Bending Strength of Connection Joints of Prestressed Reinforced Concrete Pipe Piles

Abstract

The connection joint of prestressed concrete pipe piles is a typical steel–concrete structure, and its bending strength has evolved into a critical factor affecting the safety of supporting structures in underground engineering. Based on full-scale bending tests of five specimens of large-diameter prestressed reinforced concrete (PRC) pipe piles and connection joints, as well as the corresponding finite element numerical simulation, the bending bearing and deformation characteristics of connection joints of PRC pipe piles were analyzed, together with the effects of concrete strength, precompression stress, and connection mode of joints. The results showed that the crack resistance of the welded joint of PRC pipe piles was equivalent to that of the pipe pile shaft, but the ultimate bending moment of the joint was about 58–87% of that of the pile shaft. The bending failure mode of the pipe pile joint was mainly manifested in the end plate yielding into a drum shape, with the tension side of the pile hoop and the end plate clearly separated from the pipe pile, and crushed concrete at the upper edge of the pile hoop. The bending strength of the joint can be improved by increasing the bonding strength between the end plates of the joint or embedding Rachel reinforcement in concrete. In addition, synchronously increasing the strength grade and reinforcement ratio of concrete or strengthening the precompression stress of concrete are favorable measures.