In a study of previous weak-axis moment connection tests it was noticed that the most common failure mode was brittle fracture initiating near the edge of the beam flange groove weld. The cause was large stress concentrations due to force flow towards the stiffer column flanges, which is the opposite pattern as strong-axis moment connections. As part of the SAC (a partnership of SEAoC, ATC, and CUREE) study, two full-scale weak-axis moment connections, utilizing the reduced beam section (RBS) design, were statically tested under simulated seismic loading. Both specimens were able to reach the required 0.03 rad of plastic rotation without experiencing brittle fracture or large stress concentrations at the critical section. A series of parametric studies was carried out, using a finite-element analysis program, to better understand the behavior of weak-axis RBS moment connections. It was found that the RBS was able to reduce the critical strain concentration by a factor of nearly three as compared to specimens without the RBS. Based on these analytical results and experimental tests, a design procedure for weak-axis RBS moment connections was developed.
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Gilton et al. (2002) studied this question.