• Wind and Structures
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• 제2권2호
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• pp.95-104
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• 1999

The dynamic properties of one-span or multi-span reinforced concrete footbridges of catenary form (see e.g., Fig. 1) include the very low fundamental natural frequency, usually near the step-frequency of pedestrians, and the low damping of bending vibrations. The paper summarized the results of model as well as full-scale measurements with particular reference to the influence of torsional rigidity of the stress-ribbon on the magnitude of aerodynamic response, the results of measurements on footbridges of catenary form being completed by results obtained on footbridges of some other types. Additionally the influence of the local broadening of the bridge deck on the bridge response was tested. Starting from these results the criterion has been derived for the decision, whether the flutter analysis is necessary for the design of the footbridge.

• Journal of Ship and Ocean Technology
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• 제7권3호
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• pp.56-65
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• 2003

The hull monitoring systems of container ships with four long-base gages give enough information for identifying the hull girder loads such as bending and torsional moments. But such a load-identification for container ships has not been known. In this paper, a load-identification method is suggested in terms of a linear matrix equation that the measured strain vector equals to the multiplication of the transformation matrix and the desired strain component vector. The equation is proved to be mathematically complete by the property of positive-definite determinant of the transformation matrix. The method is applied to a hull stress monitoring system for 8100TED container ship during sea trial, and the estimated external loads illustrate reasonable results in comparison with the pre-estimated results. This moment decomposition concept has also been tested in real operation conditions. The typical phenomena over the Suez Canal illustrated very suitable results comparing with the physical understandings. Henceforth, one can effectively use the proposed concept to monitor the hull girder loads such as bending and torsional moments.

• 한국방재학회 논문집
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• 제8권2호
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• pp.39-43
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• 2008

Determination of strain associated with shear modulus and damping ratio during torsional test is complicated. This is due to nonuniform stress-strain variation occurring linearly with radius in a soil specimen in torsion. A conventional equivalent radius approach proposed by Chen and Stokoe appears to be adequate for evaluating strain associated with shear modulus at low to intermediate strain levels. This approach is less accurate for damping measurement, particularly at high strain. Modified equivalent radius approach was used to account for the nonuniform stress-strain effect more precisely. The modified equivalent radius approach was applied for hyperbolic, modified hyperbolic, and Ramberg-Osgood models. The results illustrate the usefulness of the modified equivalent radius approach and suggest that using a single value of equivalent radius ratio to calculate strains is not appropriate.

• Structural Engineering and Mechanics
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• 제10권2호
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• pp.165-180
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• 2000

An analytical model with tension softening for the prediction of the capacity of prestressed concrete beams under pure torsion and under torsion combined with shear and flexure is introduced. The proposed approach employs bilinear stress-strain relationship with post cracking tension softening branch for the concrete in tension and special failure criteria for biaxial stress states. Further, for the solution of the governing equations a special numerical scheme is adopted which can be applied to elements with practically any cross-section since it utilizes a numerical mapping. The proposed method is mainly applied to plain prestressed concrete elements, but is also applicable to prestressed concrete beams with light transverse reinforcement. The aim of the present work is twofold; first, the validation of the approach by comparison between experimental results and analytical predictions and second, a parametrical study of the influence of concentric and eccentric prestressing on the torsional capacity of concrete elements and the interaction between torsion and shear for various levels of prestressing. The results of this investigation presented in the form of interaction curves, are compared to experimental results and code provisions.

• Structural Engineering and Mechanics
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• 제10권2호
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• pp.125-138
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• 2000

The paper analyzes the problem of torsion in an adhesive non-tubular bonded single-lap joint. The joint considered consists of two thin rectangular section beams bonded together along a side surface. Assuming the materials involved to be governed by linear elastic laws, equilibrium and compatibility equations were used to arrive at an integro-differential relation whose solution makes it possible to determine torsional moment section by section in the bonded joint between the two beams. This is then used to determine the predominant stress and strain field at the beam-adhesive interface (stress field along the direction perpendicular to the interface plane, equivalent to the applied torsional moment and the corresponding strain field) and the joint's elastic strain (absolute and relative rotations of the bonded beam cross sections). All the relations presented were obtained in closed form. Results obtained theoretically are compared with those given by a three dimensional finite element numerical model. Theoretical and numerical analysis agree satisfactorily.

• Computers and Concrete
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• 제16권1호
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• pp.67-97
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• 2015

This article presents a computing procedure developed to predict the torsional strength of axially restrained reinforced concrete beams. This computing procedure is based on a modification of the Variable Angle Truss Model to account for the influence of the longitudinal compressive stress state due to the axial restraint conditions provided by the connections of the beams to other structural elements. Theoretical predictions from the proposed model are compared with some experimental results available in the literature and also with some numerical results from a three-dimensional nonlinear finite element analysis. It is shown that the proposed computing procedure gives reliable predictions for the ultimate behaviour, namely the torsional strength, of axially restrained reinforced concrete beams under torsion.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.601-604
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• 2002

In this paper bolt-tightened Langevin type vibrator was designed using longitudinal-torsional vibration. These two vibrations make rotary displacement at the end of the vibrator. ANSYS was used to determine shape and dimension of the vibrator in addition to resonant frequency, displacement and stress distribution. This kind of vibrator can be applied for a brakeless and gearless rotary motor which has high torque at low speed.

• Macromolecular Research
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• 제8권5호
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• pp.224-230
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• 2000

Molecular mechanics technique has been used for finding energy-minimized conformation to understand the mechanism of yielding of glassy polymers in atomistic level. As a model polymer, amor- phous isotactic polypropylene (iPP) was generated by molecular mechanics and molecular dynamics methods. The stress-strain cone was successfully obtained by using molecular mechanics technique. The torsional angle distribution showed no significant change during extension, although the torsional angles of certain bonds in polymer backbone changed more largely than other bonds. No significant change in the van der Waals interaction is observed at yielding point, whereas the torsional angle energy starts to decrease at yield strain.

• 소음진동
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• 제10권4호
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• pp.655-661
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• 2000

Diesel power plant can be used as a power supplier for the isolated place where consumption of electric power is variable. The reason is that mobility and durability of diesel engine is superior to those of other thermal engines. However, there are some disadvantages for using these diesel engines such as bigger vibratory excitation force comparing to the others, which result from high combustion pressure of cylinders and inertia force of piston reciprocating masses. In this paper, control and optimization of torsional vibration of 12K90MC-S engine for diesel power plant using uneven crank angles is identified by theoretical analysis and vibration measurement.

• Steel and Composite Structures
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• 제7권3호
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• pp.241-251
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• 2007

The purpose of this study is to calculate the torsional rigidity of arbitrarily shaped composite sections on the basis of hybrid finite element approach. An analogy is used between the torsion problem and deformation of a plate which exhibits only shear behavior. In the analysis a simple hybrid finite element based on Hellinger-Reissner functional is presented and a set of numerical examples are performed to demonstrate and asses the performance of the developed element in practical applications.