• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.249-256
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• 2005

Rigorous FE(Finite Element) analyses of the cable-stayed bridge with steel-box girder, the main construction method of which is FCM (Free Cantilever Method), are presented in this paper. The analysis and the checking of design for a derrick crane under several loading conditions are performed using the software MIDAS/Civil and the beam elements are used to model the main structure. Among all the construction stages, special construction stages are chosen and considered to ensure the safety of segments of box girder The stress analysis for lifting of a segment of box girder is performed using the software SAP2000 and the shell elements of which having 6 DOF(Degrees Of Freedom) per nodes are successfully used to model the segment of box girder for the purpose of capturing the detailed behaviors on the folded-plates in the segment. Finally, concluding remarks are given to improve a design of the derrick crane and the segment based on the results from this study.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.4
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• pp.343-351
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• 2010

Bending and axial compressive stresses are distributed across the whole upper flange of a box girder bridge which has the span-to-depth ratio (B/L) of below 0.5, according to Korea Bridge Design Specifications (Minister of Land, Transport and Maritime Affairs, 2005). Shear lag phenomenon, however, can take place in the construction phase of cable-stayed bridge, in which stresses combining bending moment due to dead weight and cable vertical compression are induced. This study aims to analyze the effective width of flange over which composite stresses are given, which should be calculated during the construction phase of stiffening girder of single plane cable-stayed box girder bridge. The study results indicate that the full width of stiffening girder can be regarded as the effective flange width when the span-to-depth ratio for the deck is below 0.38. In other words, the area, where shear lag is taken into consideration, is larger than the width of box girder in single plane cable-stayed box girder bridges. Therefore, the current practice of considering the full width as the effective flange width regardless of changes of the span-to-depth ratio during the construction stage can produce an unsafe bridge. If the effective flange width is determined according to the single span structural system in the early stage of construction when the span-to depth ratio for the deck is high and composite stresses of every part expect each end of the bridge are calculated, it can result in a safe structural design. Since the span-to-depth ratio gradually decreases, however, it is appropriate to determine the effective width of flange on the basis of the full width and the cantilever structural system.

• Journal of Korean Society of Steel Construction
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• v.9 no.2 s.31
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• pp.181-191
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• 1997

Before cables are constructed, tower of suspension bridge is behaved as a cantilever type. Buffeting occured by unsteady loading of the tower due to velocity fluctuation in the oncoming flow has a wind velocity consistent with fundamental frequency of the tower and may give rise to large response by the tower resonance. To reduce the dynamic response by buffeting, the behavior of tower with TMD(Tuned Mass Damper) has studied using finite element method in time domain. The buffeting was obtained by transforming the velocity spectrum in frequency domain to random variable in certain time domain. The most probable maximum displacement which can be occured during the time interval was obtained using peak factor. The optimum location for TMD installation and TMD specification were decided by parametric study. Also, the effect of vibration control about various wind velocity was studied by the TMD which has optimum specification and location.

• Journal of Korean Society of Steel Construction
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• v.24 no.6
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• pp.683-692
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• 2012

The girders of cable stayed bridge are subjected to not only the bending moments but also additional compressive axial forces due to the horizontal components of cable forces. Because of these axial forces, the stiffness of girder can be decreased, and this problem should be considered especially for under-construction model rather than the full model. Korean domestic design specification suggests the linear elastic eigen value analysis for the stability problem of cable stayed bridges. However, this method cannot be applied to the under construction model because various geometric nonlinear characteristics cannot be considered. Therefore, in this study, 3 models which are assumed to be constructed by balanced cantilever will be considered experimentally and analytically to analyze the behavior of steel cable stayed bridges.

• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.121-129
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• 2008

study proposes a new key-segment closing method using thermal effect as a substitute to the process of set-back and reset-back for the FCM construction of a partially earth-anchored cable-stayed bridge. The proposed method is to artificially heat up the inside of girders located in the main span before closing the key-segment in a cantilever state. Then, the heat is removed after finishing the closure in a continuous bridge state. Using the changes in boundary conditions and structural systems, the proposed method can generate new member forces that reflect the advantage of the partially earth-anchored cable system. From the construction sequence analysis, it is found that the proposed method increases the efficiency of a partially earth-anchored cable-stayed bridge by reducing the compressive axial forces on the girders.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.619-622
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• 2005

Purpose of this study is to investigate the size-dependent mechanical properties in micron scale medium. Theories such as the couple stress theory and strain gradient theory explain that the deformation in the micron scale is dependent upon the size of the medium. Specimens of the cantilever type, bridge type and paddle type beam that have thickness of 900, 1000 and 1200 nm and width of 10, 20, 30 and $50{\mu}m$ were fabricated by the MEMS technique. We carried out the bending and torsion test to measure the mechanical properties such as the young's modulus, yield strength and torsional rigidity using the AFM(Atomic Force Microscopy).

• Computational Structural Engineering
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• v.9 no.4
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• pp.107-115
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• 1996

Displacement response is one of the important parameter to determine vibration characteristics of bridge structure. Reliable estimate of displacement response is obtained economically from integration of measured acceleration data in frequency domain. Proper sampling rate of frequency in discretization process of measured acceleration is proposed. Comparison of integrated and directly measured displacement response from laboratory experiment for a cantilever beam shows good agreement each other. Mode shape obtained from estimated displacement response also closely match with analytical result, thus the developed method is proved to be effective in practical use.

• Journal of Biosystems Engineering
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• v.5 no.2
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• pp.40-57
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• 1980

The aim of this study was to promote extensive use of strain gage for accurate measurement in the area of farm machinery research. The results are summarized as follows. 1. Although many strain gate transducers commercially available such as load-cells , accelerometers and pressure transducers have been used in the area of farm machinery research, many types of transducers had to be developed due to the inadaptability or high cost commercial transducers, in many instances. 2. A strain -gaged cantilever beam could be used as a good educational material to demonstrate the methods of Wheatstone bridge arrangement, calibration and theoreticval computation. A ring type load-cell and shaft torque transducer also could be used for the same purpose. 3. The torque and angular speed transducers for an auto-feed thresher and the displacement and pressure transducers for a rice whitener were made and gave satisfactory results. 4. Based on the above results, it is possible to develop simple and low-cost transducers to measure displacement, angular speed , torque and pressure of farm machine elements.

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.168-172
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• 1994

This paper reports a method measuring magnetostriction, Young's moduli of a substrate and film and ${\Delta}\;E$-effect with one apparatus. A substrate deposited with a thin magnetic film is parallely cantilevered paraIled to a metal plate electrode, forming a capacitive cell. The cantilever deflects due to own weight, applied electric and magnetic filed. The smaIl change of the capacitance caused by this deflection is measured by a sensitive capaci-tance bridge. Young's modulus, magnetostriction and ${\Delta}\;E$ effect can be calculated by theoretical analysis with the weight, applied field and deflection data.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.4
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• pp.343-351
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• 2004

The flaw assessment method based on ${delta}_5$ parameter was recently proposed and put to the practical use. However: since it is almost impossible to measure the ${delta}_5$ by the existing commercial clip gager, we need to develope the specially designed gages which are suitable for that purpose. In this research, a double cantilever type ${delta}_5$ clip gage with the traveling distance of 4mm was developed by the finite element analysis and the construction of Wheatstone bridge circuit including strain gages. The linearity of developed ${delta}_5$ clip gage was evaluated by the MTS extensometer calibrator with the proper adapters which allow the 6s clip gage to sit on the calibrator. Consequently, the 6s clip gage revealed the good linearity between the output voltage and the traveling distance of gage.