• Structural Engineering and Mechanics
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• 제59권2호
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• pp.209-226
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• 2016

Integral bridges are typically designed with flexible foundations that include one row of piles. The construction of integral bridges solves difficulties due to the maintenance of expansion joints and bearings during serviceability. It causes integral bridges to become more economic comparing with conventional bridges. Research has been focused not only to enhance the seismic performance of newly designed bridges, but also to develop retrofit strategies for existing ones. The local performance of the pile to abutment connection will have a major effect on the performance of the structure and the embedment length of pile inside the abutment has a key role to provide shear and flexural resistance of pile-abutment connections. In this paper, a simple method was developed to estimate the initial value of embedment length of the pile for retrofitting of specimens. Four specimens of pile-abutment connections were constructed with different embedment lengths of pile inside the abutment to evaluate their performances. The results of the experimentation in conjunction with numerical and analytical studies showed that retrofitting pile-abutment connections with CFRP wraps increased the strength of the connection up to 86%. Also, designed connections with the proposed method had sufficient resistance against lateral load.

• Steel and Composite Structures
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• 제20권4호
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• pp.731-748
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• 2016

Pile-to-pilecap connection performance is important as Integral abutment bridges (IABs) have no expansion joints and their flexible weak-axis oriented supporting piles take the role of the expansion joint. This connection may govern the bridge strength and the performance against various lateral loads. The intention of this study is to identify crack propagation patterns when the pile-to-pilecap connection is subjected to lateral loadings and to propose novel connections for improved performance under lateral loadings. In this study, eight different types of connections were developed and modeled, using Abaqus 6.12 to evaluate performances. Three types were developed by strengthening the connections using rebar or steel tube: (i) PennDOT specification; (ii) Spiral rebar; and (iii) HSS tube. Other types were developed by softening the connections using shape modifications: (i) cylindrical hole; (ii) reduced flange; (iii) removed flange; (iv) extended hole; and (v) slot hole connection types. The connections using the PennDOT specification, HSS tube, and cylindrical hole were shown to be ineffective in the prevention of cracks, resulting in lower structural capacities under the lateral load compared to other types. The other developed connections successfully delayed or arrested the concrete crack initiations and propagations. Among the successful connection types, the spiral rebar connection allowed a relatively larger reaction force, which can damage the superstructure of the IABs. Other softened connections performed better in terms of minimized reaction forces and crack prevention.

• 한국지반환경공학회 논문집
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• 제20권3호
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• pp.21-30
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• 2019

복합말뚝(Composite Pile)이란, 수평력이 크게 작용하는 구간에는 강관말뚝, 작게 작용하는 구간에는 PHC말뚝을 특수한 연결 장치로 결합한 말뚝으로서 토목 구조물의 기초 재료로써 상용화되는 추세에 있다. 이러한 복합말뚝의 핵심은 강관말뚝과 PHC말뚝을 연결하는 연결 장치의 안정성과, 이음 위치를 산정하는 설계기준이라고 할 수 있는데 국내에서는 복합말뚝 이음부 위치에 대한 정확한 시방규정이 없어서, LH 설계처(한국토지주택공사, 2009)에서는 도로설계요령 제3권(한국도로공사, 2001)을 참고하여 작성한 "복합말뚝 설계적용 및 설계도서 표기 방안 검토"를 복합말뚝 설계의 기준으로 사용해 오고 있지만 복합말뚝의 단면변화라고 볼 수 없어 적용에 한계성을 가지고 있는 실정이다. 이에 따라 본 연구에서는 복합말뚝의 단면 변화부(강관말뚝과 PHC말뚝의 이음부) 위치에 대한 설계기준을 제안하고 이에 대한 안정성 및 경제성을 검토하고자 실험적인 방법과 해석적인 방법을 이용하여 연결장치에 대한 안정성을 검증하였으며, 국내 교량공사 교대 79개소에 시공된 복합말뚝 설계자료를 분석하여 말뚝 본체 및 이음부에 작용하는 응력, 휨모멘트, 변위 등의 경향성을 파악하였고, 개선식이 적용된 재설계 과정을 통해 이음부에서 발생한 응력들이 연결장치와 PHC말뚝의 허용응력 수치 내로 발생하는 것을 확인하였다. 결론적으로 사례분석을 통한 복합말뚝 이음위치의 설계 제안식은 복합말뚝을 설계함에 있어서 안정성과 경제성을 모두 고려한 개선된 설계기법임을 알 수 있었다.