• Journal of the Korean Society of Safety
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• v.34 no.3
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• pp.50-56
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• 2019

Precast members have relatively good quality because they are manufactured in an environment suitable for quality control. A typical precast method in which pre-fabricated segments are assembled in the field requires a joint. Although the joint is a small part of the member, it greatly affects the behavior and quality of the structural member. In the previous study of this paper, the flexural strength of a joint, which is generally applied to half-depth precast deck systems, was verified to have higher strength than the design requirement. In addition, the proposed joint has been verified to have higher strength by reinforcing the connecting rebar. However, even if the flexural strength of the joints is sufficient, excessive deflection or lack of fatigue performance is likely to cause cracks in the half-depth precast deck system. In this study, the serviceability of the half-deck precast panel specimens with joints was evaluated and the experimental verification was conducted to evaluate the fatigue performance of the joint without connection rebar. As a result, the serviceability such as deflection and crack width was found to be higher than the design requirement in all the specimens. In the fatigue test, the fatigue effect was insignificant even in the absence of connection rebar.

• Advances in concrete construction
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• v.14 no.2
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• pp.139-151
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• 2022

Filling materials poured into precast member joint are subjected to restraint stress by the precast member and joint reinforcement. The induced stress will likely cause cracks at early ages and performance degradation of the entire structure. To prevent these issues and design reasonable joints, it is very important to analyze and evaluate the restrained shrinkage cracks of filling materials at various restraint conditions. In this study, a new time zero-that defines the shrinkage development time of a filling material-is proposed to calculate the accurate amount of shrinkage. The tensile stresses and strengths at different ages were compared through the ring test (AASHTO PP34) to evaluate the crack potential of the restrained filling materials at various restraint conditions. The mixture which contained an expansive additive and a shrinkage reducing agent exhibited high resistance to shrinkage cracking owing to the high-drying shrinkage compensation effect. The high-performance, fiber-reinforced cement composite, and ultra-high-performance, fiber-reinforced cement composite yielded very high resistance to shrinkage and cracking owing to the pull-out property of steel fibers. To this end, multiple nonlinear regression analyses were conducted based on the test results. Accordingly, a modified tensile stress equation that considered both the geometric shape of the specimen and the intrinsic properties of the material is proposed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1A
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• pp.147-154
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• 2008

The purpose of this study is to critically evaluate the structural performance of an innovative new shear resistance connecting structure of precast member. Joints such as shear resistance connecting structure require special attention when designing and constructing precast segmental structures. An experimental and analytical study was conducted to quantify performance measures and examine one aspect of detailing for developed shear resistance connecting structure. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. A joint element is used to predict the inelastic behavior of the joints between segmental members. Future work by the authors will do a model test of precast segmental prestressed concrete bridge columns with this shear resistance connecting structure, and examined both the structural behavior and seismic performance.

• International Journal of Concrete Structures and Materials
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• v.19 no.1E
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• pp.3-9
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• 2007

This paper presents a numerical procedure for analyzing the joints between precast post-tensioned segments. A computer program for the analysis of reinforced concrete structures was run for this problem. Models of material nonlinearity considered in this study include tensile, compressive and shear models for cracked concrete and a model for reinforcing steel with smeared crack. An unbonded tendon element based on the finite element method, that can describe the interaction between the tendon and concrete of prestressed concrete member, was experimentally investigated. A joint element is newly developed to predict the inelastic behavior of the joints between segmental members. The proposed numerical method for the joints between precast post-tensioned segments was verified by comparison of its results with reliable experimental results.

• Journal of the Korean Society of Safety
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• v.28 no.2
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• pp.55-59
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• 2013

The analytical model was constituted to evaluate the flexural strength of UHPFRC(ultra high performance fiber reinforced concrete) member. The analytical approach was attemped to study the effect of the joint and the result compared with the experimental study to verify the analytical model. The calculated value tends to underestimate about 23%~25% in comparison with the experimental result of the jointed test member because the bond stress between precast UHPFRC and cast-in-place UHPFRC surface is not considered in the analytical model. But in the case of the continuous test member, the analytical model provides reasonable results for the flexural strength of UHPFRC member.

• Computers and Concrete
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• v.13 no.4
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• pp.501-516
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• 2014

The purpose of this study was to investigate the performance of precast concrete pier cap system. The proposed precast pier cap provides an alternative to current cast-in-place systems, particularly for projects in which a reduced construction time is desired. Five large-scale pier cap specimens were constructed and tested under quasistatic monotonic loading. The computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used for the analysis of reinforced concrete structures. A bonded tendon element is used based on the finite element method, and can represent the interaction between the tendon and concrete of a prestressed concrete member. A joint element is used in order to predict the inelastic behaviors of segmental joints with a shear key. This study documents the testing of the precast concrete pier cap system under monotonic loading and presents conclusions and design recommendations based on the experimental and analytical findings. Additional full-scale experimental research is needed to refine and confirm design details, especially for actual detailing employed in the field.

• Journal of the Korean Society of Safety
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• v.34 no.2
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• pp.40-47
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• 2019

The Half-depth precast deck is a structural system that utilizes pre-cast panels pre-built at the factory as formwork at the construction stage and as a major structural member at the same time after completion. These systems have joints between segments, and the detail and performance of the joints are factors that have a very large impact on the quality, such as the constructability and durability of the bridge decks. In this study, strength performance evaluation was performed for improved joints using connecting rebar by experimental method. Static loading tests were conducted on the test specimen with improved joint, those with existing joint and those without joint. The test results of the specimens were compared to each other, and the flexural strength required by the design was compared. The flexural strength required in the design was presented by finite element analysis. It has been shown that the flexural strength of the specimens with joints were more than twice that required by the design. But the flexural strength of the specimen with existing joint was about 84% of that without joint. The flexural strength of the specimen with improved joints was a nearly similar degree of that compared to the specimen without joint. And a comparison of the moment-deflection relationship curves of the two specimens also shows a very similar flexural behavior. It is confirmed that improved joint has sufficient flexural strength. In addition to strength, the bridge decks require serviceability, such as deflection and cracking, and in particular, fatigue resistance due to repetitive live loads is an important performance factor. Therefore, further verification studies are required.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1363-1372
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• 2014

In the previous study, the structural performance of proposed precast concrete arch with reinforced joint was evaluated by structural experiment. In this paper, finite element analysis considering both material and contact nonlinearity was carried out on the specimens of the previous study. Based on the result of analysis and experiment, friction coefficient between concrete blocks was determined. To evaluate the strength of sectional member, elastic analysis was carried out on the arch using linear elastic analysis program. The section force was compared with the nominal strength of arch section. It was concluded that the maximum load of all the specimens exceed the nominal strength of arch section. Those results of the strength evaluation were similar to the results of structural experiments. Therefore, it is concluded that the elastic analysis and ultimate strength model can effectively evaluate the strength for the proposed precast concrete arch composed of concrete blocks and reinforced joint in design.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.178-181
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• 2006

The purpose of this study is to investigate the inelastic behavior of precast segmental prestressed concrete bridge piers. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. An unbonded tendon element based on the finite element method, that can represent the interaction between tendon and concrete of prestressed concrete member, is used. A joint element is newly developed to predict the inelastic behaviors of segmental joints. The proposed numerical method for the inelastic behavior of precast segmental prestressed concrete bridge piers is verified by comparison with reliable experimental results.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.292-299
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• 2006

The purpose of this study is to investigate the inelastic behavior of precast segmental prestressed concrete bridge columns. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. An unbonded tendon element based on the finite element method, that can represent the interaction between tendon and concrete of prestressed concrete member, is used. A joint element is newly developed to predict the inelastic behaviors of segmental joints. The proposed numerical method for the inelastic behavior of precast segmental prestressed concrete bridge columns is verified by comparison with reliable experimental results.