Abstract
The flexural pile foundation is used in integral abutment jointless bridges (IAJBs) in practical engineering to effectively dissipate the horizontal reciprocating deformation induced by the ambient temperature or earthquake loadings. Various types of flexural piles including the H-shaped steel pile (HP), prestressed concrete pile (PC), prestressed high-strength concrete pile (PHC) as well as the reinforcement concrete pile (RC) have been implemented in IAJBs. However, there is a lack of comprehensive studies on the flexural deformation and seismic performances of these piles. In order to investigate and compare their mechanical behaviors and seismic performances, a low-cycle pseudo-static test on several different types of piles was carried out. The test results indicated that the plastic hinge location of piles moved to a deeper pile depth with the increase of reinforcement ratio, buried pile depth and prestressing level, which led to better pile–soil interaction. The crack resistance of a concrete pile was improved as the reinforcement ratio and prestressing level increased. Moreover, the rectangular pile had a better soil–pile interaction and energy dissipation capacity than the circular pile. The inflection point of the pile deformation shifted deeper as reinforcement ratio, buried pile depth and prestressing level increased, which improved the effective length and horizontal deformation capacity of piles. The H-shaped steel pile showed a better elastic-plastic deformation capacity, ductility and energy dissipation capacity as compared to the concrete pile. Moreover, the pile having a higher bearing ratio sustained larger lateral loads whereas the surrounding soil was subjected to higher loads. Finally, new seismic design criteria of three-stage seismic fortification and five damage level for the concrete piles of IAJBs were proposed.
Highlights
The integral abutment jointless bridge (IAJB) has many advantages including beneficial integrity, durability, comfortable driving and favorable seismic behavior
The pile foundations of IAJBs may be subjected to cyclic longitudinal deformations due to expansion and contraction of girders induced by ambient temperature and earthquakes, which result in a remarkable soil–pile interaction [1,2,3,4,5]
Various piles with different sections and materials such as the reinforcement concrete (RC) pile, prestressed concrete (PC) pile, H-shaped steel pile, steel tubular pile, and concrete-filled steel tubular (CFST) pile are widely adopted in the IAJBs
Summary
The integral abutment jointless bridge (IAJB) has many advantages including beneficial integrity, durability, comfortable driving and favorable seismic behavior. Huang et al [22] proposed a displacement-based simplified calculation method to analyze the soil–pile interaction of reinforced concrete and PHC pipe piles for IAJBs. It was shown that results obtained from the simplified method had a good agreement with the test results. Most of the aforementioned studies were concentrated on the behavior of one type of pile foundation for the IAJBs and, clearly, there is a lack of comparative study on the seismic performance of various types of pile for the practical engineering of IAJBs. in this research, a pseudo-static low-cyclic test was conducted on various types of pile having different cross-sections, materials, reinforcement ratios, prestressing levels and buried length. New seismic design criteria of three-stage seismic fortification and five damage level for the concrete piles of integral bridges were put forward based on the seismic design criteria of piers, which can be provided as a reference for the design specifications
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