• Structural Engineering and Mechanics
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• 제38권5호
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• pp.573-592
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• 2011

Comprehensive and accurate analysis of a finite foundation beam is a challenging engineering problem and an important subject in foundation design. One of the limitation of the traditional Winkler elastic foundation model is that the model neglects the effect of the interface resistance between the beam and the underneath foundation soil. By taking the beam-soil interface resistance into account, a deformation governing differential equation for a finite beam resting on the Winkler elastic foundation is developed. The coupling effect between vertical and horizontal displacements is also considered in the presented method. Using Galerkin method, semi-analytical solutions for vertical and horizontal displacements, axial force, shear force and bending moment of the beam under symmetric loads are presented. The influences of the interface resistance on the behavior of foundation beam are also investigated.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.1132-1143
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• 2008

A single Column/Shaft which extended the pile to the column of the bridge with same diameter has better safety and economical profit, but it usually has larger lateral displacement due to lateral loads such as wind, earthquake, wave, etc. A series of horizontal pile load testing were performed to study the lateral behavior of single column/shaft with varying different free lengths and embedded pile lengths. Eight instrumented test piles were cast-in-placed by bonding strain gauges at certain locations on both faces of the pile to measure bending moment, from two-way loadings. Linear variable differential transformers(LVDTs) were installed to measure the lateral pile displacement. Based on this, it is found that the test single column/shaft with different free lengths shows different failure modes. If the test pile has a longer free length, the failure occurs at the near the ground surface, but the shorter one's failure occurs at the below the ground surface.

• 대한조선학회논문집
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• 제43권4호
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• pp.484-493
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• 2006

Recently, direct load analysis using ship motion program is required to confirm structural safety for the Post-Panamax class large container carrier. However, there is no exact comparative study data for structural response between 20 and 30 wave load. So, in this paper, to compare the hull girder stress response between 20 versus 3D wave load calculation method, direct load analysis and global F.E analysis have been performed for three kinds of large container vessels using each 20 and 30 wave load calculation program. The results of 2D wave load RAO(Response Amplitude Operator) of each dominant load parameter(vertical, torsional and horizontal moment) are generally bigger than that of 30 results, especially in vertical wave bending moment. And the results of structural analysis based on the equivalent design wave method shows that there is a big difference in view of stress, but the stress distribution is very similar for each wave load case.

• Journal of Advanced Marine Engineering and Technology
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• 제36권2호
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• pp.267-275
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• 2012

본 논문은 정상풍속과 돌발풍속을 수학적으로 모델링하고 풍향에 따라 전달되는 메인축에서의 전달모멘트를 조사하여 기어박스에 전달되는 풍하중의 특성을 파악하였다. 정상풍속은 지상에서 고도가 높아짐에 따라 속도가 증가하게 설정을 하였다. 풍하중에 의해서 메인축으로 전달되는 모멘트의 평균값과 하모닉값을 풍향 입사각을 $-45^{\circ}{\sim}45^{\circ}$로 변화를 주며 특성을 파악하였다. 또한 기어 트레인의 미스 얼라인먼트를 유발시키는 굽힘 모멘트의 특성을 파악하였다. 정상풍속모델에서는 블레이드의 3배수 주파수(3X)로 하는 토크의 가진이 생기며, 바람의 방향이 $+22.5^{\circ}$일 때 수평방향의 굽힘 모멘트가 주축으로 들어가는 토크의 50%수준으로 발생하는데 이는 수평방향으로의 탄성 축 휘임을 유발하여 치가 모서리에서 물림이 발생하게 하는 원인을 제공함을 알 수 있었다. 돌발풍속의 경우, 3X, 6X, 9X를 가진 주파수로 하는 토크의 가진이 바람의 방향이 +방향으로 커질수록 하모닉항의 상대 비율이 증가하였다.

• Geomechanics and Engineering
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• 제13권5호
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• pp.715-742
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• 2017

Earth berms are often left in place to support retaining walls or piles in order to eliminate horizontal struts in excavations of soft soil areas. However, if the excavation depth is relatively large, an earth berm-supported retaining system may not be applicable and could be replaced by a multi-bench retaining system. However, studies on multi-bench retaining systems are limited. The goal of this investigation is to study the deformation characteristics, internal forces and interaction mechanisms of the retaining structures in a multi-bench retaining system and the failure modes of this retaining system. Therefore, a series of model tests of a two-bench retaining system was designed and conducted, and corresponding finite difference simulations were developed to back-analyze the model tests and for further analysis. The tests and numerical results show that the distance between the two rows of retaining piles (bench width) and their embedded lengths can significantly influence the relative movement between the piles; this relative movement determines the horizontal stress distribution in the soil between the two rows of piles (i.e., the bench zone) and thus determines the bending moments in the retaining piles. As the bench width increases, the deformations and bending moments in the retaining piles decrease, while the excavation stability increases. If the second retaining piles are longer than a certain length, they will experience a larger bending moment than the first retaining piles and become the primary retaining structure. In addition, for varying bench widths, the slip surface formation differs, and the failure modes of two-bench retained excavations can be divided into three types: integrated failure, interactive failure and disconnected failure.

• Computers and Concrete
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• 제21권1호
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• pp.95-102
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• 2018

Reinforced concrete corbel beams (span to depth ratio of a corbel is less than one) are designed with primary reinforcement bars to account for bending moment and with the secondary reinforcement placed parallel to the primary reinforcement (shear stirrups) to resist shear force. It is interesting to note that most of the available analytical procedures employ empirical formulas for the analysis of reinforced concrete corbels. In the present work, a generalized and a simple strut and tie models were employed for the analysis of reinforced corbel beams. The models were benchmarked against experimental results available in the literature. It was shown here that increase of shear stirrups increases the load carrying capacity of reinforced concrete corbel beams. The effect of horizontal load on the load carrying capacity of the corbel beams has also been examined in the present paper. It is observed from the strut and tie models that the resistance of the corbel beam subjected to combined horizontal and vertical load did not change with increase in shear stirrups if the failure of the corbel is limited by concrete crushing. In other words, the load carrying capacity was independent of the horizontal load when failure of the beam occurred due to concrete crushing.

• 대한조선학회논문집
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• 제30권4호
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• pp.112-126
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• 1993

본 논문에서는 선급규칙중 파랑하중 부분의 개정과 관련하여 선체종강도의 국제선급연합 통일규칙(IACS UR)을 검증하기 위하여 단기파랑하에서 비선형 파랑하중 해석을 수행하였고, 선체구조의 직접강도해석시에 사용하여야 할 지침으로 IACS WAVE DATA에 대한 검증을 수행하였다. 컨테이너선등과 같은 대형개구를 가진 선박의 응력을 구하기 위하여 수평전단력, 수평굽힘모멘트 및 비틂모멘트 산식을 일관성 있게 구하여 새로이 제시하였다. 또한 선체 외관에 작용하는 유체동압력을 선박의 길이 및 깊이방향에 대한 분포 산식으로 제시하였고 이를 타 선급 규칙과 비교, 검토하였다. 이상의 제시된 산식들은 각 선종, 크기 별로 17척 선박의 실선계산을 통하여 결정되었다. 이 산식들은 앞으로 선체구조부재 Scantling 산식이 결정되면 실선에 대한 적용계산을 통하여 검증될 것이다.

• Ocean Systems Engineering
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• 제7권4호
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• pp.413-433
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• 2017

The dynamic and structural responses of a 1000-m long circular submerged floating tunnel (SFT) with both ends fixed under survival irregular-wave excitations are investigated. The floater-mooring nonlinear and elastic coupled dynamics are modeled by a time-domain numerical simulation program, OrcaFlex. Two configurations of mooring lines i.e., vertical mooring (VM) and inclined mooring (IM), and four different buoyancy-weight ratios (BWRs) are selected to compare their global performances. The result of modal analysis is included to investigate the role of the respective natural frequencies and elastic modes. The effects of various submergence depths are also checked. The envelopes of the maximum/minimum horizontal and vertical responses, accelerations, mooring tensions, and shear forces/bending moments of the entire SFT along the longitudinal direction are obtained. In addition, at the mid-section, the time series and the corresponding spectra of those parameters are also presented and analyzed. The pros and cons of the two mooring shapes and high or low BWR values are systematically analyzed and discussed. It is demonstrated that the time-domain numerical simulation of the real system including nonlinear hydro-elastic dynamics coupled with nonlinear mooring dynamics is a good method to determine various design parameters.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.108-118
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• 2009

As increasing demand on marine structures and skyscrapers, a deep shaft pile is frequently to be used for the place having weak ground strength. Because heavy horizontal force is generally applied on upper part of pile foundation used in engineering field, steel pile is highly used due to its high resistance to shear force and bending moment, and its capability to carry heavy loads. The steel pile has advantage in good constructibility, high applicability on site and easy handing, but has disadvantage in cost, more expensive than other material pile. This study is to examine the composite pile that makes economical construction possible by reducing material cost of pile; using steel and PHC pile A non welding connection method is applied to this composite pile. This study had step of comparison with the result of numerical analysis after analyzing the result of field test. Numerical analysis is the process of analyzing lateral behavior of non welding composite pile. Moreover, detailed analysis was implemented in order to evaluate joint stability. As a result of the analysis, we could interpret that the stability of the connection part is ensured as seeing the smaller internal stress than approved internal stress. Based on this study, we analyzed lateral behavior of non welding composite pile, which ensured the stability of connection part.

• Steel and Composite Structures
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• 제44권3호
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• pp.407-421
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• 2022

Prefabricated hybrid wind turbine towers (WTTs) are promising due to height increase. This study proposes the use of ultra-high performance concrete (UHPC) to develop a new type of WTT without the need to use reinforcement. It is demonstrated that the UHPC WTT structure without reinforcing bars could achieve performance similar to that of reinforced concrete WTTs. To simplify the design of WTT, a design approach for the calculation of stresses at the horizontal joints of a WTT is proposed. The stress distribution near the region of the horizontal joint of the WTT structure under normal operating conditions and different load actions is studied using the proposed approach, which is validated by the finite element method. A further parametric study shows that the degree of prestressing and the bending moment both significantly affect the principal stress. The shear-to-torsion ratio also shows a significant influence on the principal tensile stress.