• Structural Engineering and Mechanics
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• 제81권6호
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• pp.751-767
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• 2022

In the hogging bending moment area, continuous composite beams are subjected to the ultimate limit state of lateral-torsional buckling (LTB), which depends on web stiffness as well as concrete slab and shear connection stiffnesses. The design of the LTB and the determination of the elastic critical moment are produced approximately, using the European Standard EN 1994-1-1:2004, for continuous composite steel beams, but is applicable only for those with a plane web steel profile. Also, and from the previous researches, the elastic critical moment of the continuous composite beams with corrugated sinusoidal web steel profiles was determined. In this paper, a finite element analysis (FEA) model was developed using the ANSYS 16 software, to determine the elastic critical moments of continuous composite steel beams with various corrugated web profiles, such as trapezoidal, zigzag, and rectangular profiles, which were evaluated against numerical data of the sinusoidal one from the literature. Ultimately, the failure load of a composite steel beam with various web profiles was predicted by studying 46 models, based on FEA modeling, and a procedure for predicting the elastic critical moment of composite beams with various web steel profiles was proposed. When compared to sinusoidal web profiles, the trapezoidal, zigzag, and rectangular web profiles required an average increase in load capacity and stiffness of 7%, 17.5%, and 28%, respectively, according to the finite element analysis. Also, the rectangular web steel profile has a greater stiffness and load capacity. In contrast, the sinusoidal web has lower values for these characteristics.

• Steel and Composite Structures
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• 제45권5호
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• pp.653-663
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• 2022

This study reports the results of a series of tests of pultruded glass fiber reinforced polymer (P-GFRP) box section composite profile columns, geometrically similar with/without concrete core, containing 0-1-2-3% steel fiber, with different lengths. The recycled steel wires were obtained from waste tyres. The effects of steel fiber ratio on the collapse and size effect of concrete filled P-GFRP columns under axial pressure were investigated experimentally and analytically. A total of 36 columns were tested under compression. The presence of pultruded profile and steel wire ratio were selected as the primary variable. The capacity of pultruded profiles with infilled concrete are averagely 9.3 times higher than the capacity of concrete without pultruded profile. The capacity of pultruded profiles with infilled concrete are averagely 34% higher than that of the pultruded profiles without infilled concrete. The effects of steel wire ratio are more pronounced in slender columns which exhibit buckling behavior. Moreover, the proposed analytical approach to calculate the capacity of P-GFRP columns successfully predicted the experimental findings in terms of both pure axial and buckling capacity.

• 열처리공학회지
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• 제15권6호
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• pp.269-271
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• 2002

For the investigation of the hardness profiles and distortion characteristics of SCM415 steel, test pieces of SCM415 steel were gas and vacuum carburizing treated. The hardness profiles and distortion characteristics of vacuum and gas carburized SCM415 steel show different results. Vacuum carburizing can offer more improved hardness profiles than alternate methods of carburizing. Compared to alternate methods of carburizing, vacuum carburizing can offer improved mechanical properties and reduced cycle times of the process.

• Steel and Composite Structures
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• 제30권3호
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• pp.231-251
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• 2019

In the present study, a numerical and experimental investigation has been carried out on the seismic behavior of RC columns of a bridge which damaged under corrosive environments and retrofitted by various techniques including combined application of CFRP sheets and steel profiles. A novel hybrid retrofitting procedure, including the application of inner steel profiles and outer peripheral CFRP sheets, has been proposed for strengthening purpose. Seven large-scale RC columns of a Girder Bridge have been tested in the laboratory under the influence of simultaneous application of constant axial load and the lateral cyclic displacements. Having verified the finite element modeling, using ABAQUS software, the effects of important parameters such as the corrosion percentage of steel rebars and the number of CFRP layers have been evaluated. Based on the results, retrofitting of RC columns of the bridge with the proposed technique was effective in improving some measures of structural performance such as lateral strength degradation and higher energy absorption capability. However, the displacement ductility was not considerably improved whereas the elastic stiffness of the specimens has been increased.

• Steel and Composite Structures
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• 제19권6호
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• pp.1599-1610
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• 2015

Cold Formed Steel members are widely used in today's construction industry. However the structural behavior of light gauge high strength cold formed steel sections characterized by various buckling modes are not yet fully understood. Because of their simple forming and easy connections, the commonly used cold formed sections for beams are C and Z. However both these sections suffer from certain buckling modes. To achieve much improved structural performance of cold formed sections for beams both in terms of strength and stiffness, it is important to either delay or completely eliminate their various modes of buckling. This paper presents various innovative sectional profiles and stiffening arrangements for cold formed steel beams which would successfully contribute in delaying or eliminating various modes of premature buckling, thus considerably improving the load carrying capacity as well as stiffness characteristics of such innovative cold formed sections compared to conventional cold formed steel sections commonly used for beams.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1412-1416
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• 2003

Induction Heaters are commonly used in heating steel strip product, because it can rapidly and efficiently heat steel strip/bar. In this study, a inductive heating model is developed and the predictions are compared with measured temperatures. The temperatures are measured from POSCO thin-slab rolling facility (so called Minimill). Induction heater is installed between reduction unit and holding furnace This induction heater raise the temperature of steel bars from $930^{\circ}C$ to about $1100^{\circ}C$ which gives the required temperature for finishing mill process after holding period at holding furnace. Unlike other simple equation models, this model allows us to predict temperature profiles of sections of steel bars.

• Steel and Composite Structures
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• 제6권6호
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• pp.531-555
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• 2006

H-shaped welded steel column members are fabricated by welding together pre-cut flanges and the web. Modern fabricators are increasingly using plasma-cutting technique instead of traditional flame cutting. Different fabrication techniques result in different degrees of geometric imperfections and residual stresses, which can have considerable influence on the strength of steel columns. This paper presents the experimental investigation based temperature profiles, geometric imperfections, and built-in residual stresses in plasma cut-welded H-shaped steel column members and in similar flame cut-welded H-shaped steel columns. Temperature measurements were taken during and immediately after the cutting operations and the welding operations. The geometric imperfections were established at closely spaced grid locations on the original plates, after cutting plates into plate strips, and after welding plate strips into columns. Geometric imperfections associated with plasma cut element and members were found to be less than those of the corresponding elements and members made by flame cutting. The "Method of Section" technique was used to establish the residual stresses in the plate, plate strip, and in the welded columns. Higher residual stress values were observed in flame cut-welded columns. Models for idealized residual stress distributions for plasma cut and flame cut welded sections have been proposed.

• Steel and Composite Structures
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• 제33권5호
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• pp.755-765
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• 2019

This study examined geometric and physical nonlinear analyses of beams and arches specifically from rolled profiles used in mining and underground constructions. These profiles possess the ability to create plastic hinges owing to their robustness. It was assumed that displacements in beams and arches fabricated from these profiles were comparable with the size of the structure. It also considered changes in the shape of a rod cross-section and the nonlinearities of the structure. The analyses were based on virtual unit moments, effective flexural rigidity of used open sections, and a secant method. The use of the approach led to a solution for the "after-critical" condition in which deformation increased with decreases in loads. The solution was derived for static determinate beams and static indeterminate arches. The results were compared with results obtained in other experimental tests and methods.

• 한국주조공학회지
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• 제10권6호
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• pp.520-527
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• 1990

In order to reduce segregation in 12%Cr steel ingots of 60-100tons, numerical analysis by computer was applied to simulate solidification profiles and the profiles of liguid-solid coexisting zone in accordance with the ratios of H(Height) /D(diameter) of 100-ton ingot. The result is that the ratio of L(vertical length) /D(diameter) of liquid-solid coexisting zone was reduced in proportion to the decrease of H/D ratio. With the reduced H/D ratio(0.92) of ingot, the segregation in 60-ton ingot of 12% Cr steel can be much reduced and recovery was also improved by reducing ingot weight.

• 한국전산구조공학회논문집
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• 제15권3호
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• pp.453-462
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• 2002

건설공사의 설계와 시공에서 표준화된 이산형 강재단면을 이용하고 있으나, 대부분의 최적화기법에서는 표준강재단면을 사용하기 위해 별도의 이산화 과정을 가지게 되므로 설계결과의 최적성을 보장할 수 없다. 따라서, 본 논문에서는 제안된 알고리즘의 효율성을 높이기 위해 전체구조계와 구조요소계로 나누는 다단계 알고리즘을 적용하였다 수치해석 과정의 효율성과 최적해의 정확성을 예제를 통하여 비교·검토하였다.