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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korea institute for structural maintenance and inspection
Journal Basic Information
Journal DOI :
Korea Institute for Structural Maintenance Inspection
Editor in Chief :
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
The Characteristics of Strength Development and Curing Cycle of the Steam Cured Concrete
Kim, Kwang-Don ; Kim, Choon-Ho ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 63~71
This paper is about a research of steam curing which is one of the curing methods for accelerating the early-age strength of pre-cast concrete. With cylinder mold and mock-up specimen, the research was executed to study the best cycle of steam curing temperature through quantifying cycle of steam curing and maximum temperature, while the required strength is developed under the early-age. Moreover, causes and measurements for the high temperature of concrete, which is due to the steam curing, and the crack, which occurs when removing steel form, are stated. Ultimately, the economical method of producing, which satisfies early-age strength development and quality assurance while manufacturing PC structure, is stated.
PZT Sensor-based Structural Health Monitoring for CFRP Laminated Concrete Structures
Ryu, Sung-Chan ; Kim, Ju-Won ; Lee, Chang-Gil ; Park, Seung-Hee ; Park, Sun-Kyu ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 72~78
A CFRP (Carbon Fiber-Reinforced Plastic) strengthening method is being very widely used to increase the load-carrying capacity of host structures, especially for bridges. However, not only flexure and shear failures but debonding failure also might occur in CFRP strengthened concrete structures. The CFRP debonding failure would cause a collapse accident of the host structure. Therefore, real-time health monitoring about the CFRP bonding condition is strongly required. In this study, a feasibility of the impedance-based damage detection method using PZT sensors is investigated through a series of experimental study monitoring both concrete cracks and CFRP debonding defects.
Flexural Behavior of Hybrid Fiber Reinforcement Strengthened RC Beams
Yi, Seong-Tae ; Lee, Chin-Yong ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 79~86
This study was performed to evaluate the flexural behavior of Hybrid fiber sheet (HFC) and Hybrid fiber bar (HFB) strengthened reinforced concrete (RC) beams. According to test results, Hybrid fiber reinforcement strengthened RC beams showed approximately 60 to 200% higher reinforcing effects than that of un-reinforced specimens. In addition, the reinforced beams showed the ideal failure pattern, which is failed presenting the ductile behavior after yielding of the reinforcing bar. More specifically, in the case of HFB reinforced RC beams, the difference with puttying method was not apparent since HFB beams reinforced using the injection of epoxy and bonding of putty showed the similar failure patterns.
An Experimental Study on the Quality Properties of High Strength Concrete by the Replacement Ratio SFFB as Substitutes of Silica-fume
Lim, Byung-Hoon ; Lee, Sang-Soo ; Yun, Hyun-Do ; Yoon, Gil-Ho ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 87~92
This study set up 25, 35% for silica fume, SFFB's 2 level and water-combination material ratio, silica fume 10% for substitution ratio, and 4 level of SFFB 5, 10, 15(%) in order to compare and analyze the quality characteristic of ultra high strength concrete according to the substitution ratio of silica fume free binder (SFFB) that can be utilized as a substitute material for silica fume. As a result of an experimentation, the lower water-combination material ratio was, the higher addition ratio of high performance water-reducing agent for securing target liquidity increased, and it indicated the tendency that addition ratio of high performance water-reducing agent decreases because of material characteristic that SFFB has a lower absorptiveness than silica fume. The best strength was shown when SFFB substitution ratio is 10% at compressive strength and when substitution ratio is 15% at tensile strength, and it was indicated that at autogenous shrinkage contraction decreases compared to Plain(SF) regardless of substitution ratio of W/B and SFFB.
The Effects of Braking of Trains and Roughness of Rails on the Dynamic Behaviors of Bridges
Kim, Doo-Kie ; Yang, Sin-Chu ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 93~101
The effects of braking of trains and roughness of rails on the dynamic behavior of bridges are studied. The train-bridge interaction is considered by solving Lagrange's equation of motions. Newmark's direct integration is used to solve the governing equations. Dynamic train loads acting on piers at each time step are evaluated, and the wheel-rail roughness effect is considered by using the PSD curve of the rail. The model of braking forces in bridge section is based on the change of deceleration mentioned in ASTM(American Society for Testing and Materials) E503-82. Only skidding frictions without considering rolling frictions are modeled, and the friction coefficient of 0.25 is assumed. Parametric studies in a simply supported PC Box girder bridge are carried out to verify the present method and to analyze the effects of train speed, wheel-rail roughness, braking forces on dynamic train loads.
Evaluation of Bond Behavior of Reinforced Concrete Beams with High-Strength Transverse Reinforcement
Kim, Sang-Woo ; Kim, Young-Sik ; Baek, Seung-Cheol ; Kim, Kil-Hee ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 102~109
This paper investigates the bond behavior of reinforced concrete beams having high-strength transverse reinforcement. A total of four reinforced concrete beams were tested in this study to estimate the bond capacity of the proposed U-shape reinforcement. The proposed U-shape reinforcement not only has a simple structure to install, but also can increase the bond capacity of reinforced concrete beams by controling bond cracks. This study follow the test method proposed by Ichinose to obtain the bond stress and the bond slip of the specimens. The main test parameters were the yield strength, ratio, and reinforcing types of transverse reinforcements. It was found that the proposed U-shape reinforcement was able to effectively improve the bond performance of reinforced concrete beams with high-strength transverse reinforcement.
The Effect of Steel-Fiber Reinforcement on the Compressive Strength of Ultra High Performance Cementitious Composites(UHPCC)
Kang, Su-Tae ; Park, Jung-Jun ; Ryu, Gum-Sung ; Kim, Sung-Wook ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 110~118
This research dealt with the effect of steel-fiber reinforcement on the compressive strength of ultra high performance cementitious composites (UHPCC) and compared with that in normal steel-fiber reinforced concrete(SFRC). With wide range of compressive strength of UHPCC, experiments on the fiber reinforcement effect confirmed that the compressive strength in UHPCC is also improved by adding fibers as in normal SFRC. The experimental results were compared with previous researches about reinforcement effect by adding fibers, which are limited within 100MPa compressive strength. The comparison revealed the linear relationship between
and RI regardless of the magnitude of compressive strength, from which a general equation to express the effect of fiber reinforcement, applicable to various SFRC's with wide range of compressive strength including UHPCC.
A Long-term Durability Prediction for RC Structures Exposed to Carbonation Using Probabilistic Approach
Jung, Hyun-Jun ; Kim, Gyu-Seon ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 119~127
This paper provides a new approach for durability prediction of reinforced concrete structures exposed to carbonation. In this method, the prediction can be updated successively by a Bayes' theorem when additional data are available. The stochastic properties of model parameters are explicitly taken into account in the model. To simplify the procedure of the model, the probability of the durability limit is determined based on the samples obtained from the Latin Hypercube Sampling(LHS) technique. The new method may be very useful in design of important concrete structures and help to predict the remaining service life of existing concrete structures which have been monitored. For using the new method, in which the prior distribution is developed to represent the uncertainties of the carbonation velocity using data of concrete structures(3700 specimens) in Korea and the likelihood function is used to monitor in-situ data. The posterior distribution is obtained by combining a prior distribution and a likelihood function. Efficiency of the LHS technique for simulation was confirmed through a comparison between the LHS and the Monte Calro Simulation(MCS) technique.
Study on Adhesive Strength of Polymer Modified Cement Mortar for Maintenance in Concrete Structure
Park, Sang-Soon ; Kim, Jung-Heum ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 128~135
Polymer-modified cement mortar(PCM) has been widely used for strengthening of the concrete structures due to its excellent physical properties such as high strength and durability. Adhesive strength or behavior, on the other hands, between PCM and concrete is very important in strengthening the concrete member using PCM. Therefore the adhesive failure mechanism between PCM and concrete should be fully verified and understood. This study was performed to evaluate adhesive strength of PCM to the concrete by the direct pull-out test. In the direct pull-out tests, the adhesive strength under the various pre-treatment conditions such as immersion, thunder shower, freezing and thawing are evaluated. Also, the field direct pull-out test are performed to investigate the adhesive strength of mock-up test specimens. In the results of the test, the adhesive strength value by field test are lower than those of the standard curing condition. From these comparison and investigation, field test result was similar with the thunder shower test result. The results of the test was used to evaluate the korean industrial standard of polymer modified cement mortars for maintenance in concrete.
A Study on the Decision of Influence Range of External Temperature in the Tunnel Using Thermal Camera
Lee, Yu-Seok ; Lee, Tea-Jong ; Park, Gwang-Rim ; Oh, Young-Seok ; Cha, Cheol-Jun ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 136~143
There are three parts of tunnel which are influenced by outside temperature, entrance, exit and vent. These parts showed different tendency of deterioration(very rapid deterioration speed, wide range of defects, etc) compared with last parts of tunnel. Therefore, it needs to have different points of view when civil engineers analyze the defects on these parts and apply the retrofit or rehabilitation methods for them. However, when we conduct maintenance works, precise inspection and precise safety diagnosis, these defects had been neglected because those were considered as unimportant defects and caused from temporary weather and temperature change. In this study, two urban tunnels were analyzed to decide the range of tunnel which are influenced by outside temperature using a thermal camera, and to find out the causes of defects on these parts. From the results, the main points of maintenance were presented.
A Study on Bond Strength of Cement-Based Filler and Flexural Strength of RC Beam Strengthened with GFRP by Filler Thickness
Choi, Ha-Jin ; Choi, Young-Woong ; Park, Jong-Chul ; Jung, Si-Young ; Choi, Oan-Chul ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 144~152
In this study, cement-based filler is used as an adhesive instead of organic adhesive, epoxy because there were problems under wet condition. First, the bond strength of cement-based filler was measured and the result was satisfied with KS F 4716. However, in case of wet condition, bond strength of epoxy adhesive decreased
in 7 days and
in 14 days from pilot test. This implies that there would be a problem on reinforced concrete structure in wet condition, such as tunnel and sewage box. In the second experiment, the flexural strength of RC beams with GFRP using different thickness of cement-based filler was investigated, and the result was indicated 113%, 66%, 75% increase in 10mm, 20mm, 30mm thickness, respectively. From the result, it was known that 10mm filler thickness produces stable bond performance.
A Study on the Strength Property of Recycled Fine Aggregate (Wet Type) Mortar with Blast Furnace Slag
Shim, Jong-Woo ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 153~160
This study aims to obtain technical data for improvement of utilization of Blast Furnace Slag(BFS), recycled aggregate in the future by complementing fundamental problems of BFS such as manifestation of initial strength and excessive alkali quantity as well as weakness of recycled fine aggregate through manufacturing of recycled fine aggregate mortar using BFS. The recycled aggregate includes the cement paste hardened as the surface and the type of the aggregate, which contains plenty of calcium hydroxide(
) as well as the unhydrated cement. Accordingly, the objectives of this study are to inspect the manufacturing the recycled fine aggregate mortar used with blast furnace slag, to consider the effects of the recycled aggregate on the strength development of ground granulated blast furnace slag, and then to acquire the technical data to take into consideration the further usages of the recycled aggregate and blast furnace slag. In eluted ions from recycled aggregate, it showed that there were natrium(
) and kalium(
), expected to be flown out of unhydrated cement, as well as calcium hydroxide(
). Application of this water to mix cement mortar with ground granulated blast furnace slag was observed to expedite hydration as calcium hydroxide(
) and unhydrated cement component were expressed to give stimuli effects on ground granulated blast furnace slag. The results of the experiment show that the recycled aggregate mixed with blast furnace slag has comparatively higher hydration activity in 7 day than the mortar not mixed with one in 3 day mortar does, causing the calcium hydroxide in the recycled fine aggregate to work on as a stimulus to the hydration of ground granulated blast furnace slag.
Nonlinear Analysis of Cyclic Lateral Forced RC Shear Wall
Kim, Geon-Woo ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 161~168
Practicing engineers and researchers need computational tools that estimate accurately the cyclic response of RC walls, and in particular, force and deformation capacities and their materials strains. So this paper describes a nonlinear truss modeling approach for reinforced concrete walls, or in general, for plane stress reinforced concrete elements subjected to cyclic reversals. Nonlinear vertical, horizontal, and diagonal truss elements are used to represent concrete and steel reinforcement. The wall having aspect ratio of 1.2 was chosen to be compared with the experimental results. Here, four types of main diagonal member models and three types of diagonal members models were applied to find out more accurate results of analysis.
Systematic Improvement of Safety Management-Related Laws in Domestic Demolition Works
Ha, Gee-Joo ; Ha, Jae-Hoon ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 169~178
Generally speaking, the demolition works is the subsequent construction activity which has been done after building life-span of twenty two years or so. However, it was not prepared suitable systems and laws and regulations as long-term solutions. In this study, it was suggested the improvement guideline of safety management-related laws in domestic demolition works. The three improvement of laws was suggested as follows.
First, it was suggested proposals for demolition works standards in safety management plan of management law for construction activity.
Secondly, it was provided improvements for standard safety work guide of demolition works of industrial safety and health law.
Third, it was proposed integration method of redundancy in safety management plan and risk assessment regulations.
Experimental Study for Characteristics of Assessment of Neural Networks for Structural Damage Detection
Oh, Ju-Won ; Heo, Gwang-Hee ; Jung, Eui-Tae ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 179~186
When a structure is damaged, its dynamic responses (natural frequency, acceleration, strain) are found to be changed. The ANN(Artificial Neural Network) damage-assesment method is that some measured dynamic signals from the structural changing dynamic responses are applied to ANN to assess the structural damage. Although there have been some studies on a certain typical cases so far, it is rare to find studies about the characteristics of the ANN damage-assesment method or about its applicability, its strength and weakness. So this study researches on the characteristics of ANN damage assesment method and on a problem in application of the various dynamic responses to ANN. What the ANN damage assessment method usually does in past researches is to teach an ANN by using some response signals obtained from damaged structures under one kind of excitations and to identify the locations and the extents of damage of same structures under the same excitations. However, the excitations inflicted on the structures are not always the same. Thus this study experiments whether a ANN which is trained using the same excitations is able to identify the damage when different excitations inflict. All response signals are obtained from experimental models.
Study on Determination of Proper Pillar Width in Road Tunnel Design Stage
Yang, Tae-Seon ; Kim, Jae-Kyoung ;
Journal of the Korea institute for structural maintenance and inspection, volume 14, issue 5, 2010, Pages 187~194
As the design of the pillar width (PW) of the parallel tunnels in downtown area, in which are located in plains zone with deep alluvium compared with mountain tunnels, is directly related with pre-compensation payment and costs of the underground area, it has to be planned as to keep minimum distance while securing the stability of the parallel tunnels. Although PW of downtown road tunnel in Korea is standardized as 1.5D(D: diameter of the tunnels), PW sometimes has to be reduced within 1.5D to adjust the tunnel lines to the city plan in the cases of the inlet and outlet of the tunnels. In this paper, the design and the analyses of optimum PW of the NATM type road tunnel in the downtown area are introduced. The relationship among the tunnel line planning and underground compensation fee, and ground characteristics are evaluated. In the determination of PW distance, the numerical analyses of underground road tunnels were performed, including the use of the strength decrease method and strength/stress ratio method. In the cases of inlet and outlet part of the tunnels where the stability of the pillars is poor due to contiguous construction of the parallel tunnels, the reinforcement methods are recommended for securing the stability. Numerical verification was performed for the reinforcement proposed.