• Steel and Composite Structures
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• 제36권2호
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• pp.197-211
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• 2020

Application of the steel ring as a type of seismic fuse has been one of the efforts made by researchers in recent years aiming to enhance the ductility of the bracing systems which in turn, possesses various advantages and disadvantages. Accordingly, to alleviate these disadvantages, an innovative bracing system with a diamond scheme equipped with a steel ring is introduced in this paper. In this system, the braces and yielding circular damper act in parallel whose main functionality is to increase ductility, energy absorption and mitigate drawbacks of the existing bracing systems, in which the braces and yielding circular damper act in parallel. To conduct the experimental tests, specimens with three types of rigid, semi-rigid and pinned connections were built and subjected to cyclic loading so that their performance could be analyzed. Promisingly, the results indicate both great applicability and efficiency of the proposed system in energy absorption and ductility. Moreover, it was concluded that as the braces and damper are in parallel, the use of a steel ring with smaller size and thickness would result in higher energy absorption and load-resisting capacity when compared to the other existing systems. Finally, to assess the potential of numerically modeling the proposed system, its finite element model was simulated by ABAQUS software and observed that there is a great agreement between the numerical and experimental results.

• Steel and Composite Structures
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• 제20권6호
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• pp.1205-1219
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• 2016

This paper presents a new type of pre-pressed spring self-centering energy dissipation (PS-SCED) bracing system that combines friction mechanisms between the inner and outer tube members to provide the energy dissipation with the pre-pressed combination disc springs installed on both ends of the brace to provide the self-centering capability. The mechanics and the equations governing the design and hysteretic responses of the bracing system are outlined, and a series of validation tests of components comprising the self-centering mechanism of combination disc springs, the friction energy dissipation mechanism, and a large scale PS-SCED bracing specimen were conducted due to the low cyclic reversed loadings. Experimental results demonstrate that the proposed bracing system performs as predicted by the equations governing its mechanical behaviors, which exhibits a stable and repeatable flag-shaped hysteretic response with excellent self-centering capability and appreciable energy dissipation, and large ultimate bearing and deformation capacities. Results also show that almost no residual deformation occurs when the friction force is less than the initial pre-pressed force of disc springs.

• 한국공간구조학회논문집
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• 제22권4호
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• pp.39-48
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• 2022

The energy dissipation of inverted V-type eccentric steel braced frames can be achieved through the yielding of a slit link, through yielding of a number of strips between slits when the frame is subjected to inelastic cyclic deformation. On the other hand, the development of seismic resistance system without residual deformation is obtained by applying the superelasdtic shape memory alloy (SMA) material into the brace and link elements. This paper presents results from a systematic three-dimensional nonlinear finite element analysis on the structural behavior of the eccentric bracing systems subjected to cyclic loadings. A wide scope of structural behaviors explains the horizontal stiffness, hysteretic behaviors, and failure modes of the recentering eccentric bracing system. The accurate results presented here serve as benchmark data for comparison with results obtained using modern experimental testing and alternative theoretical approaches.

• 한국지진공학회논문집
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• 제18권3호
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• pp.133-140
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• 2014

The friction damper can be used for improving the seismic resistance of existing buildings. The damper is often installed in bracing members. The energy dissipation capacity of the damping systems depends on the type of the structure, the configuration of the bracing members, and the property of dampers. In Korea, there are numerous low- to mid-rise reinforced concrete moment frames that were constructed considering only gravity loads. Those frames may be vulnerable for future earthquakes. To resolve the problem, this study developed a toggle bracing system with a high density friction damper. To investigate the improvement of reinforced concrete frames after retrofit using the developed damped system, experimental tests were conducted on frame specimens with and without the damped system. The results showed that the maximum strength, initial stiffness and energy dissipation capacity of the framed with the damped system were much larger than those of the frame without the damped system.

• 대한물리의학회지
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• 제11권2호
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• pp.33-40
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• 2016

PURPOSE: The purpose of this study was to determine the impact of stable and unstable surfaces on abdominal muscle thickness and changes in trunk muscle thickness in accordance with breathing methods during bridging exercises. METHODS: Bridging exercise on a stable surface, bridging exercise on an unstable surface, bridging exercise using a drawing-in maneuver on a stable surface, bridging exercise using a drawing-in maneuver on an unstable surface, bridging exercise using bracing on a stable surface, bridging exercise using bracing on an unstable surface. In sequence, the muscles' thickness was measured three times before and after each exercise, and the measured value was averaged. RESULTS: There were significant differences in internal oblique and transversus abdominis muscles' thickness in the drawing-in maneuver in both stable and unstable surface (p<0.05). There were no significant differences in external oblique muscle's thickness in the bridging exercise in both stable and unstable surface. The type of surface did not have a significant influence on the abdominal muscles' thickness. CONCLUSION: As a result of the study, the drawing-in maneuver had a greater effect than bridging or bracing maneuver on muscle thickness. We suggest that drawing-in maneuver will be more effective in a person with a weak abdominal muscle.

• Steel and Composite Structures
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• 제22권4호
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• pp.915-935
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• 2016

Steel systems composed of Reinforced Concrete column to Steel beam connection (RCS) have been raised as a structural system in the past few years. The optimized combination of steel-concrete structural elements has the advantages of both systems. Through beam and through column connections are two main categories in RCS systems. This study includes finite-element analyses of mentioned connection to investigate the seismic performance of RCS connections. The finite element model using ABAQUS software has been verified with experimental results of a through beam type connection tested in Taiwan in 2005. According to verified finite element model a parametric study has been carried out on five RCS frames with different types of lateral restraint system. The main objective of this study is to investigate the forming of plastic hinges, distribution of stresses, ductility and stiffness of these models. The results of current research showed good performance of composite systems including concrete column-steel beam in combination with steel shear wall and bracing system, are very desirable. The results show that the linear stiffness of models with X bracing and steel shear wall increase remarkably and their ultimate strength increase about three times rather than other RCS frames.

• 대한조선학회논문집
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• 제48권4호
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• pp.289-298
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• 2011

This paper provides procedures to effectively determine arrangement of hydraulic type top-bracings, which are popular for the main engine of the mid and large sized commercial vessels. Analyzing the operation mechanism of hydraulic top-bracing, ideal unified nonlinear stiffness curve is presented for linear frequency response analysis and nonlinear transient response analysis. Nonlinear stiffnesses of the curve are determined based on the regression analysis of test results. It is noted from linear frequency response analysis, initial setting pressure is most important among the setting values of the other stiffness intervals. From transient response analyses for two top-bracing arrangement scenarios, it is recognized that, as far as initial setting pressure is well controlled for the concerning vessels, only two top-bracings are enough to suppress H-mode excitation forces from main engine.

• 한국공간구조학회논문집
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• 제16권2호
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• pp.89-96
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• 2016

Cable structures are lightweight structures of flexible type, cable members have only axial stiffness related to tension, they can carry neither bending nor compression. This study is the analysis of cable truss systems are composed of upper and low cables by connecting bracing cables, the structural principle is based on a tensegrity system by using bracing tension members, discontinuous compression members and continuous tension members. A hanging roof of cable truss system is too flexible against vertical loads, most cable members are stabilized by connecting the prestressed upper and lower cable by bracing cables. A cable truss roof system is formed by adding a set of cables with reverse curvature to the suspension cables. With the sets of cables having opposite curvature to each other, cable truss is able to carry vertical load in both upward and downward direction with equal effectiveness, and then a cable truss acts as load bearing elements by the assemble of ridge cables, valley cables and bracing cables. This paper will be shown the geometric non-linear analysis result of cable truss systems with various sag ratio for deflections and tensile forces, the analytical results are compared with the results of other researchers.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.561-567
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• 2007

This paper deals with the numerical model of a bracing-friction damper system and its deployment using the optimal slip load distribution for the seismic retrofitting of a damaged building. The Slotted Bolted Connection (SBC) type friction damper system was tested to investigate its energy dissipation characteristic. Test results coincided with the numerical ones using the conventional model of a bracing-friction damper system. The placement of this device was numerically explored to apply it to the assumed damaged-building and to evaluate its efficiency. It was found by distributing the slip load that minimizes the given performance indicies based on structural response. Numerical results for the damaged building retrofitted with this slip load distribution showed that the seismic design of the bracing-friction damper system under consideration is effective for the structural response reduction.

• Steel and Composite Structures
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• 제15권5호
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• pp.539-566
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• 2013

This paper summarises the results of a numerical study on the non linear response of steel concentric braced frames under monotonic and cyclic loads, using force-based finite elements with section fibre discretisation. The first part of the study is addressed to analyse the single brace response. A parametric analysis was carried out and discussed to evaluate the accuracy of the model, examining the influence of the initial camber, the material modelling, the type of force-based element, the number of integration points and the number of fibers. The second part of the paper is concerned with the modelling issues of whole braced structures. The effectiveness of the modelling approach is verified against the nonlinear static and dynamic behaviour of different type of bracing configurations. The model sensitivity to brace-to-brace interaction and the capability of the model to mimic the response of complex bracing systems is analyzed. The influence of different approaches for modelling the inertia, the equivalent viscous damping and the brace hysteretic response on the overall structural response are also investigated. Finally, on the basis of the performed numerical study general modelling recommendations are proposed.