Reduced Brace Section (RXS) Proof of Concept: Phase 1B

Abstract

This report presents the results from the second phase of a proof-of-concept series of tests of the reduced braced section (RXS) system. This system is intended to provide a cost-effective alternative for the design of Concentrically Braced Frames (CBFs) under earthquake loads. The second test investigated the behavior of the RXS system under cyclic loading. The hysteretic behavior of the specimen indicated that the behavior of the RXS system was sensitive to the eccentricity of the load imposed on the brace. Eccentric loading caused premature local bucking of the reduced section, which reduced the ability of the system to dissipate energy under repeated load reversals into the nonlinear range of response. The behavior observed during the test shows that local buckling is a mode of failure that must be prevented in this type of system because of its adverse effect on the ability of the system to dissipate energy. Also, the design of the system must take into account a minimum eccentricity of the load transmitted to the brace at the brace-frame connection. An alternative to improve the behavior of the system under repeated load reversals is to reinforce the reduced section in order to increase the local bucking load. This report includes the applicable information specified in TEST REPORTING REQUIREMENTS [AISC, 2002, S9].