측방유동지반상 말뚝기초교대의 측방이동 평가

홍원표(Hong Won Pyo),이광우(Lee Kwang Wu),조삼덕(Cho Sam Deok),이재호(Lee Jae Ho) 대한토목학회 2007 대한토목학회논문집 C Vol.27 No.5

국내현장에서 수집된 43개 교대의 측방이동 실측자료에 대한 분석을 통해 말뚝기초교대의 측방이동을 간편하게 평가할 수 있는 방안을 제안한다. 실측된 교대측방변위를 고려하여 연약지반의 비배수전단강도와 교대배면에 작용하는 상재압의 관계를 분석한 결과, 교대 배변의 뒤채움으로 인한 상재압이 연약지반 비배수전단강도의 3배보다 작은 경우에는 실측된 교대변위가 국내 교대의 측방이동 허용치인 15㎜ 이내인 것으로 나타나, 교대 유지관리에 문제가 발생하지 않았다. 그러나 상재압이 연약지반 비배수전단강도의 3배~8.3배인 경우는, 교대변위가 15㎜~50㎜ 발생하는 것으로 나타났다. 따라서 이 경우 교대의 측방이동을 고려한 설계를 수행함으로써, 교대 측방변위를 허용치인 15㎜ 이하로 감소시켜야 한다. 특히 상재압이 비배수전단강도의 8.3배 이상이면, 50㎜ 이상의 심각한 교대변위가 발생할 수 있기 때문에, 적절한 교대 측방이동 대책공법이 강구되어야 하는 것으로 나타났다. 이러한 결과는 상재압과 비배수전단강도의 상관관계를 나타내는 사면지반의 안정수를 이용하면 측방유동지반상 말뚝기초교대의 측방이동 가능성을 간편하게 평가할 수 있음을 의미한다. 반면에 측방유동지수와 측방이동판정지수는 교대 실측변위 및 사면안전율과 상관성이 높지 않았다. 이는 경험지수만으로 교대의 측방이동 여부를 판정하는 것은 합리적이지 않음을 의미한다. 따라서 교대를 포함한 사면의 안정수가 3보다 크면, 교대기초말뚝의 사면안정 기여효과와 교대의 허용측방변위를 반영한 사면안정해석을 통해 교대 측방이동 여부를 면밀히 검토해야 한다. Field monitoring data for forty three piled bridge-abutments were investigated to suggest an evaluation method on lateral movement of the abutments. As the results of the investigation, if the surcharge pressure by backfills behind the piled-bridge abutment is less than 3 times the undrained shear strength of the soft grounds, the lateral displacement of the abutments was within 15 ㎜. Therefore, the abutment can be maintained without any problems because the abutment will move laterally within an allowable movement range. However, if the surcharge pressure is between 3 times and 8.3 times the undrained shear strength of the soft grounds, the abutments moved laterally between 15 ㎜ and 50 ㎜. In this case, the lateral displacement of the abutment should be considered on the design because the displacement may be considerable. Moreover, if the surcharge pressure behind the abutments is greater than 8.3 times the undrained shear strength of the soft grounds, the lateral displacement of the abutments could be more than 50 ㎜. In this case, a reasonable countermeasure should be applied to prevent excessive lateral displacement of the abutment, or the design of the abutment should be changed because the lateral movement is severe enough to severely damage the abutment. In tum, the stability number, which is the ratio of the surcharge pressure to the undrained shear strength can be used as the simplified empirical index to evaluate the possibility of lateral movement of abutments. However, both the lateral flow index and the lateral movement judgement index do not always show good relationship with not only the lateral displacement of the abutments but also the safety factor of slopes. Therefore, It is not always suitable to predict the lateral movement of abutments by using only conventional empirical indexes. These empirical indexes should be used together with the safety factor of slope with consideration of the allowable limit of the lateral displacement of the abutment.

PSC 일체식 교대 교량의 거동특성 평가

안진희(Ahn Jin-Hee),윤지현(Yoon Ji-Hyun),김상효(Kim Sang-Hyo),김준환(Kim Jun-Hwan) 대한토목학회 2010 대한토목학회논문집 A Vol.30 No.4A

일체식 교대 교량은 신축이음장치 및 교좌장치가 없이 하부구조와 상부구조를 일체화한 구조형식으로, 상부구조의 온도변화 등에 의해 발생하는 변형을 교대하부에 배치한 파일의 휨 변형을 통하여 해소하는 교량형식이다. 본 연구에서는 지반-파일 상호관계 모형화 방법에 따른 일체식 교대 교량의 거동비교를 통하여 합리적인 모형화 방법을 제시하고, 매개변수 해석을 통하여 일체식 교대 교량의 상부구조 및 파일의 거동특성을 평가하였다. 매개변수 해석을 위해 파일 관입부 지반조건, 교대 높이, 파일 길이를 매개변수로 선정하였고, 지반-파일 및 온도변화-교대배면토압 상호관계를 고려하여 구조해석을 수행하였다. 지반-파일 상호관계 모형화에 따른 일체식 교대 교량의 거동을 비교한 결과 탄성지반스프링 방법이 일체식 교대 교량의 거동을 평가하는데 보다 합리적인 것으로 판단된다. 일체식 교대 교량의 매개변수 해석 결과 파일 관입부 지반강성이 증가할수록 상부구조에 작용하는 모멘트가 증가하고 파일의 변위가 감소하는 경향을 보였다. 또한, 교대의 높이가 증가할수록 교대배면토압이 증가하고 이것이 상부구조 및 파일의 거동에 영향을 주었음을 확인하였으며, 파일의 길이가 증가할수록 일체식 교대 교량이 유연한 거동을 보임을 확인하였다. Bridges constructed without any expansion joint or bridge bearing are called integral abutment bridges. They integrate the substructure and the superstructure. Possible deformation of the superstructure, due to changes in temperature for example, is prevented by the bending of the piles placed at the lower part of the abutment. This study examines the behavior of integral abutment bridges through soil-pile interaction modeling method and proposes an appropriate modeling method. Also, it assesses the behavior characteristics of the superstructure and piles of integral abutment bridges through parametric study. Soil condition around the pile, abutment height, and pile length were selected as parameters to be analyzed. Structural analysis was conducted while considering the interactions of soil-pile and temperature change-earth pressure on the abutment. Comparative behavior analysis through soil-pile interaction modeling showed that elastic soil spring method is more appropriate in evaluating the behavior of integral abutment bridges. The parametric study showed the tendency that as the soil stiffness around the pile increases, the moment imposed on the superstructure increases, and the displacement of the piles decreases. In addition, it was observed that as the bridge height increases, the earth pressure on the abutment increases and that in tum affects the behavior of the superstructure and piles. Also, as the length of the pile increased, the integral bridge showed more flexible behavior.

연약지반상에 측방유동을 받는 교대말뚝기초의 거동분석

이송(Song Lee),강대원(Dae-Won Kang) 한국철도학회 2004 철도저널 Vol.7 No.2

Pile Bridge Abutments constructed on a soft base are affected by a lateral flow. Laterl flow pressure acting on Pile is very difficult to calculate because of, interation of ground and Pile. So, it is difficult to estimate displacement of Pile Bridge Abutments. This paper studied about possibility of the displacement estimation of Pile Bridge Abutments by using the equivalent sheet pile wall theory that was Randolph proposed in 1981. Analysis program through using the SAGE CRISP that is FEM program. Analysis data used Centrifuge test results of Springman(1991), Bransby(1997) and Ellis(1997)'s paper. In conclusion, maxium displacement that is carried out by centrifuge test and numerical analysis has occured at the head of pile, as well as Maximum displacement of pile is closely similar. But the moment acting on pile of numerical analysis is under estimated compare to the centrifuge test. Through the comparative study, it is found that displacement estimation by equivalent sheet pile wall is in relatively good agreement with the results of centrifuge test.

측방유동 연약지반상 파일슬래브로 보강된 교대의 안정

송영석,홍원표 한국지반공학회 2006 한국지반공학회논문집 Vol.22 No.8

A site investigation has been performed for bridge abutments constructed on soft ground, which are deformed laterally by backfill. As the result from the evaluation of lateral movement in bridge abutment, the foundation piles were not considered as the passive pile at the design stage and the period for soft ground improvement was not proper. In order to prevent lateral movement of bridge abutment, the pile slab is proposed as a countermeasure. This method can effectively prevent the lateral flow of soft ground, since the overburden surcharge due to backfill on soft ground would be effectively delivered to bedrock through the piles in soft ground. The instrumentation system is designed and installed to investigate the behavior of bridge abutment on soft ground reinforced by pile slab. The instrumentation results show that pile slab effectively resists to the lateral movement of bridge abutment due to backfill. Also, the surcharge loads due to backfill are transmitted to the bedrock through piles. It confirms that the pile slab effectively resists to the lateral movement of bridge abutment due to backfill and the applied design method is reasonable.

연약지반상에 측방유동을 받는 교대말뚝기초의 거동분석

이송,강대원,Lee, Song,Kang, Dae-Won 한국철도학회 2004 한국철도학회논문집 Vol.7 No.2

Pile Bridge Abutments constructed on a soft base are affected by a lateral flow. Laterl flow pressure acting on Pile is very difficult to calculate because of, interation of ground and Pile. So, it is different to estimate displacement of Pile Bridge Abutments. This paper studied about possibility of the displacement estimation of Pile Bridge Abutments by using the equivalent sheet pile wall theory that was Randolph proposed in 1981. Analysis program through using the SAGE CRISP that is FEM program. Analysis data used Centrifuge test results of Springman(1991), Bransby(1997) and Ellis(1997)'s paper. In conclusion, maxium displacement that is carried out by centrifuge test and numerical analysis has occured at the head of pile, as well as Maximum displacement of pile is closely similar. But the moment acting on pile of numerical analysis is under estimated compare to the centrifuge test. Through the comparative study, it is found that displacement estimation by equivalent sheet pile wall is in relatively good agreement with the results of centrifuge test.

Retrofitting of steel pile-abutment connections of integral bridges using CFRP

Seyed Saeed Mirrezaei,Majid Barghian,Hossein Ghaffarzadeh,Masood Farzam 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.59 No.2

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.

일체식 교대 교량의 파일-교대 연결부 거동에 관한 실험적 연구

김상효(Kim Sang-Hyo),윤지현(Yoon Ji-Hyun),안진희(Ahn Jin-Hee),이상우(Lee Sang-Woo) 대한토목학회 2009 대한토목학회논문집 A Vol.29 No.6A

본 연구는 일체식 교대 교량의 파일-교대 연결부의 거동에 관한 것이다. 본 연구에서는 일체식 교대 교량 연결부의 강체거동을 위하여 교대에 매입된 파일(H형강)에 관통철근을 배치한 형태, 스터드 전단연결재를 설치한 형태의 두 가지의 파일­교대 연결부를 제안하였다. 제안된 파일-교대 연결부의 거동 평가를 위하여 제안된 연결부가 설치된 파일-교대 축소모형 시험체와 일체식 교량 설계지침에서 제시한 연결부가 설치된 파일-교대 축소모형 시험체를 제작하여 하중재하시험을 수행하였다. 하중재하시험 결과, 모든 시험체에서 탄성영역 내의 초기강성은 일반적인 일체식 교대 교량에 적용이 가능할 정도로 나타났다. 그러나 항복 이후 강성과 하중저항 성능, 균열진전양상, 회전 강성 및 지압강도 측면에서 비교한 결과, 본 연구에서 제안한 파일-교대 연결부 방식이 일체식 교대교량의 파일 연결부의 강체거동에 더욱 효과적인 것으로 평가되었다. This study dealt with the behavior of pile-abutment joints in integral abutment bridges. Two types of pile-abutment joints were proposed to strengthen its rigid action. One was fabricated with transverse rebars which penetrated the H-pile in the abutment. The other was composed of stud shear connectors on the flanges of the H-pile. Three half scaled pile-abutment joint specimens were fabricated and loading tests were performed to evaluate the behavior of proposed joints. The results showed that the initial stiffness in elastic region of all specimens was sufficient to be applied for the integral abutment bridges. However, the performances of the proposed joints were shown to be more effective in rigid action compared to the joints types suggested by the integral Bridge Design Guideline. The results from stiffness, strength, rotation and crack propagation tests supported this matter.

일체식 교량의 교대와 CFT Pile 연결부 성능에 관한 실험적 연구

김대혁 ( Kim Dae Hyeok ),한상윤 ( Han Sang Yun ),이호찬 ( Lee Ho Chan ),신성진 ( Shin Sung Jin ),강영종 ( Kang Young Jong ) 한국복합신소재구조학회 2016 복합신소재구조학회논문집 Vol.7 No.4

Two types of connection between the abutment and CFT pile were proposed for the sub-structure of the integral abutment bridge. One was a bolt connection (Type-A) and the other was a hook connection (Type-B). To analyze the performance of connection Type-A and Type-B, a quasi-static experiment was carried out. According to experimental results, the destruction occurred at the connection point and so both type A and type B need to have a reinforced design as the link between the abutment and CFT pile. However, when the load resistance performance and energy dissipation capacity was analyzed, the performance of connection Type-B was superior to the performance of connection Type-A.

Soil Interaction of H-shaped Steel-RC Stepped Pile of Integral Abutment Bridge: Experimental Evaluation

Yizhou Zhuang,Kun-Sheng Song,Said M. Easa,Yong-Qing Song 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.3

The reinforced concrete piles (RC) in integral abutment bridges (IABs) are challenging to meet the longitudinal deformation of bridges with significant lateral stiffness. The H-shaped steel (HS) piles are costly and prone to corrosion. This paper proposes a new form of pile comprised of HS and RC piles in series to meet the longitudinal deformation demand of IABs. Tests were conducted for one HS pile under reciprocating low-cycle pseudo-static test and two HS-RC stepped piles with different bending stiffness ratios of HS/RC (0.25 and 0.5) using the HS-RC pile test model,. The influence of the stiffness ratio on the mechanical behavior of stepped pile-soil was studied. The mechanical behavior of the stepped pile was also compared with single HS and RC piles. and the applicability of the m and p-y curve methods to the calculation of horizontal displacement of stepped pile is discussed. The results show that the elastic deformation range of the HS pile is 2 mm to 25 mm, and its horizontal deformation capacity and bearing capacity are excellent. As the stiffness ratio increases, the stepped pile-soil system's yield displacement and yield load increased. The stiffness ratio has no significant effect on the failure mode of the piles. The hysteretic ring of the stepped pile shows a squeezing shape at the initial loading stage, but becomes a full spindle in the later loading stage. The stepped pile shows an excellent energy consumption effect and a horizontal deformation ability, indicating it is suitable for IABs. The m method has better accuracy only up to 2 mm displacement, while the p-y curve method still has higher accuracy within 15 mm.

Low-cycle fatigue in steel H-piles of integral bridges; a comparative study of experimental testing and finite element simulation

Memduh Karalar,Murat Dicleli 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.1

Integral abutment bridges (IABs) are those bridges without expansion joints. A single row of steel H-piles (SHPs) is commonly used at the thin and stub abutments of IABs to form a flexible support system at the bridge ends to accommodate thermal-induced displacement of the bridge. Consequently, as the IAB expands and contracts due to temperature variations, the SHPs supporting the abutments are subjected to cyclic lateral (longitudinal) displacements, which may eventually lead to low-cycle fatigue (LCF) failure of the piles. In this paper, the potential of using finite element (FE) modeling techniques to estimate the LCF life of SHPs commonly used in IABs is investigated. For this purpose, first, experimental tests are conducted on several SHP specimens to determine their LCF life under thermal-induced cyclic flexural strains. In the experimental tests, the specimens are subjected to longitudinal displacements (or flexural strain cycles) with various amplitudes in the absence and presence of a typical axial load. Next, nonlinear FE models of the tested SHP specimens are developed using the computer program ANSYS to investigate the possibility of using such numerical models to predict the LCF life of SHPs commonly used in IABs. The comparison of FE analysis results with the experimental test results revealed that the FE analysis results are in close agreement with the experimental test results. Thus, FE modeling techniques similar to that used in this research study may be used to predict the LCF life of SHP commonly used in IABs.