Abstract: The integral abutment jointless bridge (IAJB) has lots of advantages, so it has been widely used in western countries. The pile foundation of IAJB requires higher horizontal deformation capacity. H-beam steel piles are often used to construct integral bridges in the west, while RC piles are mainly adopted in China. Lots of studies and engineering examples show that the application of RC piles can meet the deformation requirements of IAJBs, but the influence of the earth pressure behind abutment on RC piles is not clear. Therefore, based on a practical IAJB in China as an engineering background, with certain RC pile reinforcement ratio and the shape of the section as parameter, four integral abutment-RC pile test models were designed. The reciprocating low-cycle pseudo-static test on interaction of integral abutment-H-shaped pile-soil was carried out to study the hysteretic behavior, lateral deformation law and interactive mechanism. The test results show that under the reciprocating displacement loading, the soil behind the abutment will be emptied, and the failure positions of the specimens are mainly concentrated at the connection between the bottom of the abutment and the top of the pile. Increasing the reinforcement ratio of RC piles or using rectangular section RC piles can lower the failure positions and improve their mechanical properties. The hysteretic curve of the integral abutment-RC pile-soil system is full in the first quadrant, indicating better energy dissipation capacity, while the third quadrant hysteretic curve has a smaller covering area. The experimental results also show that the abutment movement can be regarded as a rigid displacement with rotation, and under the action of reciprocating displacement beyond the limit of elastic deformation, the abutment and the pile appear obvious cumulative deformation. Besides, the relative angle between abutment and pile head increases as the damage degree increases. Accordingly, by increasing the reinforcement ratio of RC piles or adopting rectangular section RC piles, 1) the energy dissipation capacity of the whole bridge-RC pile-soil system can be increased; 2)the elastic cracking displacement of RC piles can also be increased, which leads to its later yield and failure and increases the bearing capacity of the whole system; 3) the stiffness degradation rate and degradation amplitude of the system are significantly reduced; 4) the failure of bridge abutment and pile joint, along with the accumulated deformation, can be effectively reduced.

Key words: bridge engineering, pseudo-static test, interaction of abutment-pile-soil, RC pile, ratio of reinforcement, shape of pile section, deformation capacity