• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.769-774
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• 2000

The first thing in developing precast post-tensioned concrete frame system verify the shear resistance capacity of the beam-column connection at which the transfer of member forces become discontinuous. Complying with the necessity of such experimental research, shear tests have been performed for six test specimens which were cast and cured at Dong-Ah Concrete Manufacturing Company and post-tensioning at Concrete Laboratory of Inha University. Shear key and magnitude of post-tensioned force are taken test variables. From the test results, it has been observed that the shear resistance of the specimens attained to higher values than those of theoritical calculations based on the shear friction with shear friction coefficient being 0.6.

• International Journal of Concrete Structures and Materials
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• v.10 no.4
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• pp.425-434
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• 2016

In this experimental study, six post-tensioned light weight concrete (LWC) continuous one-way slabs were tested in the following manner: the flexural behaviors of the members were compared with the calculations from the existing standards. The test also examined the effect of prestressing in tendons and proper prestress conditions to reduce the deflection and crack width, and to enhance the flexural capacity and ductility of LWC members. Flexural capacity and stress increments in unbonded tendons of the specimens were compared with those of the simply supported normal and the lightweight concrete members. The suggested safety limit from the American Concrete Institute (ACI) regulation on the maximum capacity and the stress incremental in unbonded tendons were also compared with the test results under simple and continuous supporting conditions.

• Journal of Korean Association for Spatial Structures
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• v.18 no.3
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• pp.117-124
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• 2018

In the post-tensioned concrete member, additional reinforcement is required to prevent failure in the anchorage zone. In this study, the details of reinforcement suitable for the anchorage zone of the post-tensioned concrete member using circular anchorage was proposed based on the experimental results. The tests were conducted with the compressive strength of concrete and reinforcement types as variables. The experimental results indicated that the additional reinforcement for the anchorage zone is required when the compressive strength of concrete is less than 17.5 MPa. U-shaped reinforcement shows most effective performance in terms of maximum strength and cracks patterns.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.89-90
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• 2010

Three post-tensioned lightweight concrete beams were tested to examine the effect of the reinforcement index on the unbonded tendon stress at ultimate strength of the beams. The reinforcement index selected for main variables were 0.06, 0.15, 0.30. Test results showed that the stress of the unbonded tendons in the ultimate strength of the post-tensioned lightweight concrete beams can be conservatively evaluated using the empirical equations specified in ACI 318-08.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.481-486
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• 2002

A precast concrete beam which is larger than the limits of domestic transportation regulation in weight, length, and volume is divided into three parts, transported separately, and erected with a composite beam by post-tensioning in site. Shear tests are performed on the post-tensioned composite segmental beam models with 1/2 scale. The jacking force and the ratio of area of shear key to beam section are major experimental variables. Nine shear strength are resulted from the tests with two variables. Rational equation for estimation of shear strength are obtained from the regression analysis on test results.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.135-140
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• 2001

A post-tensioned reinforced concrete slab bridge is analyzed by specially orthotropic laminate theory. Symmetrically reinforced slab with tension and compression steel is considered for convenience of analysis. Each longitudinal and transverse steel layer is regarded as a lamina, and material constants of each lamina is calculated by the use of the rule of mixture. This bridge is under uniformly distributed vertical loads, and axial loads and end moments due to post-tensioning. In this paper, finite difference method is used for numerical analysis of this bridge. Theory and analysis method of specially orthotropic laminate plates used in this paper can be used for design of new bridges, and maintenance and repair of old bridges.

• Computers and Concrete
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• v.28 no.6
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• pp.549-557
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• 2021

Nowadays, strengthening of buildings is an inclusive and effective field in civil engineering that is not only applicable to the buildings but also it can be developed for the bridges. Rehabilitation and strengthening of structures are highly recommended for the existing structures due to the alter in codes and provisions as well as buildings' use change. Extensive surveys have been conducted in this field in the world that propose wide variety of methods for strengthening of structures. In recent years, more specific researches have been carried out that present novel materials for rehabilitation beside proposing methods and performing techniques. In the current study, a novel technique for developing the bending capacity of reinforced concrete beams to enhance their performance as well as rehabilitating and reforming the performance of reinforced concrete beams with nonstandard lap splices, has been proposed. In this method, a post-tensioned concrete layer is added to the side face of the concrete beams built in 1:1 scale. Results reveals that addition of the post-tensioned layer enhances the beams' performance and covers their weaknesses. In this method, 18 reinforced concrete beams were prepared for the bending test which were subjected to the four-point pushover test after they were reinforced. The testing process ended when the samples reached complete failure status. Results show that the performance and flexural capacity of reinforced beams without lap splice is improved 22.7% compared to the samples without the post-tensioned layer, while it is enhanced up to at least 80% compared to the reinforced beams with nonstandard lap splice. Furthermore, the location of plastic hinges formation was transformed from the beam's mid-span to the 1/3 of span's end and the beam's cracking pattern was significantly improved.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.303-306
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• 2005

The cracking behavior of prestressed concrete members is important for the rational design of prestressed concrete structures. However, the test data on the cracking behavior of prestressed concrete structures are very limited. The purpose of the present study is to investigate the crack spacing and crack width in transversely post-tensioned decks of concrete box girder bridges under applied loading. For this purpose, large scale test members of concrete box girder segments were fabricated and tested. The crack widths, crack spacings and crack patterns were investigated for various load levels. The crack widths and steel strains were continuously monitored during the loading process. To derive a rational predicton equation for crack width, the bond characteristics of post-tensioned steel and nonprestressed rebar in the PSC members were explored first. This was done by measuring the strains of prestressing steel and nonprestressed rebar in the test members under loading. A simple equation for the prediction of maximum crack width in transversely post-tensioned concrete one-way slabs is proposed by considering bond characteristic of prestressing steel and nonprestressed reinforcement. The comparison of proposed equation with experimental data shows good correlation. The present study indicates that ACI and CEB-FIP code equations exhibit rather large deviation from test data on prestressed concrete members.

• Structural Engineering and Mechanics
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• v.43 no.4
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• pp.459-473
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• 2012

Post-tensioned concrete voided slab girders are widely used in highway bridge constructions. To obtain greater section hollow rate and reduce the self-weight, the plate thickness of slab girders are designed to be small with the adoption of flat anchorage system. Since large prestress is applied to the anchor end section, it was found that longitudinal shear cracks are easy to occur along the voided slab girder. The reason is the existence of great shearing effect at the junction area between web and bottom (top) plate in the anchor end section. This paper focuses on the longitudinal anti-cracking problem at the anchor end of post-tensioned concrete voided slab girders. Two possible models for longitudinal anticracking analysis are proposed. Differential element analysis method is adopted to derive the solving formula of the critical cracking state, and then the practical analysis method for longitudinal anti-cracking is established. The influence of some factors on the longitudinal anti-cracking ability is studied. Results show that the section dimensions (thickness of bottom, web and top plate) and prestress eccentricity on web plate are the main factors that influence the anti-cracking ability. Moreover, the proposed method is applied into three engineering examples to make longitudinal anti-cracking verification for the girders. According to the verification results, the design improvements for these girders are determined.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.223-228
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• 2011

The initial joint width design of the terminal joint between post-tensioned concrete pavement (PTCP) and jointed concrete pavement (JCP) was studied in this research. The joint width between PTCP and JCP directly affects noise and ride quality. If the initial joint width is very large, noise increases and ride quality decreases. If the initial joint width is very small, on the other hand, under high temperatures, PTCP slabs can blow up, or failures near the joint can occur due to excessive compressive stresses. The terminal joint width behavior between PTCP and JCP near Jumunjin at Donghae expressway under temperature changes was measured in August and November 2010 and the data was analyzed. From this study, the design methodology of the optimal initial terminal joint width was proposed.