Numerical Investigation on the Global Behavior of Jack-Up Unit Next to Footprint With Rectangular-Shaped Spudcan

2020 ◽  
Author(s):  
Ye Yuan ◽  
Menglan Duan
Keyword(s):  
Bending Moment ◽  
Global Behavior ◽  
The Novel ◽  
Loading Conditions ◽  
Structural Failure ◽  
Moment Distribution ◽  
Offset Distance ◽  
Unit Model ◽  
Flat Base ◽  
Jack Up

Abstract Footprints were left on the seabed due to previous operations, and the problem of the spudcan-footprint interactions gradually becomes one of the major concerns of jack-up unit installation. The spudcan is subjected to eccentric loading conditions, which can lead to structural failure and the overturn of the jack-up unit. This paper reports the global behavior of the three-legged jack-up unit with a novel rectangular-shaped spudcan when it needs to reinstall near an existing footprint. The coupled Eulerian-Lagrangian (CEL) approach was used. A simplified three-legged jack-up unit model was developed and the flexible stiffness between the hull and legs was considered. The free-rotation heading and force-controlled loading conditions were also adopted. The bending moment distribution along the legs, horizontal force and the overturn of the jack-up unit are discussed to assess the potential of the jack-up unit sliding toward the footprint center. The critical offset distance was found at 0.3D and an offset distance of at least 1 times of the spudcan diameter is able to diminish influence of the footprint. The ability of the novel rectangular large spudcan with a flat base is shown to be effective at easing spudcan-footprint interactions, compared with generic circular spudcan.

An Analysis of Flexural Systems under Arbitrary Distortion and End Loading

1957 ◽  
Vol 61 (559) ◽  
pp. 475-484
Author(s):  
P. J. Midgley
Keyword(s):  
Bending Moment ◽  
Beam Equation ◽  
Loading Conditions

SummaryThe effects of end loading on an arbitrarily distorted flexing beam are investigated, with particular reference to bending moment distributions along the span of the beam, and the effects of lengthwise strains. Cross-spring and “ spider ” type flexural systems are treated in detail. Curves are presented which enable the stiffness and stressing of any flexural system to be calculated for any loading conditions, subject only to the restriction that deflections are small, so that the linearised beam equation may be applied.

Study on the Design Method of Deepwater Steel Lazy Wave Riser

2019 ◽  
Author(s):  
Zhao Wang ◽  
Wei Qin ◽  
Xiaojie Zhang ◽  
Jiannan Zhao ◽  
Yong Bai
Keyword(s):  
Oil And Gas ◽  
Design Method ◽  
Bending Moment ◽  
Design Criterion ◽  
Design Flow ◽  
Distribution Law ◽  
Gas Field ◽  
Field Development ◽  
Moment Distribution ◽  
Oil And Gas Field

Abstract The steel lazy wave riser has been used in deep-water oil and gas field development because it has good adaption to the movement of the upper platform and economic efficiency. The typical design criterion and design flow of steel lazy wave riser are introduced in this paper. The design method and the equivalence principle of distributed buoyancy modules are given. The formulas of equivalent hydrodynamic parameters are derived in this paper. The influences of distributed buoyancy modules (DBM) and the buoyancy factor on the configuration of the riser, the top tension, and the bending moment distribution are discussed and summarized. The distribution law of effective stress response along the pipe can be analyzed by dynamic analysis, and it provides reference for the global design of steel lazy wave riser.

scholarly journals Finite Element Analysis and Parametric Study of Spudcan Footing Geometries Penetrating Clay Near Existing Footprints

2019 ◽  
Vol 7 (6) ◽  
pp. 175 ◽  
Author(s):  
Long Yu ◽  
Heyue Zhang ◽  
Jing Li ◽  
Xian Wang
Keyword(s):  
Bending Moment ◽  
Vertical Force ◽  
Leg Length ◽  
Element Analysis ◽  
Centrifuge Tests ◽  
Flat Base ◽  
Key Factor ◽  
The Stability ◽  
Resultant Forces ◽  
Theoretical Analyses

Most existing research on the stability of spudcans during reinstallation nearing footprints is based on centrifuge tests and theoretical analyses. In this study, the reinstallation of the flat base footing, fusimform spudcan footing and skirted footing near existing footprints are simulated using the coupled Eulerian–Lagrangian (CEL) method. The effects of footprints’ geometry, reinstallation eccentricity (0.25D–2.0D) and the roughness between spudcan and soil on the profiles of the vertical force, horizontal force and bending moment are discussed. The results show that the friction condition of the soil–footing interface has a significant effect on H profile but much less effect on M profile. The eccentricity ratio is a key factor to evaluate the H and M. The results show that the geometry shape of the footing also has certain effects on the V, H, and M profiles. The flat base footing gives the lowest peak value in H but largest in M, and the performances of the fusiform spudcan footing and the skirted footing are similar. From the view of the resultant forces, the skirted footing shows a certain potential in resisting the damage during reinstallation near existing footprints by comparing with commonly used fusiform spudcan footings. The bending moments on the leg–hull connection section of different leg length at certain offset distances are discussed.

Time History Analysis of Steel Tall Buildings

2014 ◽  
Vol 1025-1026 ◽  
pp. 918-921 ◽  
Author(s):  
Yong Chul Kim ◽  
Sung Won Yoon
Keyword(s):  
Wind Direction ◽  
Time History ◽  
Tall Buildings ◽  
Bending Moment ◽  
Ground Level ◽  
Structural Systems ◽  
Loading Conditions ◽  
Normal Stresses ◽  
History Analysis ◽  
Principal Axes

The results of wind tunnel experiments were used to conduct time history analyses of three conventional square cross-section tall buildings with different structural systems. The primary purpose of the study was the direct comparison of the effects of the wind loads on the steel tall buildings. Time history analyses were conducted by applying local wind forces to the center of each floor. The results showed that, although the bending moments in the ground-level column on the two principal axes were different, the peak normal stresses were almost the same regardless of the structural systems. Similar observations were made regarding the tip displacements. Furthermore, analyses for the various loading conditions revealed that the contribution of the bending moment in the across-wind direction was the largest, followed by that in the along-wind direction. The ratio of the peak normal stresses for different loading conditions were observed to be almost the same regardless of the structural systems.

EQUIVALENT MOMENT APPROACH FOR ELASTIC LATERAL-TORSIONAL BUCKLING OF TAPERED BEAMS

2010 ◽  
Vol 10 (03) ◽  
pp. 387-409 ◽  
Author(s):  
JOSÉ R. IBAÑEZ ◽  
MIGUEL A. SERNA
Keyword(s):  
Bending Moment ◽  
Elastic Buckling ◽  
Lateral Torsional Buckling ◽  
Critical Moment ◽  
Uniform Beam ◽  
Moment Distribution ◽  
Buckling Resistance ◽  
Moment Approach ◽  
Buckling Length ◽  
Tapered Members

The assessment of the design buckling resistance of single members is usually based either directly on the elastic buckling resistance of the member or indirectly on its non-dimensional slenderness computed from the elastic buckling resistance. Specifically, Eurocode 3 buckling curves define the buckling reduction factors as a function of non-dimensional slenderness and, according to EC3 "General Method", these curves may also be used for non-uniform members. In this context, a new procedure will be presented for the computation of the elastic critical moment of tapered members. As is well known, the elastic critical moment strongly depends on both the bending moment diagram and end support restrictions. For uniform members, elastic critical moments may be computed using a relatively simple formula in which the bending moment distribution is taken into account by an equivalent uniform moment factor, and the end support restrictions are introduced through the buckling length. Unfortunately, this formula has not been extended to tapered members and, as a consequence, the elastic critical moment for tapered beams must be obtained using numerical methods such as the finite element methods. Based on a comprehensive parametric study for the elastic critical moment of tapered beams with different moment diagrams, this paper offers a new procedure, called the Equivalent Moment Approach, for the substitution of a tapered beam with any moment diagram by an equivalent uniform beam. One advantage of the present procedure is that closed form expressions valid for uniform beam can be generalized and used for tapered beams.

Evaluation of dual-axis fatigue testing of large wind turbine blades

2011 ◽  
Vol 226 (7) ◽  
pp. 1693-1704 ◽  
Author(s):  
Peter R Greaves ◽  
Robert G Dominy ◽  
Grant L Ingram ◽  
Hui Long ◽  
Richard Court
Keyword(s):  
Service Life ◽  
Wind Turbine ◽  
Fatigue Testing ◽  
Turbine Blades ◽  
Bending Moment ◽  
Fatigue Tests ◽  
Simulation Software ◽  
Wind Turbine Blades ◽  
Moment Distribution ◽  
Large Wind

Full-scale fatigue testing is part of the certification process for large wind turbine blades. That testing is usually performed about the flapwise and edgewise axes independently but a new method for resonant fatigue testing has been developed in which the flapwise and edgewise directions are tested simultaneously, thus also allowing the interactions between the two mutually perpendicular loads to be investigated. The method has been evaluated by comparing the Palmgren–Miner damage sum around the cross-section at selected points along the blade length that results from a simulated service life, as specified in the design standards, and testing. Bending moments at each point were generated using wind turbine simulation software and the test loads were designed to cause the same amount of damage as the true service life. The mode shape of the blade was tuned by optimising the position of the excitation equipment, so that the bending moment distribution was as close as possible to the target loads. The loads were converted to strain–time histories using strength of materials approach, and fatigue analysis was performed. The results show that if the bending moment distribution is correct along the length of the blade, then dual-axis resonant testing tests the blade much more thoroughly than sequential tests in the flapwise and edgewise directions. This approach is shown to be more representative of the loading seen in service and can thus contribute to a potential reduction in the weight of wind turbine blades and the duration of fatigue tests leading to reduced cost.

Numerical Simulations for Bending Moment Distribution on Linings of Tunnel Excavated by Shield

2015 ◽  
Vol 744-746 ◽  
pp. 1033-1036
Author(s):  
Zi Chang Shangguan ◽  
Shou Ju Li ◽  
Li Juan Cao ◽  
Hao Li
Keyword(s):  
Numerical Simulations ◽  
Axial Force ◽  
Shear Force ◽  
Bending Moment ◽  
Geological Data ◽  
Fem Model ◽  
Maximum Moment ◽  
Moment Distribution ◽  
Negative Moment ◽  
The Moment

In order to simulate moment distribution on linings of tunnel excavated by shield, FEM-based procedure is proposed. According to geological data of tunnel excavated by shield, FEM model is performed, and the moment, axial force and shear force distributions on linings are computed. The maximum moment on segments decreases while Poisson’s ratio of soil materials touching to segments increases. The moment value and distribution vary with Young’s modulus of soil materials. The maximum positive moment on linings is approximately equal to the maximum negative moment.

Breaking Length of Sheet Ice Against Sloping Structure

2004 ◽  
Author(s):  
W. Feng ◽  
Z. M. Shi ◽  
L. M. Liu ◽  
F. Li
Keyword(s):  
Experimental Data ◽  
Field Experiment ◽  
Analytic Solution ◽  
Ice Sheet ◽  
Bending Moment ◽  
Moment Distribution ◽  
Breaking Length ◽  
Bending Failure ◽  
Resistant Structure ◽  
Theoretical Results

The interaction between sheet ice and sloping structure was studied. Models were built up according to the emersed part and floating part of the ice sheet respectively. Bending moment distribution in ice sheet was analyzed to determine where bending failure would occur. The analytic solution of breaking length for sheet ice was got. And some new conclusions were also deduced, which could provide reference for design and field experiment of offshore ice-resistant structure. The results in this paper are consistent with the experimental data from previous researchers. The theoretical results of this paper can directly be used in the analysis of wide inclined structures.

scholarly journals Model Test Study on Bearing Capacity and Deformation Characteristics of Symmetric Pile–Bucket Foundation Subjected to Cyclic Horizontal Load

Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1647
Author(s):  
Zunan Fu ◽  
Guoshuai Wang ◽  
Yanming Yu ◽  
Li Shi
Keyword(s):  
Model Test ◽  
Bending Moment ◽  
Cyclic Behavior ◽  
Marine Clay ◽  
Cycle Number ◽  
Bucket Foundation ◽  
Test Study ◽  
Moment Distribution ◽  
New Type ◽  
Force Displacement

The pile–bucket foundation that features a bucket slipped onto a monopile is a new type of symmetric offshore foundation supporting the wind turbine. Its load bearing and deformation resistance capacity are unclear, especially when subjected to cyclic horizontal loadings. In this paper, a model test has been designed and carried out for investigating the cyclic behavior of the pile–bucket foundation embedded in soft marine clay. Cyclic horizontal loads are applied in a displacement-controlled manner with different amplitudes and frequencies. The influences of cyclic loading parameters, including the amplitude, the frequency and the cycle number, have been studied from the perspectives of stiffness-degradation and damping effect that are evaluated from the recorded horizontal force–displacement relationships at the loading point. In addition, the influences of cyclic horizontal loading on the bending moment distribution and on the p–y curve have been presented and discussed. The results show that significant reductions in the foundation stiffness and in the soil resistance may be observed during the first few cycles when the loading displacement is relatively high.

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