• Journal of the Society of Naval Architects of Korea
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• v.28 no.1
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• pp.117-124
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• 1991

In this paper, a method to overcome inefficiency of the finite element method in the calculation of compressive strength of one-sided stiffened plates, is proposed. In this method the collapse modes of stiffened plates are assumed as follows. a) Overall buckling $\rightarrow$ Overall collapse b) Local buckling $\rightarrow$ Overall collapse c) Local buckling $\rightarrow$ Local collapse In each collapse mode, shape of deflection is assumed, and then elastic large deformation analysis based on the Rayleigh-Ritz method is carried out. One-sided stiffening effect is considered by taking into account of the moment due to eccentricity. Plastic analysis by assuming hinge lines is also carried out. The ultimate strength of a stiffened plate is obtained as the point of intersection of the elastic analysis curve and the plastic one. From this study, it is concluded that the angles between the plastic hinge lines in plastic collapse mode are determined as the ones which give the minimum collapse load, and these angles are different from the ones assumed in the previous studies. Minimum stiffness ratios can also be calculated. Calculated results according to this method show good agreements with the results by the finite element method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.117-124
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• 2007

An experimental research has been performed to evaluate the load transfer capacity for the planar joints between existing and new slab in an apartment remodelling constructions expecially for enlarging the interior space. Post-installed dowel bars were used as a joint connector. The existing slabs were obtained from the existing apartment housing which will be demolished, and were retrofitted with carbon fiber plate. Test results showed that the planar joints with post-installed dowel bars behaved in full composite modes until ultimate capacity of test specimens, so sufficient ultimate and serviceability performance are confirmed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.542-550
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• 2020

The use of high-strength aluminum alloys for ships and of shore structures has many benefits compared to carbon steels. Recently, high-strength aluminum alloys have been widely used in onshore and of shore industries, and they are widely used for the side shell structures of special-purpose ships. Their use in box girders of bridge structures and in the topside of fixed platforms is also becoming more widespread. Use of aluminum material can reduce fuel consumption by reducing the weight of the composite material through a weight composition ratio of 1/3 compared to carbon steel. The characteristics of the stress strain relationship of an aluminum structure are quite different from those of a steel structure, because of the influence of the welding[process heat affected zone (HAZ). The HAZ of aluminum is much wider than that of steel owing to its higher heat conductivity. In this study, by considering the HAZ generated by metal insert gas (MIG) welding, the buckling and final strength characteristics of an aluminum reinforcing plate against longitudinal compression loads were analyzed. MIG welding reduces both the buckling and ultimate strength, and the energy dissipation rate after initial yielding is high in the range of the HAZ being 15 mm, and then the difference is small when HAZ being 25 mm or more. Therefore, it is important to review and analyze the influence of the HAZ to estimate the structural behavior of the stiffened plate to which the aluminum alloy material is applied.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.5
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• pp.463-474
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• 2009

Double symmetric patch repair of existing structures always causes membrane action only, however, in many cases this technique is not practical. On the other hand, the bending stiffness of the patch and the skin increases as tensile loading is increased and affects the bending deformation significantly in the case of single-sided patch repair. In this study, the p-convergent full layerwise model has been proposed to determine the stress concentration factor in the vicinity of a circular hole as well as across the thickness of plates with single-sided patch repair. In assumed displacement field, the strain-displacement relations and 3-D constitutive equations of a layer are obtained by the combination of 2-D and 3-D hierarchical shape functions. The transfinite mapping technique has been used to represent a circular boundary and Gauss-Lobatto numerical integration is implemented in order to directly obtain stresses occurred at the nodal points of each layer without other extrapolation techniques. The accuracy and simplicity of the present model are verified with comparison of the previous results in literatures using experiment and conventional 3-D finite element. Also, the bending effect has been investigated with various patch types like square, circular and annular shape.

• Journal of the Korean GEO-environmental Society
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• v.15 no.12
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• pp.87-95
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• 2014

Recently, there are increasing technical needs for foundation retrofit project such as vertical extension of apartment building. This paper focuses on the load distribution characteristics of existing and reinforcing piles when reinforcing pile is installed to the existing foundation. Allowable bearing load was initially applied on the foundation slab supported with four existing piles and then, one reinforcing pile was installed at the center of foundation slab and additional load was applied. The experimental results showed the Load Distribution Ratio (LDR) between existing and reinforcing piles converged after the applied load exceeded allowable bearing capacity of all piles. Laboratory tests were also performed for the cases of 60 %, 80 %, 100 % unloading level of allowable bearing load. After unloading step, one reinforcing pile was installed at the center of foundation slab and additional load was applied. The results showed that reloading load level at which LDR between existing and reinforcing piles converged decreased as the amount of unloading load increased.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.633-640
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• 2023

In this study, numerical analysis was performed based on field investigation to derive an appropriate reinforcement method by analyzing the displacement behavior characteristics of concrete blocks generated in the direct fixation track on the bridges of the serviced light rail transit. The track of this study was a direct fixation track on a sharp curved track, and the problem of movement of the concrete blocks installed on the bridge deck in the longitudinal and lateral directions occurred. In this study, based on the finite element model using 3D solid elements, the behavior of the direct fixation track that could be occurred under operating load conditions was analyzed. In addition, the reinforcement effect of various reinforcement methods was analyzed. As a result of analyzing the lateral displacement before and after reinforcement, it was analyzed that the maximum lateral displacement after reinforcement under the extreme lateral wheel loads significantly decreased to about 3% (about 0.1mm) compared to before reinforcement. In addition, as a result of examining the generated stress of the filling mortar, bridge decks, and reinforcing bar, it was analyzed that all of them secured a sufficient safety factor of 2.6 or higher, and the optimal conditions for the reinforcement method were derived. Therefore, it is judged that the number of anchoring reinforcements and symmetrical anchor placement reviewed in this study will be effective in controlling the occurrence of lateral displacement of concrete blocks and securing the structural integrity of bridges and concrete blocks.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.04a
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• pp.139.1-142
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• 1999

• Geotechnical Engineering
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• v.25 no.6
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• pp.41-48
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• 2009

• Magazine of the Korea Concrete Institute
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• v.23 no.1
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• pp.51-55
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• 2011

• Magazine of the Korea Concrete Institute
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• v.10 no.5
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• pp.109-115
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• 1998

철근콘크리트 구조물이 과소설계되어 있거나 과다 하중이 작용하게 되면 그 구조물의 구조성능을 파악하여 보수.보강을 시행하게 된다. 최근에 가장 맣이 사용되는 보수.보강 재료로는 특히 휨내력을 보강하는데 탄소섬유를 들 수 있다. 탄소섬유쉬트는 내열성과 내호염성에 있어서 회재가 발생할 경우 보강재료로서 충분한 성능을 가지고 있다. 그러나 이를 접착시키는데 사용되는 에폭시는 유기계 물질로서 화재시 유독가스가 발생하고 내열성능도 30$0^{\circ}C$정도에도 지탱하기 어려워 화재 발생이 가능한 구조물에 사용하기 어렵다. 이 연구에서는 무기계 폴리머 복합재료로 접착된 탄소섬유를 고온(약 800~100$0^{\circ}C$, 1시간)으로 가열한 후 가열된 섬유판의 인장, 휨 전단내력을 검토하여 내열성능을 파악하고 이 섬유쉬트로 보강한 철근콘크리트 부재의 휨 성능을 실험적으로 규명하여 화재의 위험이 있는 구조물에 구조적인 보강재료로 사용이 가능한가를 검토하였다. 연구 결과, 개발된 무기계 폴리머 복합체는 인장강도, 휨강도 및 접착강도가 유기계 접착제와 유사하게 나타났고 800~100$0^{\circ}C$ 정도로 1시간 가열한 이후에도 상온 시험체 휨내력과 전단내력의 63%, 33% 정도를 유지하여 화재의 위험이 있는 부위에도 사용이 가능한 것으로 판단되었다.