There has been a lot of recent discussion on base plate design, including
available software and the merits and demerits of stiffeners. There is another
design issue that needs to be considered in high seismic zones.
Specifically, how do you design a column base plate to ensure that hinging forms
in the column before:
a) the base plate yields or fractures
b) the anchor bolts yield or fracture, or
c) the concrete crushes?
I know that SAC is touching on the topic, although not to the same level of
detail of the beam-to-column moment connections. I am also aware of the
doctoral dissertation work done at the University of Michigan by Fahmy,
Stojadinovic, and Goel.
All indications are that the use of thicker column base plates leads to an
increase in strength, ductility, and rotational stiffness of the connection, all
desirable features in high seismic areas. I am sure that there are also
significant welding considerations to ensure the desired performance. These
"high seismic" considerations may invalidate all the base plate design and cost
"rules of thumb" that have been discussed.
Is anyone else doing work in this area?
Rick Drake, SE
Fluor Daniel, Aliso Viejo, CA