• Journal of the Korean Society of Safety
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• v.32 no.3
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• pp.60-65
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• 2017

This study examined the effect of rotational stiffness of joints between vertical and horizontal members in system supports. In order to prevent repeated disasters of system supports, it is important to examine the accurate behavior of system supports. Among various factors affecting the complex behavior of system supports, this study focused on the stiffness of joints between vertical and horizontal members. The considered joint was modelled by a rotational spring, but the translational displacements were fixed. The stiffness of rotational spring was calculated by utilizing the usable experimental data. In addition, the hinge connection condition, which is generally considered in design and only restrict the translational displacements, was modelled to compare the results. The case with the rotational stiffness in joints showed 3.5 times buckling loads compared to the case without the rotational stiffness. Thus, the structural behavior of the vertical member in system supports was similar to the vertical member with the fixed condition. For the combined stresses of vertical members, the combined stress ratios were reduced 5~6% by considering the rotational stiffness of connecting parts. However, for the horizontal member where showed relatively small stress range, the stresses were increased 2.3~7.6 times by considering the rotational stiffness in connecting parts.

• Structural Engineering and Mechanics
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• v.89 no.1
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• pp.77-91
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• 2024

During strong seismic events, inelastic shear deformation occurs in beam-column joints. To capture inelastic shear deformation, an analytical model for beam-column joint in reinforced concrete (RC) frame structures has been proposed in this study. The proposed model has been developed using a rotational spring and rigid links. The stiffness properties of the rotational spring element have been assigned in terms of a moment rotation curve developed from the shear stress-strain backbone curve. The inelastic rotation behavior of joint has been categorized in three stages viz. cracking, yielding and ultimate. The joint shear stress and strain values at these stages have been estimated using analytical models and experimental database respectively. The stiffness properties of joint rotational spring have been modified by incorporating a geometry factor based on dimensions of adjoining beam and column members. The hysteretic response of the joint rotational spring has been defined by a pivot hysteresis model. The response of the proposed analytical model has been verified initially at the component level and later at the structural level with the two actually tested RC frame structures. The proposed joint model effectively emulates the inelastic behavior precisely with the experimental results at component as well as at structural levels.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.5
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• pp.1-9
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• 1995

The purpose of this study is to develop a computer simulation program for analyzing load transmission characteristics of a helical gear system in design stage. In this analysis, the rotational delay, load distribution, root stress, and contact area are investigated. That is, the influence function of deflection is obtained by finite element analysis and the influence function of approach and gear tooth error are considered. Load distribution, rotational delay, and contact area are calculated by solving load-deflection equation which includes these influence functions and tooth error, and the influence function of the bending moment is obtained by finite element analysis. The root stress is calculated by the load distribution and the influence function of the bending moment. The results of the simulation are cross-checked through a specially designed experimental set-up.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.700-705
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• 2005

This study presents a fatigue line with a plastic rotational angle to a great extent of plastic strain of Low-Cycle-fatigue period, such as earthquake, etc. This fatigue line with a plastic rotational angle is measured and analysed more simply in practice rather than Woehler's fatigue line which is developed in stress variation of the structure. It shows that the slope of fatigue line with a plastic rotational angle is equal to that with plastic strain through the experiments by proving the correlation that the plastic strain ratio is directly proportional to the plastic rotational angle in plastic hinge.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.6
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• pp.353-360
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• 2018

This paper is to investigate the micro-behavior of the double-span beams with WUF-W seismic connection under combined axial tension and moment and to propose the rational rotational capacity of it for progressive collapse-resistant analysis and design addressing the stress and strain transfer mechanism. To this end, the behavior of the double-span beams under the column missing event is first investigated using the advanced nonlinear finite element analysis. The characteristics of fracture indices of double-span beams with WUF-W connection under combined axial tension and flexural moment are addressed and then proposed the rational rotational capacity as the basic datum for the progressive collapse-resistant design and analysis. The distribution of fracture indices related to stress and strain for the double-span beams is investigated based on a material and geometric nonlinear finite element analysis. Furthermore, the micro-behavior for earthquake and progressive collapse is explicitly different.

• Journal of the Korea Concrete Institute
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• v.11 no.6
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• pp.47-56
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• 1999

In this paper, a nonlinear finite element procedure is presented for the analysis of reinforced concrete shell structures. The 4-node quadrilateral flat shell finite element with drilling rotational stiffness is developed. The layered approach is used to discretize behavior of concrete and reinforcement through the thickness. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. The steel reinforcement is assumed to be in a uniaxial stress state and to be a smeared in a layer. The proposed numerical method for nonlinear analysis of reinforce concrete shells will be verified by comparison with reliable experimental results.

• Journal of the Korean Society of Mechanical Technology
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• v.20 no.6
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• pp.790-795
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• 2018

In this study, we analyzed the structural safety and vibration characteristics of rotational drive in 3D CT scan equipment using finite element analysis. The analysis results showed a safety factor of 9.2 and a left and right vertical deflectional deviation of 0.24mm from the maximum equivalent stress. After applying weight compensation of 27.7kgf, the structural analysis reduced the safety factor to 7.6, but the deflectional deviation of the left and right structure was reduced to 0mm. Also, we presented the optimum design of rotational drive through the vibration analysis.

• Wind and Structures
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• v.31 no.4
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• pp.373-380
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• 2020

For large-scale 5MW offshore wind turbines, the discrete equation of fluid domain and the motion equation of structural domain with geometric nonlinearity were built, the three-dimensional modeling of the blade considering fluid-structure interaction (FSI) was achieved by using Unigraphics (UG) and Geometry modules, and the numerical simulation and the analysis of the vibration characteristics for wind turbine structure under rotating effect were carried out based on ANSYS software. The results indicate that the rotating effect has an apparent effect on displacement and Von Mises stress, and the response and the distribution of displacement and Von Mises stress for the blade in direction of wingspan increase nonlinearly with the equal increase of rotational speeds. Compared with the single blade model, the blade vibration period of the whole machine model is much longer. The structural coupling effect reduces the response peak value of the blade displacement and Von Mises stress, and the increase of rotational speed enhances this coupling effect. The maximum displacement difference between two models decreases first and then increases along wingspan direction, the trend is more visible with the equal increase of rotational speed, and the boundary point with zero displacement difference moves towards the blade root. Furthermore, the Von Mises stress difference increases gradually with the increase of rotational speed and decreases nonlinearly from the blade middle to both sides. The results can provide technical reference for the safe operation and optimal design of offshore wind turbines.

• Korea-Australia Rheology Journal
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• v.15 no.4
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• pp.187-196
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• 2003

The recent renaissance in controlled-stress rheometry has meant that more and more commercial models of this type of instrument have appeared in the (rheological) marketplace and many papers now deal with the results obtained by their use. It is therefore both timely and appropriate that this mode of rheometry should be reviewed for the sake of new and old users who are probably not be aware of its development. The history of controlled-stress measurements is therefore given, and the particular efforts of the late Jack Deer in the 1970s are chronicled, and then the later developments that have made it possible that such low torques can now be applied and such low rotational speeds measured. These have been mostly in the areas of air bearing and optical disc technologies. The typical results now obtained are illustrated.

• Structural Engineering and Mechanics
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• v.4 no.4
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• pp.383-396
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• 1996

In this paper, the behavior of plates partially restrained against rotation under stress gradient is investigated. As a first stage, an energy formulation is presented to model this boundary condition and a general expression is derived for the prediction of the elastic buckling of the plate under this general loading condition. The accuracy of the derived expression is compared numerically using the Galerkin method with other available data for the two limiting conditions of rotationally free and clamped boundaries. Results show that the prediction is within a 5% difference. The influence of rotational restraint and stress gradient upon the buckling load and the associated buckling mode is investigated. Numerical results show sensitivity of the buckling mode to the degree of rotational restraint and the variation of the buckling load with the stress gradient.