Fatigue Behavior of Welded Diaphragm-to-Beam Connections

Abstract

The purpose of this study was to evaluate the fatigue strength of a particular welded diaphragm-to-beam connection. The connection consisted of wide flange diaphragm members welded directly to the web of a deeper main beam member. Cyclic tests were performed to determine the fatigue resistance of the detail and to evaluate three different repair methods. The repair methods investigated involved combinations of diaphragm removal, drilling holes at the beam crack tips, and peening the bottom flange weld toes. This study has shown that the web and bottom flange welds of nonstaggered diaphragms are more susceptible to fatigue cracking than comparable staggered diaphragm configurations. It was also found that the fatigue life of the detail is not greatly reduced because of the formation of web and bottom flange weld fatigue cracks, because cracks formed in the beam web at the end of the bottom flange diaphragm weld controlled the fatigue behavior. Moreover, the repair methods were found to be effective in significantly extending the cyclic life of the diaphragm detail.