• Journal of Navigation and Port Research
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• v.30 no.3 s.109
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• pp.173-179
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• 2006

A number of perforated plates are utilized for the passage of the crew and the equipment, reducing weight and the arrangement of piping. Hull girders in double bottom and floor plates are the typical parts which have those plates in a ship structure, and the perforated plate is usually positioned at the place which has less loading without local strength problems. In the case of utilizing the plate inevitably at the place which has large strength, an opening of the plate has large effect on the buckling strength due to in-plane rigidity and ultimate strength. Therefore the assessments of the elastic buckling strength and the ultimate strength for the perforated plate are the essential requirements for determining the dimensions of the parts at the initial design stage. With above reason, a need of the reasonable assessments for the elastic buckling strength and the ultimate strength has evolved. The numerical series analysis with the consideration of the effect due to various aspect ratios and slenderness ratios were performed using finite element method in this research. Simple formulas for the design are also proposed from the above analysis.

• KCI Concrete Journal
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• v.12 no.1
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• pp.101-111
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• 2000

It has been a well known fact that buildings having inappropriate expansion joints in their spacings may be subject to exterior damages due to extensive cracks on the outer walls under service loads and structural damages due to excessive moment induced by temperature changes at ultimate load conditions. Unfortunately, consistent code provisions are unavailable regarding spacings of expansion joints from different foreign structural codes. And a more serious problem is that no quantitative measurements on spacings is given in our codes for building structures. In order to establish a rational guideline on the spacing of expansion joints, theoretical approaches are taken in this study. The developed theoretical formula is, then, converted to a design chart for structural designers' convenience in its use. The chart considers both service and ultimate load stages.

• Structural Engineering and Mechanics
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• v.19 no.5
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• pp.567-580
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• 2005

Numerous tests on concrete structure members under local pressure demonstrated that the compressive strength of concrete at the loaded surface is increased by the confinement effect provided by the enveloping concrete. Even though most design codes propose specific criteria for preventing bearing failure, they do not take into consideration size effect which is an important phenomenon in the fracture mechanics of concrete/reinforced concrete. In this paper, six series of square prism concrete blocks with three different depths (size range = 1:4) and two different height/depth ratios of 2 and 3 are tested under concentrated load. Ultimate loads obtained from the test results are analysed by means of the modified size effect law (MSEL). Then, a prediction formula, which considers effect of both depth and height on size effect, is proposed. The developed formula is compared with experimental data existing in the literature. It is concluded that the observed size effect is in good agreement with the MSEL.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.2
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• pp.210-224
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• 2010

The aim of the present study is to investigate the buckling strength of plates and stiffened panels with opening under transverse thrust and shear actions. It is observed that the existing design formulation for critical-buckling strength of plates are not valid for perforated plates, because the current design formulation trends can significantly overestimate or underestimate the load-carrying capacity of plates when plates have large opening and/or are thick. A series of eigen value and elastic.plastic large deflection finite element analyses are carried out with varying the aspect ratio of plate, the opening size and location on plate until and after the ultimate strength is reached. Based on the results obtained from the present study, closed-form design formulations for the elastic buckling strength of plates and stiffened panels with opening are derived. The derived design formulations are considered plasticity correction of the material and verified by experimental tests and results of nonlinear finite element computations.

• Journal of Korean Society of Steel Construction
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• v.24 no.4
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• pp.383-398
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• 2012

A finite element analysis study was performed to investigate the behavior and strength of a Plate-Circular Hollow Section joint stiffened with Rib-plate, Since The strength of plate-Circular Section joint is reduced by joint of stress and local plastic deformation which is caused by wall moment, rib plates are attached to the upper and lower Plate-Circular Hollow Section joint for redistribution of stress. The behaviors of joints stiffened with Rib-plate according to shape of rib and reinforcing method, etc are different from those of joints which is not stiffened. However, the criterion of hollow structural section was limited on some parts. Therefore, this study intends to investigate the behavior and structural capacity of Plate-Circular Hollow Section joints stiffened with Rib-plate and compare the Finite element analysis with the Design Equation. Finally, this study proposes the reasonable ultimate strength formula through the comparisons with other design guide.

• Journal of Ocean Engineering and Technology
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• v.23 no.5
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• pp.71-78
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• 2009

In ship design or offshore structure design, the evaluation of buckling strength (or ultimate strength) is critical to the determination of scantling of stiffened plates. For this reason, it is useful to study the effect of applying different formula or the relationship between stiffened plate with buckling utilization factor (UF). It can facilitate a designer to decide how much the scantling should be reinforced or how much can be reduced for an optimal design. This paper conducts a comparative study for three buckling check methods; DNV-Ship-Rule, DNV-RP-C201, DNV-PULS. The capacity curves and 2D contour plot for utilization factors versus bi-axial in-plane stresses are compared. The contour plots of DNV-Ship-Rule and DNV-PULS show smoothly increasing trends of UF as the applied in-plane stresses increase, however that of DNV-RP-C201 shows rapidly increasing trend as the applied stresses go beyond transverse buckling stress. A sensitivity analysis is performed to investigate the influence level of each parameter of a stiffened plate on UF. Resulting from the analysis, plate thickness is identified to be the most affective parameter to UF regardless of the buckling check methods. Based on the addressed study, optimal designs for bottom plate of 165 K tanker corresponding to three formulas are compared with each other. DNV-PULS yields 1 mm and 2 mm less thickness than DNV-Ship-Rule and DNV-RP-C201, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.735-742
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• 2006

In this study, the ultimate shear strength behavior of transversely stiffened curved web panels was investigated through nonlinear finite element analysis. It was found that if the transverse stiffener has a sufficient rigidity, then curved web panels used in practical designs are able to develop the postbuckling strength that is equivalent to that of straight girder web panels having the same dimensional and material properties. The nonlinear analysis results indicate that in order for curved web panels to develop the potential postbuckling strength. The rigidity of the transverse stiffener needs to be increased several times the value obtained from the Guide Specifications (AASHTO, 2003). However, in the case of thick web panels where the shear design is governed by shear yielding, the stiffener rigidity does not have to be increased. From the analysis results, a simple design formula is suggested for the rigidity of transverse stiffener under strength limit state.

• Steel and Composite Structures
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• v.29 no.1
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• pp.77-90
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• 2018

This paper presents a combined numerical, experimental, and theoretical study on the behavior of the concrete-filled double circular steel tubular (CFDT) stub columns under axial compressive loading. Four groups of stub column specimens were tested in this study to find out the effects of the concrete strength, steel ratio and diameter ratio on the mechanical behavior of CFDT stub columns. Nonlinear finite element (FE) models were also established to study the stresses of different components in the CFDT stub columns. The change of axial and transverse stresses in the internal and external steel tubes, as well as the change of axial stress in the concrete sandwich and concrete core, respectively, was thoroughly investigated for different CFDT stub columns with the same steel ratio. The influence of inner-to-outer diameter ratio and steel ratio on the ultimate bearing capacity of CFDT stub columns was identified, and a reasonable section configuration with proper inner-to-outer diameter ratio and steel ratio was proposed. Furthermore, a practical formula for predicting the ultimate bearing capacity was proposed based on the ultimate equilibrium principle. The predicted results showed satisfactory agreement with both experimental and numerical results, indicating that the proposed formula is applicable for design purposes.

• Steel and Composite Structures
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• v.42 no.3
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• pp.407-426
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• 2022

Superior to traditional welded studs, high strength friction-grip bolted shear connectors facilitate the assembling and demounting of the composite members, which maximizes the potential for efficiency in the construction and retrofitting of new and old structures respectively. Hence, it is necessary to investigate the structural properties of high strength friction-grip bolts used in steel concrete composite beams. By means of push-out tests, an experimental study was conducted on post-installed high strength friction-grip bolts, considering the effects of different bolt size, concrete strength, bolt tensile strength and bolt pretension. The test results showed that bolt shear fracture was the dominant failure mode of all specimens. Based on the load-slip curves, uplifting curves and bolt tensile force curves between the precast concrete slab and steel beam obtained by push-out tests, the anti-slip performance of steel-concrete interface and shear behavior of bolt shank were studied, including the quantitative analysis of anti-slip load, and anti-slip stiffness, frictional coefficient, shear stiffness of bolt shank and ultimate shear capacity. Meanwhile, the interfacial anti-slip stiffness and shear stiffness of bolt shank were defined reasonably. In addition, a total of 56 push-out finite element models verified by the experimental results were also developed, and used to conduct parametric analyses for investigating the shear behavior of high-strength bolted shear connectors in steel-concrete composite beams. Finally, on ground of the test results and finite element simulation analysis, a new design formula for predicting shear capacity was proposed by nonlinear fitting, considering the bolt diameter, concrete strength and bolt tensile strength. Comparison of the calculated value from proposed formula and test results given in the relevant references indicated that the proposed formulas can give a reasonable prediction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.483-493
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• 2013

The high strength materials have been more widely used in a large reinforced concrete structures. It is known that the use of high strength material in RC structures give the benefits of the mechanical and durable properties, but the ductility decreases with an increase in the strength of the materials. In the design of a reinforced concrete beam, both the flexural strength and ductility need to be considered. So, it is necessary to assess accurately the ductility of the beam with high strength materials in order to ensure the ductility requirement in design. In this study, the effects of the material strength on the flexural behavior and curvature ductility factor of reinforcement concrete beam sections with various reinforcement conditions have been evaluated and a newly prediction formula for curvature ductility factor of RC beam has been developed considering the stress of compression reinforcement at ultimate state. The proposed predictions for the curvature ductility factor which is applicable to both singly and doubly reinforced concrete beam are verified by comparisons with other prediction formulas and the proposed formula offers fairly accurate within 9% error and consistent predictions for curvature ductility factor of reinforced concrete beam.