SUMMARY A new buckling restrained braced frame system is proposed for reinforced concrete building structures, which is featured by the zigzag configuration of the braces and the corresponding connection details. The connection details tend to separate the vertical and horizontal components of force imposed by the braces to be resisted by independent structural components to make the behavior of the connection easier to estimate and control. The performance of the brace connection details was evaluated through cyclic load testing on 1/2‐scale subassemblies of the proposed system, each of which consisted of a reinforced concrete part and a set of buckling restrained braces. To simplify the test control, the specimens were rotated 90° in the test and were loaded by two displacement controlled actuators. The test results show that the normal and the shear resistance of the gusset plate connection are essentially independent of each other. However, the rotation of the gusset plate with respect to the beam‐to‐column joint may result in nonuniform force distribution of the anchor bolts, the primary resistance for tensile force. At the same time, such rotation may also subject the concrete corbels, the primary shear resistance, to unfavorable tensile force. In addition, it is also confirmed that the buckling restrained braces performed well in the proposed system. Copyright © 2012 John Wiley & Sons, Ltd.

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An unconstrained gusset connection for buckling restrained braces in reinforced concrete frame structures is proposed and tested as an effort to mitigate the complicated and usually harmful interactions between the steel gusset plate and the adjoining reinforced concrete column. Local damage control incorporating the rearrangement of beam flexural strength is also proposed to enhance the reliability of the gusset connection by moving the potential plastic hinge of the beam away from the connection region. Two different connecting methods, one with post-tensioned steel rods and the other embedded stud groups, were considered. The results of the cyclic loading tests on RC beam-gusset connection subassemblies confirmed that both connecting methods are available as long as the local damage control is implemented, which is not only helpful in eliminating the unfavorable deformation loss at the connection, but more importantly, can prevent the BRBs from being dislocated as a result of the beam end failure in extreme earthquake events.

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