• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.378-384
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• 1995

This paper descrides on the economical design of apartment house. * The optimal problems are made by considering the objective function which minimize the construction cost of frame. * The object functions are taken as the codfficient equations of the cost function for a unit area. * Constraints are the design limits defined by the ultimate flexural strength, the ultimate shear strength. the minimum thickness, and the ratio of steel in accordance with ACI 318-89 Code. * Optimization is achieved by optimum nonlinear GINO(General interactive Optimizer)program. In design examples, it is compared with the optimum design results of apartment house and underground parking lot for structural systems.

• Journal of Welding and Joining
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• v.9 no.2
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• pp.44-50
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• 1991

The use of high tensile steel plates is increasing in the fabrication of ship and offshore structures. The softening region which has lower yield stress than base metal is located to prevent cracking in the conventional high tensile steel. Also, thermo mechanical control process(TMCP) steel with low carbon equivalent has the softening region which occurs in the heat affected zone when high heat input weld is carried out. The softening region in the high tensile steel gives rise to serious effect on structural strength such as tensile strength, fatigue strength and ultimate strength. In order to make a reliable structural design using high tensile steel plates, the influence of the softening on plate strength should be evaluated in advance. In the previous paper, the authors discussed the ultimate compressive strength of 50HT steel square plates with softening region. In this paper, the ultimate compressive strength with varying the yield stress of softening region and the aspect ratio of the plate is investigated by using the elasto-plastic large deformation finite element method.

• Journal of Korean Society of Steel Construction
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• v.23 no.5
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• pp.523-533
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• 2011

The demand for the circular hollow section (CHS) has been increasing due to its structural advantage in long-span structures and high-rise buildings. There are not enough researches on the CHS structure, though. The behavior of the gusset plate CHS joint, to predict the ultimate strength, is not easy to predict because the load deflection curve does not show consistency. Therefore, in this study, experiments and finite element analysis (FEA) were carried out to determine the ultimate strength according to the proposed ultimate deformation limit. Finally, a reasonable ultimate strength formula was proposed through comparisons with other design guides.

• Proceedings of KOSOMES biannual meeting
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• 2004.05b
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• pp.113-119
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• 2004

A steel plated is typically composed of plate panels. The overall failure of the structure is certainly affected and can be governed by the bulking and plastic collapse of these individual members In the ultimate limit state design. therefore. a primary task is to accurately calculate the budding and plastic collapse strength of such structural members. Structural elements making up steel palated structures do not work separately. resulting in high degree of redundancy and complexity in contrast to those of steel framed structures. To enable the behavior of such structures to be analyzed, simplifications or idealizations must essentially be made considering the accuracy need and degree of complexity of the analysis to be used Generally the more complex the analysis the greater is the accuracy that may be obtained. The aim of this study is the investigation of the effect of the tripping behaviour including section characteristic for a plate under uniaxial compression.

• Journal of Korean Society of Steel Construction
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• v.23 no.6
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• pp.679-690
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• 2011

Since the elastic buckling problem of the plate has been studied both experimentally and theoretically, the buckling loads with various boundary conditions and loads can be easily determined. Currently, flange and web design specifications are based on the buckling stress and the post-buckling strength and include a safety-factor. Therefore, this study extended suchresearch to the linear buckling theory with ideal conditions and to the ultimate state with post-buckling. The current specifications are based on elastic buckling stress; and therefore, further research on the ultimate behavior of the plate is required. The ultimate strength design concept, which allows finite deflection, is used in this studyto maximize the post-buckling strength in a steel box. An empirical equation, which provides the ultimate strength of the steel box due to the change in the slenderness and optimum rigidity, are suggested based on the experiment results. Moreover, the appropriateness of the current design specifications was analyzed and discussed.

• Computers and Concrete
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• v.25 no.1
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• pp.75-81
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• 2020

The purpose of this paper is to provide an experimental and analytical study on the reinforced large diameter pretensioned high strength concrete (R-LDPHC) pile. R-LDPHC pile was reinforced with infilled concrete, longitudinal, and transverse rebar to increase the flexural and shear strength of conventional large diameter PHC (LDPHC) pile without changing dimension of the pile. To evaluate the shear and flexural strength enhancement effects of R-LDPHC piles compared with conventional LDPHC pile, a two-point loading tests were conducted under simple supported conditions. Nonlinear analysis on the basis of the conventional layered sectional approach was also performed to evaluate effects of infilled concrete and longitudinal rebar on the flexural strength of conventional LDPHC pile. Moreover, ultimate strength design method was adopted to estimate the effect of transverse rebar and infilled concrete on the shear strength of a pile. The analytical results were compared with the results of the bending and shear test. Test results showed that the flexural strength and shear strength of R-LDPHC pile were increased by 2.3 times and 3.3 times compared to those of the conventional LDPHC pile, respectively. From the analytical study, it was found that the flexural strength and shear strength of R-LDPHC pile can be predicted by the analytical method by considering rebar and infilled concrete effects, and the average difference of flexural strength between experimental results and calculated result was 10.5% at the ultimate state.

• Special Issue of the Society of Naval Architects of Korea
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• 2011.09a
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• pp.82-89
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• 2011

In general, a number of lifting lugs have been used in shipbuilding industry and the D-type lugs are mainly used. The aim of this paper is to increase the cycle of the use and to reduce the size of lifting lugs to introduce lightweight shackle. In this study, nonlinear elasto-plastic analysis has been performed to confirm the ultimate strength of lifting lugs. In order to evaluate the proper design-load distribution around lug eye, the contact force between lifting lug and shackle pin has been realized by gab element model. Gap element modeling and nonlinear analysis are carried out using the finite element program MSC/PATRAN & ABQUS. Additionally the ultimate strength tests were performed to verify the structural adequacy of newly designed lifting lug and to insure safety of it. The D-10, 15, 20 & 40 ton models which are mainly used in the block erection are selected in the strength test. According to the results of the analysis and strength test, the ultimate strength of the newly designed lifting lugs has been estimated to exceed 3 times of design working load.

• Journal of the Korean Society of Safety
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• v.21 no.2 s.74
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• pp.57-62
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• 2006

Recent trends in the construction of building frame feature the use of composite steel concrete members. One of such system, RCS(Reinforced Concrete column and Steel beam) system, is known as a type of system to maximize the structural and economic benefits in the most efficient manner. This paper is focusing on an study of ultimate shear strength estimation of the interior beam-column joints of RCS system, with reinforced concrete column and steel beam. Current design methods as well as the majority of the previous researches for ultimate shear strength of the interior beam-column joint of RCS system are not easy to apply actual manner. There is a need to propose the rational macro models based on analytical approach. In this study, design method variables for interior beam-column joints of RCS system is studied assuming shear resistance of steel web panel, diagonal concrete strut mechanism and truss mechanism. Finally, calculated results based on the proposed design model are compared with test data.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.43-50
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• 1998

The current design equations for ultimate strength of tubular joints are based on a limited number of experimental results performed on simple joints with simple loading conditions and depend on value of the branch to the chord diameter- ratio $\beta$ too much. Therefore, the purpose of this study is to estimate the ultimate strength of CHS tilbular joints considering the effects of branch inclination angles $\theta$, chord length to diametel ratio $\alpha$ and chord end conditions by finite element analysis. The analyses are performed using finite element software ADINA that is capable of modeling elasto-plastic material behavior as well as geometric nonlinearities. The results show that the current use of sin $\theta$ in normalized design equations for inclined branches is reasonable, but somewhat conservative. When compared with the previous experimental database, the close numerical results are obtained from the parametric studies on the static strength of T-, Y-, DT- and X-joints. Also, a new design equation for ultimate stregth of CHS tubular joints is derived using a modified version of the ring model which can include the effects of $\alpha$ and chord end condtion.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.479-482
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• 2005

The concrete box girder members are extensively used as a superstructure in bridge construction. The load carrying capacity of concrete box girders in lateral direction is generally influenced by the sizes of haunch and web. The internal upper decks are restrained by the webs and exhibit strength enhancement due to the development of aching action. The current codes do not have generally consider the arching action of deck slab in the design because of complexity of the behavior. However, there are significant benefits in utilizing the effects of arching action in the design of concrete members. The main objective of this paper is to propose a rational method to predict the ultimate load of deck slab by considering various haunch sizes and web restraint effect of concrete box girder bridges. To this end, a comprehensive experimental program has been set up and seven large-scale concrete box girders have been tested. A transverse analysis model of concrete box girders with haunches is proposed and compared with test data. The results of present study indicate that the ultimate strength is significantly affected by haunch dimension. The increase of strength due to concrete arcing action is reduced with an increase of prestressing steel ratio in laterally prestressed concrete box girders and increases with a larger haunch dimension. The proposed theory allows more realistic prediction of lateral ultimate strength for rational design of actual concrete box girder bridges.