• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.215-226
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• 2008

A column test was performed for a hollow composite column to evaluate its seismic performance. The seismic performances of a hollow composite column and a reinforced concrete (RC) column were evaluated and compared by quasi-static tests. Lateral displacements and lateral loads of the column specimens were measured during tests. Ductilities, absorbed energy, equivalent damping ratios, and damage indices were calculated from the recorded data. From the test results, the hollow composite column showed a seismic performance superior to the column in terms of double moment capacity, ultimate energy, and energy absorption.

• Journal of Korean Society of Steel Construction
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• v.29 no.1
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• pp.61-71
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• 2017

The flexural behavior of composite ring stiffened by GFRP and steel pipe is presented in this paper. The effective width is required to construct FEM beam element model to verify the composite flexural behavior of stiffened ring of cylindrical shell structure. The experimental results are compared with the theoretical and FEM results by commercial program ABAQUS to verify the effective width coefficient. The yield, crack and ultimate loads is calculated using theoretical strains that varies depending on yield state and compared with experiment result and FEM results by ABAQUS solid model.

• Wind and Structures
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• v.8 no.3
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• pp.197-212
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• 2005

Tall buildings under wind action usually oscillate simultaneously in the along-wind and across-wind directions as well as in torsional modes. While several procedures have been developed for predicting wind-induced loads and responses in along-wind direction, accurate analytical methods for estimating across-wind and torsional response have not been possible yet. Simplified empirical formulas for estimation of the across-wind dynamic responses of rectangular tall buildings are presented in this paper. Unlike established empirical formulas in codifications, the formulas proposed in this paper are developed based on simultaneous pressure measurements from a series of tall building models with various side and aspect ratios in a boundary layer wind tunnel. Comparisons of the across-wind responses determined by the proposed formulas and the results obtained from the wind tunnel tests as well as those estimated by two well-known wind loading codes are made to examine the applicability and accuracy of the proposed simplified formulas. It is shown through the comparisons that the proposed simplified formulas can be served as an alternative and useful tool for the design and analysis of wind effects on rectangular tall buildings.

• Wind and Structures
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• v.22 no.1
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• pp.43-63
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• 2016

In conventional buffeting theory, it is assumed that the aerostatic coefficients along a bridge deck follow the strip assumption. The validity of this assumption is suspect for a cable-stayed bridge in the construction stages, due to the effect of significant aerodynamic interference from the pylon. This situation may be aggravated in skew winds. Therefore, the most adverse buffeting usually occurs when the wind is not normal to bridge axis, which indicates the invalidity of the traditional "cosine rule". In order to refine the studies of static wind load on the deck of cable-stayed bridge under skew wind during its most adverse construction stage, a full bridge 'aero-stiff' model technique was used to identify the aerostatic loads on each deck segment, in smooth oncoming flow, with various yaw angles. The results show that the shelter effect of the pylon may not be ignored, and can amplify the aerostatic loading on the bridge deck under skew winds ($10^{\circ}-30^{\circ}$) with certain wind attack angles, and consequently results in the "cosine rule" becoming invalid for the buffeting estimation of cable-stayed bridge during erection for these wind directions.

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.349-356
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• 2011

In this paper, the optimal diagrid angle of atypical tall buildings has been found using diagrid optimization technique which is based on parametric algorithm. A diagrid is a diagonal grid which can be seen among atypical tall buildings and structures which effectively resist horizontal and vertical direction loads. Therefore, it is also the objective of this studyto find the maximum stiffness of atypical tall buildings by optimizing diagrid angle. Moreover, this study touches on both cylindrical and tapered off cylindrical structures, as shown in the examples to check the compatibility of optimum diagrid angle, which effectively resists horizontal deformation on top by optimization algorithm.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1473-1478
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• 2010

For the cassion type of breakwater under the condition of large wave loads, stability about lateral movement of breakwater was investigated by performing centrifuge model experiments. Prototype of breakwater was modelled by scaling down to centrifuge model and the soft ground reinforced with grouting was also reconstructed in the centrifuge model experiments. Sandy ground beneath breakwater was prepared with a soil sampled in field so that identical value of internal friction angle could be obtained. Centrifuge model experiments were carried out to reconstruct the construction sequence in field. Lateral static wave load was applied to the model caisson after the final stage of construction sequence was rebuilt and the measured lateral movement of caisson was compared with allowable value by the code to assess the stability about lateral movement of the breakwater.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.466-469
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• 2006

This paper presents the structural characteristics of slab-column connections by using nonlinear finite element analysis. FEA considering material non-linearity was performed to investigate average column strain, failure mode, principal stress distribution, and steel yielding conditions for various slab-column members. In addition, to investigate alternative methods for improving the strength of interior column-slab joints, some specimens were provided with different reinforcing types of high-strength concrete puddling, high-strength column longitudinal steels, dowel bars, and high-strength concrete core. To make certain of the reliability of the analytical program, analysis results for concrete material model developed and two specimens with and without puddling were compared with experimental results. It was found that providing the alternative reinforcing methods in the slab-column joint results in a significant improvement in performance. This includes an increase in the axial compressive strength, greater loading stiffness, and ductility.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.250-251
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• 2014

With the recent movement toward sustainable development, many efforts have been made to reduce environmental loads in various domains of industry. In particular, a great deal of research and technology development has been underway on approaches to reducing industrial waste and the emission of greenhouse gases. For this reason, a quantitative analysis of the reduction in CO₂ emission that could be achieved by replacing limestone material with cementitious waste powder was performed in this study. Through the analysis, it was found that CO₂ emissions were reduced by up to 50 percent compared with the scenario in which OPC was used, which suggests that it is possible to reduce global CO₂ emissions by approximately 5percent, or by 446.4 Tg of the 965 Tg of CO₂ emissions generated by the cement industry, in the total global CO₂ emissions of 19300Tg.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1434-1441
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• 2005

For anchored system applications, each ground anchor is tested after installation and prior to being put into service to loads that exceed the design. This load testing methodology, combined with specific acceptance criteria, is used to verify that the ground anchor can carry the design load without excessive deformations and that the assumed load transfer mechanisms have been properly developed behind the assumed critical failure surface. After acceptance, the ground anchor is stressed to a specified load and the load is locked-off. The two types of load tests conducted during the research program included performance test and creep test which were carried out in accordance with testing procedures by AASHTO(AASHTO 1990) and FHWA(Weatherby 1998) at Samsung-Dong 00 Site. Form the measurements, ultimate load and creep rate of anchors are proposed for straight shaft pressured grouted anchors in waste landfill. The load distribution on the grout was obtained from the measured strain data at each fraction of the ultimate load during the load tests.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.407-414
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• 2004

Interfacial properties between rock mass and shotcrete play a significant role in the transmission of loads from the ground to shotcrete. These properties have a major effect on the behaviours of rock mass and shotcrete. They, however, have merely been assumed in most of numerical analyses, and little care has been taken in identifying them. This paper aimed to identify interfacial properties including cohesion, tension, friction angle, shear stiffness, and normal stiffness, through direct shear tests as well as interface normal compression tests for shotcrete/rock cores obtained from a tunnel sidewall. Mechanical properties such as compression strength and elastic modulus were also measured to compare them with the time-dependent variation of interfacial properties. Based on experiments, interfacial properties between rock and shotcrete showed a significant time-dependent variation similar to those of its mechanical properties. In addition, the time-dependent behaviours of interfacial properties can be well regressed through exponential and logarithmic functions of time.