Experimental Study of an All-Steel Two-Segment Core Buckling Restrained Brace

Buckling Restrained Braces (BRBs) have been exceedingly used for resisting seismicforces in framed structures. However, their design criteria are not fully establishedyet. In other words, existing codes do not specify the process of design of bucklingrestrained braces. A type of fully steel brace has been designed in the present studythat provides ease of construction and replacement of the core. The end parts of thecore and shield are so designed as to eliminate the problems that have existed in theprevious designs. the core consists of two segments that can go plastic. In all thesespecimens, the geometry and materials were the same and only the lengths of theyielding core elements were different. These specimens were tested under quasi-staticloading up to a target displacement. The results for all three specimens tested showthat minimum values of parameters specified by the AISC Steel code (maximumcompressive stress factor,  = 1.3, and minimum energy absorption factor η=200)have been achieved and in all cases they exceeded the code requirements by a largemargin ( 1.18 max  , 1108 min  ). each specimen was capable of carrying severaladditional cycles of loading (11 or more) at the end of the test. Cyclic behavior of thespecimens showed high energy absorption capabilities with strains of up to 4.6%.The idea of using multi-zone cores not only allows a better distribution of plasticregion but also enables us to stabilize the shield to the core at the middle zone, whereno plastic deformation takes place. In this way, the stability of the shield is achievedby a simple mechanism without requiring elaborate details of a stopper.

کلیدواژه ها:

Buckling restrained ، Mechanism shield ، Fatigue ، Core length ، Sliding stopper