Improved Large Spring / Stiffness Technique for Dynamic Response Analysis of Structures Subjected to Base Excitations

2011 ◽  
Vol 474-476 ◽  
pp. 1974-1979
Author(s):  
Guo Liang Zhou ◽  
Xiao Jun Li ◽  
Xiao Bo Peng
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Response Analysis ◽  
Spring Stiffness ◽  
Seismic Excitations ◽  
Structural Dynamic ◽  
Theoretical Methods ◽  
Rayleigh Damping ◽  
Stiffness Method ◽  
Improved Technique

Based on the large spring/stiffness method (LSM), this paper develops an improved technique (I-LSM) applicable to structural dynamic analysis with the assumption of Rayleigh damping. To estimate the accuracy of the technique, the dynamic response is analyzed for a 2-DOFs model respectively subjected to uniform/nonuniform seismic excitations. It indicates that the traditional LSM is inapplicable when Rayleigh damping is adopted. And the errors increase monotonously with the aggrandizement of damping. It’s also validated that the I-LSM based on the modification of displacement considering the influences of Rayleigh damping presented in this paper is able to effectively yield results almost identical to those of theoretical methods with errors beneath 4%.

Overestimation Analysis of Interval Finite Element for Structural Dynamic Response

2019 ◽  
Vol 11 (04) ◽  
pp. 1950035
Author(s):  
Tuanjie Li ◽  
Hangjia Dong ◽  
Xi Zhao ◽  
Yaqiong Tang
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Structural Parameters ◽  
Upper And Lower Bounds ◽  
Response Analysis ◽  
Uncertain Parameters ◽  
Engineering Structures ◽  
Structural Dynamic ◽  
Dynamic Response Analysis ◽  
Interval Parameters

Dynamic response analysis plays an important role for the structural design. For engineering structures, there exist model inaccuracies and structural parameters uncertainties. Consequently, it is necessary to express these uncertain parameters as interval variables and introduce the interval finite element method (IFEM), in which the elements in stiffness matrix, mass matrix and damping matrix are all the function of interval parameters. The dependence of interval parameters leads to overestimation of dynamic response analysis. In order to reduce the overestimation of IFEM, the element-based subinterval perturbation for static analysis is applied to dynamic response analysis. According to the interval range, the interval parameters are divided into different subintervals. With permutation and combination of each subinterval, the upper and lower bounds of displacement response are obtained. Because of the large number of degrees of freedom and uncertain parameters, the Laplace transform is used to evaluate the dynamic response for avoiding to frequently solve the interval finite element linear equations. The numerical examples illustrate the validity and feasibility of the proposed method.

Dynamic Response analysis of Long Span Transmission Tower under Tornado

2012 ◽  
Vol 450-451 ◽  
pp. 1257-1260
Author(s):  
Qiang Gao ◽  
Chao Ren ◽  
Yang Xu ◽  
Zhen Yao Liu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Response ◽  
Dynamic Analysis ◽  
Wind Direction ◽  
Response Analysis ◽  
Transmission Tower ◽  
Dynamic Response Analysis ◽  
Long Span ◽  
Element Method

To study the effects of tornado on long span transmission tower, a model of the tower is built and the features of the tornado are considered. Three different wind cases are discussed in dynamic analysis with finite element method. The analysis results show that dynamic response is more significant at 45° wind direction.

Dynamic Response of an Offshore Wind Turbine System Using Coupled and Limited Coupled Methods

2012 ◽  
Author(s):  
Fasuo Yan ◽  
Cheng Peng ◽  
Jun Zhang ◽  
Dagang Wang
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Wind Turbine ◽  
Numerical Code ◽  
Offshore Wind Turbine ◽  
Response Analysis ◽  
Time Step ◽  
Coupled Method ◽  
Floating Wind Turbine ◽  
Wind Turbine System

Offshore turbines are gaining attention as means to capture the immense and relatively calm wind resources available over deep waters. A coupled dynamic analysis is required to evaluate the interactions between the wind turbine, floating hull and its mooring system. In this study, a coupled hydro-aero dynamic response analysis of a floating wind turbine system (NREL offshore-5MW baseline wind turbine) is carried out. A numerical code, known as COUPLE, has been extended to collaborate with FAST for the simulation of the dynamic interaction. Two methods were used in the analysis; one is coupled method and the other is limited coupled method. In the coupled method, the two codes are linked at each time step to solve the whole floating system. The limited coupled method assumes wind load is from a turbine installed on top of a fixed base, namely it doesn’t consider real-time configuration of floating carrier at each time step. Coupled technique is also mentioned to integrate the hydro-aero dynamic analysis in this paper. Six-degrees of freedom motion and mooring tensions are presented and compared. The numerical results derived in this study may provide crucial information for the design of a floating wind turbine in the future.

scholarly journals Dynamic Response of Self-Supported Power Transmission Tower Subjected to Wind Action

2018 ◽  
Vol 7 (4.35) ◽  
pp. 476
Author(s):  
Nur Hamizah Hamzah ◽  
Fathoni Usman ◽  
Mohd Yazee Mat Yatim
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Power Transmission ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Time History ◽  
Transmission Tower ◽  
Electrical Transmission ◽  
Structural Dynamic ◽  
Wind Action

A power transmission tower carries electrical transmission conductor at adequate distance from the ground. It must withstand all nature’s forces besides its self-weight. In structural analysis, natural frequency, mode shape and damping ratio are used to define the structural dynamic properties which relate to the basic structural features. This paper described the dynamic analysis including the modal and the time history analysis on each segment of the self-supported transmission tower to understand its dynamic responses subjected to wind action. The factors such as different height above ground, a different value of wind speed and different wind angle of attack were included in this study to see the influence of those factors towards dynamic response of the structure. The contribution of the wind towards the displacement of the structure is determined in this study by comparing the result obtained in a linear static analysis which considered the load combination without and with the presence of wind action. It was found that displacement using dynamic analysis is bigger than static linear analysis. The result illustrates that the studied factors gave a significant effect on the dynamic response of the structure and the findings indicate that dynamic analysis is vital in structural design.

scholarly journals Rocking Response Analysis of Self-Centering Walls under Ground Excitations

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Xiaobin Hu ◽  
Qinwang Lu ◽  
Yang Yang
Keyword(s):  
Dynamic Response ◽  
Equations Of Motion ◽  
Numerical Procedure ◽  
Elastic Stiffness ◽  
The Self ◽  
Response Analysis ◽  
Seismic Excitations ◽  
Parametric Studies ◽  
Initial Force ◽  
Rocking Response

This paper presents a numerical procedure to simulate the rocking response of self-centering walls under ground excitations. To this aim, the equations of motion that govern the dynamic response of self-centering walls are first formulated and then solved numerically, in which three different self-centering wall structural systems are considered, that is, (i) including the self-weight of the wall only, (ii) including posttensioned tendon, and (iii) including both posttensioned tendon and dampers. Following the development of the numerical procedure, parametric studies are then carried out to investigate the influence of a variety of factors on the dynamic response of the self-centering wall under seismic excitations. The investigation results show that within the cases studied in this paper the installation of posttensioned tendon is capable of significantly enhancing the self-centering ability of the self-centering wall. In addition, increasing either the initial force or the elastic stiffness of the posttensioned tendon can reduce the dynamic response of the self-centering wall in terms of the rotation angle and angular velocity, whereas the former approach is found to be more effective than the latter one. It is also revealed that the addition of the dampers is able to improve the energy dissipation capacity of the self-centering wall. Furthermore, for the cases studied in this paper the yield strength of the dampers appears to have a more significant effect on the dynamic response of the self-centering wall than the elastic stiffness of the dampers.

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