• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• v.6 no.1
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• pp.38-43
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• 2003

This paper presents the results of a post-tensioning test and analysis of a pyramidal unit structure that is basic element for space structures. The behavior characteristics was analyzed and compared with the numerical analysis and the mechanism in test model was confirmed with geometrical analysis. The results of this paper show that the behaviors of space structures can be predicted in multi-directional Mero joint system. And the authors suggest the possibility of erection and shaping formation with comparatively small post-tensioning, and space structure with the mechanism should consider the nonlinear behavior due to large deformation.

• Journal of Korean Association for Spatial Structures
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• v.15 no.1
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• pp.47-55
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• 2015

This paper shows the simplified equation to predict the ultimate moment capacity and corresponding rod stress in reinforced concrete beam with external post-tensioning rods. Because the stress of external post-tensioning rod depends on the beam deflection, the previous analytical model for post-tensioned beams requires a tedious iteration process. Also, the stress equations in ACI code or other researchers' models are suitable only for internal tendons in concrete beams. In this study, given the lack of analytical approaches to predict the nominal stress of the external unbonded rod, a simple and robust equation has been proposed for externally post-tensioned concrete beams. It is concluded that the proposed equation predicted the stress of external steel rods in post-tensioned concrete beams reasonably well.

• 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.

• 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 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.127-128
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• 2009

This study was conducted to develop the design methodology of longitudinal post tensioning for the prestressed concrete pavement (PSCP).

• Structural Engineering and Mechanics
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• v.6 no.6
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• pp.693-710
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• 1998

This paper concerns studies on the shape formation of post-tensioned and shaped steel domes. The post-tensioned and shaped steel domes, assembled initially at ground level in an essentially flat condition, are shaped to a curved space form and erected into the final position by means of a post-tensioning technique. Based on previous studies on this shape formation principle, three post-tensioned and shaped steel domes have been constructed. The results of the shape formation tests and finite element analyses are reported in this paper. It is found that the first two test domes did not furnish a part-spherical shape as predicted by finite element analyses, because the movements of some mechanisms were not controlled sufficiently. With a revised post-tensioning method, the third dome obtained the theoretical prediction. The test results of the three post-tensioned and shaped domes have shown that a necessary condition to form a desired space shape from a planar layout with low joint stiffnesses is that the movements of all the existing mechanisms must be effectively controlled as indicated by the finite element analysis. The extent of the maximum elastic deformation of a post-tensioned and shaped steel structure is determined by the strength of the top chords and their joints. However, due to the semi-rigid characteristic of the top chord joints, the finite element analyses cannot give a close prediction for the maximum elastic deformations of the post-tensioned and shaped steel domes. The results of the current studies can be helpful for the design and construction of this type of structure.

• 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.

• 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.

• 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.