Updated Design Procedure for Free Spanning Pipelines DNV-RP-F105: Multi-Mode Response

2006 ◽  
Author(s):  
Olav Fyrileiv ◽  
Kim Mo̸rk ◽  
Muthu Chezhian ◽  
Gudfinnur Sigurdsson
Keyword(s):  
Design Procedure ◽  
Oil Fields ◽  
Vibration Modes ◽  
Design Code ◽  
Vortex Induced Vibrations ◽  
Offshore Development ◽  
Multi Mode ◽  
Mode Response

In search for new gas and oil fields, the trend in offshore development points towards deeper waters, harsher environment, increased use of subsea installations and use of pipelines to transport the hydrocarbons to processing facilities onshore or in shallower waters. This also implies installation of pipelines at very uneven seabed causing a high number of spans that can be difficult and very costly to intervene. Conventional free span design according to the DNV Recommended Practice DNV-RP-F105 (2002) allows for vortex induced vibrations (VIV) as long as the integrity of the pipeline is within acceptable limits. However, the 2002 issue of the design code mainly covers short and moderate spans. As the knowledge about very long and/or multiple spans, where several vibration modes may be activated, has been limited, such cases have been treated in an assumed conservative way. This paper discusses the technical advancements in free span design in general and with respect to both long free spans and multi-spanning sections where several vibration modes may be activated simultaneously in particular. These advancements form the basis for the updated DNV-RP-F105 (2006). Changes from the former 2002 version are illustrated by an examples and the technical background is discussed.

Motion and Vibration Control of Three Dimensional Flexible Shaking Table Using LQI Control Approach

2001 ◽  
Author(s):  
Hidefumi Hiramatsu ◽  
Daijiro Fuji ◽  
Kazuto Seto ◽  
Toru Watanabe
Keyword(s):  
Vibration Control ◽  
Three Dimensional ◽  
Design Procedure ◽  
Equation System ◽  
State Equation ◽  
Shaking Table ◽  
System Model ◽  
Vibration Modes ◽  
Control Approach ◽  
Control Forces

Abstract This paper deals with a design procedure of control system for a three-dimensional flexible shaking table. The shaking table should be less weighted so that actuators require less control forces and higher fidelity to control commands. However, as the weight of shaking table is reduced, the natural frequencies of vibration modes of the table appear on operating frequency region. Such vibration modes get into problem that may cause spillover instability. So, the research purpose is to control such vibration and motion by using the modeling method presented by Seto [1]. Utilizing the model, state equation system model including integrator is composed and feedback controller is designed by using LQI control law. As the system model both includes the multi-degree-of -freedom-structure model and integrator, the designed controller achieves simultaneous motion and vibration control. Computer simulation and control experiments are carried out and the effectiveness of the presented procedure is investigated.

Simplified Hydrodynamic Design Procedure of a Submerged Floating Tube Bridge Across the Digernessund of Norway

2017 ◽  
Author(s):  
Xu Xiang ◽  
Arianna Minoretti ◽  
Mathias Egeland Eidem ◽  
Kjell Håvard Belsvik ◽  
Tale Egeberg Aasland ◽  
...  
Keyword(s):  
Cross Sections ◽  
Present Model ◽  
Design Procedure ◽  
Analysis Procedure ◽  
Hydrodynamic Coefficients ◽  
Bending Moments ◽  
Vortex Induced Vibrations ◽  
Simplified Method ◽  
Hydrodynamics Coefficients ◽  
The Given

The paper will look into the hydrodynamic loads and responses on the proposed Submerged Floating Tube Bridge (SFTB) through the Digernessund by the Norwegian Public Roads Administration (Statens vegvesen, NPRA). The aim is to show how different hydrodynamics aspects during the prelimiary design can be simply addressed under the given environmental conditions. Different SFTB systems are introduced as the first step. A simplified method based on modal analysis is introduced and implemented for evaluation of the motions and stress, bending moments along the bridge. Firstly, a 2D Boundary Element Method (BEM) solver is developed and verified, which is further used for solving the hydrodynamics coefficients of different bridge cross sections. The 3D hydrodynamic coefficients of pontoons are solved by the commercial software AQWA. The analysis procedure of the simplified method for the global SFTB responses is presented. The Eigen periods of the Bjørnefjord SFTB is re-calculated by the present model as a first validation of the implementation. The loads and responses of the bridge under given wave conditions are then estimated. The evaluation of the possibility of vortex induced vibrations of the current SFTB design is given.

Seismic Response of Long-Span Domes Supported by Multi-Storey Substructures

2020 ◽  
Vol 61 (2) ◽  
pp. 140-157
Author(s):  
Deepshikha Nair ◽  
Yuki Terazawa ◽  
Ben Sitler ◽  
Toru Takeuchi
Keyword(s):  
Seismic Response ◽  
Response Spectrum ◽  
Design Procedure ◽  
Mode Shapes ◽  
Vertical Acceleration ◽  
Vibration Modes ◽  
Higher Modes ◽  
Long Span ◽  
Excited Vibration ◽  
Buckling Restrained Braced Frames

This paper investigates the seismic response characteristics of long-span domes. The natural periods of the prominent modes are longer than medium-span domes, which leads to a greater contribution from the higher modes to the response of the long-span dome. The acceleration distributions, particularly the vertical acceleration distributions are sensitive to the dominant mode shapes of these higher modes. This leads to inaccuracies when applying the previously proposed response evaluation methods. The vibration modes of multi-storey supporting substructures also affect the excited vibration modes of the roof. In this paper, the dynamic characteristics and seismic response of 150m-span domes supported by multi-storey substructures are studied. The effects of the post- yield stiffness of multi-storey substructures are also analysed by considering two structural systems, buckling- restrained braced frames (BRBF) and damped spine frames. A simple design procedure to evaluate the equivalent static loads using amplification factors and incorporating the effects of higher modes is proposed based on response spectrum analysis and equivalent linearisation procedures. The accuracy of the proposed method is evaluated by comparing the responses with those obtained from non-linear response history analysis.

Investigation of flexible multi-mode harmonic vibration for the automatic washing process

2008 ◽  
Vol 222 (12) ◽  
pp. 2373-2384
Author(s):  
J-L Kuo ◽  
T-Y Wang
Keyword(s):  
Automatic Process ◽  
Vibration Modes ◽  
Blade Angle ◽  
Sinusoidal Vibration ◽  
Automatic Process Control ◽  
Flexible Control ◽  
Operating Modes ◽  
Washing Process ◽  
Mode Vibration ◽  
Multi Mode

This article discusses multi-mode vibration for the vibration motor in the washing process. Sinusoidal vibration modes for the speed servo command are carefully designed for flexible control. Different kinds of operating modes for possible automatic process control are provided. Three basic and five extended vibration modes for different operations are proposed. Simulation and experimental results will be compared to verify the formulation. To make the washing process more flexible, various servo commands are provided to be reconfigurable for the required vibration motion. Differing from the conventional approach of mechanically regulating the blade angle of the vibration motor, multi-mode vibration developed by the software approach is successfully proposed. It is easier for the washing process to be electrically regulated instead of it being a mechanical operation only. It is believed that this article will be beneficial for the application of an automatic washing process of the washing machine.

Structural Response of Pipeline Free Spans Based on Beam Theory

2002 ◽  
Author(s):  
Olav Fyrileiv ◽  
Kim Mo̸rk
Keyword(s):  
Natural Frequencies ◽  
Structural Response ◽  
Beam Theory ◽  
Vertical Vibration ◽  
Mode Shapes ◽  
Ocean Current ◽  
Vibration Modes ◽  
Wave Loading ◽  
Vortex Induced Vibrations ◽  
Subsea Pipelines

One of the main risk factors for subsea pipelines exposed on the seabed is fatigue failure of free spans due to ocean current or wave loading. This paper describes how the structural response of a free span, as input to the fatigue analyses, can be assessed in a simple and still accurate way by using improved beam theory formulations. In connection with the release of the DNV Recommended Practice, DNV-RP-F105 “Free Spanning Pipelines”, the simplified structural response quantities have been improved compared to previous codes. The boundary condition coefficients for the beam theory formulations have been updated based an effective span length concept. This concept is partly based on theoretical studies and partly on a large number of FE analyses. The updated expressions are general and fit all types of soil and pipe dimensions for lower lateral and vertical vibration modes. The present paper focus on estimation of simplified response quantities such as lower natural frequencies and associated mode shapes. Hydrodynamical aspects of Vortex Induced Vibrations (VIV) are outside the scope of this paper.

scholarly journals Column strength requirements in multi-storey seismic frames

1989 ◽  
Vol 22 (3) ◽  
pp. 135-144
Author(s):  
E. L. Blaikie
Keyword(s):  
Flexural Strength ◽  
Ground Motions ◽  
Design Procedure ◽  
Capacity Design ◽  
Design Code ◽  
Factors Affecting ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
Column Design ◽  
Future Evaluation

This paper examines factors affecting the strength requirements of columns in multi-storey frames responding to seismic ground motions. The examination is carried out using an inelastic static analysis approach and the concept of an "equivalent condensed frame". In particular, the influence of higher modes and the effect of varying the pattern of beam flexural strength over the frame height are evaluated. It is suggested that the current capacity design approach of the NZ Concrete Design Code overstates the importance of higher mode effects while neglecting the potentially more important influence of the beam flexural strength pattern that is provided for a frame. Some tentative modifications to the current column design procedure are suggested for future evaluation under inelastic dynamic response conditions.

scholarly journals Vibration Suppression of a 3-DOF Parallel Manipulator Based on Hybrid Negative Impulses Multi-Mode Input Shaping

2011 ◽  
Vol 2-3 ◽  
pp. 372-377 ◽  
Author(s):  
Yan Yan Han ◽  
Bing Li ◽  
Yu Lan Wei ◽  
Shou Xin Zhu ◽  
Ying Jun Dai
Keyword(s):  
Time Delay ◽  
Numerical Simulations ◽  
Parallel Manipulator ◽  
Vibration Suppression ◽  
Input Shaping ◽  
Vibration Modes ◽  
Residual Vibration ◽  
Input Shaper ◽  
Multi Mode

The classic multi-mode negative impulses input shapers can suppress the residual vibration of the multi-mode system effectively. But when these several frequencies bandwidths and amplitudes of vibration modes are greatly different, the time delay and the suppression performances of input shapers are decreased. However, the hybrid multi-mode negative impulses input shapers can overcome the disadvantage. The hybrid double-mode negative impulses input shapers of a 3-DOF parallel manipulator and are constructed and compared with the classic multi-mode negative impulses input shapers. And the numerical simulations are shown out, for different frequencies bandwidths and amplitudes of vibration, and the hybrid multi-mode negative impulses input shapers can increase the total suppression performance of input shaper.

An improved multi-mode seismic vibration control method using multiple tuned mass dampers

2022 ◽  
pp. 136943322110509
Author(s):  
Xuan Zhang ◽  
Qiang Han ◽  
Kaiming Bi ◽  
Xiuli Du
Keyword(s):  
Vibration Control ◽  
Control Method ◽  
Numerical Study ◽  
Ground Motions ◽  
Vibration Modes ◽  
Tuned Mass Dampers ◽  
Location Factor ◽  
Mass Damper ◽  
Multi Mode ◽  
Multiple Tuned Mass Dampers

Multiple vibration modes of an engineering structure might be excited by earthquake ground motions. Multiple tuned mass dampers (MTMDs) are widely used to control these multi-mode vibrations. However, in the commonly used MTMD system, the mass element in each tuned mass damper (TMD) is normally assumed to be the same. To improve the performance of MTMDs for seismic-induced vibration control, non-uniform MTMD masses are adopted in the present study to improve the mass utilization of TMD, and a location factor is proposed to determine the best location of each TMD in the MTMD system. The effectiveness of the proposed method is validated through numerical study. The results show that the proposed method effectively reduces the seismic responses of the structure induced by multiple vibration modes.

Dynamic loading and testing of bridges in Ontario

1984 ◽  
Vol 11 (4) ◽  
pp. 833-843 ◽  
Author(s):  
J. R. Billing
Keyword(s):  
Dynamic Load ◽  
Dynamic Testing ◽  
Highway Bridge ◽  
Vibration Modes ◽  
Design Codes ◽  
Test Results ◽  
Design Code ◽  
Bridge Design ◽  
Strain Measurements ◽  
Bridge Testing

The Ontario Highway Bridge Design Code (OHBDC) contains provisions on dynamic load and vibration that are substantially different from other codes. Dynamic testing of 27 bridges of various configurations, of steel, timber, and concrete construction, and with spans from 5 to 122 m was therefore undertaken to obtain comprehensive data to support OHBDC provisions. Standardized instrumentation, data acquisition, and test and data processing procedures were used for all bridge tests. Data was gathered from passing trucks, and scheduled runs by test vehicles of various weights. Accelerometer responses were used to determine bridge vibration modes, and dynamic amplifications were obtained from displacement or strain measurements. The form of the provisions adopted for dynamic load and vibration was confirmed by the test results, subject to minor adjustment of values. Observations on the distribution of dynamic load, and its relationship to span length and vehicle weight, may provide a basis for future refinement of the dynamic load provisions. If the stiffness of curbs and barrier walls is not included in deflection calculations, bridges designed by deflection could be penalized. Key words: bridges, vibration, bridge testing, bridge design codes.

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