• International journal of steel structures
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• v.18 no.4
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• pp.1153-1166
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• 2018

This paper was concerned with the nonlinear analysis on the overall stability of H-type honeycombed composite column with rectangular concrete-filled steel tube flanges (STHCC). The nonlinear analysis was performed using ABAQUS, a commercially available finite element (FE) program. Nonlinear buckling analysis was carried out by inducing the first buckling mode shape of the hinged column to the model as the initial imperfection with imperfection amplitude value of L/1000 and importing the simplified constitutive model of steel and nonlinear constitutive model of concrete considering hoop effect. Close agreement was shown between the experimental results of 17 concrete-filled steel tube (CFST) specimens and 4 I-beams with top flanges of rectangular concrete-filled steel tube (CFSFB) specimens conducted by former researchers and the predicted results, verifying the correctness of the method of FE analysis. Then, the FE models of 30 STHCC columns were established to investigate the influences of the concrete strength grade, the nominal slenderness ratio, the hoop coefficient and the flange width on the nonlinear stability capacity of SHTCC column. It was found that the hoop coefficient and the nominal slenderness ratio affected the nonlinear stability capacity more significantly. Based on the results of parameter analysis, a formula was proposed to predict the nonlinear stability capacity of STHCC column which laid the foundation of the application of STHCC column in practical engineering.

• Journal of the Korean Geotechnical Society
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• v.22 no.10
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• pp.121-129
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• 2006

Stone column is one of the ground improvement systems which is being used for accelerating consolidation and increasing bearing capacity for settlement sensitive structures like load embankments, bridge abutments, oil storage tanks etc. The effects of this method are enhancement of ground bearing capacity, reduction of settlement, prevention of liquefaction and prevention of lateral ground movement. Recently, geosynthetic reinforced (encased) stone column approach has been developed to improve its load carrying capacity through increasing confinement effect. Although such a concept has successfully been applied in practice, fundamentals of the method have not been fully explored. This paper presents the results of an investigation on the bearing capacity and failure mechanism of geogrid-encased stone column by model tests. The results of the analyses indicated improved bearing capacity of the geogrid reinforced stone column method over the conventional strone column method with no encasing.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.3
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• pp.287-295
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• 2023

The collapse of bridges due to earthquakes results in many casualties and property damages. Thus, accurate prediction and preparation are required for the behavior of bridges during earthquakes. In particular, columns play an important role in the seismic behavior of bridges. The risk of collapse due to an earthquake increases when there is a problem of the insufficient lap splice in the column. In this study, to analyze the characteristics of the lap splice in the column, a numerical model was defined for the insufficient lap-spliced columns and verified using experimental data. The developed column model was applied to a commonly used RC slab bridge. Nonlinear static analysis for the column was performed to evaluate the change in the performance of the column according to the lap-spliced length. In addition, this study assessed the effect of the lap-spliced length on the seismic fragility analysis.

• Economic and Environmental Geology
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• v.35 no.3
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• pp.221-227
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• 2002

Column experiments were performed to evaluate the removal efficiency of soil vapor extraction (SVE) iota TCE (trichloroethylene) and toluene in soil. Homogeneous Ottawa sands and real soils collected from contaminated area were used to investigate the effect of soil properties and SVE operation conditions on the removal efficiency. In column teats with two different sizes of Ottawa sand, the maximum effluent TCE concentration in a coarse sand column was 442 mg/L and 337 mg/L in a fine sand column. However, after 20 liter gas flushing, the effluent concentrations were very similar and more than 90% of initial TCE mass were removed from the column. For two real contaminated soil columns, the maximum effluent concentration decreased 50% compared with that in the homogeneous Ottawa coarse sand column, but 99% of initial TCE mass were extracted from the column within 40 liter air flushing, suggesting that SVE is very available to remove volatile NAPLs in the contaminated soil. To investigate the effect of contaminant existing time on the removal efficiency, an Ottawa sand column was left stable for one week after TCE was injected and the gas extraction was applied into the column. Its effluent concentration trend was very similar to those for other Ottawa sand columns except that the residual TCE after the air flushing showed relatively high. Column tests with different water contents were performed and results showed high removal efficiency even in a high water content sand column. Toluene as one of BTEX compounds was used in an Ottawa sand column and a real soil column. Removal trends were similar to those in TCE contaminated columns and more than 98% of initial toluene mass were removed with SVE in both column.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.4
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• pp.257-266
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• 2008

PAHs are of mainly anthropogenic origin from urban runoff, oil spill and combustion of fossil fuels. Some PAHs are potentially carcinogenic and mutagenic to aquatic organisms. This study was carried out to survey the contamination of PAHs in the column sediments around Gwangyang bay. Yeosu petrochemical industrial complex, POSCO(Pohang steel compony) and Gwangyang container harbor are located near the bay. The column sediments were collected at 4 stations(A, B, C and D) and fractionated at intervals of two-centimeter depth on July 29, 1999. PAHs in colmn sediment samples were extracted in soxhlet extractor and were identified and quantified by GC-MS. PAHs compounds were analyzed and found to be 13 species. Total PAHs concentrations in the column sediments ranged from 275.04 to 2,838.64${\mu}g/kg$ dry wt. Naphthalene had the highest concentration in the range of 40.60 to 2,294.06${\mu}g/kg$ dry wt. and Anthracene had the lowest concentration in the range of 2.63 to 11.30${\mu}g/kg$ dry wt. The correlation coefficients between individual PAHs and total PAHs in the column sediments were relatively higher in the low molecular compounds such as Naphthalene, Acenaphthylene and Phenanthrene. The relationship between the P/A(Phenanthrene/Anthracene)ratio and F/P(Fluoranthene/Pyrene)ratio showed that P/A ratio was generally above 10 and F/P ratio was above 1 in all sediment samples. These data indicate that PAHs in the column sediments around Gwangyang bay seem to be of both pyrolytic and petrogenic origin The values of PAHs in the column sediments were lower than the biological effect guidelines.

• Structural Engineering and Mechanics
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• v.45 no.3
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• pp.277-309
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• 2013

Beam-to-column connections behaviour plays an important role in the analysis and design of steel and precast concrete structures. The paper presents a computer-based method for geometrically nonlinear frames with semi-rigid beam-to-column connections. The analytical procedure employs modified stability functions to model the effect of axial force on the stiffness of members. The member modified stiffness matrix, and the modified fixed end forces for various loads were found. The linear and nonlinear analyses were applied for two planar steel structures. The method is readily implemented on a computer using matrix structural analysis techniques and is applicable for the efficient nonlinear analysis of frameworks.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.04a
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• pp.142-147
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• 1993

In the reinforced concrete structure, as the height of building structure increases, the accurate estimation of differential column shortening is important factor in the structural design. In this study, the analysis of column shortening is applied to 36-story building structure to be built in time. As a result, it may found that, as the difference of compressive stress become larger, differential shortening effect due to creep and shrinkage are more signicant factor to structural designer.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.10a
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• pp.267-274
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• 1996

Differential shortening of vertical members in high-rise buildings affect other structural members that have to be considered such as horizontal members and exterior cladding. of many elements which affect the total amount of shortening, different loading history mainly comes from the different construction time. Shortening of 66 story concrete columns were investigated and compared according to the different construction time, little difference was found between the total shortening of interior and that of exterior column.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.10a
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• pp.45-51
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• 1992

Trilinear analytical models representing the behavior of composite beam-steel column joints and seismic shear design method for the joints are presented. Emphasis is placed on the effect of the concrete slab on the behavior of the joints. To validate the analytical models, Comparisons with the experimental results are made. Application of the proposed method to seismic shear design of joints improves the seismic resistance of the steel frame with composite slab.

• International Journal of High-Rise Buildings
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• v.11 no.3
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• pp.181-187
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• 2022

POSCO E&C has completed Parc.1 project successfully. The construction period was 42months, and 1.5 million workers were participated till completion. To meet schedule management and quality control, POSCO E&C has adopted a lot of technologies such as GPS measurement, 3D scanning, vibration control, stack effect control, column shortening control, etc