Abstract
The seismic design of bridges may require a large-diameter deep pile foundation such as a cast-in-steel-shell (CISS) pile where a reinforced concrete (RC) member is cast in a steel casing. In practice, the steel casing is not considered in the structural design and the pile is assumed to be an RC member. It is partially attributed to the difficulties in evaluation of composite action of a CISS pile. However, by considering benefits provided by composite action of the infilled concrete and the steel casing, both the cost and size of CISS pile can be reduced. In this study, the structural behavior of the RC pier and the CISS pile connection is simulated by using an advanced 3D finite element (FE) method, where the interface between the steel and concrete is also modeled. Firstly, the FE model is verified. Then, the parametric study is conducted. The analysis results suggest that the embedment length and the friction coefficient between the steel casing and the infilled concrete affect the structural behavior of the RC pier. Finally, the minimum embedment length with reference to the AASHTO design guideline is suggested considering the composite action of the CISS pile.
Highlights
Cast-in-steel-shell (CISS) piles are driven pipe piles filled with cast-in-place reinforced concrete (RC) with longitudinal and transverse reinforcing bars
The objective of this study is to investigate the behavior of the RC pier and the CISS pile connection considering the interface between the steel casing and the infilled concrete
Tensile cracking below reinforcement
Summary
Cast-in-steel-shell (CISS) piles are driven pipe piles filled with cast-in-place reinforced concrete (RC) with longitudinal and transverse reinforcing bars. The construction sequences of a CISS pile are as follows: (1) a steel casing is driven, (2) soil inside the steel casing is removed, (3) a mesh of longitudinal and transverse reinforcing bars is placed, and (4) the concrete is poured and cured. These elements can exceed 2 m in diameter and more than 70 m in length. In this case, the steel casing is 1.8 m in diameter and 25 mm thick. The CISS pile is reinforced with 32 #14 longitudinal bars (the diameter of #14 reinforcing bar is 43 mm) and heavy spiral transverse reinforcement
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