• Proceedings of the KSME Conference
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• 2001.06b
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• pp.540-545
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• 2001

In this paper dynamic responses of an engine, which is supported by hydraulic mount, to throttle tip-in/tip out are analyzed. Because the hydraulic mounts have non-linearity which the characteristics of stiffness and damping vary with frequencies, it is difficult to analyze the dynamic behavior of an engine using general integral algorithms. Convolution integrals and relationships between unit impulse response functions and frequency response functions are therefore used to simulate the transient behavior of an engine indirectly. In time domain, impulse response functions are calculated by two-side discrete inverse Fourier transform of frequency response function achieved by Laplace transform of equations of motion. Considering the fact that the shapes of behavior of an engine simulated by the proposed method are in good agreement with test results, it is confirmed that the proposed method is very effective for the analysis of transient response to throttle tip-in/out of an engine with hydraulic mounts.

• Structural Engineering and Mechanics
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• v.33 no.3
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• pp.261-284
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• 2009

The seismic behavior of a framed structure with chevron-type buckling restrained braces was investigated and their behavior factors, such as overstrength, ductility, and response modification factors, were evaluated. Two types of structures, building frame systems and dual systems, with 4, 8, 12, and 16 stories were designed per the IBC 2003, the AISC LRFD and the AISC Seismic Provisions. Nonlinear static pushover analyses using two different loading patterns and incremental dynamic analysis using 20 earthquake records were carried out to compute behavior factors. Time history analyses were also conducted with another 20 earthquakes to obtain dynamic responses. According to the analysis results, the response modification factors turned out to be larger than what is proposed in the provision in low-rise structures, and a little smaller than the code-values in the medium-rise structures. The dual systems, even though designed with smaller seismic load, showed superior static and dynamic performances.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.275-283
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• 2002

In this study, the shaking table tests of block systems on the rigid base have been performed to identify the seismic response and the dynamic behavior of the piled multi-block systems. To understand the characteristics of seismic response of piled multi-block systems, it is necessary to understand the dynamic behavior of single block system. Therefore, the skating table test of the single block system has been performed first. Moreover, by performing the shaking table tests of multi-block systems, the characteristics of dynamic behavior of piled multi-block systems have been analyzed. Also in this study, the distinct element method(DEM) has been used to analyze the nonlinear behavior of the piled multi-block systems. The results of the shaking table tests show that the response of the multi-block systems is very complicated. But by using DEM, the behavior of piled multi-block systems has been predicted and described well.

• Structural Engineering and Mechanics
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• v.87 no.2
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• pp.173-189
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• 2023

For a given structural geometry, the stiffness and damping parameters of the soil and the dynamic response of the structure may change in the face of an equivalent linear soil behavior caused by a strong earthquake. Therefore, the influence of equivalent linear soil behavior on the impedance functions form and the seismic response of the soil-structure system has been investigated. Through the substructure method, the seismic response of the selected structure was obtained by an analytical formulation based on the dynamic equilibrium of the soil-structure system modeled by an analog model with three degrees of freedom. Also, the dynamic response of the soil-structure system for a nonlinear soil behavior and for the two types of impedance function forms was also analyzed by 2D finite element modeling using ABAQUS software. The numerical results were compared with those of the analytical solution. After the investigation, the effect of soil nonlinearity clearly showed the critical role of soil stiffness loss under strong shaking, which is more complex than the linear elastic soil behavior, where the energy dissipation depends on the seismic motion amplitude and its frequency, the impedance function types, the shear modulus reduction and the damping increase. Excellent agreement between finite element analysis and analytical results has been obtained due to the reasonable representation of the model.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.113-120
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• 1999

When we design the large rockfill dams the safety of dams against the quake must be considered. Generally pseudostatic analysis method has been used for slope stability and evaluation of safety but the case of dynamic response analysis of earthquake was not in general in Korea. Therefore we need to perform the dynamic response analysis of rockfill dams from these results we analyze the dynamic behavior of dam body such as response displacement and response acceleration. consequently we analyse the selected model of rockfill dam using the FLAC-2D (FDM) program.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.117-124
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• 2002

The major purpose of this study is to determine the dynamic behavior of soil-pile-structure interaction system considering the underground cavity. For the analysis, a numerical method fur ground response analysis using FE-BE coupling method is developed. The total system is divided into two parts so called far field and near field. The far field is modeled by boundary element formulation using the multi-layered dynamic fundamental solution that satisfied radiational condition of wave. And this is coupled with near field modeled by finite elements. For the verification of dynamic analysis in the frequency domain, both forced vibration analysis and free-field response analysis are performed. The behavior of soil non-linearity is considered using the equivalent linear approximation method. As a result, it is shown that the developed method can be an efficient numerical method to solve the seismic response analysis considering the underground cavity in 2D problem.

• Advances in aircraft and spacecraft science
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• v.5 no.3
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• pp.385-400
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• 2018

In this paper dynamic behavior (modal analysis and dynamic transient response) of a novel sandwich T-joint is numerically and experimentally investigated. An epoxy adhesive is selected for bonding purpose and making the step wise graded behavior of adhesive region. The effect of the step graded behavior of the adhesive zone on dynamic behavior of a sandwich T-joint is numerically studied. Finite element analysis (FEA) of the T-joints with carbon fiber reinforced polymer (CFRP) face-sheets is performed by ABAQUS 6.12-1 FEM code software. Modal analysis and dynamic half-sine transient response of the sandwich T-joint are presented in this paper. Two verification processes employed to verify the dynamic modeling of the manufactured sandwich panels and T-joint modeling. It has been shown that the step wise graded adhesive zone cases have changed the second natural frequency by about 5%. Also, it has been shown that the different arranges in the step wise graded adhesive zone significantly affect the maximum stresses due to transient dynamic loading by 1112% decrease in maximum peel stress and 691.9% decrease in maximum shear stress on the adhesive region.

• Earthquakes and Structures
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• v.11 no.2
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• pp.245-264
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• 2016

A suitable ground motion intensity measure (IM) plays a crucial role in the seismic performance assessment of a structure. In this paper, we introduce a scalar IM for use in evaluating the seismic response of single-layer reticulated domes. This IM is defined as the weighted geometric mean of the spectral acceleration ordinates at the periods of the dominant vibration modes of the structure considered, and the modal strain energy ratio of each dominant vibration mode is the corresponding weight. Its applicability and superiority to 11 other existing IMs are firstly investigated in terms of correlation with the nonlinear seismic response, efficiency and sufficiency using the results of incremental dynamic analyses which are performed for a typical single-layer reticulated dome. The hazard computability of this newly proposed IM is also briefly discussed and illustrated. A conclusion is drawn that this dominant vibration mode-based scalar IM has the characteristics of strong correlation, high efficiency, good sufficiency as well as hazard computability, and thereby is appropriate for use in the prediction of seismic response of single-layer reticulated domes.

• Structural Engineering and Mechanics
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• v.70 no.1
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• pp.1-11
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• 2019

This study deals with a method based on the modified bivariate gamma function for reconstructions of dynamic behavior of delaminated composite plates subjected to impact loads. The proposed bivariate gamma function is associated with micro-genetic algorithms, which is capable of solving inverse problems to determine the stiffness reduction associated with delamination. From computing the unknown parameters, it is possible for the entire dynamic response data to develop a prediction model of the dynamic response through a regression analysis based on the measurement data. The validity of the proposed method was verified by comparing with results employing a higher-order finite element model. Parametric results revealed that the proposed method can reconstruct dynamic responses and the stiffness reduction of delaminated composite plates can be investigated for different measurements and loading locations.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.451-458
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• 2001

The structural dynamic responses by wind load consist of alongwind, acrosswind and torsional behavior. Specially, dynamic alongwind response can be obtained from theoretical approach presented by Davenport, Vellozzi and Cohen. Generally the structural dynamic alongwind response can be obtained using the approximate analysis, under the condition that only the first mode shape of the structure is considered and the mode shape is assumed to be a linear function. In this paper, the dynamic alongwind responses are performed by using spectrum of longitudinal velocity fluctuations presented by Davenport and Kaimal, respectively.