Application of low yield strength steel on controlled plastification ductile concentrically braced frames

The hysteretic behavior of buckling inhibited braces (BIBs) (or unbonded br aces) made of low yield strength steel is investigated experimentally. Test results from four large-scale specimens showed that the BIB is able to pre vent early buckling and cracking that occur in conventional braces and deve lop to the full capacity the strength, ductility, and energy-dissipation ca pacity of the steel used. In addition, the use of low yield strength steel results in small yield deformation and dramatic strain hardening of the BIB . Earthquake simulation tests of a 0.4-scale three-storey ductile concentri cally braced frame (DCBF), which employed low yield strength steel BIBs as concentric braces, were carried out. Test results verified the applicabilit y of the BIB and the high seismic performance of the DCBF. The idea of cont rolled plastification worked well. In addition, both the 70% lateral-force distribution requirement of the Uniform Building Code and the 30% lateral-f orce distribution requirement of CAN/CSA-S16.1-94 seem unnecessary for a DC BF system.