Bolted bea beam-to-diaphragm connections are often critical sections to under earthquake stresses. The Architectural Institute of Japan (AIJ) has recommended a coefficient for joints as a safety factor:α(y)=1.0 to allow beam yield and α(u) = 1.10 1.25 to prevent rupture. However, the target for these coefficients is beam-to-beam joints subject to comparatively small stresses in welded diaphragm connections. In this study, eight cantilever-beam-type specimens incorporating bolted friction joints were cyclically loaded to determine a suitable joint coefficient to meet the AIJ recommendation. Test results and calculations led to conclusion that for grade of SS400 (mild steel), α(y) needs to be greater than ζ (bending moment gradient), and α(u) needs to be over 1.35.
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