• Journal of the Korean Society for Precision Engineering
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• v.8 no.4
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• pp.137-145
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• 1991

A universal joint is a connecting device of two hinges which can transmit torque from one shaft to another at fixed or at varying angles of intersection. It has been used properly not only as rotational but also as intermittent motion. For the particular kinematics condition of a universal joint, torsional and bending vibrations are produced excessively in an elastic driveline. In this paper only the torsional vibration behavior of a driveline with universal joints is analyzed numerically with the discrete model and a design method of the dynamic vibration damper is proposed, in order to reduce torsional vibrations especially in resonance region as a result of parametric variation.

• Journal of Mechanical Science and Technology
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• v.20 no.11
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• pp.1790-1800
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• 2006

Dynamic behavior of flexural-torsional coupled vibration of rotating beams using the Rayleigh-Ritz method with orthogonal polynomials as basis functions is studied. Performance of various orthogonal polynomials is compared to each other in terms of their efficiency and accuracy in determining the required natural frequencies. Orthogonal polynomials and functions studied in the present work are: Legendre, Chebyshev, integrated Legendre, modified Duncan polynomials, the special trigonometric functions used in conjunction with Hermite cubics, and beam characteristic orthogonal polynomials. A total of 5 cases of beam boundary conditions and rotation are studied for their natural frequencies. The obtained natural frequencies and mode shapes are compared to those available in various references and the results for coupled flexural-torsional vibrations are especially compared to both previously available references and with those obtained using NASTRAN finite element package. Among all the examined orthogonal functions, Legendre orthogonal polynomials are the most efficient in overall CPU time, mainly because of ease in performing the integration required for determining the stiffness and mass matrices.

• Structural Engineering and Mechanics
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• v.3 no.3
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• pp.255-272
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• 1995

The paper considers aspects of the energy dissipation response of selected realistic forms of torsionally balanced and torsionally unbalanced building systems, responding to an ensemble of strong-motion earthquake records. Focus is placed on the proportion of the input seismic energy which is dissipated hysteretically, and the distribution of this energy amongst the various lateral load-resisting structural elements. Systems considered comprise those in which torsional effects are discounted in the design, and systems designed for torsion by typical code-defined procedures as incorporated in the New Zealand seismic standard. It is concluded that torsional response has a fundamentally significant influence on the energy dissipation demand of the critical edge elements, and that therefore the allocation of appropriate levels of yielding strength to these elements is a paramount design consideration. Finally, it is suggested that energy-based response parameters be developed in order to assist evaluations of the effectiveness of code torsional provisions in controlling damage to key structural elements in severe earthquakes.

• Smart Structures and Systems
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• v.25 no.5
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• pp.515-530
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• 2020

A new type of pure torsional yielding damper made from steel pipe is proposed and introduced. The damper uses a special mechanism to apply force and therefore applies pure torsion in the damper. Uniform distribution of the shear stress caused by pure torsion resulting in widespread yielding along pipe and consequently dissipating a large amount of energy. The behavior of the damper is investigated analytically and the governing relations are derived. To examine the performance of the proposed damper, four types of the damper are experimentally tested. The results of the tests show the behavior of the system as stable and satisfactory. The behavior characteristics include initial stiffness, yielding load, yielding deformation, and dissipated energy in a cycle of hysteretic behavior. The tests results were compared with the numerical analysis and the derived analytical relations outputs. The comparison shows an acceptable and precise approximation by the analytical outputs for estimation of the proposed damper behavior. Therefore, the relations may be applied to design the braced frame system equipped by the pure torsional yielding damper. An analytical model based on analytical relationships was developed and verified. This model can be used to simulate cyclic behavior of the proposed damper in the dynamic analysis of the structures equipped with the proposed damper. A numerical study was conducted on the performance of an assumed frame with/without proposed damper. Dynamic analysis of the assumed frames for seven earthquake records demonstrate that, equipping moment-resisting frames with the proposed dampers decreases the maximum story drift of these frames with an average reduction of about 50%.

• Journal of Korean Society of Steel Construction
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• v.27 no.4
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• pp.371-376
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• 2015

This study was conducted for the torsional behavior of catwalk system which is a temporary structure on a suspension bridge. The torsional deformation of the catwalk structure has a significant effect on the workability and safety of workers during main cable erection. For this reason, the torsional deformation of catwalk is controlled to be acceptable levels below by adjusting the cross bridge interval in design stage. This study analyzed the effect of separation between cross bridge associated with twist safety of catwalk system. For the analytical approach, a detailed analysis model was created including cross bridge. Both wind load within the wind velocity range that allows the construction and eccentric load of Prefabricated Parallel Wire Strand were analyzed by analysis model. Result of study shows that separation between cross bridges has a significant effect on the torsional behavior of the catwalk.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6A
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• pp.399-409
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• 2012

The flexural behavior of HSB plate girder with a non-slender web, due to inelastic lateral-torsional buckling, under uniform bending was investigated by the nonlinear finite element analysis. Both homogeneous sections fabricated from SM570-TMC, HSB600 or HSB800 steel and hybrid sections with HSB800 flanges and SM570-TMC web were considered. The flanges and web of selected noncomposite I-girders were modeled as thin shell elements and the geometrical and material nonlinear finite element analysis was performed by the ABAQUS program. The steel was assumed as an elasto-plastic strain hardening material. Initial imperfections and residual stresses were taken into account and their effects on the inelastic lateral-torsional buckling behavior were analyzed. The flexural strengths of selected sections obtained by the finite element analysis were compared with the nominal flexural strengths from KHBDC LSD, AASHTO LRFD, and Eurocode and the applicability of these codes in predicting the inelastic lateral torsional buckling strength of HSB plate girders with a non-slender web was assessed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.6
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• pp.463-470
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• 2013

In this paper, 2D simple analyses were performed in order to predict the large torsional oscillations in a suspension bridge based on Makenna and Tuama model(2001). The existing model(Makenna and Tuama, 2001) has shown unrealistic results as the wind speed increases and frequency decreases. Furthermore, resonance could not be simulated by the existing model. Therefore, in this study, new model was proposed with a consideration of the torsional resistance. The vertical and rotational behaviors of the deck in the suspension bridge were analyzed. Analysis results showed that at first vertical oscillations were observed and it was gradually transformed to the rotation oscillations. With the consideration of the torsional resistance, it was shown that vertical behavior were stabilized as time passed. However, the rotational behavior was not stabilized and was kept until the end of analysis. Beat periods decreased while the wind speed increased. The resonance of the rotational mode was dependent to the rotational resistance. Obtained results could be applied for the design of the suspension bridge under the wind load.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2A
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• pp.281-288
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• 2008

The Prestressed Concrete (hereinafter PSC) box girder bridges with corrugated steel webs have been drawing an attention as a new structure type of PSC bridge fully utilizing the feature of concrete and steel. However, the previous study focused on the shear buckling of the corrugated steel web and development of connection between concrete flange and steel web. Therefore, it needs to perform a study on the torsional behavior and develop the rational torsional analysis model for PSC box girder with corrugated steel web. In this study, torsional analysis model is developed using Rausch's equation based on space truss model, equilibrium equation considering softening effect of reinforced concrete element and compatibility equation. Validation studies are performed on developed model through the comparison with the experimental results of loading test for PSC box girder with corrugated steel webs. Parametric studies are also performed to investigate the effect of prestressing force and concrete strength in torsional behavior of PSC box girder with corrugated steel web. The modified correction factor is also derived for the torsional coefficient of PSC box girder with corrugated steel web through the parametric study using the proposed anlaytical model.

• Journal of Korean Society of Steel Construction
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• v.18 no.4
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• pp.447-456
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• 2006

In this study, a torsional test for U-type steel box girders was performed to observe the effects of the kind of panel for top lateral walateral bracings on the torsional behavior of the U-type steel girder system. For the structural tests, the test specimen with a two-thirds scale of the system actually constructed in the field was used. In the torsional test to observe the efects of top lateral bracings, the most economical arrangement of the top lateral bracing was found to be the panel width to length ratio of 1:1.5 with the inclined angle of $40^{\circ}$.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.4 s.15
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• pp.63-71
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• 2004

The centroid of rail doesn't coincide with the centroid of stringer on target truss bridge. If there is no eccentricity on the bridge, bending stress works only. But in the real design and execution, not only bending stress works but also torsional stress does because of it's eccentricity. So this study evaluates how much the torsional stress by eccentricity effects joint members on the bridge. We investigate the possibility to control torsional stress if we model longitudinal bracing between stringers.