Experimental study of buckling-restrained braces with in-line steel core plate encased in double web wide flange steel outer unit

This paper mainly presents an experimental research on a new type of buckling-restrained brace(BRB) which uses an in-line steel plate as the core and a double-web wide flange steel member as the outer unit.A thin rubber layer is used between the core plate and outer unit as unbonded material.Uniaxial cyclic loading tests of eight BRB specimens were conducted to investigate the energy dissipation capacity of the BRBs as well as the effects of core material and brace length on the energy dissipation capacity.The results show that the structure of this new BRB is applicable and all the hysteresis curves are stable and plump.Both core material properties and brace length have significant effects on the energy dissipation capacity of the BRBs.The specimen with SLY225 as the core material has better performance such as the energy dissipation capacity,low cycle fatigue performance and plastic deformation capacity than the one with SN490B as the core material.The former can provide an additional damping ratio of 45% which is larger than the latter.It is also found that the plastic deformation capacity and the low cycle fatigue performance degrade with the increase of the brace length.