This paper reports development of a new type of buckling-restrained brace (BRB) named the welded overlap core steel encased BRB. A two phase experimental research program was undertaken where BRBs were investigated under subassemblage testing. The first phase of the program aimed at studying the performance of steel encased BRBs which utilize constant width core plates. Test results indicated that these braces develop unacceptably high compression and tension resistances and the behaviors of these BRBs under uniaxial testing and subassemblage testing are markedly different. In the second phase of the research program a new type of BRB which utilizes a welded overlap core was developed to improve the cyclic performance observed in the first phase. Experimental results showed that the braces sustain axial strains that vary between 2.0 and 2.5% and resistances in tension and compression were found to improve significantly when compared with the findings of the first phase. Welded overlap core steel encased BRBs were found to sustain cumulative axial strains that are 419 times the yield strain when properly detailed. (C) 2016 Elsevier Ltd. All rights reserved.