Connections of Pipe Piles to Bridge Bent Caps: Full-Scale Tests

Abstract

Due to their durability, strength, and adaptability to challenging conditions, large diameter steel pipe piles are a promising solution for multi-span bridges. However, guidance on practical and effective connections between steel pipe piles and concrete members is limited. An ongoing study is focused on steel pipe pile to concrete bent cap connections in substructures, including full-scale tests of five connection types: (1) headed-bars, (2) hooked-bars, (3) straight-bars, (4) welded shear studs, and (4) an annular ring welded at the pile end, which are documented in this thesis. Connection subassemblages, each consisting of a 36 in. diameter pile and a 54 in. deep bent cap, were fabricated. A 3 ft diameter steel pile was used in all cases. Specimens were subjected to lateral load cycles of increasing intensity, inducing internal forces to simulate service conditions and ultimate strength. Different types of sensors were used to measure the displacement of the specimens, the strains of the steel pile and reinforcing bars, and the rotation of the pile. Constructability of the connections was discussed, comparing the ease of construction of each type of connection. Results and observed behavior of all five specimens were favorable under service- and strength-level loads. The three reinforcing steel connections vastly exceeded the capacities estimated using conservative design assumptions and principles. This demonstrates the significant contribution of the steel pipe pile to the capacity of the system. The welded mechanical anchorage connections showed a behavior closer to the estimated capacities that include the contribution of the pile. The different types of connections presented in this study demonstrated to provide an alternative to current practices. The annular ring and headed-bar connections represent a great alternative to reduce the construction time of the connections.