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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korea institute for structural maintenance and inspection
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Journal DOI :
Korea Institute for Structural Maintenance Inspection
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Volume & Issues
Volume 14, Issue 6 - Nov 2010
Volume 14, Issue 5 - Sep 2010
Volume 14, Issue 4 - Jul 2010
Volume 14, Issue 3 - May 2010
Volume 14, Issue 2 - Mar 2010
Volume 14, Issue 1 - Jan 2010
Selecting the target year
Real-time Vibration Control of Bridges by MR damper and Lyapunov Control Algorithm
Heo, Gwang-Hee ; Jeon, Joon-Ryong ; Park, Seung-Bum ; Oh, Sung-Keun ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 55~61
This paper is concerned with an experimental research to random vibration control caused by external loads specially in bridges which tend to be structurally flexible. Experimenting on a reduced structure modelled on Seohae Grand Bridge, we inflicted a reduced form of El-centro wave on the model structure to a proper proportion. On the center of its middle span, we placed a shear type MR damper which was to control its vibration and also acquire its structural responses such as displacement and acceleration at the same site. The experiments concerning controlling vibration were performed according to a variety of theories including un-control, passive on/off control, and Lyapunov stability theory. Its control performance was evaluated in terms of the peak absolute displacements, the peak absolute accelerations and the total power required to control the bridge which differ from each different experiment method. Among all the methods applied in this paper, case of Lyapunov control method turned out to be the most effective to reduces of displacement and acceleration. Also, this method could to decrease consuming of external power for vibration control. Finally, it was noteworthy that Lyapunov control method was specially effective in the vibration control employing a semi-active damper such MR damper.
Serviceability Performance Evaluation of Vertical Vibration of Waflle Shape and Duble-Tee Precast Concrete Slabs
Shin, Jae-Sang ; Chung, Lan ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 62~69
In this study, the serviceability performance of Waffle Shaped(WAS) and Double-Tee(DT) precast concrete slabs were evaluated and compared based on the vertical acceleration magnitude induced by walking and heel drop loads. Tests were conducted for practical building structures of which floor systems used WAS and DT slabs. Natural frequencies of the slabs were similar to those obtained by using analytical models. The measured acceleration level was evaluated by vertical floor acceleration criteria presented by ISO-2631, AIJ(1991, Japan) and a previous study regarding floor vibration limit. Test results showed that both WAS and DT slabs satisfied all the criteria and Peak acceleration level of WA slabs was lower than that of DT slabs.
Influences of Grouting Pressure of Microcement to Upper Structures
Hwang, Chul-Sung ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 70~77
Microcement grouting and micro pile are frequently used for ground modification during tunnel construction. The influence of grouting pressure of microcement grouting and micro pile to the existing bridge which is directly over the constructing tunnel is investigated. Three dimensional seepage flow-structure interactive analysis considering firm water pressure with full stages of construction including the construction of upper bridge, microcement grouting, micro pile and tunnel is performed. The settlement and tilting of the pier of existing bridge violate the design code and the reaction of the bridge are highly increased after grouting. The stress of tunnel bracings such as rockbolt and shotcrete also exceed the limit of the code. The pressure of microcement grouting is confined by bedrock and transmit to the surrounded soil and the upper bridge. Microcement grouting needs mid-high pressure to penetrate through weak fault plane and the pressure greatly influence the safety of the upper structure. It is important to decide and care the grouting pressure to improve weak fault plane directly under the existing structures and the pressure of microcement grouting should be considered in underground analysis.
Characteristics of Temperature Distribution of Axially Loaded CFT Column with Fire Protection
Kim, Hae-Soo ; Yoon, Sung-Kee ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 78~85
When the fire occur, concrete filled steel tube(CFT) columns expected to form a much distinction in a fire resistance performance according to a kind of fire protection because the steel surface is directly exposed to high temperature. In this study, an experiment by three factors which were kind of fire protection, thickness of protection and time was performed to get the characteristics of temperature distribution types of CFT column with fire protection. As the result of this study, on a basis of heating temperature, spray protection was the most superior in a fire resistance performance, fireproof paint was next, and without fire protection was most inferior. In a heating time-location relationship, the temperature increased slowly on the surface of the concrete, but the temperature increased sharply on the surface of the steel.
Evaluation of the Railroad Track Life Cycle Based on the Metro Rail Wear Data Regression Analysis
Jeong, Min-Chul ; Kim, Jung-Hoon ; Lee, Jee-Ha ; Kang, Yun-Suk ; Kong, Jung-Sik ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 86~93
The wear of railway track affects loss of rough ride, noise or vibration of train and traveling safety. Moreover as the track is worn away, this promotes destruction of structural mechanism of rail track which can bring about increasing of rail track maintenance cost drastically. For this reason, it is very important and interested research subject to design railway track structure and to analyse train movement mechanism based on systematic analysis of the reasons causing rail wear possible in real field. In this research, for the efficient maintenance, Life Cycle Performance of rail track and maintenance characteristics are computed considering some track components such as track type, contracting type, sleeper type and roadbed type. Time - Wear probabilistic distribution relationship as well as multiple regression analysis based on time, curvature and wear data are computed to predict the service life remainder of railway track and to be adapted to safety assessment.
Shear Performance Evaluation of the Joint between Hollow Core Slabs
Hong, Geon-Ho ; Baek, Jong-Sam ; Park, Hong-Gun ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 94~101
Recently, the interest of precast concrete is increased for rapid construction in construction fields. Experimental study about the shear performance of the joint between hollow core slabs which have internal core to reduce their weight was performed. Main test variables were thickness of the topping concrete and existence of the wiremesh. Total 8 specimens including 4 in-plane shear and 4 out of plane shear were tested. Test results were analyzed in terms of cracking load, failure load, failure aspect, stiffness and ductility, and compared its design load to develop optimum design details. Test results indicated that the shear performance of the non-shrinkage mortar specimen was similar to that of 30mm thickness topping concrete specimen, and the effect of wiremesh reinforcement did not affect the failure load or stiffness of the specimens but the increase of ductility. And this paper presents the comparison results of the test results and design load to provide the optimum detail of the joint design between the hollow core slabs.
Reliability-Optimal Design Method of High-Speed Railway Bridges Based upon Expected Life-Cycle Cost
Lee, Woo-Sang ; Bang, Myung-Seok ; Han, Sung-Ho ; Lee, Chin-Ok ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 102~110
The reliability evaluation may be a efficient method for estimating of the quantitative structural safety considering the effect of uncertainties included in high-speed railway bridges. The expected life-cycle cost(LCC) based upon the reliability evaluation will reasonably offer the safety level and design criteria of high-speed railway bridges. Therefore, this study determined the expected life-cycle cost and optimal design method of high-speed railway bridges on the basis of the result of the numerical analysis and reliability evaluation. For this, after creating various design method based upon the standard design of high-speed railway bridges, the numerical analysis is conducted on each of the alternative design methods. The reliability evaluation by the design strength limit state function is conducted considering the effect of external uncertainties on the basis of the numerical analysis result. The expected life-cycle cost of high-speed railway bridges is calculated on the basis of the reliability evaluation result by each of the alternative design methods. Also, the optimal design method is determined using the calculated expected life-cycle cost. In addition, The result of reliability evaluation and expected life-cycle cost of optimal design method are examined considering the effect of internal uncertainties. It is expected that the result of this study can be used as a basic information for the systematic safety evaluation and optimal structure design of high-speed railway bridges.
Carbonation Analysis of Bridge Structures in Urban Area Based on the Results of the Field Test
Kim, Hun-Kyom ; Kim, Sung-Bo ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 111~118
Reinforced steel corrosion due to concrete carbonation is one of main factors on the durability of RC structure. The carbonation velocity have an effect on carbon dioxide density, concrete quality and structural shape. Specially, these problems have increased in urban area. This study investigates the carbonation status of the bridges and quantifies the effect of carbonation based on various domestic field data. The failure probability of durability is evaluated on the basis of reliability concept. According to experimental results of the carbonation depth, the carbonation depth increased with structural age and carbonation velocity decreased with high strength of concrete. In most cases, the failure probability of durability by carbonation was more than 10%. Also, The results requires the minimum cover thickness of 70-80mm for target safety index(
=1.3) proposed by Korean concrete specification.
Compressive Behavior of Concrete with Loading and Heating
Kim, Gyu-Yong ; Jung, Sang-Hwa ; Lee, Tae-Gyu ; Kim, Young-Sun ; Nam, Jeong-Soo ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 119~125
The performance deformation of concrete can be caused by many factors such as load, thermal strain and creep at high temperature. Japan, Europe and America have been doing various experimental studies to solve these problems about thermal properties of concrete at high temperature, each study has generated different results due to a heating methods, heating hours, size of specimens and performance of a the loading, heating method, size of specimen and heating machine. There has been no unified experimental method so far. Therefore, this study reviewed experimental studies on the strength performance of concrete subject to heating and loading method. As a result, compressive strength of specimen prestressed increase in the temperature range of between
. Also, results can be analyzed as compare equation of compressive strength at elevated temperature with CEN and CEB code.
Service Life Prediction and Carbonation of Bridge Structures according to Environmental Conditions
Kim, Hun-Kyom ; Kim, Sung-Bo ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 126~132
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.
Material Development of Eco Water Tank with High Density Polyethylene and Low-temperature Concrete
Chang, Chun-Ho ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 133~140
The purpose of this study is to evaluate the new eco water tank which is made of high density polyethylene and concrete with low temperature cement. The strength and failure mode of eco water tank was examined through tensile test with mixture of concrete and HDPE, temperature monitoring for various kind of concrete, admixture contains etc. The strength and failure mode were examined through tensile test with mixture of concrete and HDPE, temperature monitering for different kinds of concrete, strength test with different admixtures etc. It was found that shear connector between concrete and HDPE effects significantly contributed to the combined structures. ㄱ type shear connector results in tensile strength of up to 40% compared to that of V type shear connector. Based on test result, the new eco composite tank improved the stability and safety the old one and demonstrated the applicability and capability.
Improvement of Insulation System for LNG Storage Tank Base Slab
Lee, Yong-Jin ; Lho, Byeong-Cheol ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 141~147
Liquefied natural gas(LNG) is natural gas that has been converted temporarily to liquid form for ease of storage and transport it. Natural gas is the worlds cleanest burning fossil fuel and it has emerged as the environmentally preferred fuel of choice. In Korea, the demand of this has been increased since the first import from the Indonesia in 1986. LNG takes up about 1/600th the volume of natural gas in the gaseous state by cooling it to approximately
. The reduction in volume therefore makes it much more cost efficient to transport and store it. Modern LNG storage tanks are typically the full containment type, which is a double-wall construction with reinforced concrete outer wall and a high-nickel steel inner tank, with extremely efficient insulation between the walls. The insulation will be installed to LNG outer tank for the isolation of cryogenic temperature. The insulation will be installed in the base slab, wall and at the roof. According to the insulation's arrangement, the different aspects of temperature transmission is shown around the outer tank. As the result of the thermal & stress analysis, by the installing cellular glass underneath the perlite concrete, the temperature difference is greatly reduced between the ambient temperature and inside of concrete wall, also reducing section force according to temperature load.
Effect of Repeated Addition of Admixture on Mechanical Properties of Concrete
Lee, Si-Woo ; Yi, Seong-Tae ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 148~153
Concrete used as structural materials in construction fields is supplied as a type of carry and placement by ready-mixed concrete (RMC) truck after proportioning in batch plant. However, during conveying of concrete to the field, due to traffic jam, weather, etc., it is not easy to maintain adequate slump. In this case, we think that the insert of an admixture to concrete has no problem in concrete. For RMC, when the slump is not sufficient, the truck driver insert water additionally without any considerations. After that, concrete is placed after re-mixing and this leads to serious reasons such as strength reduction less than design strength considered in the structural design. Accordingly, in this study, to solve the problem to insert water without realistic reasons in RMC, basic experimental studies were performed. Admixtures used frequently in fields were selected and addition's repeated time and elapsed time interval after initial addition of the admixture were selected as main variables. Authors want that the results of this study is used as basic data to resolve the question.
Evaluation of Creep Models with the Consideration of Concrete's Strength Level
Moon, Jae-Heum ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 154~159
Recent concrete structures have been being constructed with higher strength concrete than normal strength concrete. Therefore, it is necessary to review the applicabilities of current design codes and models for the prediction of mechanical behaviors of concrete materials such as creep. To investigate the applicability of creep model with the consideration of the strength level of concrete, three current models (ACI 209R, CEB-FIP MC90 and EC2) were studied and compared with series of experimental results. It was shown that EC2 model which is the updated model of CEB-FIP MC90 better predicts creep coefficient for high strength level concretes and showed relatively good agreements with experimental data.
Chloride Ion Penetration Properties of Normal Strength High-Fluidity Concrete Using Lime Stone Powder
Choi, Yun-Wang ; Moon, Jae-Heum ; Eom, Joo-Han ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 160~168
Recently, there are a lot of researches related to the high-fluidity concrete (HFC) with field applications. However, most applications and studies are with concretes with high strength level so there are little studies about durability evaluations such as chloride ion penetration properties with normal strength concrete. Therefore, to evaluate the durability of HFC with normal strength level, this study performed the chloride ion penetration test and observed the micro pore distribution with normal strength HFC which contains limestone powder. Experimental results showed that most micro-pores have diameters between 0.005 to 0.05
with HFCs using limestone powder and the average diameter becomes larger with the increase of limestone powder content. Also, it was shown that, with the increase of the limestone powder content, penetration depth and diffusion coefficient of chloride ion increased and diffusion coefficient had good relationships with compressive strength and average pore diameter with the coefficient of determination over 0.90.
Optimal strengthening in RC Hollow Slab Bridges using
Choi, Se-Hyu ; Park, Kyung-Sik ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 4, 2010, Pages 169~178
In this study, the optimal strengthening by micro genetic algorithm(
-GA) method is proposed for improvement of load-carrying capacity of RC hollow slab bridges using external prestressing. The Qeen-post type and King-post type are considered for the optimal strengthening. The type for optimal strengthening, deviator, areas of tendons and the number of anchor are calculated by
-GA. The objective function is constituted with dimensionless cost of tendon and steel for optimal strengthening. The constraints are formulated by design specification for bridges and anchors. The validity of this study is presented by analysis of the results after the optimal strengthening of the RC hollow slab bridge.