▁of ▁the ▁material . ▁Studies ▁indicate ▁that ▁the ▁effects ▁of ▁cold ▁work ▁on ▁formed ▁steel ▁members ▁depend ▁largely ▁upon ▁the ▁spread ▁between ▁the ▁tens ile ▁and ▁the ▁yield ▁strength ▁of ▁the ▁vir gin ▁material . ▁▁ ▁D uct ility ▁criteria ▁▁ ▁D uct ility ▁is ▁defined ▁as ▁‘ ‘ an ▁extent ▁to ▁which ▁a ▁material ▁can ▁sust ain ▁pl astic ▁de formation ▁without ▁ru pt ure .’ ’ ▁It ▁is ▁not ▁only ▁required ▁in ▁the ▁forming ▁process ▁but ▁is ▁also ▁needed ▁for ▁pl astic ▁red ist ribution ▁of ▁stress ▁in ▁members ▁and ▁connections , ▁where ▁stress ▁concentration ▁would ▁occur . ▁The ▁du ct ility ▁criteria ▁and ▁performance ▁of ▁low - duct ility ▁ste els ▁for ▁cold - formed ▁members ▁and ▁connections ▁have ▁been ▁studied ▁by ▁D hal la , ▁Winter , ▁and ▁Er rera ▁at ▁Corn ell ▁University . ▁It ▁was ▁found ▁that ▁the ▁du ct ility ▁measurement ▁in ▁a ▁standard ▁t ension ▁test ▁includes ▁local ▁du ct ility ▁and ▁uniform ▁du ct ility . ▁Local ▁du ct ility ▁is ▁designated ▁as ▁the ▁local ized ▁el ong ation ▁at ▁the ▁event ual ▁f ract ure ▁zone . ▁Un iform ▁du ct ility ▁is ▁the ▁ability ▁of ▁a ▁t ension ▁cou pon ▁to ▁under go ▁size able ▁pl astic ▁de form ations ▁along ▁its ▁entire ▁length ▁prior ▁to ▁neck ing . ▁This ▁study ▁also ▁revealed ▁that ▁for ▁the ▁different ▁du ct ility ▁ste els ▁investig ated , ▁the ▁el ong ation ▁in ▁ 2 - in . ▁( 5 0 . 8 - mm