• Earthquakes and Structures
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• v.9 no.3
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• pp.673-698
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• 2015

This paper investigates inelastic seismic demands of the normal component of near-fault pulse-like ground motions, which differ considerably from those of far-fault ground motions and also parallel component of near-fault ones. The results are utilized to improve the nonlinear static procedure (NSP) called Displacement Coefficient Method (DCM). 96 near-fault and 20 far-fault ground motions and the responses of various single degree of freedom (SDOF) systems constitute the dataset. Nonlinear Dynamic Analysis (NDA) is utilized as the benchmark for comparison with nonlinear static analysis results. Considerable influences of different faulting mechanisms are observed on inelastic seismic demands. The demands are functions of the strength ratio and also the pulse period to structural period ratio. Simple mathematical expressions are developed to consider the effects of near-fault motion and fault type on nonlinear responses. Modifications are presented for the DCM by introducing a near-fault modification factor, $C_N$. In locations, where the fault type is known, the modifications proposed in this paper help to obtain a more precise estimate of seismic demands in structures.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.1
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• pp.33-39
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• 2018

This study performed experimental validation of the hysteretic steel slit damper's basic and dependent characteristics, which should be considered for the design. The basic characteristic of the steel slit damper is used for determining design properties of non-linear analysis, such as yielding strength, yielding displacement, elastic stiffness and post-yielding stiffness. In order to evaluate dependent characteristics of the hysteretic steel slit damper, repeated deformation capacity with respect to the displacement, velocity and aspect ratio of the damper was evaluated. In this study, steel slit damper, which is widely used in Korea, was considered. The slit dampers with 55kN and 240kN of yielding strength were produced and tested. It was concluded that the slit damper's hysteresis behavior was affected by the dependent characteristics: displacement, velocity and aspect ratio. In other words, the steel slit damper's behavior was stable within limit displacement, and aspect ratio of the strut affected repeated deformation capacity of the damper subjected to large deformation. In addition, it was observed that the repeated deformation capacity abruptly decreased at the high speed range (${\geq}60mm/sec$). Furthermore, the experimental results were evaluated with the criterion of the damping device specified in ASCE7-10.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.167-172
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• 1992

To analyze the effects compressive strength of concrete and longitudinal steel ratio on second-order moment of columns, 30tied rein reinforced concrete columns with hinged ends were tested. The 80mm square cross section was used and the amount of eccentricity was 24mm. The compressive strengths of column specimens with slenderness ratios of 10, 60, and 100were 250, 648 and 880kg/$\textrm{cm}^2$, and the longitudinal steel ratios were 1.98%(4-D6) and 3.95%(8-D6). The ratio of ultimate load capacity to that of short column with the same eccentricity (Pu/Pn) was much decreased at high slenderness ratio with increasing the compressive strength of concrete. And the lateral displacement of slender column at the ultimate load was decreased as the strength was increased. These are due to that at high slenderness ratio the load capacity and behavior of column are affected by flexural rigidity. And, it was also found that with increasing steel ratio, the value of Pu/Pn and the lateral displacement at the ultimate load were larger for the same slenderness ratio.

• The Journal of Engineering Geology
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• v.26 no.3
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• pp.403-411
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• 2016

A three-dimensional finite element analysis was conducted to analyze the predictable distances of a fault zone by using longitudinal displacement on tunnel face, trend line, L/C ratio, and C/C₀ ratio at tunnel crown. The analysis used 28 numerical models with various fault attitudes. As a result, those faults that have drives with dip could be predicted earliest in L/C and C/C₀ ratio analysis. And those faults that have drives against dip could be predicted earliest in L/C ratio and longitudinal displacement analysis. In addition, the fault zone ahead of tunnel was predicted in most models by using longitudinal displacement, trend line, L/C ratio, and C/C₀ ratio. However, the longitudinal displacement among these methods may be most usefully predict a fault zone since it is displacements can be measured immediately after tunnel excavation.

• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.593-604
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• 2005

In this paper, the parametric study on the local displacement and the local moment due to a concentrated load is performed for stiffened plates with open ribs and the orthotropic rigidity ratio of stiffened plates is selected as the parameter. For estimating the local behavior, stiffened plates loaded on the center of plates between the ribs were considered and for the global behavior, stiffened plates loaded on the rib at the center of plates were analyzed. The Analyzed results for the local behavior of stiffened plates show that the increasing ratio of the local moment according to rib sizes is constant regardless of rib spaces and the ratio of the local displacement to the global displacement can be expressed as a function of the rib space and the rigidity ratio. The application of functions to examples shows good accuracy in comparison with the local behavior of stiffened plates loaded on the center of plates and the application to the orthotropic analysis of stiffened plates improves accuracy. Therefore, using functions proposed in this study, the local behavior can easily be estimated from the global behavior of stiffened plates with open ribs.

• Structural Engineering and Mechanics
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• v.59 no.4
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• pp.719-737
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• 2016

The present study investigated the earthquake behavior of R/C structures considering the vertical earthquake motion with the help of a comparative study. For this aim, the linear time-history analyses of a high-rise R/C structure designed according to TSC-2007 requirements were conducted including and excluding the vertical earthquake motion. Earthquake records used in the analyses were selected based on the ratio of vertical peak acceleration to horizontal peak acceleration (V/H). The frequency-domain analyses of the earthquake records were also performed to compare the dominant frequency of the records with that of the structure. Based on the results obtained from the time-history analyses under the earthquake loading with (H+V) and without the vertical earthquake motion (H), the value of the overturning moment and the top-story vertical displacement were found to relatively increase when considering the vertical earthquake motion. The base shear force was also affected by this motion; however, its increase was lower compared to the overturning moment and the top-story vertical displacement. The other two parameters, the top-story lateral displacement and the top-story rotation angle, barely changed under H and H+V loading cases. Modal damping ratios and their variations in horizontal and vertical directions were also estimated using response acceleration records. No significant change in the horizontal damping ratio was observed whereas the vertical modal damping ratio noticeably increased under H+V loading. The results obtained from this study indicate that the desired structural earthquake performance cannot be provided under H+V loading due to the excessive increase in the overturning moment, and that the vertical damping ratio should be estimated considering the vertical earthquake motion.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.4
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• pp.23-28
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• 2010

This study evaluated the effect of vibration, level of lateral yielding strength, site conditions, ductility factor, strain-hardening ratio, and post-capping ratio of the strength limited bilinear SDF systems on the inelastic displacement ratio. The nonlinear response history analysis was conducted using 240 ground motions which were collected at the sites classified as site classes B, C, and D according to the NEHRP. To account for the P-$\Delta$ effects, this study considered negative stiffness ratios ranging from -0.1 to -0.5 of elastic stiffness. Four different damping ratios are used: 2, 5, 10, and 20%. From this study, an equation of inelastic displacement ratio was proposed using nonlinear regression analysis.

• Journal of Korean Association for Spatial Structures
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• v.3 no.2 s.8
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• pp.85-90
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• 2003

If we use a third order approximation for the displacement function of beam element in finite element methods, finite element solutions of beams yield nodal displacement values matching to beam theory results to have no connection with the number increasing of elements of beams. It is assumed that, as the member displacement value at beam nodes are correct, the calculation procedure of beam element stiffness matrix have no numerical errors. A the member forces are calculated by the equations of $\frac{-M}{EI}=\frac{{d^2}{\omega}}{dx^2}\;and\;\frac{dM}{dx}=V$, the member forces at nodes of beams have errors in a moment and a shear magnitudes in the case of smaller number of element. The nodal displacement value of plate subject to the lateral load converge to the exact values according to the increase of the number of the element. So it is assumed that the procedures of plate element stiffness matrix calculations has a error in the fundamental assumptions. The beam methods for the high accuracy ratio solution Is also applied to the plate analysis. The method of reducing a error ratio of member forces and element stiffness matrix in the finite element methods is studied. Results of study were as follows. 1. The matrixes of EI[B] and [K] in the equations of M(x)=EI[B]{q} and M(x) = [K]{q}+{Q} of beams are same. 2. The equations of $\frac{-M}{EI}=\frac{{d^2}{\omega}}{dx^2}\;and\;\frac{dM}{dx}=V$ for the member forces have a error ratio in a finite element method of uniformly loaded structures, so equilibrium node loads {Q} must be substituted in the equation of member forces as the numerical examples of this paper revealed.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.4
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• pp.51-61
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• 2003

This research is a park of a research program to develope a new design method for reinforced concrete bridge columns under axial load and cyclic lateral load. The objectives of this paper are to investigate the relationship between curvature ductility and displacement ductility and to propose a correlation equation for designing of reinforced concrete bridge columns under axial load and cyclic lateral load. Computer program NARCC was used for parametric study, which was proved to provide good and conservative analytical result especially for deformation capacity and ductility factor compared with test result. A total of 7,200 spirally reinforced concrete columns were selected considering the main variables such as section diameter, aspect ratio, concrete strength, yielding strength of longitudinal and confinement steel, longitudinal steel ratio, axial load ratio, and confinement steel ratio. A new equation between curvature ductility factor displacement ductility factor with the aspect ratio was proposed by investigation of 21,600 data produced from the selected column models by applying 3 different definitions of yield displacement.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.651-658
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• 2004

In this study, we introduced the spiral pipe nailing system (refer as SPN system) with self drilling method, can apply to ground which is hard to keep shape of bore hole, and performed limit equilibrium analysis with simplilied trial wedge method while length ratio and bond ratio were altered to evaluate slope stability considered of tensile strength and bending stiffness. A newly soil nailing system named as the SPN system is respected to reduce displacement of nail and increase global slope stability. And effects of various factors related to the design of the SPN system, such as the type of drilling method and the bit, are examined throughout a series of the displacement-controlled field pull-out tests. 6 displacement-controlled field pull-out tests are performed in the present study and the volume of grouting arc also evaluated based on the measurements. In addition, short-term characteristics of pull-out deformations of the newly proposed SPN system are analyzed and compared with those of the general soil nailing system by carrying out the displacement-controlled field pull-out tests.