where: *d* and *t* are diameter and thickness of the circular hollow profile, respectively; *N*_{Ed} is the brace design axial force; *N*_{pl,Rd} is the brace plastic resistance; *N*_{b,Rd} is the brace buckling resistance; is the brace normalized slenderness; *Ω* is the over-strength factor; *γ*_{Rd} is the steel over-strength factor that is the ratio between the average and the characteristic values of the yielding strength; *γ*_{pb} is a factor representative of the residual brace strength after buckling; *N*_{EdG} is the axial force corresponding to non-seismic loads and *N*_{EdE} is the axial force corresponding to seismic loads. |