• Journal of Korean Association for Spatial Structures
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• v.12 no.3
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• pp.71-78
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• 2012

The dynamic behavior of spatial structures is different depending on the aspect ration of arch structure, as the rise-span ratio or open-angle, and these spatial structures show differently the character of seismic response in accordance with stiffness and connection of the lower support structures that are directly influenced by earthquake. Therefore, in this paper, dynamic analysis is conducted for seismic response of single layer arch structures by the influence of column's stiffness and connection, to reflect the different vertical and horizontal vibration mode of single layer arch structures. The vertical response of single layer arch structures is more influence by lower columns and the influence of column's connection rotational stiffness is not large, except to the hinged connections.

• Steel and Composite Structures
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• v.26 no.5
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• pp.635-647
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• 2018

In order to improve the efficiency of the Reinforced Concrete, RC, structures against progressive collapse, this paper proposes a procedure using alternate path and specific local resistance method to resist progressive collapse in intermediate RC frame structures. Cap truss consists of multiple trusses above a suddenly removed structural element to restrain excessive collapse and provide an alternate path. Steel strut is used as a brace to resist compressive axial forces. It is similar to knee braces in the geometry, responsible for enhancing ductility and preventing shear force localization around the column. In this paper, column removals in the critical position at the first story of two 5 and 10-story regular buildings strengthened using steel strut or cap truss are studied. Based on nonlinear dynamic analysis results, steel strut can only decrease vertical displacement due to sudden removal of the column at the first story about 23%. Cap truss can reduce the average vertical displacement and column axial force transferred to adjacent columns for the studied buildings about 56% and 61%, respectively due to sudden removal of the column. In other words, using cap truss, the axial force in the removed column transfers through an alternate path to adjacent columns to prevent local or general failure or to delay the progressive collapse occurrence.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.718-733
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• 2021

A prediction method, based on the Morison equation as well as Froude-Krylov formula, is presented to simulate the loads acting on the columns and caissons of the semi-submersible platform induced by Internal Solitary Wave (ISW) respectively. Combined with the experimental results, empirical formulas of the drag and inertia coefficients in Morison equation can be determined as a function of the Keulegan-Carpenter (KC) number, Reynolds number (Re) and upper layer depth h₁/h respectively. The experimental and calculated results are compared. And a good agreement is observed, which proves that the present prediction method can be used for analyzing the ISW-forces on the semi-submersible platform. Moreover, the results also demonstrate the layer thickness ratio has a significant effect upon the maximum horizontal forces on the columns and caissons, but both minimum horizontal and vertical forces are scarcely affected. In addition, the incoming wave directions may also contribute greatly to the values of horizontal forces exerted on the caissons, which can be ignored in the vertical force analysis.

• Computational Structural Engineering
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• v.8 no.1
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• pp.95-106
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• 1995

Noise and vibration induced by subway operation are one of the major factor that annoy residents living near the subway tracks. In general, lateral vibration is the major concern when we are considering vibration of a building. However, the vertical vibration is the major concern in considering the vibration induced by the subway operation. Analysis model for the vertical vibration of the structure should consider the effect of beam vibration. Thus, the same model used for the lateral vibration analysis can not be used for an analysis of vertical vibration of the structure. Appropriate analysis model which can consider the inertia force of the beam is necessary when analyzing a structure for the vertical vibration. Modeling technique for the vertical vibration analysis of structures has been studied on this paper. It is recommended to use one or more elements for columns and to use two or more elements for beams when analyzing structures for vertical vibration induced by subway operation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.4 s.74
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• pp.375-387
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• 2006

Different from the previous studies which investigated seismic P-$\Delta$ effect in slender columns though comparison of response spectra according to stability coefficients obtained from the analyses based on the assumed moment-curvature relationship, the axial force and P-$\Delta$ effect in RC columns are investigated on the basis of the layered section method which can effectively consider the changes of stiffness and yield strength due to the application of axial force in RC members. Practical ranges of slenderness and stability coefficient are assumed, and sixty sets of horizontal/vertical earthquake inputs are used in the analysis. From the parametric study, it is noted that the maximum deformation of the slender RC column is hardly affected by P-$\Delta$ effect or vortical earthquake but dominantly affected by the applied axial force. Therefore, it can be concluded that no additional consideration for the P-$\Delta$ effect and vortical earthquake is required in the seismic design of a slender RC column if the axial force effect is taken into account in the analysis and design procedures.

• Journal of the Korean Wood Science and Technology
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• v.50 no.4
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• pp.246-255
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• 2022

The need for non-destructive testing and evaluation of Korean traditional wooden buildings is increasing because of their widespread deterioration. Among all types of deterioration, termite damage in wooden columns is the most difficult to detect with the naked eye because it starts inside the wood, and the initial deterioration is small. X-ray computed tomography (CT) is the best technology to investigate the inner state of wood that has less damage, but applying it to wooden columns between walls is challenging. Therefore, the feasibility of tomosynthesis, which is a method to reconstruct a coronal section of a subject with a few X-ray projections from a limited angle of rotation, was studied as an alternative to CT. Pine (P. densiflora) with three artificial holes was prepared as a specimen to evaluate the quality of reconstructed tomosynthesis images according to the different number of projections. The quality of the tomosynthesis images in the in-focus plane was evaluated using the contrast-to-noise ratios, while a vertical resolution between the images was assessed by determining the artificial spread function. The quality of the tomosynthesis image in the in-focus plane increased as the number of projections increased and then remained constant as the number of projections reached 21 or over. In the case of vertical resolution, there was no significant difference when 21 projections or more were used to reconstruct the images. A distinct difference between coronal section images was found when the distance was more than 10 mm from one plane to another plane.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.793-796
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• 2005

In this paper, we propose a method which can improve uniformity of a miniaturized electron beam array for inspection of very small pattern with high speed using vertical interconnection. This method enables the individual control of columns so that it can reduce the deviation of beam current, beam size, scan range and so on. The test device that used vertical interconnection method was fabricated by multiple wafer bonding and metal reflow. Two silicon and one glass wafers were bonded and metal interconnection by melting of electroplated AuSn was performed. The contact resistance was under $10{\Omega}$.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.5-8
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• 2004

In order to investigate the effect of the height of application point of lateral loads and reinforcing steel bars in walls and columns in improving the seismic behavior of confined concrete block masonry walls, an experimental research program is conducted. A total of four one-half scale specimens are tested under repeated lateral loads. Specimens are tested to failure with increasing maximum lateral drifts while a vertical axial load was applied and maintained constant. The constant vertical axial stresses applied are 0, 0.84 and 1.80MPa, while the amount of reinforcements in horizontal and vertical directions are $0\%,\;0.08\%\;and\;0.18\%$ respectively. Test results obtained for each specimen include cracking patterns, load-deflection data, and strains in reinforcement and walls in critical locations. Analysis of test data showed that above parameters generate a considerable effect on the seismic performance of confined concrete block masonry walls.

• Computers and Concrete
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• v.20 no.4
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• pp.369-380
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• 2017

The effects of the vertical component of a ground motion on the earthquake performances of semi-ductile high-rise R/C structures were investigated in the present study. Linear and non-linear time-history analyses were conducted on an existing in-service R/C building for the loading scenarios including and excluding the vertical component of the ground motion. The ratio of the vertical peak acceleration to the horizontal peak acceleration (V/H) of the ground motion was adopted as the main parameter of the study. Three different near-source earthquake records with varying V/H ratio were used in the analyses. The linear time-history analyses indicated that the incorporation of the vertical component of a ground motion into analyses greatly influences the vertical deflections of a structure and the overturning moments at its base. The lateral deflections, the angles of rotation and the base shear forces were influenced to a lesser extent. Considering the key indicators of vertical deflection and overturning moments determined from the linear time-history analysis, the non-linear analyses revealed that the changes in the forces and deformations of the structure with the inclusion of the vertical ground motion are resisted by the shear-walls. The performances and damage states of the beams were not affected by the vertical ground motion. The vertical ground motion component of earthquakes is markedly concluded to be considered for design and damage estimation of the vertical load-bearing elements of the shear-walls and columns.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.3
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• pp.219-226
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• 2012

Columns are the key elements supporting load in structure. Column failure causes the structure to collapse. It is important to evaluate residual strength for damaged columns under blast load for preventing progressive collapse. In this paper, columns were investigated to compare the blast resistance on the change of the number of steel bars within the range of reinforcement ratio. And this study was carried out 4 different analytical models to evaluate effects of aspect ratio. The results indicate that the vertical strain was unaffected by the number of steel bars and aspect ratio. As the number of steel bars facing blast load increase, the blast resisting capacity of the columns was improved in the lateral strain. Also, the analysis results showed that a large moment of inertia of area, as compared to a small one would be superior in residual strength as well as force of restitution.