New design methodology for seismic column-to-foundation anchorage connections

Earlier studies have shown that post-installed reinforcing bars are capable of developing bond behavior equivalent to cast-inplace reinforcing bars. Therefore, connections with post-installed starter bars using qualified adhesives can be designed according to conventional anchorage design provisions. However, this approach often results in development lengths which cannot be accommodated in structural joints without hooks due to the limited thickness of members. The results of 16 full-scale tests presented in this paper show the beneficial effect of increased bond strengths due to column moment loading and the adverse effect of reduced bond strengths due to cyclic loading on the seismic performance of column-to-foundation connections. The quantification of both effects is a prerequisite for the development of a new design methodology for these joints, which are based on current bonded anchor design provisions. The proposed design approach potentially allows a reduction of the development length to the extent that hooks may not be required.