• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.433-439
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• 1996

본 논문에서는 스트럿-타이 모델을 이용한 콘크리트 구조물의 설계 및 해석과정에서 필요로 하는 스트럿 유효강도의 결정 및 절점영역 지지력의 검토를 일반적이고 일관성 있게 수행할 수 있는 방법을 제안하였다. 콘크리트 스트럿의 유효강도는 스트럿-타이 모델의 스트럿 영역에 해당되는 유한요소들의 주응력비를 고려하여 결정하였으며, 스트럿의 기하하적인 형상을 이용하여 형성된 절점영역의 지지력은 조합응력을 받는 콘크리트의 파괴기준을 고려하는 비선형 유한요소 해석을 이용하여 검토하였다. 제안한 방법을 예증하기 위해 실험된 철근콘크리트 보의 해석을 스트럿-타이 모델 방법을 이용하여 실시하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.199-208
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• 2011

The purpose of this study is to evaluate of the strength and deformation capacity of metallic dampers with the variable slit shape. For this purpose, 12 metallic damper specimens were prepared and shear testing was performed. According to the test results, the S shaped metallic damper with the strut height of 200mm and angle of $60^{\circ}$ shows better hysteretic performance than any other specimens. By making a comparison between the yield strength in test and the proposed strength formula, test results shows larger yield strength than calculation method.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.1
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• pp.24-40
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• 1997

Horseshoe vortices generated around the juncture between the ship and her appendages often lower a performance of the ship by increasing the appendage drag and making a non-uniform wake on the propeller plane. This paper investigates numerically how the fillet around the juncture of the leading edge influences the juncture flow and the appendage drag. Computation has been made by solving Navier-Stokes equations with MAC method and the flows are at the Reynolds number of 5,000. Five fillets with different height-breath ratios and curvatures are chosen as test models to find out the effects of the shape of fillets on the appendage drag and wake. Computational results show that fillets with a smaller height-breath ratio and/or with a concave curvature has smaller appendage drag and more uniform wake.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.78-86
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• 2014

The purpose of this study is the displacement and velocity dependence evaluation of I type and S type metallic dampers. For this purpose, 12 metallic damper specimens are prepared and dependence test are performed. Test variables are strut type, displacement and velocity dependence. From the evaluation results of dependence tests, number of cycles are fully exceeded than minimum 5 cycles described in ASCE 7-10. According to displacement dependence test results, larger target displacement (50mm) shows lower cyclic numbers and cumulated energy dissipated area than lower target displacement (25mm). Also it show higher strength and early failure than short target displacement. In velocity dependence evaluation, fast target velocity (60mm/sec) shows lower cyclic numbers and cumulated energy dissipated area than target velocity (40mm/sec). As a results of basic properties, dependence evaluation and cumulated energy dissipated area evaluation, dependence capacity of S type metallic damper is far superior than I type.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.123-130
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• 2010

The aim of this paper is a seismic performance evaluation of metallic damper devices which are efficient in workability and installation process. For this V shape and S shape dampers is considered. The strut figures of dampers are V shape and S shape and, the research parameters are strut height and angle of the dampers. ABAQUS program is used for nonlinear finite element analysis. The analysis is performed with the hysteretic curve that has maximum displacement with 50mm and has increased progressive. As a results of evaluating the yield strength, maximum strength and energy dissipation capacity of each device, V and S shape have a good strength capacity and the devices with strut angle $60^{\circ}$ and strut height 140 and 200mm are evaluated stable in seismic behaviors. The response of S shape is more efficient than that of V shape. In the yield strength estimation process, proposed formula can not estimate the yield strength of V and S shape dampers. Even though, the formula can not consider the variation of strut heights and strut angles. Finally the S shape damper is recommended in seismic performance than V shape damper.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.4
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• pp.45-52
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• 2019

In this study, the seismic strengthening technique considering the rocking behavior of the wall was developed. The rocking system rotates left and right around the vertical axis of the wall. The development system is a method of dissipating energy by installing a damper which was attached at a large displacement portion. The damper was made of a steel material, and the shape and height of the strut were selected as variables. Experimental results showed that in case of shorter strut make strength capacity increasement and in case of longer strut make deformation capacity increasement. As a result of comparing the abilities according to I and S type strut shapes, it was evaluated that S type has better seismic performance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1081-1094
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• 2014

The strut-tie model approach has proven to be effective in the ultimate analysis and design of structural concrete with disturbed regions. For the reliable analysis and safe design of the structural concrete, however, the effective strengths of concrete struts must be determined accurately. In this study, the equations of the effective strengths of concrete struts, which are useful for the three types of determinate and indeterminate strut-tie models of reinforced concrete corbels, were proposed. The effects of shear span-to-effective depth ratio, the vertical-to-horizontal force ratio, and flexural and horizontal shear reinforcement ratios were reflected in the development of the proposed equations. To examine the appropriateness of the proposed and existing equations, the ultimate strengths of 243 reinforced concrete corbels tested to failure were evaluated by using the three types of corbel strut-tie models.

• Composites Research
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• v.26 no.4
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• pp.223-229
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• 2013

Hybrid composite strut tower was designed to prevent permanent deformation of upper mount by the impact from the uneven road. When exceeding energy absorption capacity of tire and suspension systems, residual impact is delivered to upper mount. Especially, in case of using high-rigidity suspension system for high driving performance, the conventional strut tower can be easily deformed due to reduction of energy absorption capacity of suspension systems. In this study, optimal design of hybrid composite strut tower which made of back-up metal and carbon fiber reinforced composite was suggested by using finite element analysis, and low velocity impact test was performed to investigate their dynamic characteristics. Also, 3D measuring and ultra c-scanning methods were carried out to diagnose damages in the strut towers.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.621-637
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• 2006

Although the approaches implementing strut-tie models are the valuable tools for designing discontinuity regions of structural concrete, the approaches of the current design codes have to be improved for the design of structural concrete subjected to complex loading and geometrical conditions because of the uncertainties in the selection of strut-tie model, in the use of an indeterminate strut-tie model, and in the effective strengths of struts and nodal zones. To improve the uncertainties, a grid struttie model approach is proposed in this study. The proposed approach, allowing to perform a consistent and effective design of structural concrete, employs an initial grid strut-tie model in which various load combinations can be considered. In addition, the approach performs an automatic selection of an optimal strut-tie model by evaluating the capacities of struts and ties using a simple optimization algorithm. The validity and effectiveness of the proposed approach is verified by conducting the analysis of the four reinforced concrete deep beams tested to failure and the design of shearwalls with two openings.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.531-539
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• 2017

The strut-tie model approach has been recognized as an efficient methodology for the design of all types of concrete members with D-regions, and the approach has been accepted in design codes globally. However, the design of concrete members with the approach requires many iterative numerical structural analyses, numerous graphical calculations, enormous times and efforts, and designer's subjective decisions in terms of the development of appropriate strut-tie model, determination of required areas of struts and ties, and verification of strength conditions of struts and nodal zones. In this study, a computer graphics program, that enables the design of concrete members efficiently and professionally by overcoming the forementioned limitations of the strut-tie model approach, is developed. In the computer graphics program, the numerical programs that are essential in the strut-tie model analysis and design of concrete members including finite element analysis programs for the plane truss and solid problems with all kinds of boundary conditions, a program for automatic determination of effective strengths of struts and nodal zones, and a program for graphical verification of developed strut-tie model's appropriateness by displaying various geometrical shapes of struts and nodal zones, are loaded. Great efficiency and convenience during the application of the strut-tie model approach may be provided by the various graphics environment-based functions of the proposed program.