Dynamic Effect in the Mechanical Behavior of Friction Dissipator
Résumé
Rockfall is a natural event that causes damage to urban areas. To mitigate this
danger, flexible barriers are installed as a protective measure. This structure has dissipators that
absorb the impacting blocks' energy, thus reducing the stress in other barrier components.
According to the flexible barrier certification standard (EOTA 2018), the dissipator’s
mechanical behavior is characterized by a quasi-static tensile test at a velocity 0.002 m/s.
However, on site, the impacting blocks can reach velocities ranging between 5 and 30 m/s.
Consequently, the dissipator is loaded at higher rates during rockfall events compared to the
characterization test. Moreover, the non-activation of dissipators during rockfall events raises
questions about the adequacy of the regulatory load used to assess the dissipator’s performance. In this context, during the C2ROP national project, a friction dissipator was tested by 3 similar quasi-static and 3 similar dynamic tests. The results revealed notable variability in the dissipator's behavior during dynamic tests, while a slightly scattered behavior was observed
during quasi-static tests. Furthermore, a significant increase in the dissipator’s elastic rigidity
and plastic displacement was recorded during the dynamic tests compared to quasi-static tests.
Hence, a dynamic effect seems to exist in the dissipator’s behavior during rockfall events.