Experiment on Interaction of High Performance Concrete Pile-Soil in IAJBs

High-performance concrete (ECC and UHPC) pile foundations have the advantages of excellent crack resistance and high bearing capacity, which can better meet the longitudinal deformation of piles in integral abutment jointless bridges (IAJBs). Low-cycle reciprocating pseudo-static tests were carried out on interaction of high-performance concrete pile-soil. The failure characteristics, crack resistance and bearing capacity of the pile were obtained. The distribution laws of pile strain, pile deformation and pile side soil resistance were analyzed and compared with the reinforced concrete (RC) pile. Meanwhile, the usability of commonly used codes were discussed. Some findings were as follows. ECC and UHPC materials can significantly reduce the damage of the pile foundation, increase the horizontal bearing capacity and crack resistance compared to RC. The damage position of the high-performance concrete pile is deeper, the effective pile length of the pile is longer, and the seismic performance is better. In special, the ECC pile has the strongest anti-cracking ability, its cracking displacement and cracking load can reach 15 mm and 5.8 kN, respectively. The deformation of high-performance concrete piles continuously reduces along the buried depth, and approaches zero at 15 m and deeper. The soil resistance of pile side increases first and then decreases, the resistance and deformation of the pile bottom soil are both 0; the strain of the pile shaft is symmetrically distributed with an "olive" shape, and there is larger strain in the interval of 4D to 6D buried depth. Furthermore, both the "m" method and the new API standard method can estimate the high-performance concrete pile displacement better when the displacement of pile top is within 10 mm. When the displacement exceeds 10 mm, the "m" method is no longer applicable. Neither the "m" method nor the new API standard method can predict the bending moment of the high-performance concrete pile well, indicating poor applicability. The new API standard method is recommended for estimating soil resistance of pile side.