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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 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
Selecting the target year
A Study on the Diagnostic System for Architectural Elements Using Radio Frequency
Kim, Dong Hyun ; Choi, Young Wha ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 2, 2012, Pages 1~9
DOI : 10.11112/jksmi.2012.16.2.001
Reinforced concrete buildings will be deteriorated as passed time or effect of an earthquake, etc in main elements. In order to manage such cracks, time and efforts, expense, etc, are required. So micro lead switch sensors are embedding or bonding in flexible specimens, and these are smart elements for diagnostic crack damages by external force such as physical load, dynamic load, etc in this study. The monitoring to crack damages are studied using radio frequency system. If load is received on the center of flexible specimens, embedded and bonded lead switch sensors will be destroyed, and these become to send signals of damages at radio frequency system connected with lead switch sensors. This study is fundamental research of the diagnostic system for architectural elements using radio frequency.
A Study on the Shear Strengthening Characteristic of Reinforced Concrete T-shaped Beams
Kim, Jeong Sup ; Shin, Yong Seok ; Moon, Keum Hwan ; Yoo, Myeong Hwan ; Lee, Chang Hyun ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 2, 2012, Pages 10~18
DOI : 10.11112/jksmi.2012.16.2.010
Most of studies on existing strengthening methods were mainly on increase of stiffness and strength of shear strengthening to rectangular beam. As concrete of beam and slab is poured simultaneously on the characteristics of construction in reinforced concrete beam-slab structure, adjacent slab uniformed after hardening has T-shaped beam cross section which makes the flange of beam, enhances the stiffness of the beam and widens the area supporting compressive strength, but available data of flexural behavior of T-shaped beam are lacking. In this research the T-shaped beams would be made, then the reinforced effects and structural properties can be estimated according to the kinds of reinforced materials and reinforced position. The conclusions are shown as below. To sum up the experimental results, The specimen which was reinforce by CB embedded inside of concrete indicated excellent resistive behavior, internal force and stiffness when it was destroyed. The steel plate reinforced specimen of stiffness and internal force were increase but it expressed lower reinforce effects because of lowering anchored force between concrete. Fiber sheet strengthening showed superior effects but the interfacial delamination was found due to the lack of anchored force in destruction. So the measure is needed now.
Structural Behavior of Slab in the Partial Demolition for the Apartment Remodeling
Choi, Hoon ; Joo, Hyung Joong ; Kim, Hyo Jin ; Yoon, Soon Jong ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 2, 2012, Pages 19~30
DOI : 10.11112/jksmi.2012.16.2.019
Due to the fact that the social environment is improved and the urban development is stabilized, the demand of new construction of apartment becomes slowdown. Accordingly, there are many researches to lengthen the service life of the existing apartment through the remodeling and its importance is continuously rising. However, reliable design specifications and guidelines for the design of remodeling with partial demolition are not provided yet in Korea. Specially, in the apartment remodeling, slab collapse accidents take major portion in all accidents that reported by Korean Government. It is very important to prevent intial crack of slab because intial crack could cause severe accident like collapse of all structure in a short period of time. The purpose of this study is to develop structural guidelines that could guarantee the structural safety and serviceability of slab structure and could be adopted in Korean remodeling with partial demolition. There are mainly two components to determine structural behavior of slab structure. One is the shape of slab structure and the other is load which is resisted by the slab structure. In this study, the weight per unit volume of concrete debris and concrete strength are estimated through the analysis of previous researches to recognize the relationship between the shape of slab and load that loaded on the slab. Accordingly, approximately 300 pieces of floor plan are collected and analyzed. The finite element analysis is conducted using these analyzed and estimated results. From the finite element analysis results, the limited stacking height of debris is suggested and the stacking method is also discussed. In addition, to find the relationship between movement of demolition equipment and structural behavior of slab, the static and dynamic loading tests are conducted. From the results of loading tests, the impact factor which will be considered in the remodeling design could be estimated.
An Experomental Study on the Connection of Diaphragm in Modular Bridge
Lee, Hyun Ho ; Lee, Sang Seung ; Cho, Doo Yong ; Kim, Tae Wan ; Park, Sun Kyu ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 2, 2012, Pages 31~39
DOI : 10.11112/jksmi.2012.16.2.031
Recently new construction and reconstruction of the bridge have been required to minimize traffic congestion, environmental disadvantage, to reduce the period of construction, and to improve the quality and workability during the construction. For this reason, the application of modular bridge system, which is assembly of the structural members, is necessary to prepare for near future. Fall of girders can occur at the moment to connect between precast girders during the construction, so appropriate cross beams should be installed to solve the mentioned problem. In this study, understanding the structural characteristics and domestic and international case of cross beam, alternative cross beam system for modular bridge was developed. To inspect the structural characteristics of the alternative system, specimens were built and static loading test was performed. Afterward, the behavior of cross beam interms of joints and load distribution was observed. Experimental results were analyzed and compared with each data. Therefore, the appropriate cross beam system for modular bridge will be chosen and proposed in this paper.
Non Destructive Technique for Steel Corrosion Detection Using Heat Induction and IR Thermography
Kwon, Seung Jun ; Park, Sang Soon ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 2, 2012, Pages 40~48
DOI : 10.11112/jksmi.2012.16.2.040
Steel corrosion in concrete is a main cause of deterioration and early failure of concrete structures. A novel integration of electromagnetic heat induction and infrared (IR) thermography is proposed for nondestructive detection of steel corrosion in concrete, by taking advantage of the difference in thermal characteristics of corroded and non-corroded steel. This paper focuses on experimental investigation of the concept. An inductive heater is developed to remotely heat the embedded steel from concrete surface, which is integrated with an IR camera. Concrete samples with different cover depths are prepared. Each sample is embedded with a single rebar in the middle, resulting an identical cover depth from the front and the back surfaces, which enable heat induction from one surface and IR imaging from the other simultaneously. The impressed current (IC) method is adopted to induce accelerated corrosion on the rebar. IR video images are recorded during the entire heating and cooling periods. The test results demonstrate a clear difference in thermal characteristics between corroded and non-corroded samples. The corroded sample shows higher rates of heating and cooling than those of the non-corroded sample. This study demonstrates a potential for nondestructive detection of rebar corrosion in concrete.
An Experimental Study on Development Connection System of Concrete Barrier in Modular Bridges
Jung, Ho Sung ; Lee, Sang Seung ; Choi, Jin Woong ; Kim, Tae Wan ; Park, Sun Kyu ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 2, 2012, Pages 49~57
DOI : 10.11112/jksmi.2012.16.2.049
Recently, in field of bridge construction, modular technology has been studied to reduce construction period. However, main stream of the study is limited to the pier, girder and deck of bridge, which are huge or main members. Studies on incidental facilities like concrete barrier is out of sight. Thus, in this study, connection system of concrete barrier was developed to apply to modular bridges and static experiment was performed in order to verify structural capability of proposed system. Variables of experiment are composed of bolt direction such as vertical and horizontal. The experimentation due to the designed variables was conducted by comparison with a standard concrete barrier, which is a traditional barrier. As a result, vertical joint way of the bolt showed nearly identical structural performance and healthy to standard specimen`s. it can be applied to modular bridges.
Mixture Study for Early-age Strength Improvement of NAC-typed High-strength Concrete Piles
Yi, Seong Tae ; Noh, Jae Ho ; Heo, Hyung Seok ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 2, 2012, Pages 58~64
DOI : 10.11112/jksmi.2012.16.2.058
Due to the influence of global oil prices, industrial productivity, which oil consumption is high, was significantly reduced. AC type of high-strength PHC piles is being manufactured through twice the steam curing process and this have resulted in a significant rise for product`s manufacturing costs. NAC way other types of file manufacturing process has the advantage of reducing manufacturing costs by a turn of the steam curing. Nevertheless, because the initial strength be poor than that of AC method, shipment is being after the curing period of approximately three days. In addition, the growth of the product enhance with curing period can not be avoided, as a result, cost of inventory is acting as the rise. Piles by the AC method is immediately shipped after curing, damaging problems does not occur when they are introduced to the field site (for example, pile on-site). In the case of NAC, however, at least after the curing period of three days and after expressing the strength of 80 MPa or more, they are shipped on the scene. Therefore, NAC type has problems as follows: (1) increase in moderate inventory holding costs with type and (2) breakage in the field due to lack of strength. In this study, for NAC-typed PHC files, mixing characteristics research for the strength development at 1 day equivalent to AC method were conducted and strength characteristics with changes of original materials were evaluated were also identified.
The Unified Wireless Control System for the Vibration Control of Bridge
Heo, Gwang Hee ; Kim, Chung Gil ; Oh, Ju Won ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 2, 2012, Pages 65~74
DOI : 10.11112/jksmi.2012.16.2.065
This paper aimed at the development of a unified wireless control system in order to control various forms of vibration of bridges. This unified wireless control system unified all different systems each of which functioned for difference purpose such as measurement, analysis, judgement, and control of data acquired from the movement of structure. It was designed to control structures with feedback which was returned according to each different situation after analyzing various signals measured about the structure. In this system, every information in each step from measurement to control was wirelessly transmitted to its central system so that a manager was able to effectively monitor the whole process. Just for the case when any system control need to intervene occurred, a graph user interface was designed for better access. In order to evaluate its basic performance, an experiment was carried out to see how signal input and output were done by comparing its results with those of a wired system. On the basis of the experiment, a vibration control experiment was performed on a model of cable-stayed bridge to see if the unified wireless control system worked well in realtime. This was carried out under four conditions, and the graph and quantitative result under each condition were compared each other. All experiments proved that the unified wireless control system functioned as well as the wired one in terms of its basic performance and vibration control.
An Experimental Study on the Durability and Load Carrying Capacity of RC Structure Repair System Using FR-ECC
Kim, Jeong Hee ; Lim, Seung Chan ; Kim, Jae Hwan ; Kwon, Yung Jin ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 2, 2012, Pages 75~86
DOI : 10.11112/jksmi.2012.16.2.075
This paper presents some research results on the shrinkage characteristics and frost resistance before and after cracking of FR-ECC(Fire Resistance-Engineered Cementitious Composite). Also, a waterstop performance and exfoliating resistance of multi-layer lining specimens using FR-ECC and flexural performance of beam member by repaired FR-ECC are estimated in this paper. Experimental results indicate that the plastic shrinkage crack and length change ratio of FR-ECC have been reduced as compared with that of the existing repair mortar, and that its crack resistance on the dry shrinkage is improved under the confining stress. As well as FR-ECC has been great in the frost resistance and its tensile properties under the cracked state have been not reduced by freezing and thawing reaction. In addition, beam member by repaired FR-ECC have been increased in the flexural properties such as initial crack moment, yeild moment, and its crack width has been controled in a stable by the frexural failure.
Damage Estimation Method for Wind Turbine Tower Using Modal Properties
Lee, Jong Won ; Bang, Je Sung ; Kim, Sang Ryul ; Han, Jeong Woo ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 2, 2012, Pages 87~94
DOI : 10.11112/jksmi.2012.16.2.087
A damage estimation method of wind turbine tower using natural frequency and mode shape is presented for effective condition monitoring. Dynamic analysis for a wind turbine was carried out to obtain the response of tower from which modal properties were identified. A neural network was learned based on training patterns generated by the changes of natural frequency and mode shape due to various damages. The changes of modal property were calculated using a program for modal parameter estimation. Damage locations and severities could be successfully estimated for 10 damage cases including multi-damage cases using the trained neural network. The damage severities for very small damages generally tends to be slightly under-estimated however, the identified damage locations agreed reasonably well with the accurate locations. Enhancement of the estimation result for very small damage and verification of the proposed method through experiment will be carried out by further study.
Influence of Cement Matrix`s Compressive Strength and Replacement of Expansive Admixture on the Mechanical Properties of Synthetic Polyethylene (PE) Fiber-Reinforced Strain-Hardening Cement-Based Composites (SHCCs)
Song, Young Jae ; Yun, Hyun Do ; Min, Byung Sung ; Rokugo, Keitetsu ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 2, 2012, Pages 95~103
DOI : 10.11112/jksmi.2012.16.2.095
In order to improve the dimensional stability and mechanical performance of cement-based composites, the effect of an expansive admixture based on calcium sulphoaluminate (CSA) on the shrinkage and mechanical properties of strain-hardening cement-based composite (SHCC), which exhibits multiple cracks and pseudo strain-hardening behavior in the direct tension, is investigated. Polyethylene fibers reinforced SHCC mixtures with three levels (30, 70, and 100MPa) of compressive strength were compared through free shrinkage, compressive strength, flexural strength, and direct tensile strength measurements. The SHCC mixtures were cast with and without replacing 10% of Portland cement content with CSA admixture. According to test results, CSA admixture is effective in reducing shrinkage of SHCC material. SHCC mixture with CSA admixture exhibited a little higher strength than companion mixture without CSA admixture.
Tenon Reinforcement Technique on Tradition Wooden Structures Using Spiral Hardware
Yu, Hye Ran ; Kwon, Ki Hyuk ;
Journal of the Korea institute for structural maintenance and inspection, volume 16, issue 2, 2012, Pages 104~112
DOI : 10.11112/jksmi.2012.16.2.104
The failure of tenon in a traditional wood-framed structure may collapse of the entire structure. This study evaluates the strength and stiffness of tenon joints between the beams and pillars through experimental study and suggests reinforcing method of the tenon joint without dismantling the main structures. The main experimental parameters are the number, distance, shape, and inserting depth of spiral-shaped reinforcing steels. As the thickness of the tenon in beams increases, the strength and the initial shear stiffness of the joint increases and, however, the tenons in pillar becomes weaker, resulting in the safety problem of the structure. It is recommended that three spiral-shaped reinforcing steels be placed in the central parts of the tenon to effectively improve the strength and the shear stiffness of the joint.