Experimental study on bending resistance of large diameter double layer reinforced pipe pile joints

The failure of welded joint of the traditional lateral force pipe pile due to insufficient bending capacity has become a key problem affecting its safety and use. In this paper, a full-scale model test was carried out based on the large-diameter double reinforced pipe pile joint, and the influence of reinforcement measures such as optimizing double reinforced structure, improving reinforcement anchorage mode, improving concrete strength grade, adding steel fiber on the flexural performance, deformation and failure characteristics, crack distribution characteristics of pipe pile joint was studied. The results show that the ultimate bending moment of welded pipe pile joint can not reach the standard value of the whole pile, and the main failure mode is that the upper part of the two ends of the plate is squeezed and deformed, the lower part of the pile is opened in a drum shape, the concrete on the upper edge of the pile hoop is crushed, and the concrete under the pile body is deformed and cracked. The strengthening measures only raise the threshold of cracking moment of two pipe pile joints to a certain extent, and the bending capacity of pipe pile joints decreases with the increase of the number of holes in the end plates. Finally, a new type of bending resistant pipe pile joint is proposed, which adopts the structure form of stiffener joint at the sleeve and end plate, and replaces the steel fiber reinforced concrete pile body at the pile joint. This kind of joint effectively improves the flexural performance of the pipe pile joint, and makes the pipe pile have good toughness and ductility.