Calibration of a Dynamic Analysis Procedure Using Measurements from a North Sea Jack-up in a Severe Storm

1995 ◽  
Author(s):  
T.O. Weaver ◽  
C.R. Brinkmann
Keyword(s):  
Dynamic Analysis ◽  
North Sea ◽  
Analysis Procedure ◽  
Severe Storm ◽  
Jack Up

On the Bases of Wrench Spaces for the Kinematic and Dynamic Analysis of Mechanisms

2003 ◽  
Vol 125 (3) ◽  
pp. 552-556 ◽  
Author(s):  
Koichi Sugimoto
Keyword(s):  
Dynamic Analysis ◽  
Lie Algebra ◽  
Lie Algebras ◽  
Closed Loop ◽  
Computational Procedure ◽  
Analysis Procedure ◽  
Dual Basis ◽  
Passive Joint

The aim of this paper is to find out a computational procedure for the kinematic and dynamic analysis of a mechanism with multiple loops having motion spaces of a Lie algebra or Lie algebras. The basis of a motion space of the loop is determined such that it consists of passive joints axes in a loop, and a basis of a wrench space is determined to be its dual basis. The analysis of a closed loop mechanism can be done by selecting loop-cut-joints and computing values of wrenches acting on these joints from the condition that virtual works of passive joints are zero. By expressing these wrenches in the coordinate vectors on the dual bases, the concise analysis procedure can be obtained. Because a formulation for the analysis is developed based on the bases consisting of passive joint axes and their dual bases, the computational procedure can be applied to a mechanism with any Lie algebras.

scholarly journals Incremental dynamic analysis of underground subway station structure

2021 ◽  
Vol 293 ◽  
pp. 03007
Author(s):  
Tong Liu ◽  
Fuwang Xu ◽  
Qinghe Wang ◽  
Huaiyu Xu
Keyword(s):  
Dynamic Analysis ◽  
Seismic Vulnerability ◽  
Limit State ◽  
Incremental Dynamic Analysis ◽  
Analysis Procedure ◽  
Subway Station ◽  
Seismic Performance Evaluation ◽  
State Determination ◽  
Underground Subway Station ◽  
Station Structure

Incremental dynamic analysis constitutes the basis of seismic performance evaluation and seismic vulnerability assessment. In this paper, a typical two-story three-span subway station structure is selected as an example structure and its incremental dynamic analysis procedure are presented, including selection of ground motion, intensity measure and limit state determination. The incremental dynamic analysis procedure provided in this study can be a basis for further study on seismic design for underground structural systems.

scholarly journals Proximate underwater soundscape of a North Sea offshore petroleum exploration jack-up drilling rig in the Dogger Bank

2020 ◽  
Vol 148 (6) ◽  
pp. 3971-3979
Author(s):  
Victoria L. G. Todd ◽  
Laura D. Williamson ◽  
Jian Jiang ◽  
Sophie E Cox ◽  
Ian B. Todd ◽  
...  
Keyword(s):  
North Sea ◽  
Petroleum Exploration ◽  
Dogger Bank ◽  
Drilling Rig ◽  
Jack Up ◽  
Offshore Petroleum

Nonlinear Random Wave Time Domain Analysis of Jack-Up Rigs Including Foundation

2017 ◽  
Author(s):  
Partha Chakrabarti ◽  
Deepak Sankar Somasundaram ◽  
Abhijeet Chawan
Keyword(s):  
Time Domain ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Analysis Procedure ◽  
Random Wave ◽  
Two Stage ◽  
Deterministic Analysis ◽  
One Stage ◽  
Stage Analysis ◽  
Jack Up

A jack-up rig has to be designed for extreme storm conditions in its elevated mode during operations. Guidelines of ISO 19905-1 [1] and SNAME TR-5-5A [2] for site specific assessment of jack-up rigs explain in detail such analysis and assessment requirements. It is well known that for higher water depths and extreme environment, structural dynamics and spudcan-soil interaction plays a very significant role. The extreme storm response can be determined either by a two-stage deterministic storm analysis procedure using a quasi-static analysis that includes an inertial load set or by a more detailed fully integrated (random wave) dynamic analysis procedure that uses a stochastic analysis. More commonly, however, jack-up rigs are assessed using a two-stage deterministic wave model along with steady wind loads, since this is much simpler. In two-stage deterministic analysis, the first step is the determination of the inertial load set and structural analysis for all the environmental and gravity loads. To include the effects of the spudcan and soil foundation, an initial rotational stiffness or fixity is assumed that depends on the soil type and the preload. Assessment of the foundation is performed thereafter using the yield interaction approach. This is normally an iterative approach to arrive at the right fixity that satisfies the assessment. The two-stage approach, although simpler could be conservative leading to adverse conclusions for the suitability of a jack-up at a site. As indicated, the other approach is the one-stage approach involving random time domain analysis which is normally not used and reported in the literature probably due to its complexity and difficulty. The present paper describes random wave time domain analysis of a specific jack-up using a 3D model in 400 ft water depth using USFOS software [3]. This software has the spudcan-soil interaction integrated, to simulate the foundation behavior. In this one-stage analysis, the assessment for the foundation is performed through an iterative approach inside the software using yield and bounding surfaces. Extreme values of some of key responses are compared with traditional deterministic analysis. Benefits and limitations of random wave time domain analysis are explained and quantified. These benefits are sometimes so significant that one-stage analysis may lead to favorable conclusions where the conservative two-stage analysis approach had failed to show the adequacy of the rig. These observations and the overall methodology of analysis used here could be beneficial to any rig’s applicability at a specific site.

scholarly journals ANOMALOUS DISPERSION OF FOURIER COMPONENTS OF SURFACE GRAVITY WAVES IN THE NEAR SHORE AREA

1978 ◽  
Vol 1 (16) ◽  
pp. 12 ◽  
Author(s):  
Fritz Busching
Keyword(s):  
Water Level ◽  
Storm Surge ◽  
North Sea ◽  
Gravity Waves ◽  
Anomalous Dispersion ◽  
Beach Profile ◽  
Severe Storm ◽  
Surface Gravity Waves ◽  
Near Shore ◽  
Frequency Components

Water level deflections ri (t) have been measured synchronously at some positions in a beach profile on the isle of SYLT / North Sea during severe storm surge conditions as well as at attenuating wave action. A steadily increasing wave period T in the upbeach direction, turning out from strip chart evaluations, is in accordance with the result of FOURIER syntheses. Near shore wave deformation is explained by ANOMALOUS dispersion of the frequency components.

Dynamic Analysis of a Jack-Up Rig, SDOF Approach: Design Consideration — I

2013 ◽  
Author(s):  
Francisco J. Godoy ◽  
Fernando Lorenzo
Keyword(s):  
Dynamic Analysis ◽  
Static Analysis ◽  
Dynamic Effect ◽  
Wave Loads ◽  
Inertial Load ◽  
Base Shear ◽  
Oil Drilling ◽  
Analogy Method ◽  
Specific Assessment ◽  
Jack Up

A jack up rig, such as those used for oil drilling in the Gulf of Mexico, is a dynamic sensitive system subjected to random and periodic environmental loads (wave, wind, current, etc.), in which the inertia forces cannot be ignored. However, a static load analysis approach can be justified only if an extra inertial load set, due to the dynamic effect response, is included in the analysis. The Society of Naval Architects and Marine Engineers, SNAME T&R 5-5A, “Guidelines for Site Specific Assessment of Mobile Jack-Up Units”[1], addresses the calculation of the inertial load set by using the classical Single Degree of Freedom (SDOF) analogy to calculate such dynamic effect. This study evaluates how far apart crucial structural members’ stresses/loads obtained by using the SDOF analogy method are from those values obtained from a more realistic modal dynamic analysis. The analysis is performed for wave loads at different heights and frequencies such as those existing on extreme or severe design conditions as a storm. Although a jack up rig structure presents some non-linearities, especially in the legs-hull contact areas and the spud-cans interaction with the soil; a modal superposition analysis can be used if proper linearization is considered. The results of this study for a jack show that the SDOF analogy method tends to underestimate the base shear loads for high wave periods and conversely overestimate some stresses on crucial members, such as the legs’ chords close to the hull for all the wave periods. This study shows that the stresses on one of the legs’ chord of the most loaded leg, due to the dynamic effect produced by the harmonic loads calculated with the SDOF analogy developed in this study tend to be overestimated as the wave period decreases. Conversely, the calculation of the base shear of the structure employing a quasi-static analysis with inertial load set (ILS) as calculated in this study shows that the base shear forces difference between the modal dynamic analysis and the quasi static analysis tends to decrease as the periods of the wave decreases.

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