. The thread rolling maintains the steel integrity of the rebar, which assures an excellent résistance of the splice. The strength of the rebar is therefore not affected by the threading process. Hérisson® couplers are the only forged couplers,a manufacturing technique preserving the integrity of the steel fibre, which ensures the splice holds under severe constraints.