Moment Transfer at Column-Foundation Connections: Analytical Studies

Steel and precast columns are commonly designed to transfer moments to foundations through cast-in-place headed anchors. The concrete breakout failure mode is not routinely checked, even though recent tests have shown it can limit the connection 's strength. This paper describes how physical test data are used to calibratefinite element models ofcolumn-foundation connections to investigate critical variables. When designing column-foundation connections with cast-in-place anchors, both beam-column joint shear strength and concrete breakout failure strength should be calculated, with the connection strength taken as the smaller of the two values. Results suggest that properly detailed distributed shear reinforcement in the foundation can increase connection strength and displacement capacity if the connection is controlled by the concrete breakout failure mode. This effect is ignored by current building codes.