Sketch of column gusseted base

A gusseted base is used for heavy column loads (sometimes with moment), where a plain slab base would need a very thick plate. The column is connected through gusset plates and angle cleats (or channels) to the base plate, so the load spreads over a larger area of concrete and the base plate is stiffened.

elevation (looking at the face of a gusset plate)

              |  column  |
              |          |
        +-----+          +-----+   <- gusset plate
       /      |          |      \
      /       |          |       \
     +--------+----------+--------+
     |__ cleat angle along gusset _|
  ====================================  base plate
  |         concrete pedestal        |
       o anchor bolt          o

plan

  +--------------------------------+
  |  o   =====================   o |  <- gusset plate + cleat
  |        +---------------+       |
  |        |    column     |       |
  |        +---------------+       |
  |  o   =====================   o |  <- gusset plate + cleat
  +--------------------------------+      base plate

Main parts:

• Column (rolled section, usually with flange cover plates) carrying the load.
• Gusset plates welded or bolted to the column flanges and connected to the base plate; they spread the load.
• Gusset angles / cleats (two per gusset) connecting the gusset plate or column flange to the base plate by bolts or welds.
• Base plate resting on the concrete pedestal; its thickness is found from the bending of the plate beyond (and between) the gussets and cleats.
• Anchor bolts fixing the base to the foundation.
• Grout between the base plate and the concrete.