Effect of Column Studs on Column-Pile Joints in Buildings without Underground Beams

Column-pile joints without underground beams are becoming a de-facto standard for foundation structures of over-track buildings. In the current design guideline, steel column-pile joints are constructed by embedding the steel column at the top of a cast-in-place concrete pile, and the joint is reinforced by an outer steel pipe. If the joint is to retain seismic performance of the joint with a thinner steel pipe, it will need more reinforcement in the form of studs along the sides of the column and reinforcing bars. Loading tests were conducted with specimens to evaluate performance of the column-pile joint. Specimens with thinner steel pipes and without column studs show smaller strength. However, specimens with column studs and reinforcing bars show greater strength than specimens with thicker steel pipes. From the findings of the experiments above, column-pile joints with thinner outer steel pipes and column studs would seem to be most effective.