Seismic Behavior of Concentrically Braced Frame

Abstract

Seismic tests on a full‐scale six‐story steel building have been conducted as part of the U.S.‐Japan Joint Research Program. The first phase of this research includes extensive tests on a concentrically braced frame, and detailed results of these tests are described. The concentrically braced frame is tested for elastic, moderate, and final tests. The elastic test simulates a small, frequent earthquake, and the structure remains elastic throughout the test. The moderate test simulates an intermediate‐size earthquake. Limited yielding and brace buckling and an unusual three‐piece tear in the web of the beam at the second floor brace beam splice are noted. This unusual failure is analyzed and is compared to U.S. design practice. The final test simulates a major earthquake, and extensive brace buckling and yielding are noted. The distribution of energy dissipation within the structure is analyzed for both the moderate and final tests. The effect of brace buckling and composite action of the floor system on the seismic behavior is studied. The results of the experiments are correlated to U.S. design practice, and design recommendations are made.