• Journal of the Society of Naval Architects of Korea
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• v.51 no.4
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• pp.283-290
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• 2014

Environmental changes, especially global climate change, are creating new routes to reduce a shipping service distance in Arctic area. The Arctic routes are shorter than 60% of existing ways Panama or Suez canal). For this reason, ship owners prefer to navigate in Arctic area and a transportation of goods though the Arctic area is increasing. But the low temperature in Arctic condition changes the material properties. Especially, the material will be brittle and strength will increase. And an ultimate strength analysis of ship stiffened panels is changed depending on temperatures. In present study, the ultimate strength analysis of stiffened panels in double hull oil tankers is performed under various low temperatures with the material properties obtained by tensile coupon test. The analytical method as named ALPS/ULSAP was used for analysis method and 6 kinds of temperature (20, 0, -20, -40, -60 and $-80^{\circ}C$) were considered to investigate the effect of Arctic conditions.

• Journal of Korean Society of Steel Construction
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• v.26 no.2
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• pp.119-132
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• 2014

In this paper, a series of numerical analyses were performed to evaluate the flexural resistance of steel plate girder with longitudinally stiffened and slender web. The SM490 steel was adopted for the study and the flexural resistances evaluated from the numerical analysis were compared with those suggested by the AASHTO LRFD and the Eurocode 3 codes, respectively. It was found that the AASHTO LRFD code could considerably underestimate the flexural resistance as the web slenderness becomes smaller. This comes from the fact that current AASHTO LRFD code does not consider a possible increase of slenderness limits for compact and noncompct web, and also an additional effect of web restraint on the rotation of compression flange in longitudinally stiffened web. Therefore, the slenderness limits of web and flange have been newly proposed for the plate girders with longitudinally stiffened web and it is analytically verified that the flexural resistance can be appropriately estimated by applying the proposed slenderness limits to the AASHTO LRFD code.

• Proceedings of KOSOMES biannual meeting
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• 2005.05a
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• pp.141-146
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• 2005

Ship have cutout inner bottom and girder and floor etc. Ship's structure is used much, and structure strength must be situated, but establish new concept when high stress interacts sometimes fatally the area. There is no big problem usually by aim of weight reduction, a person and change of freight, piping etc. Because cutout's existence grow up in this place, and, elastic buckling strength by load causes large effect in ultimate strength. Therefore, stiffened perforated plate considering buckling strength and ultimate strength is one of important design criteria which must examine when decide structural concept at initial design. Therefore, and, reasonable buckling strength about perforated stiffened plate need to ultimate strength limited design . Calculated ultimate strength varied several web height and cutout's dimension, and thickness in this investigated data. Used program(ANSYS) applied F.E.A code based on finite element method.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.269-276
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• 2001

Tubular structures are widely used for offshore platforms and truss type structures. In this paper, nonlinear finite element analysis is used to assess the static strength of stiffened tubular T-joints subjected to compressive brace loading. This joints was modelled with and without internal ring stiffener According to variation of ring geometries, the effect of ring stiffener for T-joints are investigated. Internal ring stiffener is found to be efficient improving ultimate strength of tubular joints. Relations of ring thickness and axial strength are observed considering geometric parameters of ring stiffeners.

• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.537-547
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• 2005

MABB(Editor's note: Please spell out "MABB" upon first mention)is a new structural type of arch that connects arch ribs and stiffened girders with two internal arches. In this study, the static and dynamic behavior of MABB were analyzed in comparison with those of conventional arches for the investigation of the structural effect of MABB on moving loads. For the purpose of surveying the effect of internal arches on the dynamic behavior of structure, natural frequency and natural vibration mode were investigated and the static and dynamic behavior were analyzed by the method of idealizing train loads as traveling loads consisting of a group of concentrated loads. From the results, the following conclusions were known. First, it is concluded that with MABB, decreasing the section of stiffened girders is possible as compared with conventional arches because the increase of stiffness by internal arches is larger than that of the mass of internal arches. Second, MABB has the advantage of assurance of stability of dynamic behavior because the dynamic behavior of MABB on moving loads is usually investigated in a more stable way than that of conventional arches.

• Steel and Composite Structures
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• v.27 no.5
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• pp.577-598
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• 2018

The imperfect steel-concrete interface bonding is an important deficiency of the concrete-filled double skin tubular (CFDST) columns that led to separating concrete and steel surfaces under lateral loads and triggering buckling failure of the columns. To improve this issue, it is proposed in this study to use longitudinal and transverse steel stiffeners in CFDST columns. CFDST columns with different patterns of stiffeners embedded in the interior or exterior surfaces of the inner or outer tubes were analyzed under constant axial force and reversed cyclic loading. In the finite element modeling, the confinement effects of both inner and outer tubes on the compressive strength of concrete as well as the effect of discrete crack for concrete fracture were incorporated which give a realistic prediction of the seismic behavior of CFDST columns. Lateral strength, stiffness, ductility and energy absorption are evaluated based on the hysteresis loops. The results indicated that the stiffeners had determinant role on improving pinching behavior resulting from the outer tube's local buckling and opening/closing of the major tensile crack of concrete. The lateral strength, initial stiffness and energy absorption capacity of longitudinally stiffened columns with fixed-free end condition were increased by as much as 17%, 20% and 70%, respectively. The energy dissipation was accentuated up to 107% for fixed-guided end condition. The use of transverse stiffeners at the base of columns increased energy dissipation up to 35%. Axial load ratio, hollow ratio and concrete strength affecting the initial stiffness and lateral strength, had negligible effect of the energy dissipation of the columns. It was also found that the longitudinal stiffeners and transverse stiffeners have, respectively, negative and positive effects on ductility of CFDST columns. The conclusions, drawn from this study, can in turn, lead to the suggestion of some guidelines for the design of CFDST columns.

• Steel and Composite Structures
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• v.33 no.6
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• pp.793-803
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• 2019

Concrete-filled steel tubular (CFST) beam-columns are widely used owing to their good performance. They have high strength, ductility, large energy absorption capacity and low costs. Externally stiffened CFST beam-columns are not used widely due to insufficient design equations that consider all parameters affecting their behavior. Therefore, effect of various parameters (global, local slenderness ratio and adding hoop stiffeners) on the behavior of CFST columns is studied. An experimental study that includes twenty seven specimens is conducted to determine the effect of those parameters. Load capacities, vertical deflections, vertical strains and horizontal strains are all recorded for every specimen. Ratio between outer diameter (D) of pipes and thickness (t) is chosen to avoid local buckling according to different limits set by codes for the maximum D/t ratio. The study includes two loading methods on composite sections: steel only and steel with concrete. The case of loading on steel only, occurs in the connection zone, while the other load case occurs in steel beam connecting externally with the steel column wall. Two failure mechanisms of CFST columns are observed: yielding and global buckling. At early loading stages, steel wall in composite specimens dilated more than concrete so no full bond was achieved which weakened strength and stiffness of specimens. Adding stiffeners to the specimens increases the ultimate load by up to 25% due to redistribution of stresses between stiffener and steel column wall. Finally, design equations previously prepared are verified and found to be only applicable for medium and long columns.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1802-1812
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• 2001

The theoretical method is developed to investigate the effects of ring stiffeners on free vibration characteristics and transient response for the ring stiffened composite cylindrical shells subjected to the impulse pressure Loading. In the theoretical procedure, the Love's thin shell theory combined with the discrete stiffener theory to consider the ring stiffening effect is adopted to formulate the theoretical model. The concentric or eccentric ring stiffeners are laminated with composite and have the uniform rectangular cross section. The modal analysis technique is used to develop the analytical solutions of the transient problem. The analysis is based on an expansion of the loads, displacements in the double Fourier series that satisfy the boundary conditions. The effect of stiffener's eccentricity, number, size, and position on transient response of the shells is examined. The results are verified by comparison with FEM results.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.883-888
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• 2001

The theoretical method is developed to investigate the effects of ring stiffeners on free vibration characteristics and transient response for the ring stiffened composite cylindrical shells subjected to the impulse pressure loading. In the theoretical procedure, the Love's thin shell theory combined with the discrete stiffener theory to consider the ring stiffening effect is adopted to formulate the theoretical model. The concentric or eccentric ring stiffeners are laminated with composite and have the uniform rectangular cross section. The modal analysis technique is used to develop the analytical solutions of the transient problem. The analysis is based on an expansion of the loads, displacements in the double Fourier series that satisfy the boundary conditions. The effect of stiffener's eccentricity, number, size, and position on transient response of the shells is examined. The theoretical results are verified by comparison with FEM results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.10
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• pp.788-794
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• 2014

In this paper, the transient response analysis of the trapezoidal corrugated plate subjected to the pulse load is investigated by the theoretical method. Three types of pulse loads are considered: stepped, isosceles triangular and right triangular pulse loads. The corrugated plates can be represented as an orthotropic plate. Both the effective extensional and flexural stiffness of this equivalent orthotropic plate are considered in the analysis. The plate is stiffened by concentric stiffeners perpendicular to the corrugation direction. The stiffening effect is represented by the discrete stiffener theory. This theoretical results are validated by those obtained from 3D finite element analysis based on shell elements. Some numerical results are presented to check the effect of the geometric properties.