Studying on Bending Resistance of Monolithic Steel Structure of Pile–Pier

This paper describes the structural features, design procedure, and bending performance of a novel substructure—monolithic steel structure of pile–pier (MSSPP), which does not have footings, and all the piles and piers are continuous. In other words, one monolithic member functions as both the foundation and column. Such structures exhibit many advantages, such as reduced construction time and occupied area. However, the lack of footing and continuity of the piles–piers generally reduce the bending resistance and stiffness. To increase the bending resistance, an MSSPP is constructed using steel pipes with a diameter of approximately over 1000 mm and concrete is partially filled along the length of the pipes. Such an MSSPP can be applied to large-span bridges of approximately 40 m. In this study, we focus on the bending resistance of MSSPP and conduct a bending test on a part of a full-scale MSSPP. The test results indicate that the bending resistance of the MSSPP reaches the ultimate design value of the concrete-filled steel tube specified in TCVN 11823-2017, even though the inner concrete is only partially filled into the steel pipe.