• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.254-254
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• 2017

• Structural Engineering and Mechanics
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• v.91 no.4
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• pp.403-416
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• 2024

The single-column pier girder bridge, due to its low engineering cost, small footprint, and aesthetic appearance, is extensively employed in urban viaducts and interchange ramps. However, its structural design makes it susceptible to eccentric loads, flexural-torsional coupling effects, and centrifugal forces, among others. To evaluate its anti-overturning performance reasonably, it is crucial to determine the reaction force of the support for the single-column pier girder bridge. However, due to the interaction between vehicle and bridge and the complexity of vibration modes, it poses a significant challenge to analyze the theory or finite element method of single-column pier girder bridges. The unit load bearing reaction coefficient method is proposed in this study to facilitate the static analysis. Numerous parameter analyses have been conducted to account for the dynamic amplification effect. The results of these analyses reveal that the dynamic amplification factor is independent of road surface roughness but is influenced by factors such as the position of the support. Based on parameter analysis, the formula of the dynamic amplification factor is derived by fitting.

• Wind and Structures
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• v.14 no.3
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• pp.187-208
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• 2011

Based on the ANSYS, an approach of full-mode aerodynamic flutter analysis for long-span suspension bridges has been presented in this paper, in which the nonlinearities of structure, aerostatic and aerodynamic force due to the deformation under the static wind loading are fully considered. Aerostatic analysis is conducted to predict the equilibrium position of a bridge structure in the beginning, and then flutter analysis of such a deformed bridge structure is performed. A corresponding computer program is developed and used to predict the critical flutter wind velocity and the corresponding flutter frequency of a long-span suspension bridge with double main span. A time-domain analysis of the bridge is also carried out to verify the frequency-domain computational results and the effectiveness of the approach proposed in this paper. Then, the nonlinear effects on aerodynamic behaviors due to aerostatic action are discussed in detail. Finally, the results are compared with those of traditional suspension bridges with single main span. The results show that the aerostatic action has an important influence on the flutter stability of long-span suspension bridges. As for a suspension bridge with double main spans, the flutter mode is the first anti-symmetrical torsional vibration mode, which is also the first torsional vibration mode in natural mode list. Furthermore, a double main-span suspension bridge is better in structural dynamic and aerodynamic performances than a corresponding single main-span structure with the same bridging capacity.

• Earthquakes and Structures
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• v.16 no.6
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• pp.715-726
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• 2019

Several municipal seismic vulnerability investigations have been identified pounding of adjacent structures as one of the main hazards due to the constrained separation distance between adjacent buildings. Consequently, an assessment of the seismic pounding risk of buildings is superficial in future adjustment of design code provisions for buildings. The seismic lateral oscillation of adjacent buildings with eccentric alignment is partly restrained, and therefore a torsional response demand is induced in the building under earthquake excitation due to eccentric pounding. In this paper, the influence of the eccentric seismic pounding on the design demands for adjacent symmetric buildings with eccentric alignment is presented. A mathematical simulation is formulated to evaluate the eccentric pounding effects on the seismic design demands of adjacent buildings, where the seismic response analysis of adjacent buildings in series during collisions is investigated for various design parameters that include number of stories; in-plan alignment configurations, and then compared with that for no-pounding case. According to the herein outcomes, the effects of seismic pounding severity is mainly depending on characteristics of vibrations of the adjacent buildings and on the characteristics of input ground motions as well. The position of the building wherever exterior or interior alignment also, influences the seismic pounding severity as the effect of exposed direction from one or two sides. The response of acceleration and the shear force demands appear to be greater in case of adjacent buildings as seismic pounding at different levels of stories, than that in case of no-pounding buildings. The results confirm that torsional oscillations due to eccentric pounding play a significant role in the overall pounding-involved response of symmetric buildings under earthquake excitation due to horizontal eccentric alignment.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.1
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• pp.29-34
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• 2022

In this paper, the floor acceleration for the seismic design of non-structural elements was evaluated using the core shape as a planar variable. Linear time history analysis using 20 models with 5 different planes and 4 different floors on each plane depending on the change in the shape (position and specific gravity) of the core in the square biaxially symmetric plane was performed. The analysis confirmed that the torsional amplification of the floor acceleration was up to 1.7 times in the plane subjected to eccentricity depending on the position of the core, and the effect of torsion was the greatest in the middle floor of the structure. In a plane where only the specific gravity of the core was changed without eccentricity, when the period was less than 0.4694 s, the maximum floor acceleration decreased in the lower floors and increased in the upper floors as the period increased. Conversely, when the period was 0.4694 s or more, it was confirmed that the floor acceleration increased in the lower part and decreased in the upper part as the period increased.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.2
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• pp.165-178
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• 2000

The simplified model for 3-dimensional analysis of vehicle-bridge interactions is presented in this study. By using the analysis model which includes the eccentricity of axle loads and the effect of the torsional forces acting on the bridge, the more accurate analysis results of the behavior of the bridge can be obtained. The equations of kinetic energy, potential energy and damping energy are expressed by degrees of freedom of the vehicle and the bridge. And then by applying Lagrange's equations of motion, the equations of motion of the vehicle and the bridge are obtained. By deriving the equations of forces acting on the bridge considering the vehicle-bridge vertical interactions and also by identifying the position of vehicle as time goes by, mass matrix, stiffness matrix, damping matrix and load vector of vehicle-bridge system are constructed in accordance with the position of vehicles. Then using Newmark's β-method(average acceleration), the equations of motion for the total vehicle bridge system are solved.

• Journal of Power System Engineering
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• v.12 no.2
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• pp.23-28
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• 2008

The primary objective of this study is to truly understand reaction force be due to engine exciting force. Exciting forces of the engine apply a source of the vehicle NVH(Noise, Vibration, Harshness). To understand reaction force was applied MSC.Nastran software. Analyzed frequency response analysis of powertrain mount system. First, engine exciting force was applied field function. Also nonlinear characteristics was applied field function : such as dynamic spring constant and loss factor. And nonlinear characteristics was applied CBUSH. Generally characteristics of rubber mount is constant frequency. But characteristics of hydraulic mount depend to frequency. Therefore nonlinear characteristics was applied. Powertrain mounting system be influenced by powertrain specification, mount position, mount angle and mount characteristics etc. In this study, we was analyzed effects of powertrain mounting system. And we was varied dynamics spring constant and loss factor of mounts.

• Steel and Composite Structures
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• v.21 no.5
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• pp.963-980
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• 2016

The jib system with middle strut is widely used to achieve the large arm length in the large scale tower crane and the deployability in the mobile construction crane. In this paper, an analytical solution for the out-of-plane buckling of the jib system with middle strut is proposed. To obtain the analytical expression of the buckling characteristic equation, the method of differential equation was adopted by establishing the bending and torsional differential equation of the jib system under the instability critical state. Compared with the numerical solutions of the finite element software ANSYS, the analytical results in this work agree well with them. Therefore, the correctness of the results in this work can be confirmed. Then the influences of the lateral stiffness of the cable fixed joint, the dip angle of the strut, the inertia moment of the strut, and the horizontal position of the cable fixed joint on the out-of-plane buckling behavior of the jib system were investigated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.12
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• pp.881-887
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• 2015

The stiffness and natural frequencies for blades, flexbeam, and torque tube of bearingless rotor system are measured to determine the material input properties such as mass distributions and stiffness distribution for the rotor dynamics and load analysis. The flap stiffness, lag stiffness, and torsional stiffness are calculated by measuring section strain or twist angle, gages position, and applied loads through bending and twist tests. The modal tests are undertaken to find out the natural frequencies for flap, lag, torsion modes in non-rotating conditions. The stiffness values and mass properties are tuned and updated to match prediction frequencies to the measured frequencies. The rotorcraft comprehensive code(CAMRAD II) is used to analyze the natural frequencies of the specimens. The analysis results with the updated material properties agree well with the measured frequencies. The updated properties will be used to analyze the rotor stability, dynamic characteristics and loads for the rotor rotation test in a whirl tower.

• Journal of the Institute of Convergence Signal Processing
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• v.4 no.3
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• pp.55-60
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• 2003

In the controller design of position or velocity control system, the flexibility of the mechanical system is always the limiting factor to the higher performance. Most mechanical systems coupled with rotary shaft are 2-Inertia systems which are consist of motor and load inertia. These inertias make a torsion In rotary shaft and cause torsional vibration. To suppress vibration, various control strategies have been proposed mainly for controlling 2-inertia system. In this paper, a speed controller design for a 2-inertia system composed of voltage controlled DC motor and load inertia is made by using CDM(coefficient diagram method). First, the 2-inertia system model is derived. Then the CDM is used to design the proper controller. A validity of this approach is confirmed by simulation and experimental results.