• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.4
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• pp.126-132
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• 2010

Carbonation is the results of the interaction of carbon dioxide gas in the atmosphere with the alkaline hydroxides in the concrete. Reinforced steel corrosion due to concrete carbonation is one of main factors on the decrease in durability of RC structure. This study investigates the influence of carbonation on the bridges under various environment condition and quantifies the effect of carbonation various domestic field data. The failure probability of durability is evaluated on the basis of reliability concept. In addition, service life of the structures is predicted based on the intended probability of durable failure in domestic concrete specification. According to experimental results of the carbonation depth, the carbonation depth increased with structural age. It is analyzed that carbonation velocity of the structures under urban area and sea condition is 1.6-1.9 times faster than the river condition. Service life of the bridges under urban area and sea condition is decreased about 2.4-3.3 times than river condition.

• Journal of Digital Convergence
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• v.14 no.8
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• pp.211-221
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• 2016

The rapid trends toward outsourcing and collaboration have created complex multi-tier supply chains for construction and engineering industries. Working with suppliers and sub-suppliers requires continuous integration activities in order to maximize the performances of the entire supply chain. The purpose of this study is to identify the factors influencing the performances and long-term business relationship of second-tier suppliers in directed sourcing environment. This study proposes the asset specificity, trust, information-sharing and collaboration, as antecedents variables, and collected the survey responses from the second-tier suppliers in rebar manufacturing works. The statistical results indicate that the asset specificity, trust, information-sharing and collaboration have significant influences on the long-term business relationship of rebar manufacturing second-tier suppliers, but trust has no impact on the performances of second-tier suppliers at 5% significance level. Practical implications are also discussed.

• Journal of the Korea Concrete Institute
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• v.14 no.3
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• pp.321-330
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• 2002

This paper presents the experimental results of composite basement wall in which H-pile and reinforced concrete wall are combined using shear connector Twelve specimens are tested to evaluate the shear capacity of the wall. Main variables in the test are composite ratio, distribution of shear connector, thickness of wall, shear-span ratio, and shear reinforcement. Test results indicate that the shear capacity of test specimens varies with the foregoing variables except the composite ratio. The results are compared with strengths predicted using the equations of ACI 318-99, Zsutty, and Bazant. Based on this investigation, a method for predicting the shear strength of composite basement walls is proposed.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.530-539
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• 2002

In designing the boundary confinement of shear walls, the current design provisions and recommendations are empirical and prescriptive; they specify a certain confinement length and details, regardless of the actual requirement of ductility Therefore, they are inappropriate to the performance based-design. The purpose of the present study is to develop a ductility design method that Is applicable to the performance based-design of shear wall. For the purpose, experimental studies were performed to investigate variations in the ductility of shear walls with the length of the boundary confinement. Five specimens modeling the compressive zone of cross sections with different confinement area were tested against eccentric vertical load. Through the experimental studies, strength, ductility, and failure mode of the compression zone were investigated. In addition, nonlinear numerical analyses for the overall cross-sections of shear wall were performed to investigate variations of the stress and strain profiles with the length of compression zone. On the basis of the experimental and numerical studies, a ductility design method for shear wall was developed. By using the proposed design method, for a given ductility demand, the area of lateral confinement and corresponding reinforcement ratio can be precisely determined so that the ductile behavior and economical design are assured.

• Journal of the Korea Concrete Institute
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• v.23 no.6
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• pp.781-790
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• 2011

This paper contains the experimental results on strengthening effect of RC beams strengthened with NSM CFRP reinforcement and various strengthening details. A total of 14 beams have been tested to analyze strengthening effects of NSMR with various reinforcement details. Variables were cross-sectional shape of CFRP reinforcements, strengthening areas, grooves the number and location etc. Test results revealed that failure modes of NSMR showed two types. One was bond failure at interface between concrete and filler and the other was CFRP rupture. Also, failure mode of specimens with two grooves occurred premature bond failure because of superposition of failure surfaces at concrete around grooves. failure mode of MI specimens considered the equivalent section have changed bond failure to CFRP rupture and CFRP efficiency has improved 83% to 100%.

• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.341-349
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• 2012

Recently, as structures in Korea and other countries become much taller, larger, and more specialized, concrete used for constructions of these structures is required to have high performance characteristics. Especially, seismic performance of concrete must be improved to resist cyclic loading from earthquakes. Consequently, this study was performed to focus on developing optimal mixtures of high ductile fiber reinforced mortar with high ductility and durability, which have good serviceability, stability and reliability performances. Eventually, this material is expected to improve seismic performance of concrete structures such as load carrying capacity, ductility capacity, and energy dissipation capacity when applied to critical regions of flat plate slab-column joint. Ultimately, this research is intended to develop a material for basic designs and practical constructions of reinforced concrete structures. Test results showed that the maximum load carrying capacity, the ductility capacity, and the energy dissipation capacity of the test specimens titled RCFPP series were increased by 15%~34%, by 33%~37%, and by 2.14 times, respectively, compared to those of the standard specimen titled SRCFP.

• Journal of the Korea Institute of Building Construction
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• v.14 no.3
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• pp.216-222
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• 2014

Chloride attack to reinforced concrete structures located in seaside can cause a serious problem of durability and maintenance during the service life. Corrosion of reinforced steel bars in concrete decreases the bond strength and finally causes the detachment of concrete cover. Polymer cement mortar is usually adopted to repair the deteriorated RC structures because of its strong bonding property. The recovered load-carrying capacity after the repair was simulated by non-linear FEM analysis. The properties of concrete, repairing materials, bonding materials and reinforced bar were used as input data. Four types of redispersible polymer powders were used as components of polymer cement mortar. Pull-off tests were carried out to examine the bond properties such as rigidity and strength. Effects of a corrosion inhibitor and the loss of reinforced bars due to the corrosion were also considered in this study. FEM modeling and analysis were conducted to propose the universal model. Physical bonding in the relationship between repair materials and steel reinforced bar is more dominant than chemical bonding.

• Journal of the Korea Institute of Building Construction
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• v.14 no.5
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• pp.397-405
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• 2014

There are many literatures reporting that the service life of re-bars in concrete structures is reduced in the oceanic environment due to chloride attack. To solve this problem, this study used geo-polymer as a mix material for concrete to increase its resistance to salt damage, and the external voltage method, one of the electric methods, is was applied to evaluate the likelihood of re-bars in the oceanic structure being exposed to the extreme salt environment. The items evaluated include the natural potential of re-bars and the corrosion rate. The results of the tests showed that in all of the salt environmental conditions (submerged zone, tidal zone, and crack), the tested materials were remarkably effective compared with ordinary concrete. The corrosion protective property was found not only in the evaluation of the natural potential but also in the evaluation of the corrosion rate, suggesting that the external voltage method can be used stably for geo-polymer RC structures in an extreme salt environment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.175-181
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• 2010

The three truss models(equilibrium truss model, Mohr compatibility truss model, and the soften truss model) based on a rotating angle is called the rotating-angle model. The three rotating-angle models have a common weakness: they are incapable of predicting the so-called "contribution of concrete". To take into account this "contribution of concrete", the modern truss model(MCFT, STM) treats a cracked reinforced concrete element as a continuous material. By combining the equilibrium, compatibility, and the softened stress-strain relationship of concrete in biaxial state, MTM is capable of producing the nonlinear analysis of reinforced concrete structures composed of membrane element. In this paper, an efficient algorithm is proposed for the solution of proposed model incorporated with failure criteria. This algorithm is used to analyze the behavior of reinforced membrane element using the results of Hsu test.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.148-155
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• 2010

The purpose of this study is to propose and evaluate the continuous joint constructed with MRS system which is utilized for floor system in the parking structures or commercial retail buildings. Four specimens were fabricated and tested to examine the structural performance of the continuous joint with different joint detailing. Structural test for the specimens was undertaken to simulate the actual stress condition of the negative moment resisting connection in the prestressed precast concrete parking structures with 8m span. Based on the experimental results, the MRS system could be designed as the ductile continuous joint governed by flexural behavior. Therefore the MRS system developed in this study would provide a superior joint behavior to conventional double-tee system when constructing monolithic joint composed of simply supported precast members.