Cyclic hardening criteria in EN 15129 for steel dissipative braces

Abstract The EN 15129 standard specifies the requirements for anti-seismic devices in Europe. The nonlinear displacement dependent device (NLD) group collects solutions that typically use the nonlinear properties of their material to dissipate energy and mitigate seismic damage. EN 15129 controls the cyclic hardening behavior of NLDs with a set of stringent regulations. The primary objective of this paper is the investigation of the background and consequences of these regulations through a series of numerical analyses. Nonlinear cyclic hardening of pure S235 grade steel and a buckling restrained brace are evaluated in a material level and an element level analysis, respectively. Numerical results confirm that steel-based NLDs can hardly comply with EN 15129 regulations. The secondary objective of the paper is the proposal and verification of an advanced set of regulations for NLD hardening control. Advantageous properties of the proposed regulations are confirmed by numerical analysis at both material and element levels.