Experimental and Numerical Investigation on the Behaviour of Prestressed High Strength Concrete Pile-to-pile Cap Connections

Six Prestressed High Strength Concrete (PHC) pile-to-pile cap connections were tested to evaluate their damage process and failure modes under low cyclic loading. The hysteretic behaviour, rotation angle, ductility and bearing capacity were observed and analyzed. In addition, the effect of connecting forms and cutting-off piles on seismic performance of pile-cap connections was considered and investigated. The experimental results showed that flexural bending failure occurred in all connections. There were two main failure modes. One was tensile rupturing of prestressed bars and headings, resulting in loss of bearing capacity of the connections. The other type was more severe damage due to anchor bar yield and appearance of plastic hinge. Moreover, bond-slip failure of anchor bars was not observed in the cap, and the length of anchor bars met requirements. The analysis indicated that the bearing capacity and energy dissipation capacity increased along with the rotation capacity of the pile connections. Nonlinear finite element models were established to analyze the mechanical properties of these connections using OpenSees. The load-displacement curves obtained from the numerical analysis agreed with the experimental results. The effects of various parameters on the behaviour of the connections were conducted based on the numerical model.