• Journal of Korean Association for Spatial Structures
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• v.1 no.2 s.2
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• pp.67-74
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• 2001

This paper is to estimate the load carrying capacities of concrete-filled steel tubular columns and the important parameters are selected the size, length and concrete strength. he concrete-filled tube structures has many excellent structural properties, that is, high load capacity, good plastic deformation and high resistance local buckling. Under these background, this study Investigated to the structural compression behaviors, the maximum strength, the confinement effects, the fracture mechanism, local buckling failure and concrete strength effects.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.129-136
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• 2005

Concentrically braced steel frames are considered as being quite prone to soft-story response due to the degradation in brace compressive resistance after buckling under severe ground motions. When combined with the system P-Delta effects, collapse of the concentrically braced frames by dynamic instability becomes a highly probable. In this study, a new, relatively simple dynamic instability coefficient was proposed for diagonally braced steel frames by considering the strength degradation of the brace after buckling. Nonlinear dynamic analysis was conducted to check the robustness of the proposed index based on simulated ground motions. The analysis results showed that the dynamic instability index proposed predicts the collapse potential more consistently than the conventional one. Dynamic instability was triggered when the index value was close to 0.7.

• Steel and Composite Structures
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• v.22 no.1
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• pp.79-89
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• 2016

Cold formed steel shear panel is one of the main components to bearing lateral load in low and mid-rise cold formed steel structures. This paper uses finite element analysis to evaluate the stiffness, strength and failure mode at cold formed steel shear panels whit steel sheathing and nonlinear connections that are under monotonic loading. Two finite element models based on two experimental model whit different failure modes is constructed and verified. It includes analytical studies that investigate the effects of studs and steel sheathing thickness changes, fasteners spacing at panel edges, one or two sides steel sheathing and height-width ratio of wall on the lateral load capacity. Dominant failure modes include buckling of steel sheet, local buckling in boundary studs and sheet unzipping in the bottom half of the wall.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.763-768
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• 2004

CWR(Continuous Welded Rail) has many advantage over the conventional jointed rail track. The use of CWR track not only reduces the track maintenance cost, but increase the life cycle of track components. As the use of CWR increases in track structures, derailing disasters associating with track buckling also increase in great numbers due to high compressive thermal stress. Despite the importance, the number of studies relevant to the instability is quite limited. In this paper, It considers the contribution of rail-pad-fastener resistance, uplift of tie and nonlinear analysis. Influence of various track components on CWR track temperature and mode shape were characterized.

• Steel and Composite Structures
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• v.28 no.1
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• pp.51-61
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• 2018

A new I-girder consisted of top concrete-filled tubular flange and corrugated web has been proved to have high resistance to both global buckling of the entire girder and local buckling of the web. This study carries out theoretical analysis and experimental tests for this new I-girder to investigate the stress distribution in the flanges and in the corrugated web. Based on some reasonable assumptions, theoretical equations for calculating the normal stress in the flanges and the shear stress in the corrugated web are presented. To verify the accuracy of the presented equations, experimental tests on two specimens were carried out, and the experimental results of stress distribution were used to assess the theoretical prediction. Comparison between the two results indicates that the presented theoretical equations have enough accuracy for calculating the stress in the new I-girder, and thus they can be used reliably in the design stage.

• Structural Engineering and Mechanics
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• v.80 no.5
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• pp.609-623
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• 2021

Buckling restrained bracing (BRB) was firstly introduced in Japan construction industry in year 1989. With time, BRB performance has been advanced to self-centering BRB (SC-BRB) which has exceptional energy dissipation, addressing the improvement in the structure performance in post-seismic affect. Although the BRB performance specifications are defined in design codes of several countries, specific design provisions are not generally provided since BRBs are usually considered a manufactured device. Furthermore, most of review papers focused on BRB rather than SC-BRB. Thus, this paper explores the background of both BRB and SC-BRB. The importance of self-centering components in BRB and literature related to it have been studied. This review study also highlights the significance of corrosion-resistance materials in the configuring BRB and SC-BRB since most of such members are made of carbon steel that is susceptible to corrosion.

• Advances in nano research
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• v.16 no.2
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• pp.201-215
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• 2024

The present research study emphasizes the utilization of mathematical simulation on a nanoelectromechanical systems (NEMS) sensor to facilitate the detection of injuries in players and equipment. Specifically, an investigation is conducted on the thermal buckling behavior of a small-scale truncated conical, cylindrical beam, which is fabricated using porous functionally graded (FG) material. The beam exhibits non-uniform characteristics in terms of porosity, thickness, and material distribution along both radial and axial directions. To assess the thermal buckling performance under various environmental heat conditions, classical and first-order nonlocal beam theories are employed. The governing equations for thermal stability are derived through the application of the energy technique and subsequently numerically solved using the extended differential quadratic technique (GDQM). The obtained results are comprehensively analyzed, taking into account the diverse range of effective parameters employed in this meticulous study.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.866-876
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• 2003

Experiments were performed for the real sized 12 reinforced concrete columns of 350${\times}$350${\times}$3350 mm with normal concrete in order to observe the fire-damaged behavior of these columns. Columns were heated according to the ISO heating curve. Main experimental parameters were: magnitude of axial load, heating time, cover thickness, and eccentricity. Effects of these parameters on the axial expansion and contraction, rotation, buckling, ISO fire resistance, and structural stability were experimentally quantified. It has been observed that the contraction rate of axial deformation was affected mostly by the duration of heating time and buckling of reinforcement or member by the magnitude of axial load, duration of heating time, cover thickness and eccentricity in order. Based on the experimental observations, ISO fire resistance criteria were qualiatively criticized.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.21-22
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• 2015

The CFT(Concrete Filled Tube) system has been developed to behave well in a structural performance such as stiffness, stress, ductility, fire resistance that is derived from its mechanical advantages of composite structure. There were number of studies about unprotected CFT columns for improving their fire resistance through reinforcing bars or plates being placed inside the steel tube. It was also known that reinforcing plates of flat type need stiffeners in a certain distance to avoid their buckling failure so it cost as much as their using consequentially. This paper is planned to test the work of beam elements attached inner side of CFT depending on its shape. More discussions on beam's design could be followed after some fire tests accordingly conducted within this project.

• Steel and Composite Structures
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• v.5 no.2_3
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• pp.181-192
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• 2005

The effective length method for flexural (column) buckling has been used for many decades but its use is somewhat limited in various contemporary design codes to moderately slender structures with elastic critical load factor (${\lambda}_{cr}$) less than 3 to 5. In pace with the use of higher grade steel in recent years, the influence of buckling in axial buckling resistance of a column becomes more important and the over-simplified assumption of effective length factor can lead to an unsafe, an uneconomical or a both unsafe and uneconomical solution when some members are over-designed while key elements are under-designed. Effective length should not normally be taken as the distance between nodes multiplied by an arbitrary factor like 0.85, 1.0, 2.0 etc. Further, the classification of non-sway and sway-sensitive frames makes the conventional design procedure tedious to use and, more importantly, limited to simple regular frames. This paper describes the practical use of second-order analysis with section capacity check allowing for $P-{\delta}$ and $P-{\Delta}$ effects together with member and system imperfections. Most commercial software considers only the $P-{\Delta}$ effect, but not member and frame imperfections nor $P-{\delta}$ effect, and engineers must be very careful in their uses. A verification problem is also given for validation of software for this type of powerful second-order analysis and design. It is a trend for popular and advanced national design codes in using the second-order analysis as a norm for analysis and design of steel structures while linear analysis may only be used in very simple structures.