• 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.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.490-494
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• 2008

U-Channel Bridge is effective bridge type, because its edge beam performs role of barrier and enables to reduce additional dead loads. Although it is effective to reduce additional dead loads, there is possibility of bridge collapse under impact load due to car crash. Also, edge beam must have ability to induce safe driving and prevent falling accidents. Therefore, it requires behavior analysis and property investigation through the vehicle impact crashing edge beam. This study presents method of structural analysis of U-channel bridge and investigates design specifications for the effect of the edge beam under the vehicle impact. Also, it carries out stability investigation of behavior of edge beam and slab, based on Korean Highway Bridge Design Specifications and AASHTO LRFD Bridge Design Specification.

• KCI Concrete Journal
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• v.14 no.3
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• pp.111-120
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• 2002

This study proposes a joint model consisting of different types of members as a new structural system, and then investigates the resulting structural behavior. The joint model consists of a concrete-filled steel tube column (CFT) together with a steel reinforced concrete at the end plus reinforced concrete beam at the center. For comparison, two other joint models were designed, that are, a CPT with a reinforced concrete beam, and a CFT with a steel reinforced concrete at the end plus steel concrete beam at the center, then their joint capacity and rigidity, energy absorption capacity, etc., were all investigated. From the results, the CFT column with a steel reinforced concrete at the end plus steel concrete beam at the center was outstanding in terms of its capacity and rigidity. The results of this analysis demonstrate that an adequate connection type and reinforcement method with different materials of increasing the rigidity, thereby producing a capacity improvement along with protection from pre-fractures.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1282-1287
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• 2004

The bubble behavior and the radiation mechanism from a laser-induced collapsing bubble were investigated theoretically using the Keller-Miksis equation for the bubble wall motion and analytical solutions for the vapor inside bubble. The calculated time dependent bubble radius is in good agreement with observed ones. The half-width of the luminescence pulse at the collapse point, which was calculated under assumption that the light emission mechanism is black body radiation from the vapor bubble agreed well with observed value of several nanoseconds. The gas content inside the vapor bubble was too small to produce the light emission due to bremsstrahlung.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.241-245
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• 2012

In this study, one type of circular shaped composite tube was used, combined with reinforcing foam and without foam. Furthermore, CFRP (Carbon Fiber Reinforced Plastic) circular member manufactured from CFRP prepreg sheet for lightweight design. CFRP is an anisotropic material which is the most widely adapted lightweight structural member. The crashworthy behavior of circular composite material tubes subjected to static axial compression under same conditions is reported in this paper. The collapse mode during the failure process were observed and analyzed. The behavior of polymeric foams to the tubes crashworthiness were also investigated.

• Computers and Concrete
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• v.7 no.4
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• pp.303-315
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• 2010

In this paper, we present a new finite Timoshenko beam element with a model for ultimate load computation of reinforced concrete frames. The proposed model combines the descriptions of the diffuse plastic failure in the beam-column followed by the creation of plastic hinges due to the failure or collapse of the concrete and or the re-bars. A modified multi-scale analysis is performed in order to identify the parameters for stress-resultant-based macro model, which is used to described the behavior of the Timoshenko beam element. The micro-scale is described by using the multi-fiber elements with embedded strain discontinuities in mode 1, which would typically be triggered by bending failure mode. A special attention is paid to the influence of the axial force on the bending moment - rotation response, especially for the columns behavior computation.

• Computers and Concrete
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• v.12 no.6
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• pp.819-829
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• 2013

The objective of this study is to determine whether or not the yield line theory, an effective method widely used for slabs made of ordinary concrete, can be used also for the reinforced concrete slabs made of high-strength concrete. Flexural behavior of simply supported slabs in three different sizes were investigated under concentrated load at mid-span. Additionally, behavior of high strength reinforced concrete slabs with 50 mm and 150 mm reinforcement spacings also studied. Failure loads, deflections, experimental and theoretical failure mechanisms were evaluated. The difference between the moments based on yield line theory and experimental moments varied between 1% to 3%. Experimental and analysis results revealed that yield line analysis could conveniently be employed in the analysis of high strength reinforced concrete slabs.

• Structural Engineering and Mechanics
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• v.51 no.6
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• pp.1017-1036
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• 2014

Steel tubes have an efficient shape with large second moment of inertia relative to their light weight. One of the main problems of these members is their low buckling resistance caused from having thin walls. In this study, steel foams with high strength over weight ratio is used to fill the steel tube to beneficially modify the response of steel tubes. The linear eigenvalue and plastic collapse FE analysis is done on steel foam filled tube under pure compression and three point bending simulation. It is shown that steel foam improves the maximum strength and the ability of energy absorption of the steel tubes significantly. Different configurations with different volume of steel foam and composite behavior is investigated. It is demonstrated that there are some optimum configurations with more efficient behavior. If composite action between steel foam and steel increases, the strength of the element will improve, in a way that, the failure mode change from local buckling to yielding.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.757-764
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• 2004

This paper deals with the numerical study on the displacement behavior of corner areas in an excavation site. Several corner areas always exist in the excavation site. The corner area has two free surfaces, which may become serious weak point from the viewpoint of structural stability. If the structural reinforcements are not applied adequately in corner areas, significant displacement of retaining wall could occur. What is worse, the collapse of retaining system rarely happens. In this paper, 3D numerical analyses were performed to investigate the effect of the arrangement of diagonal and normal strut. From the analysis results, it is found that the spacing between diagonal strut and normal strut should be less than 4m to avoid excessive displacement due to excavation.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.550-555
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• 2000

Nonlinear oscillation of a microbubble under ultrasound was investigated theoretically. The bubble radius-time curves calculated by the Rayleigh-Plesset equation with a polytropic index and by the Keller-Miksis equation with the analytical solution for the Navier-Stokes equations of the gases were compared with the observed results by the light scattering method. This study has revealed that the bubble behavior such as the expansion ratio and the bouncing motion after the first collapse under ultrasound depends crucially on the retarded time of the bubble motion to the applied ultrasound.