Interfacial shear behavior of a high-strength pile to sleeve grouted connection

Lee, Jeong-Hwa,Won, Deok-Hee,Jeong, Youn-Ju,Kim, Seong-Hwan,Kang, Young-Jong Elsevier 2017 ENGINEERING STRUCTURES Vol.151 No.-

<P><B>Abstract</B></P> <P>A grouted connection is a type of structural composite connection member produced from two different-sized steel tubes and a grout annulus between them. The grouted connection has been widely used in offshore oil and gas platforms and wind turbine structures by simply grouting between the pile and sleeves. In general, the axial compression strength of the connection is known to be affected by the grout strength, shear-key spacing and radial stiffness parameters of the composite section. In this study, concentric and eccentric loading tests were performed to investigate the interfacial shear behavior of the high-strength grouted connections according to the shear-key spacings. The interface shear behaviors, focusing on the strength, failure mode, and strain of the grout and steel tubes, were evaluated by tests and finite element (FE) analysis. The test results showed that the primary strength of the connection was mainly affected by the grout strength, whereas the ultimate strength was affected by the yield strength of the sleeves and the friction coefficient between the steel tubes and grout. It was also concluded that the test results on the high-strength grouted connections were similar to those of previous studies on normal-strength grouted connections, and the eccentric loading did not reduce the axial capacity of the connection. Although the ultimate failure modes of the connections could not be considered in the current design equations, they may contribute to the safe design of high-strength grouted connections.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This study investigated the interfacial shear behavior of high-strength grouted connections. </LI> <LI> Experimental studies were conducted to evaluate the strength and failure behavior of the connections. </LI> <LI> FE analysis was performed to elaborate upon the test results. </LI> <LI> The current design codes can enable the safe design of connections, although they do not consider the ultimate behavior of the sleeve and pile. </LI> <LI> The interfacial shear behavior of the connection was evaluated by the strength, failure mode, strains of the steel tubes and the grout annulus. </LI> </UL> </P>

An Experimental Study of Welded Bar Sleeve Wall Panel Connection under Tensile, Shear, and Flexural Loads

Jen Hua Ling,Ahmad Baharuddin Abd. Rahman,Izni Syahrizal Ibrahim,Zuhairi Abdul Hamid 한국콘크리트학회 2017 International Journal of Concrete Structures and M Vol.11 No.3

This paper presents an experimental study of a new grouted splice connection for wall panels, called Welded Bar Sleeve (WBS). The connections were made from steel pipes and tested with incremental tensile, shear and flexural loads until failure. The aim is to determine the behaviour of the connection under the three load cases. For this, the connections are evaluated in terms of the load–displacement responses, ultimate capacities, ductility responses and some feasibility assessment criteria. WBS was found to provide sufficient strength at the bar embedded length of 8, 8 and 11 times the bar diameter under tensile, shear and flexural loads, respectively. It is effective under tension, but could only service up to 1/3 of its ultimate shear capacity. Flexural load is the most critical load case for the connection. For this, further enhancements are required when subjected to shear and flexural loads.

시공오차가 있는 선기초기둥에 공장제작보의 설치가 용이한 탑다운공사용 접합기술개발

김승원 ( Seung Weon Kim ),정희원 ( Hee Weon Jung ),박대영 ( Dae Yung Park ),김동건 ( Dong Gun Kim ),박주현 ( Joo Hyun Park ) 한국건축시공학회 2011 한국건축시공학회 학술발표대회 논문집 Vol.11 No.1

Almost prefounded columns for top-down construction certainly have construction tolerances in plan and plumbness. Therefore, it is very difficult to connect prefabricated beams to prefounded columns at each floor level after excavation by usual top-down connection method and this usual connection method leads to long construction time, increasing cost and decreasing quality. This paper presents a new method for connecting prefabricated beam to prefounded column with GROUT-JACKET CONNECTION SYSTEM consisting of sleeve, bearing-shear bands and grout. Details and illustrations of the connections and applications by GROUT-JACKET CONNECTION SYSTEM for the top-down construction are also included in this paper.

Seismic Performance of a Full-Scale Precast Concrete L-Shaped Column Frame Structure with a Grouted Connection

Wei-Bin Ni,De-Hao Qiao,Hong-Wei Sun,Xu Zhang,Zhong-Wen Zhang,Shao-Jie Wang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.2

Precast concrete frame structure with nonrectangular columns are becoming attractive to researchers and engineers owing to advantages such as avoiding column protrusion from walls and saving space. This paper presents the experimental investigation of a full-scale precast concrete frame structure with L-shaped columns (PCFS) subjected to reverse cyclic loading. The precast connection adopted grouted anchor connection. As a comparison and benchmark, one full-scale monolithic sample (RCFS) was also tested. The results indicates that the greater steel ratio in the grouted anchor connection region leads to a high local stiffness of the elements, which contributed to delaying occurrence of the first crack at the grouting holes. The failure mode, lateral load capacity, stiffness degradation, load-carrying capacity degradation, energy-dissipating capacity, ductility and interlayer residual deformation were compared between two specimens. PCFS specimen exhibited comparatively better hysteretic behavior, energy-dissipating capacity, residual deformation-resisting capacity and ductility. For RCFS and PCFS specimens, the peak load difference was within 7%. About 15% increases in ductility were observed for PCFS specimen compared with RCFS specimen. The test results would provide reference for the application of the precast concrete structure with nonrectangular columns in the new residential buildings.

고성능 시멘트 그라우트로 충진된 풍력타워 연결부의 정적 및 피로부착특성

서교,김상현,오홍섭 한국방재학회 2016 한국방재학회논문집 Vol.16 No.6

In this study, authors developed a high-performance fiber reinforced grout for applying the steel tube connections of offshore supporting structure and then conducted a bond tests for verifying the static and fatigue behavior of the grouted connection. The cement grout is composed with portland type 1 cement, alumina cement, silka fume, and added steel fiber to enhance the strength and toughness of grout and the compressive strength at 28day is at least 130MPa. Experimental variables for bond test are adopted aspect ratio (0.013 and 0.056) of shear key in steel connection, aspect ratio (30 to 67) and volume fraction (0.5, 0.9 and 2.3%) of steel fiber. The specimen with 2.3% fiber volume fraction and 0.056 aspect ratio of shear key has highest bond strength than other specimens and the fatigue life under cyclic loads up to 65% of ultimate strength is more than 1,600,00 cycles. 본 연구에서는 고성능시멘트 그라우트를 개발하여 해상 지지구조물 강재 튜브연결부에 적용하고자 하였으며, 그라우트에 의한 연결부의 정적 및 피로부착거동을 분석하기 위하여 부착실험을 수행하였다. 시멘트 그라우트는 인성과 강도를 높이기 위하여 1종 포틀란트 시멘트와 알루미나 시멘트 및 실리카 흄과 함께 강섬유를 사용하였으며, 130MPa이상의 28일 압축강도를 발현하였다. 부착강도 실험시 실험변수는 연결부 전단키의 형상비, 섬유혼입율과 섬유형상비를 적용하였다. 전단키의 형상은 0.013, 0.056이었으며, 섬유형상비(l/d)는 30~67, 섬유혼입율은 0.5%,0.9%,2.3%를 사용하였다. 실험결과 섬유혼입율 2.3%이상, 전단키 0.056인 경우의 부착강도가 가장 높게 나타났으며, 최대정적강도를 보인 실험변수의 피로수명 역시 응력수준 65%에서 1,600,000회 이상의 수명을 나타내었다.

프리파일링 자켓 하부구조물의 그라우트 연결부에서 전단키 배열이 축하중 용량에 미치는 영향

이승연(Seungyeon Lee),이유진(Yujin Lee),장재국(Jaeguk Jang),구영철(Yeongcheol Gu),지광습(Goangseup Zi) 한국방재학회 2022 한국방재학회논문집 Vol.22 No.6

자켓 구조물과 해저에 관입되는 파일은 그라우트 연결부로 연결되며, 연결부의 전단강도 향상을 위해 전단키 형상을 설계한다. 시공 시 해양 환경하중으로 인해 내측과 외측 강관의 높이 오차를 제어하기 어려우며, 설치 오차가 발생할 경우, 전단키의 배열에도 오차가 발생하여 구조물의 성능이 저하된다. 자켓 구조물을 설치하는 공법 중 프리파일 공법은 포스트파일 공법 대비 대규모 단지에서 경제성이 뛰어나지만 시공 오차의 발생 가능성이 크다. 본 연구는 프리파일 자켓 구조에서 전단키의 배열오차에 따른 파괴 형상과 최대 축하중 용량을 평가하였다. 평가모델은 그라우트 층의 두께, 그라우트의 강도, 전단키의 배열오차비율 세 가지를 변수로 하였다. 검토 결과, 전단키의 배열 오차가 발생하였을 경우 최대 축하중은 최대 10% 이내로 저하되었다. Jacket structures and piles penetrating the seabed are connected through grouted connections. The shear key shape is designed to improve the shear strength of grouted connections. On a construction site, it is difficult to control the height error of the inner and outer steel tubes because of the environmental load. In addition, an installation error leads to an error in the arrangement of the shear keys, degrading the structure's performance. Among the construction methods for installing jacket structures, prepiling is more economical than the post-file method, but construction errors are likely. In this study, the fracture shape and maximum axial load capacity were evaluated according to the arrangement error of the shear key. It was found that when an arrangement error of the shear key occurred, the maximum axial load decreased to within 10%.

Fatigue Evaluation of Grouted Connections under Bending Moment in Offshore Wind Turbines Based on ABAQUS Scripting Interface

Xian Wang,Tao Chen,Qi Zhao,Guokai Yuan,Jinchao Liu 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.4

The fatigue behavior evaluation under bending moment is extremely important to the grouted connection in monopile offshore wind turbines. Based on the scripting interface of ABAQUS software, finite element model of the grouted connections was established automatically in accordance with the user defined parameters by Python language. Based on the experimental material test of grout material, the grout material was simulated by using three-dimensional concrete damaged plasticity (CDP) model in ABAQUS. Full model and half model were compared under fatigue limit state (FLS), and numerical results are presented in terms of hot spot stress in steel and third principle stress in grout material. It was found that half model could decrease calculation time significantly with more conservative evaluation result. Furthermore, parametric studies were conducted based on the half models about two different shear keys’ arrangements as well as the height and distance of shear keys. And it is found that there are slight differences for two models in calculated design life when the interface behavior between steel and grout material is modeled by Coulomb friction law.

고강도 모르타르가 적용된 파일-슬리브 그라우트 연결부의 피로강도에 대한 실험 연구

이정화,강성용,UY Lymei,엄영호,김성환,강영종 한국방재학회 2016 한국방재학회논문집 Vol.16 No.6

Increasing fatigue strength of offshore structures is important as the structures are continuously subjected to environmental loads such as wave and wind load. Recently, there are efforts improving the fatigue strength of pile to sleeve grouted connections by utilizing high strength mortar which is widely used as connections of monopile or jacket structures. In this study, fatigue strength of pile to sleeve grouted connections using high strength mortar was evaluated by experimental tests and compared to previous researches and a related design standard. Well-instrumented five fatigue tests and two static tests specimens of the grouted connections were tested. The experimental results show that the fatigue strength of the grouted connections using high strength mortar was evaluated conservative compared to the design standard. 해양에 건설되는 구조물은 파도, 바람 등의 환경하중의 영향을 지속적으로 받으므로, 해양구조물의 피로성능향상은 매우 중요하다. 최근에는 해양 모노파일과 해양 자켓의 기초연결부로써 적용되고 있는 파일-슬리브 그라우트 연결부의 피로 성능을 향상시키기 위한 노력으로 고강도 모르타르를 이용하고 있다. 본 연구에서는 실험을 통하여 고강도 모르타르가 적용된 파일-슬리브 그라우트 연결부의 피로 성능을 평가하고, 이를 선행 연구 및 관련 설계기준과 비교분석하였다. 실험은 총 5개의 그라우트 연결부 피로 실험체와 2개의 정적 실험체에 대하여 수행되었다. 실험 결과, 고강도 모르타르가 적용된 파일-슬리브 그라우트 연결부의 피로 성능은 관련 설계기준에 비하여 보수적으로 평가되었다.

고강도 콘크리트가 적용된 해상 파일-슬리브 그라우트 연결부의 축력 실험

이정화,김평화,김성환,엄영호,강영종 한국복합신소재구조학회 2016 복합신소재구조학회 학술발표회 Vol.2016 No.04

Grouted connections have been widely used for offshore structures such as connection method of jacket and mono-pile structures. It is recommended high strength concrete for grouting between pile and sleeve because it is so rapidly hardening that helpful to fatigue strength. This study investigates axial strength of pile to sleeve grouted connections made by 130MPa of high strength concrete. Push-out test were performed to evaluate the axial strength of the grouted connections with different shear-key spacing.

섬유보강 고성능시멘트계 그라우트가 적용된 강관 연결부의 부착특성에 대한 실험적 연구

오홍섭,서교,김상현,고상진,이현기 한국구조물진단유지관리공학회 2014 한국구조물진단유지관리공학회 논문집 Vol.18 No.6

본 연구에서는 모노파일지지구조의 고성능 그라우트연결부의 부착거동을 다루고 있다. 강관파일 연결부의 일체화를 위하여 섬유보강 고성능 그라우트를 개발하였으며, 재령 7일 압축강도 125MPa와 직인장강도 7.5MPa를 나타내었다. 축하중을 받는 상태에서의 그라우트의부착거동을 평가하기 위하여 강관파일에 그라우트를 충진하여 부착실험을 수행하였으며, 그 결과를 기존의 설계기준과 분석하였다. 실험변수는 섬유혼입율 (0%, 0.5% and 0.9%), 섬유의 형상비 (60 and 80)와 전단키의 높이와 간격의 비 (0.013 and 0.056)로 선정하였다. 실험결과 최대부착강도는 30.8MPa로 관찰되었으며, 섬유 혼입율보다는 전단키의 높이와 간격의 비가 부착강도에 영향을 미치는 것으로 분석되었다. This paper deals with the bonding characteristic of grouted joint connections of monopile support structures for offshore windpower facilities. For the integration of pile connection of wind power supporting structure, fiber reinforced high performance cementeous grout was developed and the ultimate compressive strength of it is 125MPa and the direct tensile strength is 7.5 MPa at 7 days. To assess the bond strength of grout filled in pile connection, small scaled direct bond tests under axially loaded wasperformed and analyzed according the existing guidelines. The fiber volume fraction (0%, 0.5% and 0.9%), aspect ratio of fiber(60 and 80) and the ratio of height to spacing of shear key (0.013 and 0.056) were adopted as the experimental variables. From the test results, the maximum bond strength among the all specimens was 30.8MPa and the bond strength of grouted connectionwas affected by the ratio of height to spacing of shear key than the fiber volume fraction.