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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 16, Issue 6 - Nov 2012
Volume 16, Issue 5 - Sep 2012
Volume 16, Issue 4 - Jul 2012
Volume 16, Issue 3 - May 2012
Volume 16, Issue 2 - Mar 2012
Volume 16, Issue 1 - Jan 2012
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Experimental Study on the Confinement Effect of Headed Cross Tie in RC Column Subjected to Cycling Horizontal Load
Seo, Soo Yeon ; Ham, Ju Ho ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 1~10
DOI : 10.11112/jksmi.2012.16.5.001
This paper presents an experimental result and suggests the confinement effect of headed cross tie in reinforced concrete(RC) columns subjected to cycling horizontal loads under constant axial load. Five RC columns specimens were manufactured, taking confined type of transverse reinforcement, whether or not using cross tie, end detail of cross tie (hooked or headed), and axial stress in column as major variables, Cyclic horizontal load applied to the columns under constant axial stress and the effect of cross tie to structural capacity of column was evaluated from the test. The column without cross tie failed showing bending deformation of hoop with crack in core concrete at low horizontal load while the column with cross tie showed quite improved strength and ductility by suppressing bending deformation of hoop as well as buckling of longitudinal bar at once even after crack in core concrete. At high lateral displacement, the column with hooked cross tie showed the failure pattern loosing the confining force of cross tie since the
hooked part of cross tie was stretched out and the cracked core concrete lumps were came off. However, the column with headed cross tie showed very stable behavior since the head of cross tie effectively confined the hoop and longitudinal bars even at high lateral displacement.
Development of Strengthening Method Using the Vacuum Impregnation in RC Members
Yi, Seong Tae ; Song, Yeong Sun ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 11~18
DOI : 10.11112/jksmi.2012.16.5.011
Deterioration and weakening is advanced in compliance with flowing of time and the change of environment in RC structures. Consequently, strength and serviceability decreases, finally, the life of infrastructure shortens and safety characteristics decreases. Accordingly, in this study, a new method to develop a strengthening method using the vacuum impregnation, which increases durability of the infrastructure occurred the safety reduction due to the performance degradation and increases the life of infrastructure by improving the durability compared to the existing method, was planned. For flexural tests, the maximum strength was a low-end order from high order as follows: (1) vacuum impregnation with 2 fold reinforcement, (2) fiber sheet 2 fold reinforcement, (3) vacuum impregnation with 1 fold reinforcement, (4) fiber sheet 1 fold reinforcement, and (5) nothing. Also, for confirmation results about durability, when the fiber reinforcement is being exposed to the inferior environment, the remaining tensile strength exceeded of 90% or more for all environments. This is because the reinforcement used in this research shows the excellent resistance in severe environment.
A Case Study on Cause Analysis for Longitudinal Crack of Duct Slab in Tunnel
Park, Sung Woo ; Park, Seung Su ; Hwang, In Baek ; Cha, Chul Joon ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 19~28
DOI : 10.11112/jksmi.2012.16.5.019
In this study, cause of longitudinal crack which is found on duct slab of road tunnel is studied. In-depth investigation, such as visual inspection, non-destructive testing and geometrical surveying of duct slab, is carried out. In order to perform cause analysis, the investigated results are compared to the results of numerical analysis. Many factors, which cause longitudinal crack, are classified as constrained condition of the duct slab, location of the rebar, temperature, shrinkage and so on. According to the classified causes of longitudinal crack, numerical analysis is performed considering construction stage of the tunnel lining. Especially, in order to predict shrinkage stain due to discrepancy of curing date, ACI-209 model, KCI structural design code and other researcher's shrinkage test results are compared. The results show that shrinkage strain is one of the main factors causing longitudinal crack. Other investigated tunnels are classified along with the construction method of duct slab and patterns of cracks. As a result, improving ways to construct duct slab are suggested.
The Risk Assessment and Prediction for the Mixed Deterioration in Cable Bridges Using a Stochastic Bayesian Modeling
Cho, Tae Jun ; Lee, Jeong Bae ; Kim, Seong Soo ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 29~39
DOI : 10.11112/jksmi.2012.16.5.029
The main objective is to predict the future degradation and maintenance budget for a suspension bridge system. Bayesian inference is applied to find the posterior probability density function of the source parameters (damage indices and serviceability), given ten years of maintenance data. The posterior distribution of the parameters is sampled using a Markov chain Monte Carlo method. The simulated risk prediction for decreased serviceability conditions are posterior distributions based on prior distribution and likelihood of data updated from annual maintenance tasks. Compared with conventional linear prediction model, the proposed quadratic model provides highly improved convergence and closeness to measured data in terms of serviceability, risky factors, and maintenance budget for bridge components, which allows forecasting a future performance and financial management of complex infrastructures based on the proposed quadratic stochastic regression model.
Experimental Study on Shear Performance of RC Beams with Electric Arc Furnace Oxidizing Slag Aggregates
Lee, Yong Jun ; Jeong, Chan Yu ; Lee, Bum Sik ; Kim, Sang Woo ; Kim, Kil Hee ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 40~48
DOI : 10.11112/jksmi.2012.16.5.040
This study evaluates the shear performance of reinforced concrete beams with electric arc furnace oxidizing slag aggregates generated from iron manufacture. A total of six simple supported specimens were cast and tested in shear. The main test variables were the type of aggregates and the amount of shear reinforcements. The specimens under four point loading had a shear span-to-depth ratio of 2.5 and a rectangular section with a width of 200mm and an effective depth of 300mm. Existing equations to predict the shear strength of the specimens were used in this study. Furthermore, a finite element analysis using shear analytical model was performed to trace the shear behavior of the specimens with electric arc furnace oxidizing aggregates. From the test results, the shear performance of specimens with electric arc furnace oxidizing aggregates is similar to that of specimens with natural aggregates.
Evaluation of Structural Performance of Reinforced Concrete Beams According to Water Absorption of Recycled Coarse Aggregate
Kim, Sang Woo ; Han, Dong Seok ; Lee, Hyun Ah ; Ko, Man Young ; Kim, Kil Hee ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 49~58
DOI : 10.11112/jksmi.2012.16.5.049
This study estimates the flexural behavior of reinforced recycled aggregate concrete beams. Three specimens with different types and water absorption of coarse aggregates were constructed and tested. Not only all specimens were designed to be subjected to 4-point concentrated loads, but also the shear span-to-depth ratio of 2.5 was adjusted to all specimens to increase the effect of shear. A nonlinear flexural analysis considering the tension stiffening effect of concrete was performed to predict the moment versus curvature relationships of the specimens. Furthermore, a nonlinear finite element analysis considering the effect of shear was carried out to estimate the behavior of the specimens. It can be found from experimental results that the flexural strength and the crack properties of the specimens with recycled coarse aggregate having a water absorption of 6% were similar to those of the specimen with natural aggregates. The comparison between the experimental and analytical results showed that existing analytical methods can be successfully used to predict the behavior of reinforced recycled aggregate concrete beams.
Durability Characteristics of Limestone Powder added Concrete for Environment-Friendly Concrete
Choi, Woo Hyeon ; Park, Cheol Woo ; Jung, Won Kyung ; Jeon, Beom Joon ; Kim, Gyu Seon ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 59~67
DOI : 10.11112/jksmi.2012.16.5.059
During the manufacturing of Portland cement, CO2 gas is also necessarily produced through both decarbonation of calcium carbonate and kiln burning. By partially replacing the Portland cement with limestone powder, which is an inert filler in a concrete mixture, CO2 consumption can be reduced in a construction field. This study is to investigate the fundamental durability characteristics of limestone powder added concrete. Experimental variable was the replacement ratio of limestone powder from 0% to 25% with 5% increment. Durability characteristics were investigated by resistance to freeze-thaw, alkali-silica reaction and de-icing chemical in addition to the properties of fresh concrete. From test results, it was observed that the addition of limestone powder did not significantly affect the resistance to freeze-thaw reaction and de-icing chemical. The addition of limestone powder reduced the occurrence potential of alkali-silica reaction by reducing an alkali content in Portland cement.
An Experimental Study on Bending Behaviour of Steel Grid Composite Deck Joint
Shin, Hyun Seop ; Lee, Chin Hyung ; Park, Ki Tae ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 68~77
DOI : 10.11112/jksmi.2012.16.5.068
The joint of existing steel grid composite deck is composed of lap splice of reinforcing bar with end hooks and field-placed concrete. In this study, bending tests of deck joint composed of concrete shear key and high tension bolts are carried out for the design variable, concrete shear key strengthened with steel plate or not, and test results are compared with flexural performance of the existing deck joint. Test results showed that the mechanical deck joint has about 30% ~ 60% more ultimate bending strength than the existing joint. According to analysis results of moment-curvature relationship, the initial bending stiffness of the existing deck joint is some higher than that of mechanical joint. But, after crack failure the structural performance of the existing deck joint is rapidly reduced. Furthermore, the deck joint with the strengthened shear key with steel plate has more bending moment capacity than the deck joint without strengthening. And strengthening of shear key has positive influence on the increase of bending stiffness.
Development and Application of Anti-Corrosive Steel Using Electro-Deposition of Sea Water (1) -Development of Electro-Deposition System Using Sea Water
Kwon, Seung Jun ; Lee, Myeong Hoon ; Park, Sang Soon ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 78~87
DOI : 10.11112/jksmi.2012.16.5.078
This study is for developing a system for electro-deposition utilizing sea water containing various ions like calcium and magnesium. This is the first step research for the final goal which is a development of anti-corrosive steel for RC structure, so that this paper is mainly focused on the development for electro-deposition system. Optimum conditions for steel coating is obtained through various tests considering anode type, temperature, duration time, and current density. The composition of electro-deposition is analyzed through SEM, EDS, and XRD and it is evaluated to be
. Through measuring polarization potential and current density in the coated steel, the coating layer from the developed system is evaluated to have high resistance to steel corrosion. Additional tests and discussions on durability and structural performance in the coated steel from this work will be performed for the second step research.
Seismic Performance of Square RC Column Confined with Spirals
Ko, Seong Hyun ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 88~97
DOI : 10.11112/jksmi.2012.16.5.088
The objective of this research is to investigate the seismic performance and flexure-shear behavior of square reinforced concrete bridge piers with solid and hollow cross section. Test specimens were nonseismically designed with the aspect ratio 4.5 Two reinforced concrete columns were tested under constant axial load while subjected to lateral load reversals with increasing drift levels. Longitudinal steel ratio was 2.217 percent. The transverse reinforcement ratio As/(
), corresponding to 58 percent of the minimum lateral reinforcement required by Korean Bridge Design Specifications for seismic detailing, which represent existing columns not designed by the current seismic design specifications or designed by limited ductility concept. This study are to provide quantitative reference data for the limited ductility design concept and tendency for performance or damage assessment based on the performance levels such as cracking, yielding, collapse, etc. Failure behavior, ultimate displacement/drift ratio, displacement ductility, response modification factor, equivalent viscous damping ratio, residual deformation, effective stiffness, plastic hinge length, strain of reinforcements and nonlinear analysis are investigated and discussed in this paper.
Study on the Shape of a Longitudinal Joint of the Slab-type Precast Modular Bridges
Lee, Sang Yoon ; Song, Jae Joon ; Kim, Hyeong Yeol ; Lee, Young Ho ; Lee, Jung Mi ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 98~111
DOI : 10.11112/jksmi.2012.16.5.098
In this study, a longitudinal joint connection was proposed for the short-span slab-type precast modular bridges with rapid construction. The slab-type modular bridge consists of a number of precast slab modules and has the joint connection between the modules in the longitudinal direction of the bridge. The finite element based parameter analysis and the push-out test were conducted to design the shape and the dimensions of the longitudinal joint connection. Number of shear keys within the joint, height and depth of the shear key, tooth angle, and the spacing were considered as the design parameters. Using the local cracking load obtained from the analytical and experimental results, an efficiency factor was proposed to evaluate the effectiveness of the longitudinal joint connection. The dimensions of shear key were determined by comparing the efficiency factors.
Fire Resistance Performance of High Strength Concrete with 4 Deformation Factors
Lee, Tae Gyu ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 112~120
DOI : 10.11112/jksmi.2012.16.5.112
A numerical model considering the internal vaporization and the creep effect, in the form of a analytical program, for tracing the behavior of high strength concrete(HSC) members exposed to fire is presented. The two stages, i.e., spalling procedure and fire resistance time, associated with the thermal, moisture flow, creep and structural analysis, for the prediction of fire resistance behavior are explained. The use of the analytical program for tracing the response of HSC member from the initial pre-loading stage to collapse, due to fire, is demonstrated. Moisture evaporates, when concrete is exposed to fire, not only at concrete surface but also at inside the concrete to adjust the equilibrium and transfer properties of moisture. Finite element method is employed to facilitate the moisture diffusion analysis for any position of member, so that the prediction method of the moisture distribution inside the concrete members at fire is developed. The validity of the numerical model used in this program is established by comparing the predictions from this program with results from others fire resistance tests. The analytical program can be used to predict the fire resistance of HSC members for any value of the significant parameters, such as load, sectional dimensions, member length, and concrete strength.
Numerical Analysis of Load Carrying Capacity of RC Structures Based on Concrete Damage Model
Woo, Sang Kyun ; Lee, Yun ; Yi, Seong Tae ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 121~128
DOI : 10.11112/jksmi.2012.16.5.121
In this paper, nonlinear analysis for reinforced concrete structure for power transmission line is performed by considering the characteristics of the failure, which are depend on loading conditions and concrete material models. On the numerical evaluation for the failure behavior, the finite element analysis is applied. For the concrete material model, microplane model based on concrete damage is introduced. However, to describe the crack bridging effect of long and short fiber of steel fiber reinforced concrete (SFRC), tensile softening model is suggested and applied for SFRC. An numerical results by finite element technique are compared with the experiment results for box culvert specimen. Comparing on the experimental and analytical results, validity and reliability of numerical analysis are investigated.
Development of Integrated Wireless Sensor Network Device with Mold for Measurement of Concrete Temperature
Lee, Sung Bok ; Park, Seong Sik ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 129~136
DOI : 10.11112/jksmi.2012.16.5.129
Temperature of fresh concrete can be effectively used to predict the strength of concrete being cured and make an informed decision for stripping the molds. A hygrothermograph and thermo-couple sensors that require an extensive wiring have been applied to measure a temperature of concrete at the early stage of the curing process on site. However, these methods have limits to provide the temperature data in real time due to harsh working environment including frequent cutting of wires. Therefore, this study is aiming at developing a device based on wireless sensor network to measure the temperature of concrete being cured in formwork. The result showed that the wireless sensor with probe type thermistor which is developed had the same temperature data compared to the existed wire type thermistor, and we confirmed the temperature history of concrete in real time for 28 days throughout the gateway by wireless network that collects the temperature data measured from specimens in laboratory. Also, the network device for transmission can be easily separated from the probe sensor part and reused consistently. If the wireless sensor network device developed uses in the field, the temperature management of concrete will be systematically conducted from at the early stage of the curing, and especially be effective for cold weather concrete construction. In addition, it will contribute to the establishment of advanced quality control system for concrete and productivity of supervisors on site will be increased in the future.
A Study on Static and Fatigue Behavior of Restrained Concrete Decks without Rebar by Steel Strap
Jo, Byung Wan ; Kim, Cheol Hwan ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 137~147
DOI : 10.11112/jksmi.2012.16.5.137
In the steel-free bridge concrete deck, steel straps are generally used instead of conventional steel rebar while laterally restrained in the perpendicular direction to the traffic in order fir the arching effect of concrete deck. In this paper, the minimum amount of FRP bar is to be suggested based on the structural strength, crack propagation, stress level and others in order to control cracks. As a result of laboratory tests, the structural strength of deck with 0.15 percentage of steel strap showed improved structural strength including ductility. The long-term serviceability of steel strap deck with FRP bar proved to satisfy the requirements and to be structurally stable while showing the amount of crack and residual vertical displacement within the allowable limits after two million cyclic loadings. The structural failure of RC bridge deck is generally caused from the punching shear rather than moment. Therefore, the ultimate load at failure could be estimated using the shear strength formula in the two-way slab based on ACI and AASHTO criteria. However the design criteria tend to underestimate the shear strength since they don't consider the arching effects and nonlinear fracture in bridge deck with lateral confinement. In this paper, an equation to estimate the punching shear strength of steel strap deck is to be developed considering the actual failure geometries and effect of lateral confinement by strap while the results are verified in accordance with laboratory tests.
A Proposal of Durability Prediction Models and Development of Effective Tunnel Maintenance Method Through Field Application
Cho, Sung Woo ; Lee, Chang Soo ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 5, 2012, Pages 148~160
DOI : 10.11112/jksmi.2012.16.5.148
This study proposed more reasonable prediction models on compressive strength and carbonation of concrete structure and developed a more effective tunnel safety diagnosis and maintenance method through field application of the proposed prediction models. For this study, the Seoul Metro's Line 1 through Line 4 were selected as target structures because they were built more than 30 years ago and have accumulated numerous diagnosis and maintenance data for about 15 years. As a result of the analysis of compressive strength and carbonation, we were able to draw prediction models with accuracy of more than 80% and confirmed the prediction model's reliability by comparing it with the existing models. We've also confirmed field suitability of the prediction models by applying field, the average error of an estimate on compressive strength and carbonation depth was about 20%, which showed an accuracy of more than 80%. We developed a more effective maintenance method using durability prediction Map before field inspection. With the durability prediction Map, diagnostic engineers and structure managers can easily detect the vulnerable points, which might have failed to reach the standard of designed strength or have a high probability of corrosion due to carbonation, therefore, it is expected to make it possible for them to diagnose and maintain tunnels more effectively and efficiently.