• Journal of the Korean Society for Railway
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• v.9 no.2 s.33
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• pp.160-168
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• 2006

The major objective of this study is to investigate the effects and application of external post-tensioning method far steel plate girder bridge. It analyzed the mechanical behaviors of steel plate girder bridge with applying external post-tensioning on the finite element analysis, field test and laboratory test fur the lateral dynamic characteristics. As a result, the reinforcement of steel plate girder bridge the external post-tensioning method are obviously effective for the lateral dynamic response which is non-reinforced. The analytical and experimental study are carried out to investigate the post-tension force decrease lateral acceleration and deflection on steel plate girder bridge for serviceability. And the external post-tensioning method reduce dynamic maximum displacement(about $10{\sim}24%$), the increase of dynamic safety is predicted by adopting external post-tensioning method. From the dynamic test results of the servicing steel plate girder bridge, it is investigated that the change degree of natural frequency is very low with applying the external post-tensioning method The servicing steel plate girder bridge with external post-tensioning has need of the reasonable reinforcement measures which could be reducing the effect of lateral dynamic behavior that degradation phenomenon of structure by an unusual response characteristic and a drop durability.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1103-1107
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• 2016

The automatic tensioning device of the catenary system constantly maintains the tension of the trolley wire by absorbing the variations due to the elasticity of the line caused by temperature variation. The tension plays an important role in affecting the electric motorcar operation directly. This paper suggests the methodology of the life cycle extension and the maintenance of the automatic tensioning device by means of performance diagnosis of the pulley type automatic tensioning device which has been commonly used for the electric railway system. Through conducting performance diagnosis and comparative test for the wornout pulley type automatic tensioning device by replacing the components such as the bearing and the bearing shaft without replacing all the assembly, the tensioning device is analyzed whether it is properly functioned. Provided that the maintenance regulation is reinforced so as to implement the bearing replacement through periodical precise inspection along with random check-up inspection which is now carried out by the operating organizations, it is ensured that the life cycle extension and the reduction of maintenance cost of the tensioning device could be achieved.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.765-770
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• 2005

This paper presents a development and evaluation of a spring type tensioning device for Korea railroad. The wheel type tensioning device used in the Korea railroad requires much time and labor for maintenance including wire replacement and oil application. So, we found it necessary to develop a new type of maintenance-free tensioning device. In this paper, we introduced a spring type tensioning device for Korea railroad.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.771-776
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• 2005

This paper presents field test results of a spring type tensioning device for Korea railroad. The wheel type tensioning device used in the Korea railroad requires much time and labor for maintenance including wire replacement and oil application. So, we found it necessary to develop a new type of maintenance-free tensioning device. In this paper, we introduced field test results of spring type tensioning devices for Korea railroad.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.279-284
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• 2000

The bridge is nation's principal structure and its influence for national economy is enormous. But it is essential for maintenance of deteriorated bridge because of the increased service life and the decreased performance. For the bridge reinforced by continuos slabs and post-tensioning, we evaluate th stress properties of girders and internal support. Results are almost coincidence between measured data in the field and analysed data by computer. We compared the effects by successive order of post- tensioning and order considered distribution of each girder's camber and stress. Bridge's camber and stress showed respectively symmetry and asymmetry shape by post tensioning order. For the effect of post-tensioning force partition, we divided the post-tensioning force into 3 types (100%, 20%, 30%), and the results show t도 difference of final stress and camber.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.165-168
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• 2006

Carbon fiber reinforced polymer(CFRP) have superior mechanical and chemical properties in comparison with conventional materials. And post-tensioning method has been used for structural reinforcement of RC structures due to easy installation and good effect of resisting capacity of structures. But the higher cost of CFRP and the loss of prestressing force with time are considered the major problems to use it. In this study, CFRP Strips and external post tensioning for rehabilitation of old concrete structures were adapted and optimal combination of these methods is considered. A total of 17 concrete members were made and tested. The types and numbers of CFRP strips and post-tensioning types were selected as major test variables. From test results, it is shown that the concrete members that post tensioned and bonded CFRP strips has a pronounced effect on the strength and deformational behavior. This present study indicates that external temporally post tensioning can reduce the amount of CFRP strips required and the combination of temporally post tensioning and CFRP strips may meet the strength and ductility requirements of old structures.

• International Journal of Highway Engineering
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• v.11 no.1
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• pp.247-256
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• 2009

This research was conducted to analyze the behavior of PTCP (Post-Tensioned prestressed Concrete Pavement) under tensioning by performing field tests when the experimental PTCP slab was being constructed. The displacements in the slab under the environmental loading and tensioning were measured using temperature measurement sensors and displacement transducers. Tensioning was performed three times and appropriateness of tensioning could be determined by investigating the relationship between temperature and displacement, behavior of transverse crack, and daily change in displacement. The results of this study showed that under the first tensioning at very early age, large displacements were observed only near the joints because of the friction between slab and underlying layer and concrete inelasticity. Under consecutive tensioning, displacements were clearly observed all over the slab, but still affected by the friction. In addition, appropriate tensioning ensured the one-slab behavior of the PTCP slab even though cracks existed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6A
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• pp.587-596
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• 2009

This study analyzes the lateral distribution behavior of external post-tensioning force and evaluates the possibility of strengthening the servicing composite girder bridge by adopting the external post-tensioning force to the parts of the bridge girder. From the results of experiments and analyses, it is founded that the composite girder bridge can be strengthened by applying the external post-tensioning force to the parts of the bridge girder. It is also proved that bracing improve the lateral distribution behavior of post-tensioning force. The lateral distribution behavior of post-tensioning force which influenced by stiffness ratio, girder spacing and span length is changed by the bridge type and the location of tensioned girder. From the results of analyses, set up an equation which can predict the lateral distribution behavior of external post-tensioning force and evaluate the rationality.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.514-521
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• 2006

In strengthening structure, the external post-tensioning method which secure clearness in the structure analysis process is adopted to bridge as well as architecture structure. Therefore, the major objective of this study is to investigate the effects and application of external post-tensioning method for steel plate girder bridge. It analyzed the mechanical behaviors of steel plate girder bridge with applying external post-tensioning on the finite element analysis and laboratory test for the dynamic characteristics. As a result, the reinforcement of steel plate girder bridge the external post-tensioning method are obviously effective for the response which is non-reinforced. The analytical and experimental study are carried out to investigate the post-tension force decrease stress and deflection on steel plate girder bridge for serviceability. It is investigated that the change degree of natural frequency is very low with applying the external post-tensioning method. The servicing steel plate girder bridge with external post-tensioning is the reasonable reinforcement measures which could be secured the stability of dynamic behavior and increase a dropped durability.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.6
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• pp.3-10
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• 2018

This paper described the shear strengthening effect by deviator location in pre-damaged reinforced concrete (RC) beams strengthened with externally post-tensioning steel rods. Three reinforced concrete beams as control beam and eight post-tensioned beams using external steel rods were tested to fail in shear. The externally post-tensioning material was a steel rod of 22 mm diameter, and it had a 655 MPa yield strength and an 805 MPa tensile strength. Specimens depend on multiple variables, such as the number of deviators, location of deviator, and load pattern. The pre-damaged loads up to about 2/3 of ultimate shear capacities were applied to specimens using displacement control and the diagonal shear crack just occurred at these loading levels. And then, the post-tensioning up to when a strain of steel rod reaches about $2000{\mu}{\varepsilon}$ was continuously applied to beam. A displacement control was changed to a load control during post-tensioning. The post-tensioning resulted in increase of load-carrying capacity and restoration of existing deflection. Also, it prevented the existing diagonal cracks from excessively growing. Two deviators effectively improved the load capacity when compared with in case of test which one deviator at mid-span installed. When deviators were located near region which the diagonal crack occurred on, the strengthening impact by post-tensioning was greater.