Abolhassan Astaneh-Asl wrote:
"Dear Friends in Seaint: I am writing a Steel TIPS (Technical Information
and Product Services ) report for SSEC (Structural Steel Educational
Council) on the Behavior and Design of Base Plates for Steel
Concentrically Braced Frames with focus on seismic+gravity effects..."
Dr. Asteneh,
A few years ago I designed some big (to me) base plates for some double columns acting as cantilevers (flagpole loading). I talked with the late Robert Dexter and a graduate student of his, whose name I unfortunately don't remember, at the University of Minnesota. They had either done research, or knew of it, at Lehigh, regarding baseplates and the connection of the column to the baseplate. Among other things, they learned that a wideflange column in weak-axis bending is extremely dangerous, as there is a large stress concentration in the weld at the tips of the flanges. In their tests, this condition caused brittle fracture in a startling percentage of the tests (around 25 percent, if memory serves).
It seems to me this fact deserves wider dissemination.
For what it's worth, my solution was to weld plates across the flange tips, and then to the baseplate, eliminating the stress concentration at the flange tips due to weak-axis bending.
Most of my discussion was with Dr. Dexter's grad student, a very helpful and knowledgeable fellow from Korea. If he is reading this, my apologies for not remembering his name, as I appreciated his help greatly.
HTH,
Mike Hemstad, P.E.
MBJ
Minneapolis, Minnesota