Hollow steel column base member and welding thereof

A steel column base plate member for connecting a hollow steel column member to a concrete foundation, which base plate member is a unitary body comprising a substantially planar bottom plate portion engageable with said concrete foundation, a projection upwardly extending from the planar bottom plate portion and having a top surface whose shape is substantially identical to but somewhat wider inwardly than cross sectional shape of the steel column member, J-shaped welding grooves formed along overall outer edges of said top surface of said projection facing to a lower end of said column member extending from outer peripheries of the top surface of said projection so as to effect J-shaped groove welding between said lower end of the column member and the J-shaped welding grooves, a sloped top surface formed between said projection and said bottom plate portion so as to increase the thickness thereof as the planar bottom plate portion extends toward said projection, and abutments formed on the planar bottom portion in a sufficient thickness and having anchor bolt holes bored therethrough.