Global Structural Response Analysis of Jack-Up Ship in Transit Condition

2013 ◽  
Vol 344 ◽  
pp. 66-69
Author(s):  
Xiang Zhu ◽  
Yong Sheng Tang ◽  
Yao Zhao ◽  
Heng Kui Ye
Keyword(s):  
Structural Response ◽  
Bending Moment ◽  
Element Model ◽  
Inertia Force ◽  
Response Analysis ◽  
Wave Loads ◽  
Critical Areas ◽  
Hull Structure ◽  
In Transit ◽  
Jack Up

The global structural response of a four-leg jack-up wind turbine installation ship in the transit condition was analyzed in this paper. The finite element model of the hull and legs were established with the Software MSC. PATRAN. On the basis of long-term forecast of the wave loads, the corresponding designed wave parameters are determined with the vertical wave bending moment of the midship cross section served as the main load control parameter. Considering the gravity, hydrostatic pressure, the hydrodynamic loads induced by the wave, inertia force induced by the motion and acceleration of the ship and the wind force on the legs and hull, the direct calculated method was used to evaluate the global structural response of the vessel. The deformation and stress of the hull and legs were calculated and checked. The results showed that the strength of the hull and leg could meet the rules requirements. For the jack-up ship in the transit condition, the critical areas are mainly lower part of legs and the corresponding hull structure.

New Seismic Design Specifications of Highway Bridges in Japan

1994 ◽  
Vol 10 (2) ◽  
pp. 333-356 ◽  
Author(s):  
Kazuhiko Kawashima ◽  
Kinji Hasegawa
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Response ◽  
Seismic Design ◽  
Structural Response ◽  
Highway Bridges ◽  
Lateral Force ◽  
Inertia Force ◽  
Response Analysis ◽  
Design Specifications ◽  
Recent Earthquakes

This paper presents the new seismic design specifications for highway bridges issued by the Ministry of Construction in February 1990. Revisions of the previous specifications were based on the damage characteristics of highway bridges that were developed after the recent earthquakes. The primary revised items include the seismic lateral force, evaluation of inertia force for design of substructures considering structural response, checking the bearing capacity of reinforced concrete piers for lateral load, and dynamic response analysis. Emphasis is placed on the background of the revisions introduced in the new seismic design specifications.

Seismic Response Analysis for Pier in Considering of Uplift Effect

2011 ◽  
Vol 243-249 ◽  
pp. 4052-4055
Author(s):  
Li Dong Zhao ◽  
Bo Song
Keyword(s):  
Seismic Response ◽  
Earthquake Engineering ◽  
Seismic Isolation ◽  
Ground Motions ◽  
Bending Moment ◽  
Element Model ◽  
Simulation Software ◽  
Response Analysis ◽  
Strong Ground ◽  
Maximum Horizontal Acceleration

In earthquake engineering, researchers have found that many structures were not damaged after strong ground motions because of the rocking effect. In order to reveal the potential application value of the uplift effect on seismic isolation, it will be using numerical simulation software OpenSees to research the seismic response of pier considering uplift. Building the pier’s finite element model and considering the plasticity and nonlinear of the pier and soil spring, the ground motion from El Centro and TCU101 are taken as the input respectively. Through analyzing the result, it is shown that at the base of the pier the maximum bending moment is reduced by 36.93% and 46.70%, and the maximum curvature is also reduced by 78.42% and 87.12% respectively. Meanwhile, the maximum horizontal acceleration at the top of the pier is decreased 12.60% and 16.90%. The uplift effect significantly reduces the plastic deformation and plays a base-isolated role according to the results. It has also found that the earthquakes with velocity pulse effect are dangerous to the structures.

scholarly journals Dynamic Response Analysis of a Floating Bridge Subjected to Environmental Loads

2018 ◽  
Author(s):  
Zhengshun Cheng ◽  
Zhen Gao ◽  
Torgeir Moan
Keyword(s):  
Wind Wave ◽  
Bending Moment ◽  
Response Analysis ◽  
Ultimate Limit State ◽  
Wave Loads ◽  
Frequency Wave ◽  
Environmental Loads ◽  
Load Effects ◽  
Floating Bridge ◽  
Sway Motion

Designing floating bridges for wide and deep fjords is very challenging. The floating bridge is subjected to wind, wave, and current loads. All these loads and corresponding load effects should be properly evaluated, e.g. for ultimate limit state design check. In this study, the wind-, wave- and current-induced load effects of an end-anchored floating bridge are numerically investigated. The considered floating bridge, about 4600 m long, was an early concept for crossing Bjørnafjorden, Norway. It consists of a cable-stayed high bridge part and a pontoon-supported low bridge part, and has a number of eigen-modes, which might be excited by the relevant environmental loads. Numerical simulations show that the sway motion and strong axis bending moment along the bridge girder are primarily induced by wind loads, while variations of heave motion and weak axis bending moment are mainly induced by wave loads. Current loads mainly provide damping force to reduce the variations of sway motion and strong axis bending moment. Turbulent wind can cause significantly larger low-frequency resonant responses than second-order difference-frequency wave loads.

scholarly journals Sloshing Impact Response in LNG Membrane Carriers: A Response Analysis of the Hull Structure Supporting the Membrane Tanks

2016 ◽  
Author(s):  
Jonas W. Ringsberg ◽  
André Liljegren ◽  
Ola Lindahl
Keyword(s):  
Structural Response ◽  
Response Analysis ◽  
Impact Loads ◽  
Dynamic Amplification Factor ◽  
Insulation System ◽  
Load Duration ◽  
Hull Structure ◽  
Load Characteristics ◽  
Membrane Type ◽  
Dynamic Amplification

This study presents the determination of structural response due to sloshing impact loads in LNG carriers with membrane type cargo tanks. These loads are characterized by very short durations and are thus likely to inflict a dynamic amplification in the response of the hull. Finite element analyses are presented using a model representing parts of an LNG membrane tank. The objective was to find and quantify the dynamic amplification factor (DAF) for the structural response towards sloshing impact pressures. The influence of variations in the load characteristics such as load duration, extent of the loaded area, load location as well as the influence of the insulation system was evaluated. The study shows that the response in the studied region of the hull structure experiences significant levels of dynamic amplification during impact loads with specific durations. The response sensitivity analysis also shows that the insulation system (MARK III type) has a large effect on the dynamic behaviour of the hull structure. It has been found to alter the magnitude of the stress and deflection response for key structural members. It also changes the load time durations for which the maximum dynamic amplification occurs and increases the magnitude of the corresponding response DAF. Finally, it has been found that dynamic response gives DAF values of up to 2. The effects have been found to be present for temporal load characteristics commonly occurring in sloshing model tests and full-scale measurements and are therefore likely to occur for a vessel in operation.

Dynamic Response Analysis of Ship Hull Structures

2000 ◽  
Vol 37 (03) ◽  
pp. 117-128
Author(s):  
T. V. S. R. Appa Rao ◽  
Nagesh R. Iyer ◽  
J. Rajasankar ◽  
G. S. Palani
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Dynamic Response ◽  
Finite Element Model ◽  
Element Model ◽  
Ship Hull ◽  
Response Analysis ◽  
Dynamic Response Analysis ◽  
Hull Structure ◽  
The Finite Element Model

Finite-element modeling and use of appropriate analytical techniques play a significant role in producing a reliable and economic design for ship hull structures subjected to dynamic loading. The paper presents investigations carried out for the dynamic response analysis of ship hull structures using the finite-element method. A simple and efficient interactive graphical preprocessing technique based on the "keynode" concept and assembly-line procedure is used to develop the finite-element model of the hull structure. The technique makes use of the body plan of a ship hull to build the finite-element model through an interactive session. Stiffened plate/shell finite elements suitable to model the hull structure are formulated and used to model the structure. The finite elements take into account arbitrary placement of stiffeners in an element without increasing the number of degrees-of-freedom of the element. A three-dimensional finite-element model and a procedure based on the Bubnov-Galerkin residual approach are employed to evaluate the effects of interaction between the ship hull and water. Mode superposition technique is used to conduct the dynamic response analysis. The efficiency of the finite elements and the procedures is demonstrated through dynamic analysis of a submerged cantilever plate and a barge when both are subjected to sinusoidal forces. The dynamic responses exhibit expected behavior of the structure and a comparison with the results available in the literature indicate superior performance of the finite element and methodologies developed. Thus, the finite-element models and the procedures are found to be efficient and hence suitable for the dynamic analysis of similar structures.

Welding Distortion Minimization for an Aluminum Alloy Extruded Beam Structure Using a 2D Model

2004 ◽  
Vol 126 (1) ◽  
pp. 52-63 ◽  
Author(s):  
Bart O. Nnaji ◽  
Deepak Gupta ◽  
Kyoung-Yun Kim
Keyword(s):  
Aluminum Alloy ◽  
Quality Index ◽  
Bending Moment ◽  
Element Model ◽  
Maximum Principal Stress ◽  
Welding Distortion ◽  
Beam Structure ◽  
Critical Areas ◽  
Distortion Minimization ◽  
Nonlinear Transient

Optimization of the weld sequence of a sub-assembly composed of thin walled aluminum alloy extruded beams is investigated and presented. The main factor considered is the quality of the assembly after welding, which is measured by the deformation behavior at pre-defined critical locations. The aluminum alloy extruded beam structure is simplified by a 2-D beam element model. Our methodology consists of applying pre-estimated angular shrinkages for each welding step thus eliminating use of a complex nonlinear transient analysis which would require consideration of thermo-mechanical interactions and plasticity. Two distortion modes (angular shrinkage and tilting shrinkage) are investigated and applied to model welding distortion. Different criteria for minimization of welding distortion have been investigated, such as overall deformation or weighted deformation with emphasis on some critical areas. A composite quality index is formulated, which is a weighted measure of critical deformation and the overall deformation. For simulating welding deformation and the role of sequences, some weld sequences were selected heuristically and they were simulated in ANSYS 5.2. Based on the quality index of these sequences, some were reproduced while mutating other portions of these sequences to find better sequences. Finally, deformation data for each node and weighted measures of deformation for considered sequences are presented, and final deformed shapes for different sequences, maximum principal stress, and bending moment across the beams are shown graphically.

scholarly journals Structural response analysis of jack-up during system jacking lifting process

2020 ◽  
Vol 575 ◽  
pp. 012201
Author(s):  
Rian Burnang Purba ◽  
Juswan ◽  
Muhammad Zubair Muis Alie
Keyword(s):  
Structural Response ◽  
Response Analysis ◽  
Jack Up

The Study on Hull Structure Strength Analysis and Opening Calculation of CJ46 Jack-Up Drilling Unit

2015 ◽  
Author(s):  
Zeng Ji ◽  
Chen Gang ◽  
Mo Jian ◽  
Wang Yuhan ◽  
Zhang Wei
Keyword(s):  
Yield Strength ◽  
Element Model ◽  
Strength Analysis ◽  
Ocean Engineering ◽  
Engineering Structures ◽  
Hull Structure ◽  
Key Issues ◽  
Drilling Unit ◽  
Main Support ◽  
Jack Up

The structural strength of jack-up units is the key issues in the design of ship and ocean engineering structures. Based on ABS MODU, the yield strength of CJ46 self-elevating drilling platform main hull structure is checked. Firstly, the environmental loads (wind, wave and flow) in three loading conditions which are required by specification are calculated by using GeniE (DNV). Then the 3D finite element model of main hull structure is established. The yield strength is checked and the results shown the large stress areas are leg well, jackcase which is connected with the leg and bulkhead which is main support structure under the cantilever sliding device, while the results meet the requirements of ABS MODU. Finally, the influence of the openings located in main longitudinal bulkheads are evaluated, meanwhile the main longitudinal bulkheads under skidding box need particular concern.

Extreme Dynamic Structural Response Analysis of Catenary Moored Spar Wind Turbine in Harsh Environmental Conditions

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Madjid Karimirad ◽  
Torgeir Moan
Keyword(s):  
Wind Turbine ◽  
Fatigue Limit ◽  
Limit State ◽  
Structural Response ◽  
Bending Moment ◽  
Response Analysis ◽  
Ultimate Limit State ◽  
Average Wind Speed ◽  
Structural Responses ◽  
H 20

Proper performance of structures requires among other things that their failure probability is sufficiently small. This would imply design for survival in extreme conditions. The failure of a system can occur when the ultimate strength is exceeded (ultimate limit state (ULS)) or fatigue limit (fatigue limit state) is exhausted. The focus in this paper is on the determination of extreme responses for ULS design checks, considering coupled wave and wind induced motion and structural response in harsh condition up to 14.4 m significant wave height and 49 m/s 10 min average wind speed (at the top of the tower, 90 m) for a parked floating wind turbine of a spar type concept. In the survival condition, the wind induced resonant responses (mainly platform pitch resonance) are dominant. Due to the platform resonant motion responses, the structural responses are close to Gaussian, but wide banded. The critical structural responses are determined by coupled aerohydro-elastic time domain simulation. Based on different simulations (20 1 h, 20 2 h, 20 3 h, and 20 5 h), the mean up-crossing rate has been found in order to predict the extreme structural responses. The most probable maximum of the bending moment and the bending moment having an up-crossing rate of 10−4 are found to be close in the present research. The minimum total simulation time in order to get accurate results is highly correlated with the needed up-crossing rate. The 1 h and 2 h raw data cannot provide any information for 10−4 up-crossing rate. Comparison of different simulation periods shows that the 20 1 h simulations can be used in order to investigate the 3 h extreme bending moment if the proper extrapolation of up-crossing rate is used.

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