• Composites Research
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• v.16 no.4
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• pp.29-35
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• 2003

In this paper. various tow parameters such as equivalent tow thickness, amplitude of longitudinal tow and tow intervals were investigated and compared with each other by using microscopic observation to find out the exact deformation patterns between both directions of the fabric structure(Longitudinal and Transverse Directions). And those observation results were compared with bias extension. biaxial tests results with dry fabric which has the same tow structure as the draped helmet materials and also compared with prepreg specimen which is cured by autoclave moulding without vacuum and pressure condition. Specimens for the observation were taken from draped helmet which is made of fabric composite(Five Harness Satin Weave). From the observation results, it was found that there are different deformation pattern between tow directions and effect of geometric condition on the deformation of the fabric materials during draping process was verified.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5A
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• pp.277-287
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• 2012

The shear wall with openings built with reinforced concrete (RC) have been elaborately studied by many researchers, whereas the steel plate concrete (SC) wall structure has not been investigated as much. The recent SC wall structures developed in Korea have been partly applied to nuclear power plant structures, although its design specification or guideline for the SC wall structure with openings has not been completed yet. This study based on numerical analysis evaluates the effects of opening on the structural resistance of the SC structure in nuclear power plant. As a result from nonlinear analysis, since the strengthening for openings significantly affect the overall strength of SC wall, the openings should be considered to strengthen them around adjacent area. It is also proved that the strengthened openings have the sufficient resistance and ductility regardless their size, shape, location, and quantity.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.1
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• pp.55-60
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• 2010

The honeycomb composite joint structure designed for application to a tilting KTX railroad car body is subjected to bending loads of a cantilever type. Honeycomb sandwich composite panel-joint attached in the real tilting car body was fabricated and sectioned as several beam-joint specimens for the bending test. The fracture behaviors of these specimens under static loads were different from those under cyclic loads. Static bending loads caused shear deformation and fracture in the honeycomb core region, while fatigue cyclic bend loading caused delamination along the interface between the composite skin and the honeycomb core, and/or caused a fracture in the welded part jointed with the steel under-frame. These fracture behaviors could occur in other industrial honeycomb composite joints with similar sub-structures, and be used for improving design parameters of a honeycomb composite joint structure.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.1
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• pp.1-8
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• 2015

Recently, constructions of coastal structure including wind turbine structure have increased at southwest shore of Korea. There is a big difference of tide which rage from 3.0 m to 8.0 m at south and wet shore of Korea, respectively. In such ocean circumstance, large scour may occur due to multi-directional tidal current and transverse stress of the wind. therefore scour surrounding wind turbine structure can make system unsafe due to unexpected system vibration. In this study, hydraulic resistance capacity, i.e., critical velocity and critical shear stress, was evaluated by RCT. Uni-directional and bi-directional hydraulic resistance capacities of the samples which were consolidated by different preconsolidation pressures were correlated with soil resistivities of same samples. According to the correlation, it is possible to estimate hydraulic resistance capacity from electrical resistivity of soil. Through the updating the correlation for various soil types, it is expected that the hydraulic resistance capacity of whole construction site will be simply determined from the electrical resistivity.

• Journal of Korean Society of Steel Construction
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• v.29 no.1
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• pp.89-98
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• 2017

The offshore plant structure has been transported to the site by barge because it is hard to manufacture in site. When the structure was transported on the sea, offshore plant structures and connection were experienced repetitive submarine load. For this reason, it was known for that the axial force of high-strength bolted connection was declined. Therefore, in this study, high-strength bolted connection was evaluated the shear fatigue performance under longtime fatigue load during marine transport. The experimental variables were selected intial axial force, surface type, and bolt type because they ar important factors in the change of axial force of bolts. As a experimental results of considering various variables, the variation of axial force showed within 1%. Therefore, the high-strength bolted connection was verified structural safety under longtime fatigue load.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.45-57
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• 2016

The Inclined Earth Retaining Structure (IER) is the structure using an integrated system of both front supports and inclined back supports to increase the stability for excavation. The IER is a structurally stable temporary excavation method using the back supports restraining the lateral displacement of the front supports as stabilizing piles. The back supports connected to the front supports significantly reduce the earth pressure acting on both the front wall and the front supports by distributing it to the back supports in order to increase the structural stability. In this study, mechanical behaviors of IER according to the head connection type using fixed- or hinge-connection were found by performing numerical analysis and laboratory model tests in the sandy ground. The maximum lateral displacement of fixed-connection was 88% of that of hinge-connection in the numerical analysis. The lateral displacement of fixed-connection was 7% of that of hinge-connection in the laboratory model test results. Furthermore, the earth pressure of the fixed-connection was 67% of that of the hinge-connection in the shear-strain analysis results of the model ground.

• Coupled systems mechanics
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• v.6 no.3
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• pp.229-249
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• 2017

A new technique to mitigate irregular buildings with soil structure interaction (SSI) effect subjected to critical seismic waves is presented. The L-shape in plan irregular building for various reasons was selected, subjected to seismic a load which is a big problem for structural design especially without separation gap. The L-shape in plan building with different dimensions was chosen to study, with different rectangularity ratios and various soil kinds, to show the effect of the irregular building on the seismic response. A 3D building subjected to critical earthquake was analyzed by structural analysis program (SAP2000) fixed and with SSI (three types of soils were analyzed, soft, medium and hard soils) to find their effect on top displacement, base shear, and base torsion. The straining actions were appointed and the treatment of the effect of irregular shape under critical earthquake was made by using tuned mass damper (TMD) with different configurations with SSI and without. The study improve the success of using TMDs to mitigate the effect of critical earthquake on irregular building for both cases of study as fixed base and raft foundation (SSI) with different TMDs parameters and configurations. Torsion occurs when the L-shape in plan building subjected to earthquake which may be caused harmful damage. TMDs parameters which give the most effective efficiency in the earthquake duration must be defined, that will mitigate these effects. The parameters of TMDs were studied with structure for different rectangularity ratios and soil types, with different TMD configurations. Nonlinear time history analysis is carried out by SAP2000 with El Centro earthquake wave. The numerical results of the parametric study help in understanding the seismic behavior of L-shape in plan building with TMDs mitigation system.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.2
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• pp.181-190
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• 2005

In the conventional outrigger system, the outriggers are located in the planes of the core walls and this system has disadvantage of obstructing flexibility in the interior layout. But thc facade riggers in the structure uc located In the exterior frames in the direction of the lateral loading. The interaction between the traced frames and facade riggers is through the floor diaphragms adjacent to the chords of the riggers. This paper presents an approximate analysis technique lot preliminary analysis of multiple facade rigger stiffened braced frames in tall buildings subjected to uniformly and triangularly distributed loads as well as a lateral point load at the top of the structure. Comparisons with the results by the program MIDAS for the structural models have shown that this analysis can give reasonably accurate results for highrise braced frames with multiple facade riggers. The method allows a simple procedure for obtaining the optimum level of the facade riggers in addition to a rapid assessment of the influence of the facade riggers on the performance of the highrise structure such as the reduction in lateral deflection at the top and the overturning moment at the base of the braced frame.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.2
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• pp.137-146
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• 2007

Numerical analyses are performed to show the effect of stiffening facade riggers on the behavior of the structure and to investigate the optimum locations of facade riggers. Optimum locations of the facade riggers to minimize the drift at the top of the structure are obtained by maximizing the drift reduction caused by the facade riggers and are significantly influenced by the bending and shear stiffnesses of the braced frame and facade riggers. Three standard load cases of uniformal and triangularly distributed lateral loads as well as a lateral point load at the top of the structure are considered in this paper Optimum locations of facade riggers are plotted as functions of nondimensional relative stiffness parameters ${\omega}$ and ${\beta}$ for structures with one to four riggers. Although the analysis presented herein is based on certain simplifying assumptions, it is believed that the results do provide sufficiently accurate information for determining the optimum locations of facade riggers in highrise structures.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.4
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• pp.11-22
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• 1999

In this study, the validity of the currently used seismic regulations for seismic isolated building structures is investigated, and a new formula for vertical distribution of seismic load is proposed. The distribution formula in UBC-91 did not provide sufficient safety, and thus revised in 1994. However it is pointed out that the revised formula overestimates the seismic load because of its similarity to that of the fixed-base structure. Therefore, in the proposed approach, it is intended to satisfy safety, economy, and applicability by combining the mode shapes of the seismic isolated structure idealized as two degrees of freedom system and those of fixed-base structure. For verification of the proposed formula, both a moment resisting frame and a shear wall system are analyzed. The results obtained from the proposed method turn out to be close to the results from a dynamic analysis.