Dynamic Behavior Analysis of a Floating Artificial Base-Building Assumed as Hybrid Structure Due to Wave Forces

2006 ◽  
Author(s):  
Osamu Saijo ◽  
Hiroaki Eto ◽  
Koichi Maruyoshi
Keyword(s):  
Structural Response ◽  
Fem Analysis ◽  
Hybrid Structure ◽  
Response Analysis ◽  
Wave Forces ◽  
Structural System ◽  
Matrix Size ◽  
Floating Base ◽  
The Matrix ◽  
Natural Frequency Analysis

Dynamic response analysis of a floating artificial base-building due to wave forces was studied, which structural system was named as a hybrid structural system. It was assumed to be constructed by the combination of elastic plate and framed structure. The hybrid structure system enabled the matrix size to reduce in FEM analysis, and the improvement of the calculation efficiency was succeeded. The developed calculation tool made it possible to examine the dynamic characteristic of the building on the floating base under the various wave conditions. The natural frequency analysis and the structural response analysis were capable, besides the evaluation of habitability in relation with oscillation caused by wave motion became possible using the diagram of our result of the research.

Analytical investigation of nonlinear heave-coupled response of tension leg platform

2018 ◽  
Vol 233 (3) ◽  
pp. 699-713
Author(s):  
Mohammad Reza Tabeshpour ◽  
Reza Hedayatpour
Keyword(s):  
Degrees Of Freedom ◽  
Structural Response ◽  
Wave Theory ◽  
Equation Of Motion ◽  
Analytical Investigation ◽  
Response Analysis ◽  
Wave Forces ◽  
Tension Leg Platform ◽  
Heave Motion ◽  
Diffraction Effects

Having deep view in structural response of tension leg platform is important issue not only for response analysis but also for engineering design. Coupling between surge and heave motions of tension leg platform is such a problem. Here, tension leg platform motions are considered only in surge and heave degrees of freedom without pitch effect. The coupled term of heave is a nonlinear differential equation. Because the focus of this article is on this term, therefore, Duffing equation of motion in the surge direction is linearized. The wave forces are calculated using Airy’s wave theory and Morison’s equation, ignoring the diffraction effects. Current force also can be very important in dynamic analysis of tension leg platform. Because it affects the term of heave that is coupled with surge. It is shown that the effect of surge motion coupling on heave motion is very important in large displacement of surge motion in many sea states. The main result is that the coupling effects appeared in some frequencies such as heave and surge frequency, twice the frequency of wave, twice the natural surge frequency, and summation and difference of frequency of wave and surge frequency.

A Study on Wave Response and Evaluation of Habitability of Floating Restaurant

2008 ◽  
Author(s):  
Hiroaki Eto ◽  
Osamu Saijo ◽  
Koichi Maruyoshi
Keyword(s):  
Size Structure ◽  
Boundary Integral ◽  
Frame Structure ◽  
Medium Size ◽  
Response Analysis ◽  
Structural System ◽  
Floating Structure ◽  
Structural Dynamic ◽  
Floating Base ◽  
Wave Response

Since Japan is limited in area, the effective ocean space development is very important and urgent subject. Concerning a research and development of effective ocean space utilization, the MEGA-FLOAT was one of the most famous projects in Japan that had the purpose of a floating airport construction, and the numerous R & D were conducted aiming at actual construction and those results were reported in respect of conceptual design, construction method, fluid analysis, structural dynamic analysis, environment issue etc. However, the end was faced without achieving it, it can be said that the effect is large. After the end of that project, the realistic, small or medium size structure began to be paid to attention. As the good example of such a kind floating structure, floating pier and disaster prevention base having an advantage against an earthquake, floating restaurant etc. were constructed shown in Figure 1. In this paper, assuming the small size floating restaurant, the wave response analysis was studied, and the habitability of that structure was evaluated from the response calculation results. Concretely, the floating base part; barge type of the restaurant building was designed by the Class NK (Rules and Guidance for the survey and construction of steel ships, Part Q Steel barges). The calculation model consists of a three-story building and the base, that floating artificial base supporting the building was assumed by the elastic plate structural system, and also that building was of the frame structure system. In order to structural analysis, the restaurant model of two different structural systems was united into one body system. In this paper, it is called the hybrid structural system. Fluid effect was analyzed as the fluid-structural interaction problem. Concretely, the Boundary Integral Equation Method (BIEM) was used here, and the wave response calculation was demonstrated by that forces. The evaluation of habitability of the restaurant in vertical and horizontal motion was examined by the diagram proposed from our research results.

scholarly journals STRUCTURAL RESPONSE OF DOLOS IN WAVES

1988 ◽  
Vol 1 (21) ◽  
pp. 181 ◽  
Author(s):  
Joseph W. Tedesco ◽  
Preston B. McGill ◽  
Jeffrey A. Melby ◽  
William G. McDougal
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Models ◽  
Structural Response ◽  
Fem Analysis ◽  
Wave Forces ◽  
Structural Failure ◽  
Wave Conditions ◽  
Element Method

Several numerical models for estimating wave forces on dolosse are presented. These models are incorporated into a finite element method (FEM) analysis of a 42-ton unit. The results of the analysis permit identification of unit structural failure with respect to wave conditions.

scholarly journals Natural Frequency Analysis of Elastic Plate

1997 ◽  
Author(s):  
O. Saijo ◽  
H. Eto
Keyword(s):  
Natural Frequency ◽  
Frequency Analysis ◽  
Large Scale ◽  
Mass Matrix ◽  
Fem Analysis ◽  
Added Mass ◽  
Boundary Integral ◽  
Theoretical Development ◽  
Structural System ◽  
Natural Frequency Analysis

Large scale floating structures, such as floating airport and amusement park having two dimensional expanse in horizontal direction, which structural concept can be considered as plate-type structural system. This structural system has a great deal of potential to be applied to oceanic structures like a artificial ground. This practical fabrication will be done by a combination of units. The hydroelastic interaction problem and structural design have attracted the attention of researchers and structural engineers. This paper presents consideration and conclusion through the numerical calculation results of the natural frequency studied under the various supporting conditions by developed computer program. The theoretical development is obtained by a way of combination of finite element method (FEM) and boundary integral equation method (BIEM). As to natural frequency analysis of oceanic structures based on the fluid-structure interaction, in general, there is an assumption to make it possible by estimating properly the added mass of the structure surrounding by water. The added mass of floating plate obtained by BIEM is modified and transformed into mass matrix of plate in FEM analysis. Herein, FEM analysis is based on the bending vibration assumption.

A new approach for displacement and stress monitoring of tunnel based on iFEM methodology

2021 ◽  
Author(s):  
Pierclaudio Savino ◽  
Francesco Tondolo
Keyword(s):  
Input Data ◽  
Structural Response ◽  
Fem Analysis ◽  
Computational Procedure ◽  
Loading Conditions ◽  
Underground Structures ◽  
Stress Monitoring ◽  
Load Pattern ◽  
Structural Configurations ◽  
Structural Loading

Abstract Structural monitoring plays a key role for underground structures such as tunnels. Strain readings are expected to report structural conditions during construction and at the final delivery of the works. Furthermore, it is increasingly requested an extension to long-term monitoring from contractors with possible use of the same system in service during construction. A robust and efficient monitoring methodology from discrete strain measurements is the inverse Finite Element Method (iFEM), which allows to reconstruct the structural response without input data on the load pattern applied to the structure as well as material and inertial properties of the elements and therefore it is interesting for structural configurations affected by uncertain loading conditions, such as the tunnel. The formulation presented in this paper, based on the iFEM theory, is improved from the previous work available in literature for both the shape functions used and the computational procedure. Indeed, the approach allows to overcome inconsistencies related to structural loading conditions and a pseudo-inverse matrix preserve all the rigid body modes without imposing specific constraints which is typical for tunnels. Numerical validation of the iFEM procedure is performed by simulating the input data coming from a tunnel working in a heterogeneous soil under different loading conditions with direct FEM analysis.

scholarly journals Assessment of Structural Performance and Integrity for Vibration-based Energy Harvester in Frequency Domain

Electronics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 357
Author(s):  
Ji-Won Jin ◽  
Ki-Weon Kang
Keyword(s):  
Frequency Domain ◽  
Natural Frequency ◽  
Production Efficiency ◽  
Performance Test ◽  
Energy Harvester ◽  
Structural Integrity ◽  
Structural Response ◽  
Structural Performance ◽  
Railway Vehicle ◽  
Response Analysis

A vibration-based energy harvester (VEH) utilizes vibrations originated from various structures and specifically maximizes the displacement of its moving parts, using the resonance between the frequency of external vibration loads from the structure and the natural frequency of VEH to improve power production efficiency. This study presents the procedure to evaluate the structural performance and structural integrity of VEH utilized in a railway vehicle under frequency domain. First of all, a structural performance test was performed to identify the natural frequency and assess the structural response in frequency domain. Then, the static structural analysis was carried out using FE analysis to investigate the failure critical locations (FCLs) and effect of resonance. Finally, we conducted a frequency response analysis to identify the structural response and investigate the structural integrity in frequency domain. Based on these results, the authors assessed the structural performance and integrity of VEHs in two versions.

Numerical Simulation on Fatigue Life Assessment of Free Span for Submarine Pipeline

2015 ◽  
Vol 750 ◽  
pp. 153-159
Author(s):  
Jie Dong ◽  
Xue Dong Chen ◽  
Bing Wang ◽  
Wei He Guan ◽  
Tie Cheng Yang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Fatigue Life ◽  
Oil And Gas ◽  
Structural Response ◽  
Simulation Method ◽  
Life Assessment ◽  
Response Analysis ◽  
Submarine Pipeline ◽  
Fatigue Life Assessment ◽  
Harmonic Response Analysis

The upper and lower courses of sea oil and gas exploitationare connected by submarine pipeline which is called life line project. Free span often occurs because of the unevenness and scour of seabed, and fatigue is one of the main failure modes.In this paper, with the finite element numerical simulation method, based on the harmonic response analysis, the research on the structural response of free span under the vibration induced by vortex was investigated, and the effect of the factors such as flow velocity, length of free span. According to the analysis results,the fatigue life of free span was evaluated.

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