Simplified Dynamic Analysis Methods for Metallic Bellows Expansion Joints

1991 ◽  
Vol 113 (4) ◽  
pp. 504-510 ◽  
Author(s):  
M. Morishita ◽  
N. Ikahata ◽  
S. Kitamura
Keyword(s):  
Dynamic Analysis ◽  
Seismic Response ◽  
Dynamic Characteristics ◽  
Timoshenko Beam ◽  
Natural Frequencies ◽  
Vibration Modes ◽  
Lateral Vibration ◽  
Expansion Joints ◽  
Structure Interaction ◽  
Lateral Vibrations

An investigation into dynamic characteristics and seismic response of bellows expansion joints is described. For axial and lateral vibrations of the bellows, simplified methods are developed to evaluate their natural frequencies and seismic response, based on analogies with those of a uniform rod and a Timoshenko beam, respectively. For the lateral vibration modes, effect of fluid-structure interaction between the convolutions and flow-sleeve is taken into account. The validity and applicability of the simplified methods are shown, by comparing with the results of vibration experiments using a simple bellows model and a piping model with bellows, along with corresponding detailed FEM analyses’ results.

scholarly journals Modal Perturbation Method for the Dynamic Characteristics of Timoshenko Beams

2005 ◽  
Vol 12 (6) ◽  
pp. 425-434 ◽  
Author(s):  
Menglin Lou ◽  
Qiuhua Duan ◽  
Genda Chen
Keyword(s):  
Perturbation Method ◽  
Dynamic Characteristics ◽  
Timoshenko Beam ◽  
Natural Frequencies ◽  
Solution Process ◽  
Equation Of Motion ◽  
Timoshenko Beams ◽  
Algebraic Equations ◽  
Nonlinear Algebraic Equations ◽  
Shear Distortion

Timoshenko beams have been widely used in structural and mechanical systems. Under dynamic loading, the analytical solution of a Timoshenko beam is often difficult to obtain due to the complexity involved in the equation of motion. In this paper, a modal perturbation method is introduced to approximately determine the dynamic characteristics of a Timoshenko beam. In this approach, the differential equation of motion describing the dynamic behavior of the Timoshenko beam can be transformed into a set of nonlinear algebraic equations. Therefore, the solution process can be simplified significantly for the Timoshenko beam with arbitrary boundaries. Several examples are given to illustrate the application of the proposed method. Numerical results have shown that the modal perturbation method is effective in determining the modal characteristics of Timoshenko beams with high accuracy. The effects of shear distortion and moment of inertia on the natural frequencies of Timoshenko beams are discussed in detail.

Dynamic Characteristics of a Long-Span Cable-Stayed Bridge

2011 ◽  
Vol 480-481 ◽  
pp. 1496-1501
Author(s):  
Liu Hui
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Iteration Method ◽  
Natural Frequencies ◽  
Element Model ◽  
Vibration Modes ◽  
Cable Stayed Bridge ◽  
Long Span ◽  
Subspace Iteration ◽  
Floating System

In order to study the dynamic characteristics of a super-long-span cable-stayed bridge which is semi-floating system, the spatial finite element model of this cable-stayed bridge was established in ANSYS based on the finite element theory.Modal solution was conducted using subspace iteration method, and natural frequencies and vibration modes were obtained.The dynamic characteristics of this super-long-span cable-stayed bridge were then analyzed.Results showed that the super-long-span cable-stayed bridge of semi-floating system has long basic cycle, low natural frequencies, dense modes and intercoupling vibration modes.

Seismic Response Analysis of Liaocheng Guangyue Tower

2015 ◽  
Vol 744-746 ◽  
pp. 911-914
Author(s):  
Zhao Bo Meng ◽  
Guan Dong Qiao ◽  
Jie Jin
Keyword(s):  
Seismic Response ◽  
Soil Structure ◽  
Natural Frequencies ◽  
Timber Structure ◽  
Soil Structure Interaction ◽  
Response Analysis ◽  
Actual Situation ◽  
Seismic Response Analysis ◽  
Structure Interaction ◽  
Rare Earthquake

This paper establishes three models using ANSYS, which were timber structure of Guangyue Tower, timber structure-tower base and timber structure-tower base-foundation. The first 3 natural frequencies of timber structure respectively were 0.8524Hz、1.1273 Hz and 1.7426 Hz through modal analysis, which were compared with calculations from code. Lanzhou Wave was chosen to analyze the seismic response of Guangyue Tower, and the amplitudes were adjusted to 55gal and 310gal respectively according to the frequent earthquake and rare earthquake, which were inputted to the above models. As can be seen from the calculations, the maximum displacements of the three models were in the top nodes, and tower base had a greater impact on vibration of timber structure, which could not be ignored in seismic response analysis; considering soil-structure interaction in seismic response analysis could better reflect the actual situation of Guangyue Tower.

Hydroelastic Modal Analysis of the Perforated Cylindrical Shell in SMART

2011 ◽  
Author(s):  
Youngin Choi ◽  
Seungho Lim ◽  
Kyoung-Su Park ◽  
No-Cheol Park ◽  
Young-Pil Park ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Element Model ◽  
Mode Shapes ◽  
Steam Generators ◽  
Structure Interaction ◽  
The Finite Element Model ◽  
Reactor Internals

The System-integrated Modular Advanced ReacTor (SMART) developed by KAERI includes components like a core, steam generators, coolant pumps, and a pressurizer inside the reactor vessel. Though the integrated structure improves the safety of the reactor, it can be excited by an earthquake and pump pulsations. It is important to identify dynamic characteristics of the reactor internals considering fluid-structure interaction caused by inner coolant for preventing damage from the excitations. Thus, the finite element model is constructed to identify dynamic characteristics and natural frequencies and mode shapes are extracted from this finite element model.

Influence of Tie Beams of Pier on the Seismic Performance of a Continuous Rigid Frame Bridge with Twin-Legged Piers

2011 ◽  
Vol 368-373 ◽  
pp. 1105-1110
Author(s):  
Yun Jing Nie ◽  
Xu Yan ◽  
Tie Ying Li
Keyword(s):  
Seismic Response ◽  
Seismic Performance ◽  
Seismic Design ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Continuous Rigid Frame Bridge ◽  
Analytical Results ◽  
Rigid Frame ◽  
Rigid Frame Bridge

In this paper, the influence of tie beams for piers is investigated on the dynamic characteristics and the seismic performance of a continuous rigid frame bridge with twin-legged piers. Modal analyses and the linear seismic response analyses are performed on a practical continuous rigid frame bridge with twin-legged piers with no tie beam, one tie beam and three tie beams of pier, using software Midas/civil. The findings indicate that installing tie beams of pier can increase the natural frequencies of this kind of bridge. Setting tie beams of pier is disadvantageous to the seismic performance of the bridge beam, but advantageous to improving the seismic performance of the twin-legged piers. The influence of tie beams of pier on the seismic performance on the whole structure is relevant to the pier height. These analytical results provide a reference for the seismic design and analysis of similar structures.

scholarly journals Effect of Dead Load on Dynamic Characteristics of Rotating Timoshenko Beams

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Yan-Qi Yin ◽  
Bo Zhang ◽  
Yue-ming Li ◽  
Wei-Zhen Lu
Keyword(s):  
Finite Element ◽  
Cantilever Beam ◽  
Dynamic Characteristics ◽  
Timoshenko Beam ◽  
Natural Frequencies ◽  
Experimental Result ◽  
Dead Load ◽  
Rotating Speed ◽  
Experimental Apparatus ◽  
The Dead

The dynamic characteristics of a rotating cantilever Timoshenko beam under dead load are investigated in this paper. Considering the predeformation caused by dead load and centrifugal force, governing equation of rotating cantilever Timoshenko beam is derived based on Hamilton’s principle, and the influence of the load on natural vibration is revealed. A suit of modal experimental apparatus for cantilever beam is designed and used to test the natural frequencies under the dead load, and the natural frequencies under rotation condition are calculated with a commercial finite element code. Both the experimental result and numerical result are utilized to compare with the present theoretical result, and the results obtained by present modeling method show a good agreement with those obtained from the experiment and finite element method. It is found that the natural frequencies of cantilever beam increase with both the dead load and the rotating speed.

Bedrock Depth Effect Investigation in Seismic Response of Offshore Platforms Considering Soil-Pile-Structure Interaction

2007 ◽  
Author(s):  
B. Asgarian ◽  
M. A. Roshandel Tavana ◽  
R. H. Soltani
Keyword(s):  
Dynamic Analysis ◽  
Seismic Response ◽  
Ground Motion ◽  
Earthquake Engineering ◽  
Nonlinear Dynamic ◽  
Nonlinear Dynamic Analysis ◽  
Offshore Platform ◽  
Offshore Platforms ◽  
Structure Interaction ◽  
Strong Ground

Offshore platforms in seismically active areas should be designed to survive severe earthquake excitations with no global structural failure. In seismic design of offshore platforms, it is often necessary to perform a dynamic analysis that accounts for nonlinear soil-pile-structures interaction effects. Nonlinear dynamic analysis for offshore structures has been a major challenge in marine structural and earthquake engineering. In this paper, nonlinear dynamic analysis of jacket type offshore platforms considering soil-pile-structure interaction subjected to strong ground motion have been studied. A jacket type offshore platform is included of piles, jacket and topside with different behaviors in seismic loading. Both jacket and pile elements have been modeled using fiber cross-sections. In this paper, free field ground motion analysis with respect to bedrock excitations has been done using nonlinear stress-strain relations for soil. This model has been developed using Open System for Earthquake Engineering Simulation (OpenSEES) software. In this paper, nonlinear seismic response analysis of an existing sample offshore platform in Persian Gulf subjected to strong ground motions in different bedrock depths has been performed and the results in terms of lateral deflections of platform, soil layers displacement-time history and acceleration response spectra of pile head, top of jacket and deck have been presented.

ARX Model Identification of Shui-Kou Concrete Gravity Dam Based on Seismic Response Data

2013 ◽  
Vol 353-356 ◽  
pp. 1959-1964
Author(s):  
Wen Qiao ◽  
Guo Ming Liu ◽  
Jin Wen He
Keyword(s):  
Seismic Response ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Model Identification ◽  
Modal Identification ◽  
Gravity Dam ◽  
Concrete Gravity Dam ◽  
Arx Model ◽  
Response Data ◽  
Peak Point

Research on the dynamic characteristics of gravity dam was carried out by adopting ARX model using the seismic response data of concrete gravity dam at Shui-Kou hydropower station. The applicability and effectiveness of single-output-multiple-input ARX model were deduced and verified. A corresponding computer program was developed, and performed to identify the modal parameters of the system. The identified natural frequencies and damping ratios were basically same with the results by traditional peak point pick-up method, and also close to the finite element method (FEM) results. It is indicated that the structure natural frequencies and damping ratios are determined by the characteristics of the structure, the dynamic characteristics identified by ARX model are correct, and ARX model can avoid frequency leakiness when smoothing processing and Fourier transform are conducted in solving process of the peak point pick-up method. The modal identification can be applied to other structures.

Modal Analysis of Annular Plate with Crack and its Effect on Natural Frequency

2015 ◽  
Vol 813-814 ◽  
pp. 910-914 ◽  
Author(s):  
R. Pramod ◽  
M.E. Shashi Kumar ◽  
S. Mohan Kumar
Keyword(s):  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Annular Plate ◽  
Structural Member ◽  
Vibration Modes ◽  
Static And Dynamic Characteristics ◽  
Annular Plates ◽  
Theoretical Frequency ◽  
Theoretical Results

The study of the dynamic behavior of annular plates with circumferential cracks can find many applications in several machine components such as flywheels, clutch plates, compact discs etc. A crack on a structural member introduces a local increase of flexibility in that region then; this affects the static and dynamic characteristics. The effects of cracks on the dynamic characteristics of structures, especially on the natural frequencies and modes, were extensively studied. In this study, the natural frequencies of annular plates with circumferential cracks are investigated by using finite element method. The cracks were non-propagating and open. The annular plate with different cracks was subjected to different boundary conditions and final variation in the natural frequency was obtained, which was compared with the theoretical frequency and the change in the natural frequency was studied. The results of this study with improved elements are compared with the theoretical results in the literature. It is observed that the location and the number of cracks have various effects on the natural frequencies related to the vibration modes.

Buckling and Lateral Vibration of Drill Pipe

1968 ◽  
Vol 90 (4) ◽  
pp. 613-619 ◽  
Author(s):  
Tseng Huang ◽  
D. W. Dareing
Keyword(s):  
Differential Equation ◽  
Variable Coefficient ◽  
Natural Frequencies ◽  
Thrust Force ◽  
Drill Pipe ◽  
Vibration Modes ◽  
Lateral Vibration ◽  
Vertical Pipe ◽  
Buckling Loads ◽  
Simply Supported

Critical buckling loads and natural frequencies of lateral vibration modes are determined for a long vertical pipe, suspended in a fluid, simply supported at the top and vertically guided at the bottom. The data show the effect of thrust force at the pipe’s lower end on the magnitude of the natural frequencies. The differential equation contains a term with a variable coefficient and is solved by use of a power series.

Sign in / Sign up

Export Citation Format

Share Document