The　use　of　high　strength　steel　(HSS)　cold-formed　hollow　section　is　of　significant　interest　in　the　construction　sector　due　to　competitive　costs.　The　accurate　simulation　of　ductile　fracture　failure　at　the　micro　and　macro　scale　is　critical　for　improving　the　validity　of　predicting　structural　behaviour　of　HSS　cold-formed　hollow　sections　and　welded　joints.　In　this　study,　the　ductile　failure　of　the　cold-formed　S700　material　is　studied　using　the　Gurson-Tvergaard-Needleman　(GTN)　damage　model.　Representative　volume　element　(RVE)　models　with　the　void　volume　fraction　(VVF)　between　0.1%　and　30%　are　employed　to　investigate　the　pressure　dependency　of　the　deviatoric　limit　stress.　Different　load　conditions　corresponding　to　different　stress　triaxiality　levels　are　applied　to　unit　cells　with　random　spherical　pores.　The　inelastic　response　of　the　unit　cells　are　analysed,　and　the　parameters　q(1),　q(2),　and　q(3)　in　the　GTN　yield　surface　are　calibrated.　An　equation　is　proposed　to　determine　parameter　q(1)　for　different　VVFs.　The　parameters　critical　VVF　f(c)　and　final　VVF　f(f)　are　calibrated　by　the　coupon　test　from　the　literature.　Finally,　the　calibrated　GTN　model　is　validated　against　notched　coupon　tests.　The　finite　element　(FE)　results　show　good　agreement　with　the　experimental　results,　indicating　that　the　identified　GTN　model　could　efficiently　predict　the　behaviour　of　the　cold-formed　HSS.　(C)　2021　Elsevier　Ltd.　All　rights　reserved.