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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Earthquake Engineering Society of Korea
Journal Basic Information
Journal DOI :
Earthquake Engineering Society of Korea
Editor in Chief :
Volume & Issues
Volume 7, Issue 6 - Dec 2003
Volume 7, Issue 5 - Oct 2003
Volume 7, Issue 4 - Aug 2003
Volume 7, Issue 3 - Jun 2003
Volume 7, Issue 2 - Apr 2003
Volume 7, Issue 1 - Feb 2003
Selecting the target year
A New Hybrid Method for Nonlinear Soil-Structure Interaction Analysis
Journal of the Earthquake Engineering Society of Korea, volume 7, issue 6, 2003, Pages 1~7
DOI : 10.5000/EESK.2003.7.6.001
This paper presents a novel hybrid time-frequency-domain method for nonlinear soil-structure interaction(SSI) analysis. It employs, in a practical manner, a computer code for equivalent linear SSI analysis and a general-purpose nonlinear finite element program. The proposed method first (calculates dynamic responses on a truncated finite element boundary utilizing an equivalent linear SSI program in the frequency domain. Then, a general purpose nonlinear finite element program is employed to analyze the nonlinear SSI problem in the time domain, in which boundary conditions at the truncated boundary are imposed with the responses calculated in the previous frequency domain SSI analysis, In order to validate the proposed method, seismic response analyses are carried out for a 2-D underground subway station in a multi-layered half-space, For the analyses, a equivalent linear SSI code KIESSI-2D is coupled to ANSYS program. The numerical results indicate that the proposed methodology can be a viable solution for nonlinear SSI problems,
Study on the Vibration Control of Footbridge by Using Tuned Mass Damper(TMD)
Journal of the Earthquake Engineering Society of Korea, volume 7, issue 6, 2003, Pages 9~15
DOI : 10.5000/EESK.2003.7.6.009
This paper describes a vibration control by using tuned mass damper(i.e., TMD) for an existing footbridge. The footbridge is the simple steel box girder bridge with main span length of 47.7m. This bridge has light weight, low damping and the 1st bending frequency of 1.84㎐. Its frequency is close to a walking cycle, which is 2㎐. Therefore the uncomfortable resonant vibrations due to a pedestrian walking have occurred frequently. The vibration control by means of TMD for suppressing the pedestrian induced vibration was conducted. Taking into account economical benefits and the easiness of installation, a compact TMD installed within a handrail was designed. From field tests of the TMD, it was confirmed that the structural damping of the bridge via. the compact TMD was enhanced by 13 times and the resonant vibration due to pedestrian walking was suppressed.
Performance Based Design of Friction Dampers for Seismically Excited Structures
Journal of the Earthquake Engineering Society of Korea, volume 7, issue 6, 2003, Pages 17~24
DOI : 10.5000/EESK.2003.7.6.017
The main objective of this paper is to evaluate the control performance of a coulomb friction damper(CFD) for controlling the inelastic behavior of seismically excited structures, The seismic performances of various buildings are evaluated using capacity spectrum method(CSM), and the additional dampings are calculated If the evaluated performance levels of the buildings are below the target level. Maximum friction force of the CFD to achieve additional damping is provided using the concept of equivalent viscous damping, Numerical simulations for single degree of freedom(SDOF) systems with various structural periods and post yield stiffness ratios demonstrate the effectiveness of the proposed procedure.
Earthquake Design Method for Structural Walls Based on Energy Dissipation Capacity
Journal of the Earthquake Engineering Society of Korea, volume 7, issue 6, 2003, Pages 25~34
DOI : 10.5000/EESK.2003.7.6.025
Recently, performance-based analysis/design methods such as the capacity spectrum method and the direct displacement-based design method were developed. In these methods, estimation of energy dissipation capacity of RC structures depends on empirical equations which are not sufficiently accurate, On the other hand, in a recent study, a simplified method for evaluating energy dissipation capacity was developed. In the present study, based on the evaluation method, a new seismic design method for flexure-dominated RC walls was developed. In determination of earthquake load, the proposed design method can address variations of energy dissipation capacity with design parameters such as dimensions and shapes of cross-sections, axial force, and reinforcement ratio and arrangement, The proposed design method was compared with the current performance-based design methods. The applicability of the proposed method was discussed.
Seismic Fragility Curves for Multi-Span Concrete Bridges
Kim, Sang-Hoon ;
Journal of the Earthquake Engineering Society of Korea, volume 7, issue 6, 2003, Pages 35~47
DOI : 10.5000/EESK.2003.7.6.035
Seismic ground motion can vary significantly over distances comparable to the length of a majority of highway bridges on multiple supports. This paper presents results of fragility analysis of two actual highway bridges under ground motion with spatial variation. Ground motion time histories are artificially generated with different amplitudes, phases, as well as frequency contents at different support locations. Monte Carlo simulation is performed to study dynamic responses of the bridges under these ground motions. The effect of spatial variation on the seismic response is systematically examined and the resulting fragility curves are compared with those under identical support ground motion. This study shows that ductility demands for the bridge columns can be underestimated if the bridge is analyzed using identical support ground motions rather than differential support ground motions. Fragility curves are developed as functions of different measures of ground motion intensity including peak ground acceleration(PGA), peak ground velocity(PGV), spectral acceleration(SA), spectral velocity(SV) and spectral intensity(SI). This study represents a first attempt to develop fragility curves under spatially varying ground motion and provides information useful for improvement of the current seismic design codes so as to account for the effects of spatial variation in the seismic design of long-span bridges.
Modified Similitude Law for Pseudodynamic Test on Small-scale Steel Models
Kim, Nam-Sik ; Kwak, Young-Hak ; Chang, Sung-Pil ;
Journal of the Earthquake Engineering Society of Korea, volume 7, issue 6, 2003, Pages 49~57
DOI : 10.5000/EESK.2003.7.6.049
Although there are several experimental techniques to evaluate the seismic behavior and performance of civil structures, small-scale models in mast of physical tests, instead of prototypes or large-scale models, would be used due to a limitation on capacities of testing equipments. However, the inelastic seismic response prediction of small-scale models has some discrepancies inherently because the similitude law is generally derived in the elastic range. Thus, a special attention is required to regard the seismic behavior of small-scale models as one of prototypes. In this paper, differences between prototypes and small-scale models pseudodynamically tested on steel column specimens are investigated and an alternative to minimize them is suggested. In general, small-scale models could have the distorted stiffness induced from some experimental errors on test setup, steel fabrication and so on. Therefore, a modified similitude law considering both a scale factor for length and a stiffness ratio of small-scale model to prototype is proposed. Using the modified similitude law to compensate experimental errors, the pseudodynamic test results from modified small-scale model are much improved as compared with the results of prototype. According to the pseudodynamic test results of small-scale steel models, it can be concluded that the modified similitude law proposed could be effective in simulating the seismic response of prototype structures.
Estimation of Spectrum Decay Parameter χ and Stochastic Prediction of Strong Ground Motions in Southeastern Korea
Journal of the Earthquake Engineering Society of Korea, volume 7, issue 6, 2003, Pages 59~70
DOI : 10.5000/EESK.2003.7.6.059
We estimated the spectrum decay parameter
and the stress parameter (
) in southeastern Korea. Especially, we propose a procedure to compute site-independent
values, separately, This procedure is to use the coda normalization method for the computation of site independent Q or corresponding
value as the first step followed by the next step, the computation of
values for each site using the given
value evaluated at the first step, For the estimation of stress parameter, we used seismic data monitored from three earthquakes occurred near Gyeongju in 1999 with the method of Jo and Baag, In addition, we simulated strong ground motion using the
value and the stress parameter, In this case, we calculated the
value with conventional method. The
value of 0.016+0.000157R and the stress parameter of 92-bar was applied to the stochastic simulation, At last, we derived seismic attenuation equation using results of the stochastic prediction, and compared these results with some others reported previously.ported previously.ously.
Evaluation of Seismic Performance of Mixed Building Structures by using the Nonlinear Displacement Mode Method
Journal of the Earthquake Engineering Society of Korea, volume 7, issue 6, 2003, Pages 71~80
DOI : 10.5000/EESK.2003.7.6.071
Though a nonlinear time history analysis may be provided to estimate more exactly the seismic performance of building structure, approximation methods are still needed in the aspect of practicality and simplicity, In converting a multi-story structure to an equivalent SDOF system, the mode vectors of the multi-story structure are assumed as the mode shape in elastic state regardless of elastic or elastic-plastic state. However, the characteristics of displacement mode are also changed after the yielding made in the structural elements, because the structure becomes inelastic in each incremental load step. In this research, a method of converting MDOF system to ESDOF system is presented by using nonlinear displacement mode considering the mode change of structures after the yielding. Also, the accuracy and efficiency of the method of the nonlinear displacement mode method of the estimate of seismic response of Mixed Building Structures were examined by comparing the displacements of the roof level of the multi-story building structures estimated from this converted displacement response of ESDOF with the displacement of the roof level through the nonlinear dynamic analysis of the multi-story building structures subjected to an actual earthquake excitation.
Seismic Response of a High-Rise RC Bearing-Wall Structure with Irregularities of Weak Story and Torsion at Bottom Stories
Journal of the Earthquake Engineering Society of Korea, volume 7, issue 6, 2003, Pages 81~91
DOI : 10.5000/EESK.2003.7.6.081
Recently, many high-rise reinforced concrete(RC) bearing-wall structures of multiple uses have been constructed, which have the irregularities of weak(or soft) story and torsion at the lower stories simultaneously. The study stated herein was performed to investigate seismic performance of such a high-rise RC structure through a series of shaking table tests of a 1: 12 model. Based on the observations of the test results, the conclusions are drawn as follows: 1) Accidental torsion due to the uncertainty on the properties of structure can be reasonably predicted by using the dynamic analysis than by using lateral force procedure. 2) The mode coupled by translation and torsion induced the overturning moments not only in the direction of excitations but also in the perpendicular direction: The axial forces in columns due to this transverse overturning moment cannot be adequately predicted using the existing mode analysis technique, and 3) the hysteretic curve and the strength diagram between base shear and torque(BST) clearly reveal the predominant mode of vibrations and the failure mode.
Modeling and Theoretical Analysis of Thermodynamic Characteristic of Nano Vibration Absorber
Journal of the Earthquake Engineering Society of Korea, volume 7, issue 6, 2003, Pages 93~99
DOI : 10.5000/EESK.2003.7.6.093
In this study, new shock absorbing system is proposed by using nano-technology based on the theoretical analysis. The new shock absorbing system is complementary to the hydraulic damper, having a cylinder-piston-orifice construction. Particularly for new shock absorbing system, the hydraulic oil is replaced by a colloidal suspension, which is composed of a porous matrix and a lyophobic fluid. The matrix of the suspension is consisted of porous micro-grains with a special architecture: they present nano-pores serially connected to micro-cavities. Until now, only experimentally qualitative studies of new shock absorbing system have been performed, but the mechanism of energy dissipation has not been clarified. This paper presents a modeling and theoretical analysis of the new shock absorbing system thermodynamics, nono-flows and energy dissipation. Compared with hydraulic system, the new shock absorbing system behaves more efficiently, which absorb a large amount of mechanical energy, without heating. The theoretical computations agree reasonably well with the experimental results. As a result. the proposed new shock absorbing system was proved to be an effective one, which can replace with the conventional one.
An Equivalent Multi-Phase Similitude Law for Pseudodynamic Test on Small-scale RC Models
Journal of the Earthquake Engineering Society of Korea, volume 7, issue 6, 2003, Pages 101~108
DOI : 10.5000/EESK.2003.7.6.101
Small-scale models have been frequently used for experimental evaluation of seismic performance because of limited testing facilities and economic reasons. However, there are not enough studies on similitude law for analogizing prototype structures accurately with small-scale models, although conventional similitude law based on geometry is not well consistent in the inelastic seismic behavior. When fabricating prototype and small-scale model of reinforced concrete structures by using the same material. added mass is demanded from a volumetric change and scale factor could be limited due to size of aggregate. Therefore, it is desirable that different material is used for small-scale models. Thus, a modified similitude law could be derived depending on geometric scale factor and equivalent modulus ratio. In this study, compressive strength tests are conducted to analyze equivalent modulus ratio of micro-concrete to normal-concrete. Equivalent modulus ratios are divided into multi phases, which are based on ultimate strain level. Therefore, an algorithm adaptable to the pseudodynamic test. considering equivalent multi-phase similitude law based on seismic damage levels, is developed. In addition, prior to the experiment. it is verified numerically if the algorithm is applicable to the pseudodynamic test.
Application of Energy Dissipation Capacity to Earthquake Design
Journal of the Earthquake Engineering Society of Korea, volume 7, issue 6, 2003, Pages 109~117
DOI : 10.5000/EESK.2003.7.6.109
Traditional nonlinear static and dynamic analyses do not accurately estimate the energy dissipation capacity of reinforced concrete structure. Recently, simple equations which can accurately calculate the energy dissipation capacity of flexure-dominated RC members, were developed in the companion study. In the present study, nonlinear static and dynamic analytical methods improved using the energy-evaluation method were developed. For nonlinear static analysis, the Capacity Spectrum Method was improved by using the energy-spectrum curve newly developed. For nonlinear dynamic analysis, a simplified energy-based cyclic model of reinforced concrete member was developed. Unlike the existing cyclic models which are the stiffness-based models, the proposed cyclic model can accurately estimate the energy dissipating during complete load-cycles. The procedure of the proposed methods was established and the computer program incorporating the analytical method was developed. The proposed analytical methods can estimate accurately the energy dissipation capacity varying with the design parameters such as shape of cross-section, reinforcement ratio and arrangement, and can address the effect of the energy dissipation capacity on the structural performance under earthquake load.