Behavior and analysis of pile caps with poor anchorage details

Graduation date: 2012Pile caps are structural elements used to transmit loads from structural columns into pile groups. A pile cap is generally constructed of reinforced concrete and contains only minimal flexural reinforcing steel. Using modern design methods, the anchorage of the flexural steel may limit the design capacity of existing pile caps. To develop new data on performance of existing pile caps with poorly detailed flexural reinforcing steel, four pile cap specimens were constructed and tested. The specimens were full-size representations of in-situ pile caps used in a mid-rise hospital building. Materials used to construct the specimens were selected to represent those of the in-situ pile caps. Tests were conducted until failure or the maximum capacity of the hydraulic loading system was achieved. Design methods were used to compare the predicted design strength with the measured experimental strength of the specimens. Based on the observed experimental response, specimens exhibited either two-way punching shear or one-way shear failure modes. Widespread yielding and little relative slip of the embedded reinforcing steel were observed. The modern design methods were sometimes conservative and sometimes unconservative in predicting the strength of the specimens