• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.983-988
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• 2000

Anchoring systems with structural stability and endurance have been one of the most important elements for PSC structures, especially for the structures using non-corrosive FRP tendons. FRP tendons are in increasing use for underground and coastal structures constantly contacted with fresh water or sea water because of their superiority to metallic ones in corrosion-resistance. In this study new non-metallic anchoring system for FRP tendons has been tested and investigated. The newly developed anchoring system utilizes FRP pipes and HEM (Highly Expansive Mortar). The major factors considered in this experiment were expansive pressure of HEM during its hydration and the strength of GFRP(Glass Fiber Reinforced Plastic) Pipe. Anchoring forces of the new anchoring system were investigated from the pull-out testes. The authors analyzed pull-out procedures of the FRP tendons in the various pipe filled with HEM and suggested an improved idea to develop novel non-metallic anchoring system for FRP tendons

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.119-120
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• 2023

Corrosion of the steel rebar in coastal environment caused huge economical loss of the globe. Therefore, coating on the steel rebar being used to mitigate the corrosion. In the present study, we have applied epoxy coating on arc thermal sprayed Al coating (a dual metal/polymeric coating) vis-à-vis compared with as coated one (Al coating). The corrosion studies were performed in simulated concrete pore solution with 3.5 wt. % NaCl solution. The morphology of the dual epoxy/Al coating is smooth while Al coating shows rankle and defects. Due to defects, Al coating is susceptible to corrosion while dual epoxy/Al coating has performed excellent compared to as coated one at extended period of immersion.

• Journal of the Korean Society of Safety
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• v.33 no.5
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• pp.60-69
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• 2018

This study aims to investigate in the assessment of salt damage conditions in concrete structures under marine environment conditions. It aims also to improve the durability of new concrete bridge through applying the life prediction method of salt damaged bridges. As measuring chloride contents of these bridges on the southwest coastal area, it is shown that the average amount of chloride on these surfaces close to shore is $10.5kg/m^3$. This figure is much higher than that of the Standard Specification for Concrete($1.5kg/m^3{\sim}2.5kg/m^3$). In contrast, it is shown the average amount of chloride on these surfaces in tide zone is $13.1kg/m^3$. Its figure is much lower than that of the Standard Specification for Concrete($20kg/m^3$). And the life of bridges is estimated about 17 years. To improve the durability for salt damage, these bridges are applied to surface treatment method which the replacement rate of furnace slag is 60%. Under this condition, it is expected to be 110 years. Consequently, it is clear that the use of slag replacement rate, surface treatment agent, and anti-corrosion agent to control chloride penetration effects of a submerge-based concrete bridge will be required.

• Earthquakes and Structures
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• v.23 no.6
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• pp.493-502
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• 2022

In recent decades, infrastructural development has exploded, particularly in the coastal region of Saudi Arabia. The rising demand of most consumed aggregate in construction can be effectively compensated by the alternative material like scoria which lavishly exists in the western region. Scoria is characterized as lightweight aggregate beneficially used to develop lightweight concrete (LWC) - a potential alternative of normal weight concrete (NWC) ensuring reduction in the structural element's size, increase in building height, comparatively lighter foundation, etc. Hence, the goal of this study is to incorporate scoria-based structural lightweight concrete and evaluate its impact on superstructure and foundation design beside contributing to the economy of construction. Fresh, mechanical, and rheological properties of the novel LWC have been investigated. The structural analyses employ the NWC as well as LWC based structures under seismic and wind loadings. The commercial finite element package - ETABS was employed to find out the change in structural responses and foundations. The cost estimation and SWOT analysis for superstructure and foundation have also been carried out. It was revealed that the developed LWC enabled a more flexible structural design. Notable reduction in the steel and concrete prices of LWC might be possible in the low-rise building. It is postulated that the cost-effective and eco-friendly LWC will promote the usage of scoria as an effective alternative in Saudi Arabia and GCC countries for structurally viable LWC construction.

• Journal of the Korea Institute of Building Construction
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• v.22 no.4
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• pp.337-345
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• 2022

The foundation of high-rise concrete building in coastal areas generally must be installed in an integrated manner, not separately, in order to prevent defects caused by stress on the upper and lower parts of the mounting surface and to manage the process smoothly. However, when performing integrated punching, there is a concern that temperature stress cracks may occur due to hydration heat. Due to the large member size, it is difficult to make a sufficient commitment, so it is necessary to mix concrete with high self-charging properties to ensure workability. In this research, the amount of high-performance spray and admixture used was adjusted as experimental variables to satisfy this required performance. Through the analysis of the results for each blending variable, it was found that the unit quantity was 155kg/m³ and the cement ratio in the binder was 18%, and the target values of the pre-concrete properties and compressive strength were satisfied. A four-component binder(18% cement, 50% slag fine powder, 27% fly ash, 5% silica fume) was used.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.278-287
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• 2000

In Korea, countermeasures against earthquake disasters such as the seismic performance evaluation and/or retrofit scheme of buildings have not been fully performed since Korea had not been experienced many destructive earthquakes in the past. However, due to more than four hundred earthquakes with slight/medium intensity occurred in the off-coastal and inland of Korea during the past 20 years, and due to the great earthquakes occurred recently in neighboring countries, such as the 1995 Hyogoken-Nambu Earthquake with more than 6,500 fatalities in Japan and the 1999 Ji-Ji Earthquake with more than 2,500 fatalities in Taiwan, the importance of the future earthquake preparedness measures in Korea is highly recognized. The main objective of this paper is to provide the basic data for development of a methodology for the future earthquake preparedness in Korea by investigating the concept and applicabilities of the Japanese Standard for Evaluation of Seismic Performance of Existing RC Buildings developed in Japan among the methodologies of all over the world. In this paper, a seismic performance evaluation method of the existing reinforced concrete buildings is proposed based on experimental data of columns and walls carried out in Korea by referring the Japanese Standard, especially focusing on the Strength Index(C) among the indices in the seismic capacity index(IS) equations. Also, the seismic capacities of two existing reinforced concrete buildings in Korea are evaluated based on the proposed methodology and the Japanese Standard, and the correlations between the seismic capacities by the proposed methodology and the Japanese Standard are discussed.

• Journal of the Korean Society for Railway
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• v.8 no.4
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• pp.367-371
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• 2005

Pile foundations are utilized when soil is so weak that shallow foundations are not suitable or point load is concentrated in small area. Such soil can be formed by the land reclamation works which have extensively been executed along the coastal line of southern and western parts of the Korean Peninsula. The working load at pile is sometimes subjected to not only compression load but also lateral load sad uplift forces. But in most of the practice design, uplift capacity of pile foundation is not considered and estimation of uplift capacity is presumed on the compression skin friction. This study was carried out to determine that the effect of embedment ratio and loading rate on uplift adhesion factor of concrete pile driven in clay. Based on the test results, the critical embedment ratio is about 9. Adhesion factor is constant under the critical embedment ratio, and decreasing over the critical embedment ratio. Also, adhesion factor is increased with the loading rate is increased.

• Nuclear Engineering and Technology
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• v.49 no.5
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• pp.1079-1089
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• 2017

Nuclear power plants under expansion and under construction in China are mostly located in coastal areas, which means they are at risk of suffering strong earthquakes and subsequent tsunamis. This paper presents a safety analysis for a new reinforced concrete containment vessel in such events. A finite element method-based model was built, verified, and first used to understand the seismic performance of the containment vessel under earthquakes with increased intensities. Then, the model was used to assess the safety performance of the containment vessel subject to an earthquake with peak ground acceleration (PGA) of 0.56g and subsequent tsunamis with increased inundation depths, similar to the 2011 Great East earthquake and tsunami in Japan. Results indicated that the containment vessel reached Limit State I (concrete cracking) and Limit State II (concrete crushing) when the PGAs were in a range of 0.8-1.1g and 1.2-1.7g, respectively. The containment vessel reached Limit State I with a tsunami inundation depth of 10 m after suffering an earthquake with a PGA of 0.56g. A site-specific hazard assessment was conducted to consider the likelihood of tsunami sources.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.59-60
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• 2023

The corrosion of steel rebar embedded in the coastal areas is corroding once the chloride ions ingress through the pores of the concrete. Therefore, in the present study, a 100 ㎛ thick Al and Zn coating was deposited by an arc thermal spray process onto the steel. The corrosion studies of these deposited coatings were assessed in 3.5 wt.% NaCl contaminated concrete pore (CP) solution with immersion periods. The results show that the Al coating is more corrosion resistance compared to the Zn coating attributed to the formation of gibbsite (γ-Al(OH)₃) whereas Zn coating exhibits Zn(OH)₂ onto the coating surface as passive layer. The Zn(OH)₂ is readily soluble in an alkaline solution. Alternatively, γ-Al(OH)₃ on the Al coating surface is less solubility in the alkaline pH, which further provides barrier protection against corrosion.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.2
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• pp.71-79
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• 2003

The estimation functions were proposed for calculating diffusion coefficient, chloride binding, and evaporable water. The program estimating chloride ion penetration was developed on the basis of these functions and the effects of humidity, curing temperature, water-cement ratio, and $C_3$A on chloride penetration were analyzed. The relative humidity increases the depth of chloride ion penetration and the trend becomes greater with aging. On the contrary, the influence of curing temperature on chloride ion penetration decreases with aging. By the way, the rise of $C_3$A in cement increases total chloride concentration on the surface as the bound chloride concentration increases but it decreases total chloride concentration on the inner part as the diffusion velocity of free chloride decreases. The fall of water-cement ratio decreases the chloride penetration depth rapidly. Therefore, the reduction of water-cement ratio may be the most effective method for reducing of the steel corrosion by chloride penetration.