• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.3
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• pp.129-139
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• 2024

In this study, the SBC system, a new mechanical joint method, was developed to improve the constructability of precast concrete (PC) beam-column connections. The reliability of the finite element analysis model was verified through the comparison of experimental results and FEM analysis results. Recently, the intermediate moment frame, a seismic force resistance system, has served as a ramen structure that resists seismic force through beams and columns and has few load-bearing walls, so it is increasingly being applied to PC warehouses and PC factories with high loads and long spans. However, looking at the existing PC beam-column anchorage details, the wire, strand, and lower main bar are overlapped with the anchorage rebar at the end, so they do not satisfy the joint and anchorage requirements for reinforcing bars (KDS 41 17 00 9.3). Therefore, a mechanical joint method (SBC) was developed to meet the relevant standards and improve constructability. Tensile and bending experiments were conducted to examine structural performance, and a finite element analysis model was created. The load-displacement curve and failure pattern confirmed that both the experimental and analysis results were similar, and it was verified that a reliable finite element analysis model was built. In addition, bending tests showed that the larger the thickness of the bolt joint surface of the SBC, the better its structural performance. It was also determined that the system could improve energy dissipation ability and ductility through buckling and yielding occurring in the SBC.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1635-1642
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• 2012

The identification of the dynamic properties of structural joints is important for predicting the dynamic behavior of assembled systems. However, the identification of the properties using analytical or experimental approaches is extremely difficult or even impossible. Several studies have proposed hybrid or synthesis methods that simultaneously used analytical and experimental approaches to identify the dynamic properties of a joint. However, among the many types of joints, only the bolt joint was treated as a practical example in these studies. In this study, for a simple assembly system comprising two plates and one hinge joint, a simple methodology involving the use of the static-based subpart analysis method to identify the dynamic properties is proposed. Finally, the proposed method is applied to a glove box in a passenger vehicle that includes hinge joints.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.4
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• pp.10-21
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• 2014

The joint of prefabricated steel grid composite deck is composed of concrete shear key and high-tension bolts. The flexural and shear strength of the joint were experimentally evaluated only by the bending and push-out test of the joint element. In this study the lateral load transfer behavior of the joint in deck structure system is experimentally evaluated. Several decks connected by the joint are prefabricated and loaded centrically and eccentrically. In the case of centrically loaded specimens, the analysis results show that for the same loading step the rotation angle of the joint with 4 high-tension bolts is larger than the case of the joint with 9 high-tension bolts. Consequently, flexural stiffness of deck and lateral load transfer decrease in the case of specimen with 4 high-tension bolts. But, in the case of eccentrically loaded specimens, it is found that there are no significant differences in the load transfer behavior. The further analysis results about the structural behavior of the joint show that lateral load transfer can be restricted by the load bearing capacity of the joint as well as punching shear strength of the slab. Furthermore, considering that high-tension bolts in the joint didn't reach to the yielding condition until the punching shear failure, increase in the number of high-tension bolts from 4 to 9 has a greater effect on the flexural stiffness of the joint and deck system than the strength of them.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.7
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• pp.875-881
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• 2013

The failure of a bolted joint owing to stress corrosion cracking (SCC) has been considered one of the most important structural integrity issues in a nuclear power plant. In this study, the failure possibility of bolting, which is used to support the steam generator of a pressurized water reactor, owing to SCC and brittle fracture was evaluated in accordance with guidelines proposed by the Electric Power Research Institute, which are called the Reference Flaw Factor method. For this evaluation, first, detailed finite element stress analyses were conducted to obtain the actual nominal stresses of bolting in which either service loads or bolt preloads were considered. Based on these nominal stresses, the structural integrity of bolting was addressed from the viewpoints of SCC and toughness. In addition, the accuracy of the EPRI Reference Flaw Factor for assessing bolting failure was investigated using finite element fracture mechanics analyses.

• Structural Engineering and Mechanics
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• v.74 no.3
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• pp.395-406
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• 2020

Many prefabricated concrete frame joints have been proposed, and most of them showed good seismic performance. However, there are still some limitations in the proposed fabricated joints. For example, for prefabricated prestressed concrete joints, prefabricated beams and prefabricated columns are assembled as a whole by the pre-stressed steel bar and steel strand in the beams, which brings some troubles to the construction, and the reinforcement in the core area of the joints is complex, and the mechanical mechanism is not clear. Based on the current research results, a new type of fabricated joint of prestressed concrete beams and confined concrete columns is proposed. To study the seismic performance of the joint, the quasi-static test is carried out. The test results show that the nodes exhibit good ductility and energy dissipation. According to the experimental fitting method and the "fixed point pointing" law, the resilience model of this kind of nodes is established, and compared with the experimental results, the two agree well, which can provides a certain reference for elasto-plastic seismic response analysis of this type of structure. Besides, based on the analysis of the factors affecting the shear capacity of the node core area, the formula of shear capacity of the core area of the node is proposed, and the theoretical values of the formula are consistent with the experimental value.

• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.325-333
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• 2010

In this study, new moment-resisting precast concrete beam-column joint made up of hybrid steel concrete was developed and tested. This beam-column joint is proposed for use in moderate seismic regions. It has square hollow tubular section in concrete column and connecting plate in precast U-beam. The steel elements in column and beam members were connected using bolt. Furthermore, in order to prevent the premature failure of concrete in hybrid steel-concrete connection, ECC(engineered cementitious composite) was used. An experimental study was carried out investigating the joint behavior subjected to reversed cyclic loading and constant axial compressive load. Two precast beam-column joint specimens and monolithic reinforced concrete joint specimen were tested. The variables for interior joints were cast-in-situ concrete area and transverse reinforcement within the joint. Tests were carried out under displacement controlled reverse cyclic load with a constant axial load. Joint performance is evaluated on the basis of connection strength, stiffness, energy dissipation, and displacement capacity. The test results showed that significant differences in structural behavior between the two types of connection because of different bonding characteristics between steel and concrete; steel and ECC. The proposed joint detail can induce to move the plastic hinge out of the ECC and steel plate. And proposed precast connection showed better performance than the monolithic connection by providing sufficient moment-resisting behavior suitable for applications in moderate seismic regions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.2
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• pp.108-114
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• 2002

In this paper, nonlinear finite element analysis is performed to ensure structural safety and to suggest the design improvement of wing-to-fuselage joint of the KSR-III rocket. In the joint, wings are attached to fuselage by fitting wing attachment part into the groove on the fuselage frame, and load transfer between wing and fuselage frame is accomplished mainly throug the contact of two members as well as fastening bolts. The careful finite element modeling has been proposed for the purpose of analyzing problems with relatively complicated load path. The detailed bolt modeling is conducted and GAP elemets are used to simulate contact problem between joined members and bolts. The suggested design improvement is verified by structural testing and the analysis results are compared with test results.

• Tribology and Lubricants
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• v.25 no.4
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• pp.256-260
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• 2009

Fretting is a kind of wear which effects on reliability and durability. When machine parts are joined joint in parts such as a bolt or a rivet or a pin, fretting phenomenon is occurred by micro relative movement. When fretting occurs in joint parts, there is wear which is the cause of fatigue crack. Recently, although the ways of assessment of fatigue and damage tolerance are established, there is no way to evaluate fatigue crack initiation life by fretting phenomenon. Consequently, the prediction of life and prevention plan caused by fretting are needed to improve reliability. The objective of this paper is to predict fretting wear by using a experimental method and contact analysis considering wear process. For prediction of fretting wear volume, systematic and controlled experiments with a disc-plate contact under gross slip fretting conditions were carried out. A modified Archard equation is used to calculate wear depths from the contact pressure and stroke using wear coefficients obtained from the disc-plate fretting tests.

• Geomechanics and Engineering
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• v.21 no.6
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• pp.551-564
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• 2020

High-stress and complex geological conditions impose great challenges to maintain excavation stability during deep underground mining. In this research, large anisotropic deformation and its management by support system at a deep underground mine in Western Australia were simulated through three-dimensional finite-difference model. The ubiquitous-joint model was used and calibrated in FLAC3D to reproduce the deformation and failure characteristics of the excavation based on the field monitoring results. After modeling verification, the roles of mining depth also the intercept angle between excavation axis and foliation orientation on the deformation and damage were studied. Based on the results, quantitative relationships between key factors and damage classifications were presented, which can be used as an engineering tool. Subsequently, the performance of support system installation sequences was simulated and compared at four different scenarios. The results show that, first surface support and then reinforcement installation can obtain a better controlling effect. Finally, the influence of bolt spacing and ring spacing were also discussed. The outcomes obtained in this research may play a meaningful reference for facing the challenges in thin-bedded or foliated ground conditions.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.10
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• pp.118-125
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• 1999

In the grinding process, generally, the exciting forces with high frequency can be generated due to the wheel wear and the grinding process. As the grinding speed increases, the precise investigation about the wheel dynamic characteristics is required. Conventionally the wheel-spindle has been considered with lumped model in dynamic modeling. With this lumped model, the significant mode resulted from the shell mode of wheel can be readily ignored. This paper suggests the new analysis model which includes the shell mode of wheel in modeling the wheel-spindle assembly. Furthermore, based on the suggested model, the effects of the bolt tightening force and the taper tightening force on the dynamic properties are investigated by the finite element modal analysis and the experimental method. As a result of investigation, the shell mode vibration of wheel affects the dynamic characteristics of the spindle assembly. Also, the vibration modes of the spindle assembly are significantly affected by the joint tightening forces.