• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2005.04a
• /
• pp.592-600
• /
• 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, md, reasonable buckling strength about stiffened perforated 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 Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.564-569
• /
• 2009

Due to the uneasy controllable qualities of the substructures such as pile and foundation, which are laid on underground, geotechnical engineers have applied conservative criteria to them. Therefore, the specification criterion of cast-in-situ concrete pile, which allows only one fourth of the compressive strength of structural capacity, has forced geotechnical designers to consider the most uneconomical design regardless of satisfying the grade of quality-control, required performance, construction cost and so on. Thus, in this study, we proposed the less conservative criteria on the strength of concrete pile, based on the experimental testing results of cast-in-situ concrete piles.

• Nuclear Engineering and Technology
• /
• v.52 no.7
• /
• pp.1571-1578
• /
• 2020

As a critical material in very/high-temperature gas-cooled reactors, graphite material directly affects the safety of the reactor core structures. Owing to the complex structures of graphite material in reactors, the material typically undergoes complex stress states. It is, therefore, necessary to study its mechanical properties, failure modes, and strength criteria under complex stress states so as to provide guidance for the core structure design. In this study, compressive failure tests were performed for graphite material under the condition of different confining pressures, and the effects of confining pressure on the triaxial compressive strength and Young's modulus of graphite material were studied. More specifically, graphite material based on the fracture surfaces and fracture angles, the graphite specimens were found to exhibit four types of failure modes, i.e., tension failure, shear-tension failure, tension-shear failure and shear failure, with increasing confining pressure. In addition, the Mohr strength envelope of the graphite material was obtained, and different strength criteria were compared. It showed that the parabolic Mohr-Coulomb criterion is more suitable for the strength evaluation for the graphite material.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1991.10a
• /
• pp.140-145
• /
• 1991

Tests were conducted to get a mix proportioning of high strength concrete between σ28 and (C/W) using low quality materials easily purchased in situ. Superplasticizer was used as a chemical admixture to compensate low slump of base concrete keeping it up about 15±2㎝. General material properties such as modulus of elasticity, poisson's ratio, unit weight and stress-strain characteristic of high strength concrete were obtained. Test results show that mix proportioning of high strength concrete proposed in this paper have reasonable validity and these can be used as a design criteria in high strength concrete construction.

• Journal of the Society of Naval Architects of Korea
• /
• v.32 no.1
• /
• pp.25-36
• /
• 1995

The application of the reliability analysis is investigated as a probabilistic approach to the assessment of ship's structural strength and to the establishment of design format for longitudinal strength. Reliability analyses are carried out for 34 ships of tankers and bulk carriers built in HHI for some failure modes such as tensile yielding, compressive buckling and ultimate strength of hull girder. The safety assessment of each ship, the calculation of sensitivity factors and the derivation of target reliability index are performed. As results. the difference of reliability indices among ships is great for all modes. To provide more uniform levels of safety the establishment of new strength criteria using partial safety factors is performed. The partial safety factors for the design format are obtained according to the AFOSM method and the reliability-conditioned(RC) method. Finally, a design format using partial safety factors has been proposed. We could find out that new strength criteria can produce consistent reliability indices which are close to the target value.

• Journal of the Korea Institute of Building Construction
• /
• v.12 no.4
• /
• pp.451-459
• /
• 2012

At the Korea Land and Housing Corporation(LH), concretes with high design strength of 50 MPa and 80 MPa that are composed only of ordinary Portland cement, blast furnace slag, and fly ash are developed. To determine whether the developed high strength concretes have the same properties when they are produced in batch plant(B/P) condition in the ready mixed concrete plant, and as existing high strength concretes, field tests are performed and material properties are evaluated. To investigate the material properties of the high strength concretes before and after pumping, compressive strength, flowability, air content, hydration temperature, pumping and compactability are evaluated. In field tests, before and after pumping, flowability satisfied the relevant criteria. In terms of air content, while it was slightly decreased after pumping, it satisfied the requirements. Hydration temperature criteria were satisfied, and compactability was excellent as well. The study found that the developed ternary high strength concretes have the same properties as existing high strength concretes. They can also be useful for the construction of high-rise buildings, as they are economical.

• Computers and Concrete
• /
• v.27 no.1
• /
• pp.63-71
• /
• 2021

In this study, a new stopping criterion, called "backward controlled stopping criterion" (BCSC), was proposed to be used in Genetic Algorithms. In the study, the available stopping citeria; adaptive stopping citerion, evolution time, fitness threshold, fitness convergence, population convergence, gene convergence, and developed stopping criterion were applied to the following four comparison problems; high strength concrete mix design, pre-stressed precast concrete beam, travelling salesman and reinforced concrete deep beam problems. When completed the analysis, the developed stopping criterion was found to be more accomplished than available criteria, and was able to research a much larger area in the space design supplying higher fitness values.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.05a
• /
• pp.69-74
• /
• 2001

Steel plate or fiber composite plate are mainly used in externally bonding method. Shear strengthening by externally bonding method is to confirm shear safety and to avoid brittle failure. In case of strengthening by externally bonding method, a failure of structure occurs frequently due to delamination between strengthening plate and concrete. Therefore, it is important to consider the delamination in the strengthening design. The objective of this study is to propose a modified shear strength evaluation by considering the delamination. The delamination criteria of strengthening plate is established by the ultimate strain and shear stress. And shear strength of RC beams is proposed in terms of the delamination criteria. The proposed shear strength is compared with test results and verified through the comparison.

• Proceedings of the KSR Conference
• /
• 2004.10a
• /
• pp.934-939
• /
• 2004

The Korea high-speed rail, based on the French design. It also implements new concept to increase the strength of bridge deck by adding an impact factor (dynamic intensity factor) in static load. In order to assure the dynamic stability, SYSTRA and Jeseph Penzien, a professor in CEC (the US) conducted a dynamic stability review on design phase. Analyzing the review results, they developed design criteria for dynamic behavior. This study deal with operating PSC box GIRDER equipped with measurement equipment or measured data of Seoul $\∼$ Taejeon, P.S.C BOX GIRDER bridge and steel comsition bridge equipped with measurement equipment based on structual knowledge about configuration of measuring sensor, response analysis of structure when train runs was performed by using measured data of PSC box girder to directly compare with design criteria. moreover, the dynamic stability with comparison of high-speed rail construction criteria was reviewed and analyzed based on historical records.

• Journal of Korean Society of Steel Construction
• /
• v.13 no.2
• /
• pp.123-131
• /
• 2001

The objective of this study is to investigate the criteria of the width-to-thickness ratio and to evaluate the buckling strength of high strength steel beam-columns and to compare their buckling strength with design codes, which are the Limit State Design code and the Allowable Stress Desogn code(drift). SM520TMC and SM570Q class steels are used for high strength steels. The coupon test and the stub column test were carried out to investigate the properties of high strength steels and the stress-strain curves of stub columns. The buckling strength of high strength steel beam-columns are assessed by numerical analysis used axial force, moment and curvature relationships.