• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.220-226
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• 2016

Because MS(Multi-Strand) cables consist of many strands, a jacking force is applied to each strand one by one for cable construction. All strands should have an equal tensile force when the last one is wedged. This is the core technology for MS iso-tensioning. In this study, a new MS cable iso-tensioning system was developed for controlling and jacking the high-strength strands, with an ultimate tensile strength of 2,200MPa, for a stay cable of extra-dosed/cable-stayed bridges. The newly developed iso-tensioning system consists of electrical resistance load cells, hydraulic jacking devices, hydraulic pumps, and integrated controllers. Moreover, it is embedded with an algorithm that can control and predict the variations in tensile forces of the Master and Slave strands in real time. Actual experiments were carried out to verify the function and performance of the newly developed system. This system was applied successfully to the stay cable construction of 2nd Tae-in extra-dosed bridge in Gwangyang.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.269-279
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• 2008

This study was conducted to develop the design methodology of transverse post-tensioning for the prestressed concrete pavement (PSCP). The transverse stress distribution was analyzed when the transverse anchor spacing changed. The tensile stress distribution in the PSCP slab due to the environmental and vehicle loads was also investigated. The reasonable methods were discussed to determine the design loads including environmental and vehicle loads and the PSCP allowable tensile stress used for the basis of the selection of the stress application amount from the tensioning. The results of this study showed that as the transverse anchor spacing increased, the range of the stress loss became larger and the stress loss was significant near the shoulder. The design of the transverse post-tensioning can be performed by obtaining the stresses under the design loads and by considering the allowable tensile stress; however, the tensile stresses at different locations such as the shoulder, wheel pass, and slab interior should also be checked and kept below the allowable tensile stress.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.155-163
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• 2008

Experimental study has been performed in order to investigate the behavior of RC beams strengthened with externally bonded post-tensioned CFRP (Carbon Fiber Reinforced Polymer) strips. Specimens consist of 9 small-scaled specimens with the different post-tensioning level as a main test parameter. A control specimen and specimens with simply bonded CFRP strips have been manufactured to compare the structural performances of prestressed system. From the test results, it was observed that the specimens strengthened with simply bonded CFRP strips showed debonding failure below 50% of CFRP tensile strength due to premature debonding. On the other hand, all the specimens strengthened with post- tensioned CFRP strips reached the rupture strength of the CFRP strip. The cracking and yielding loads were also increased proportionally to the post-tensioning level, but the ultimate loads were nearly equal regardless of the post-tensioning level.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6A
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• pp.819-825
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• 2008

This paper describes the shaping formation and the erection of SCST structure by cable-tensioning. It could be a fast and economical method for constructing the space structure consisted with uniform pyramids by cable-tensioning of the cable in bottom chords. In the initial layout, the top chords and web members are left at their true length, the bottom chords are given gaps in proportion to the desired final shape. The feasibility of the proposed shaping method and the reliability of the established geometric model were confirmed with nonlinear finite element analysis and an experimental investigation on small scale and full size test models. As a result, the behaviour characteristic of MERO joint is very significant in shaping analysis of space structure. This study suggests the most reasonable modeling technique for the prediction of shaping in practices. And it is shown the characteristic of the behavior in shaping test for practical design purposes.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.167-168
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• 2012

Analysis on structural effects which are reduction of friction coefficient and increase of tendon area by HDPE greased and large size strand in post-tensioning system of reactor containment building was carried out. Effective ratio of tendon force increases 67% to 83% by HDPE greased strand and vertical, horizontal internal section forces increased maximum 51%, 41% respectively. Tendon quantity could be reduced 30% by large size and HDPE greased strand that can maintain safety of ultimate internal pressure same as at present.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.41-44
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• 2005

Three precast concrete beam-column connectors for the high-rise office buildings were considered to investigate the prestressing effects of the DDC(Dywidag Ductile Connectors) of Germany and of the modified DDC. The specimens of DDC, DDC with post-tensioning and modified DDC with post-tensioning were constructed and tested to verify the safety. The DDC with and without post-tensioning showed reliable joint strength and ductility but failed in critical x-shape crackings at the column. The modified one showed better behaviors in tests because they did not show critical column crackings at failure. The use of prestressing did not helpful significantly to increase the strength and ductility of connectors but helpful only to develop self-centering behavior for stability.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05b
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• pp.91-96
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• 2011

The flat slab is well-known as a structural system to reduce the story height, so it is broadly used for recent building. However, the normal RC flat slab is not appropriate for the long span, and the quantity of reinforcement bar and concrete is raised. Recently, the post-tensioning system has been introduced and used widely as an alternative method. Nevertheless, in Korea, it is not used broadly due to lack of the understanding and field experience. Especially, the post-tensioning system is hesitated to use due to uncertainty of construction ability and economics. This paper will introduce applicability to site and economics of unbonded post-tensioning system through construction examples.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.282-287
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• 2003

DTTS(Dynamic Track Tensioning System) system requires robust control performance for the various maneuvering tasks. However, it is very difficult to tune the controller gains in experiments. In this paper, the hydraulic unit is modeled and constructed into the DTTS control module in Matlab/Simulink The control module is interfaced to the vehicle dynamics module so that the control performance of the DTTS system can be evaluated in simulations. The dynamics data and control input data are exchanged between two modules at each control time-step. The gains in the fuzzy-logic controller are varied and the control performance is evaluated in simulations. The proposed simulation tool can be very useful for the gain tuning of track tension controller in bucked vehicles

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.204-209
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• 2000

This paper suggests that post-tensioned and dome-shaped space truss formed by post-tersionong is easy to fabricate in construction process. In particular, a laboratory model is used to show how a flat space truss system can be transformed into a dome-shaped space truss by means of post-tensioning. There are some diserpancy in vertical displacement of the dxperiment and theoretical analysis for space truss. Nonlinear analysis is used to predict the final shape shape of the space truss, the experiments tndicates that this construction method can offer economy over traditional methods. In addition, the analysis indicates that when all the sxisting mechanisms are controlled, the nonlinear finite element method is more reliable way to predict the shape of the dome-shaped space truss than the linear analysis.

• Journal of Ocean Engineering and Technology
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• v.16 no.1
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• pp.41-45
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• 2002

This paper is concerned with the erection and ultimate load test of dome shaped space structures by post-tensioning. It is a fast and economical method for constructing such a dome by post-tensioning of the cable in bottom chords. This structure consists of uniform pyramids in a flat layouts on the ground, and then the structure is shaped and erected into its final curved space structure. Ultimate load test was performed for dome shaped space structures. The feasibility of the proposed erection method and the reliability of the established geometric model were confirmed with numerical analysis and experimental investigation on a small scale steel model. As a results we can find the most reasonable modeling technique for the prediction of shape formation in practices and we can know the characteristic of the behaviour in ultimate load test for practical design purposes.