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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 15, Issue 6 - Nov 2011
Volume 15, Issue 5 - Sep 2011
Volume 15, Issue 4 - Jul 2011
Volume 15, Issue 3 - May 2011
Volume 15, Issue 2 - Mar 2011
Volume 15, Issue 1 - Jan 2011
Selecting the target year
Behavior of Reinforcement Ratio on Concrete Beams Reinforced with Lab Spliced GFRP Bar
Choi, Yun Cheul ; Park, Keum Sung ; Choi, Hyun Ki ; Choi, Chang Sik ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 67~76
DOI : 10.11112/jksmi.2011.15.1.067
The use of glass-fiber-reinforced polymer (GFRP) bars in reinforced concrete (RC) structures has emerged as an alternative to traditional RC due to the corrosion of steel in aggressive environments. Although the number of analytical and experimental studies on RC beams with GFRP reinforcement has increased in recent decades, it is still lower than the number of such studies related to steel RC structures. This paper presents the experimental moment deflection relations of GFRP reinforced beam which are spliced. Test variables were different reinforcement ratio and cover thickness of GFRP rebars. Seven concrete beams reinforced with steel GFRP re-Bars were tested. All the specimens had a span of 4000mm, provided with 12.7mm nominal diameter steel and GFRP rebars. All test specimens were tested under 2-point loads so that the spliced region be subject to constant moment. The experimental results show that the ultimate moment capacity of beam increasing of the reinforcement ratio. Failure mode of these specimens was sensitively vary according to the reinforcement ratio. The change of beam effective depth, which was caused by cover thickness variation, controlled the maximum strength and deflection because of cover spalling in tension face.
An Analysis of Continuous Beam by Material Non-linear Transfer Matrix Method
Seo, Hyun Su ; Kim, Jin Sup ; Kwon, Min Ho ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 77~84
DOI : 10.11112/jksmi.2011.15.1.077
This study is to develop nonlinear analysis algorithm for transfer matrix method, which can be applied to continuous beam analysis. Gauss-Lobatto integral rule is adopted and the transfer matrix is derived from stiffness matrix. In the transfer matrix method, the system equation has a constant number of unknowns regardless of number of D.O.F. Therefore, the transfer matrix method has computational efficiencies not only in linear elastic analysis but also in nonlinear analysis. To verify the developed method, the analysis results of several examples are compared with commercial code in moment-curvature, moment-displacement and load-displacement relation.
Performance Estimation of Semi-active Real-time Feedback Vibration Control System
Heo, Gwang Hee ; Jeon, Joon Ryong ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 85~94
DOI : 10.11112/jksmi.2011.15.1.085
This paper is concerned to constitute a semi-active realtime feedback vibration control system and evaluate it through experiments in order to control in realtime the vibration externally generated, specially on the bridges which is structurally flexible. For the experiment of vibration control, we built a model bridge structure of Seohae Grand Bridge in a 1/200 reduced form and inflicted El-centro wave on the model structure also in a reduced force considering the lab condition. The externally excited vibration was to be controled by placing a shear type MR damper vertically on the center of bridge span, and the response (displacement and acceleration) of structure was to be acquired by placing LVDT and Accelerometer at the same time. As for the experiment concerning controlling vibration, a realtime feedback vibration control experiments were performed under each different condition largely such as un-control, passive on/off control, Lyapunov stability theory control, and Clipped-optimal control. Its control performance under different condition was quantitatively evaluated in terms of the peak absolute displacements, the peak absolute accelerations and the power required for control on the center of span. The results of experiments proved that the Lyapunov control and clipped-iptimal control were effective to decrease the displacement and acceleration of the structure, and also to decrease the power consumption to a great extent. Finally, the semi-active realtime feedback vibration control system constituted in this research was proven to be an effective way to control and manage the vibration generated on bridge structure.
A Study on the Strength Evaluation of Rectangular Steel Tubular Columns Infilled with High Strength Concrete
Shim, Jong Seok ; Han, Duck Jeon ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 95~102
DOI : 10.11112/jksmi.2011.15.1.095
The CFT columns used in thin-walled steel tubes can be more economical, because it was expected the increase of strength by restriction for the local buckling of steel tubes. The purpose of this paper is to review feasibility of existing design formula and verify the applicability limit of width-to-thickness ratio for increasing the strength of rectangular CFT columns. As the main parameters of experiments, width-to-thickness ratios of steel tube, height of rectangular concrete columns, and concrete filled or not. The strength of concrete are selected to 90MPa. From the test results, the confinement effect of steel tube on the compressive strength of infilled concrete is remarkably appeared in the thin-walled rectangular steel tube columns infilled wih high strength concrete. By the non-linear analysis, the axial strength from experiment result was given higher than analysis result for all CFT stub columns.
Experimental Study on Structural Performance of Recycled Coarse Aggregate Concrete Confined by Steel Spirals
Kim, Sang Woo ; Jung, Chang Kyo ; Lee, Sun Hee ; Kim, Kil Hee ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 103~111
DOI : 10.11112/jksmi.2011.15.1.103
This paper estimated the structural behavior of recycled aggregate concrete confined with spiral reinforcement. The main test parameter was designed to be the type of aggregates and the steel ratio of spirals. A total of 18 specimens were cast and tested in this study. All the specimens had a diameter of 150mm and a height of 300mm. The specimens can be divided into two groups, based on the type of coarse aggregate used. The ratio of spiral reinforcement was varied from 0 % to 1.75%. To measure the axial and lateral deformations of the specimens, a total of six linear variation displacement transducers (LVDTs) were installed at each specimen. Furthermore strain gauges were also attached to the steel spirals to obtain the strain of spiral reinforcements. From the experimental results, the structural performance of recycled aggregate concrete specimens confined by steel spirals was similar to that of natural aggregate concrete specimens regardless of the ratio of spiral reinforcement.
Probe of Unfilled Sheath of Prestressed-Concrete Girder Bridge Using Impact-Echo Method
Lee, Sang Hun ; Kim, Sang Jin ; Endo, Takao ; Sagara, Yuzo ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 112~119
DOI : 10.11112/jksmi.2011.15.1.112
Sheaths are arranged in the web and lower part of prestressed-concrete girder bridges, and prestressing wires and concrete are indirectly bonded together by filling interior parts of the sheaths. However, when the filling is not sufficient, water can penetrate the interior parts of the sheaths and, thereby, prestressing wires can be corroded or transverse cracks would occur around sheaths by the freezing and thawing action of the penetrated water. Therefore, it is an important element in maintenance management of structures to find out the sheaths unfilled with grout early after construction. In this paper, in order not to damage bridge members, the impact-echo method with a new approach in application is used to probe sheaths unfilled with grout for real structures. The location of sheaths is first estimated with reinforcing bar probing instrument of radar type and the measurement locations of sheaths are determined. By sending elastic wave to the side of girders and receiving the response, the location of the unfilled part of a sheath was estimated from the difference between high frequency peak and twice the resonance frequency indicating thickness. To verify the location of void estimated by the impact-echo method, pictures were taken by an industrial fiber scope after drilling a hole.
Evaluation Using Dynamic Characteristic of Steel Structures under Periodical Impact Loads
Kim, Kang Seok ; Nah, Hwan Seon ; Lee, Hyeon Ju ; Lee, Kang Min ; Yoo, Kyung Seok ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 120~128
DOI : 10.11112/jksmi.2011.15.1.120
Recently, safety diagnosis of the existing structures has been emerged as important issue. In particular, systematical and precise safety diagnostics for steel structures for power substation, have been required. Steel structures for power substation are under the periodical impact loads from operations of gas insulated switchgear. These loading condition accelerates damage and aging of structure. The objective of this research is to evaluate damage of structure under periodical impact loads. To evaluate the integrity of structures as organizing mathematical models including the dynamic characteristics of structures, Frequency Domain Decomposition method was choiced and an algorism was proposed. For verifying this methods and algorism, a mathematical model is composed of the development of a variety of reverse analysis and a signal processing technology reflecting physical damage of structures. A series of analysis and test results indicatge that proposed method has a confidence for applying a filed test. Therefore, it is expected to be able to take advantage of system identification to detect damage for the maintenance and management of steel structures under periodical impact loads such as power substation.
A Study on the Resistance to Seawater Attack of Mortars and Concretes Incorporating Limestone Powder
Lee, Seung Tae ; Jung, Ho Seop ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 129~137
DOI : 10.11112/jksmi.2011.15.1.129
This study aims to evaluate the resistance to seawater attack of mortars and concretes incorporating limestone powder (0, 10, 20 and 30% of cement by mass). In order to achieve this goal, both chemical resistance by seawater and chloride ions penetration resistance of mortars or concretes were regularly monitored. From the test results, it was observed that the durability of cement matrix was greatly dependent on the replacement ratios of limestone powder. In other words, performance of cement matrix with 10% limestone powder was similar to that of OPC matrix. However, it was found that a high replacement ratio of limestone powder was ineffective to resist seawater attack.
Analysis on Shear Force of Specimens Using Perfobond Rib Shear Connector
Choi, Jin Woong ; Park, Byung Gun ; Kim, Hyeong Jun ; Jeong, Ho Seong ; Park, Sun Kyu ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 138~147
DOI : 10.11112/jksmi.2011.15.1.138
The objective of this study which it sees direct shear stress and comparative analysis of flexural shear stress leads and it is a shear stress analysis which it follows in load direction of the structure which uses Perfobond Rib shear connectors. To analyze direct shear stress, five Perfobond Rib shear connect experiments were fabricated with five variables and conducted Push-out Tests. After experiments, mechanism of Perfobond Rib shear connector was examined and direct shear formula was proposed based on primary factors which influence direct shear stress. Also, for the analysis of flexural shear steel-concrete composite slab specimens were fabricated and static flexural test. Based on the static flexural test it analyzed the flexural behavior and the flexural shear stress it calculated. Direct shear stress and EN 1994-1-1 to lead and be calculated, it compared the flexural shear stress and it analyzed in about the shear resistance stress which it follows in load direction.
User Costs Evaluation due to the Bridge Reconstruction Period
Kim, Sang Hyo ; Park, Se Jun ; Lee, Dong Ho ; Ahn, Jin Hee ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 148~158
DOI : 10.11112/jksmi.2011.15.1.148
As critical infrastructure, bridges play an indispensable role in facilitating the distribution of goods. When bridges reach their end of useful life or get damaged by natural disasters such as earthquakes or storms, they have to be removed and reconstructed. When bridges in service need to be reconstructed, user costs occur from vehicle detours and traffic congestions, and social costs occur from noise and dust during construction periods. However, these user and social costs are not considered during reconstruction and the evaluation methods of those costs are vague. Thus, there is lack of appropriate bridge types that consider these costs. Therefore, this paper identifies the social overhead costs that occur during bridge reconstruction, which is also called, users` socioeconomic values. Next, it proposes a method to evaluate user costs during bridge reconstruction, and appraises the method. User costs are evaluated based on traffic information, social and material volumes including the bridge`s daily traffic volume, peak hours, detour distance and time. In addition, time delay costs due to traffic operational costs and bridge reconstruction are also taken into consideration.
An Experimental Study on the Self-Consolidating Concrete with EP Nylon Fiber
Ryou, Jae Suk ; Lee, Yong Soo ; Jeon, Joong Kyu ; Jeon, Chan Ki ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 159~168
DOI : 10.11112/jksmi.2011.15.1.159
In this study, we find out the feasibility of self-consolidating concrete with EP nylon fiber. Three kinds of method were used; when length of nylon fiber is differed for the experiment to investigate usability of nylon fiber with enhanced performance by dispersing-agent coating in self-consolidating concrete, when mixing in other organic fibers (polypropylene, cellulose) and in case of Binary Blended and Ternary Blended concrete mixed with different types of mineral admixtures (blast-furnace slag and fly ash). Based on the results of the experiment described above, comparison was made on the basic properties and dynamic characteristics of general fiber reinforced concrete mixed with enhanced performance nylon fiber and SCC mixed with enhanced performance nylon fiber as a Mock-up test prior to the experiment of application to the actual structure. Considering characteristics and durability of the fresh and hardened self-compacting concrete, dynamic characteristics and durability were found to be more outstanding when using nylon fiber for the mineral admixtures used, dynamic characteristics and durability were found to be more outstanding when using blast-furnace slag.
A Study on the Qualification System for Raising Engineers of Maintenance for Apartment Houses - Based on the Qualification System of the United States -
Park, Sang Hoon ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 169~179
DOI : 10.11112/jksmi.2011.15.1.169
Korea owns vast amount of apartment houses no less than those of world prominent countries, but did not pay enough efforts to maintain existing apartment houses and develop policies to reuse them due to growth driven policy of housing supply like construction of new houses. Korea constructed tremendous amount of houses in short period through government led forced house supplying policy, and resulted in excess houses such that present house supply rate happened to be reaching 110%. However, recently there are growing demand of change in housing policy due to social environmental changes like low birth rate and aging of society etc and nationals` demand for improvement of residential quality. When such social changes are demanded and 80% of apartment houses in Korea are less than 20 years old, renovations and remodeling of apartment houses are anticipated to emerge as important matter. In particular, the apartment houses in Seoul and the 1st generation new cities like Bundang and Ilsan etc have passed considerable period of time after construction and require safety measure, it is quite impending to raise engineers for the maintenance of existing apartment houses. Therefore, in this paper, direction for the raising of maintenance engineers in Korea was proposed through analysis of relevant qualification system for the apartment houses maintenance engineers in the U.S.
Experimental Evaluation on Structural Performance of Large Diameter Reinforcing Steel Bars with Spliced Sleeves
Kwon, Ki Joo ; Park, Dong Su ; Joung, Won Seoup ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 180~188
DOI : 10.11112/jksmi.2011.15.1.180
Recently a number of researches about mechanical splice have been studied to apply on a large diameter reinforcing steel bars of spliced sleeves. In this study the structural performance of large diameter reinforcing bars with spliced sleeves was evaluated. For the application of nuclear power plant structures, two different types of existing splices with #11, 14, 18 rebars were fabricated and static and dynamic test were performed on the basis of ASME SEC III DIV.2CC-4330.
A Study on Composing the Structural Test Equipment of Large Scale Beam Type Test Specimen to Load Multiple Point and Capacity
Park, Dong Su ; Lee, Kyung Jin ; Ham, Kyung Won ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 189~197
DOI : 10.11112/jksmi.2011.15.1.189
In the field of structural test, it is a very important factor to apply with an appropriate test jig to enhance test accuracy and efficiency. Especially in the large scale structure test, proper test apparatus scheme will reduce overall cost and time of the test project. Actuators, oil jack and UTM is generally used to evaluate the flexural capacity of the test beam. But in the case of multiple loading point or asymmetric loading of large scale test specimen, existing test method such as UTM have a difficulty in giving an accurate load. In this study new test method which is composed of existing test apparatus will be developed to improve test accuracy and economic efficiency.
Behavior of Bearing Capacity for Shallow Foundation on a Sand overlying Clay Depending on Bearing Capacity Ratio
Jung, Min Hyung ; Shin, Hyo Hee ; Lee, Song ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 198~208
DOI : 10.11112/jksmi.2011.15.1.198
When a structure which has relatively low load constructs on soft clay, the bearing capacity of the ground will be improved by sand overlying clay. In this condition, verifying the bearing capacity is difficult from the P.B.T etcetera in the in-situ. So, it is needed to estimate precise bearing capacity in the design process. In this study, 2-dimensional chamber tests and FEM analyses are conducted to evaluate behavior of bearing capacity for shallow foundations on a sand overlying clay. Because depth ratio H/B and bearing capacity ratio
are selected as main factors, height of a sand, undrained shear strength of a clay and width of a loading are designated as variables. Results from chamber tests are very similar with those of FEM analyses. And it shows that punching shear mechanism is more suitable than the equation of Okamura et al.(1998). To make continual application of load spread mechanism, the equivalent load spread angle is proposed for H/B and
. Also, the linear regression equation of critical depth ratio Hf is suggested for
Sensing Technique of Mass Imbalance for Condition Monitoring of Wind Turbine Blade
Lee, Jong Won ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 209~214
DOI : 10.11112/jksmi.2011.15.1.209
A method to detect rotor mass imbalance, which is one of the typical faults of wind turbine, is presented for effective condition monitoring of wind turbine. Dynamic analysis for a three-bladed horizontal-axis wind turbine was carried out with adding mass to a blade for inflicting the rotor mass imbalance. It has been found that the added mass induce a resulting centrifugal force to nacelle and this leads to a transverse (relative to the rotor axis) oscillation of the nacelle. It has been also found that the amplitude of the oscillation is almost linearly increased as the added mass is increased.
The Statistical Hypothesis Verification to Influence of Addition of Metakaolin and Silica Fume on Compressive Strength and Chloride Ion Penetration of High Strength Concrete
Min, Jeong Wook ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 215~225
DOI : 10.11112/jksmi.2011.15.1.215
Metakaolin is a dehydroxylated form of the clay mineral kaolinite. Rocks that are rich in kaolinite are known as china clay or kaolin, traditionally used in the manufacture of porcelain. The particle size of metakaolin is smaller than cement particles, but not as fine as silica fume. This paper investigates the effect of the concrete containing metakaolin as a mineral admixture on the compressive strength and resistance properties to chloride ion penetration. In this study, the experiment was carried out to investigate and analyze the influence of replacement ratio of metakaolin and micro silica fume on the compressive strength and chlorine ion penetration resistance of concrete. All levels were water/binder ratio 30%, replacement ratio of metakaolin and silica fume were 0, 5, 10, 15, 20% respectively. The compressive strength of concrete using metakaolin tends to increase, as the replacement ratio increases but the chlorine ion penetration resistance was not so as lager as silica fume concrete. Therefore, the optimum mixing ratio of metakaoline to satisfy a properties of compressive strength and chlorine ion penetration resistance was was approximately10%.
Service Life Prediction and Cost Estimation of Repaired Concrete Structures Under Marine Environment
Shim, Hyun Bo ; Ann, Ki Yong ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 226~234
DOI : 10.11112/jksmi.2011.15.1.226
The service life of concrete structures exposed to a marine environment can be extended by controlling the amount of chloride in cover concrete. Patching is one of the appropriate maintenance techniques for chloride contamination. Chloride-contaminated cover concrete is removed and replaced with sound one. It can provide less risk of corrosion of steel, so that the structure can be maintained for required service life. In this study, a quantitative assessment of the service life subjected to the chloride attack is proposed to determine the effective repair options such as repair depth, repair material and timing of repair. The Crank-Nicolson based finite difference formulation from Fick`s second law is proposed to predict the profiles of chloride ion in a repaired concrete structure, considering ingress of chloride from outer and redistribution of residual chloride from the substrate concrete. Therefore, the repair application times and maintenance cost for the target service life can be estimated. Finally, the numerical examples are presented to ensure its applicability.
Seismic Control of Tuned Mass Damper System with MDOF Sliding Mode Control Accounting for the Uncertainties
Lee, Jin Ho ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 235~242
DOI : 10.11112/jksmi.2011.15.1.235
The control performance in active structural control system can be drastically deteriorated when the modeling errors and the uncertainties existing in the disturbances are disregarded in the designing stage. It can even throw the control system into an unstable phase, resulting in out of control against the seismic excitations. The purpose of the study is to investigate the control effectiveness of a non-linear control system called sliding mode controller(SMC) in cooperation with a Tuned Mass Damper subjected to the three seismic excitations selected from the FFT analysis. Even though the transient performance such as settling time and overshoot were deteriorated, the robustness against the system stability was appeared from SMC when the structural masses and stiffness perturbed within the range of
. SMC is a feasible technique for active structural control in cooperation with TMD against seismic disturbances, exhibiting robustness in perturbation of system stiffness and mass as well as uncertainties of the disturbances.
Nonlinear Behavior of Seismic-Strengthened Domestic School Building
Ryu, Seung Hyun ; Yun, Hyun Do ; Kim, Sun Woo ; Lee, Kang Seok ; Kim, Yong Cheol ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 243~253
DOI : 10.11112/jksmi.2011.15.1.243
This paper describes an analytical study on seismic performance of domestic reinforced concrete (RC) school building not designed by seismic provision. The seismic index and the seismic performance of the building were evaluated through Japanese standard and Midas Gen, respectively. Seismic index (Is) of the RC school buildings in the X-direction is below 0.4. Based on the seismic index, for seismic-strengthening the building, infill shear wall or steel brace with a capacity of 1,300 kN was used. According to nonlinear static analysis results, the contribution of the seismic-strengthening to the shear resistance of the school building was measured to be greater than 30%. However, as expected, shear strength of school building strengthened with infill wall dropt rapidly after peak load and much narrower ductile behavior range was observed compared to steel brace strengthened building. Also, the building strengthened with steel brace showed 30% larger spectral displacement than that strengthened with infill shear wall. In nonlinear dynamic analysis, for the time history analysis, the maximum displacement showed tendency to decrease as amount of reinforcement increased, regardless of strengthening method. It was recommended that variable soil properties and earthquake record should be considered for improving seismic performance of buildings in seismic zone.
Evaluation on Hysteretic Behaviors of V Shaped Metallic Dampers
Lee, Hyun Ho ; Kim, Seh Il ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 254~262
DOI : 10.11112/jksmi.2011.15.1.254
The purpose of this study is the development of V shaped metallic damper, which is superior than slit damper in energy dissipation capacity. For this purpose, 9 metallic damper specimens were prepared and shear testing were performed. According to test results, the V shaped metallic damper with strut height of 270mm and strut angle of
shows a better seismic performance than any other specimens. The result of comparison with the yield strength of the dampers using the existing strength formula shows that V type metal dampers were highly evaluated than others within analyzing existing experimental result.
A Study for Application of Polycarboxilic Type Admixture to Precast High-Strength Concrete Piles
Yi, Seong Tae ; Noh, Jae Ho ; Park, Chul Ju ; Heo, Hyung Seok ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 263~270
DOI : 10.11112/jksmi.2011.15.1.263
In this study, the performance of Poly-Naphthalene Sulfonate (PNS) type-admixture used widely in South Korea and Polycarboxilic type-admixture(i.e., WF2000) developed in the J company of the domestic, for precast concrete products produced in the factories, was evaluated. With the 20% reduced usage of WF2000 compared to PNS type-admixture, workability was considerably improved due to high water-reducing ratio, accelerating effect of concrete setting and accelerant dispersant action, which the product has, under the high temperature. In addition, the development of initial and long-term strengths of PHC plies was predominant. For WF2000, it is also possible to correspond with the change of original materials and environmental conditions since the control of water-reducing and supporting forces is feasible. Accordingly, it was noted that WF2000 is superior for deterioration of production & workability and bad casting problems in summer and the solution of initial strength reduction problem due to the delay of setting in winter.
An Analytical Evaluation of Vibration Serviceability for Each Bridge Types with Same Span
Park, Seong Kyu ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 271~280
DOI : 10.11112/jksmi.2011.15.1.271
This study intends to analytically evaluate the vibration serviceability of the bridges for each long-span type having the same span length and road width using the Meister vibration sensation curve. With MIDAS, a structural analysis program, bridges were modeled using the girders as the frame element and slabs as the plate element. The transient analysis was performed using the moving loads of the design vehicles. This study presents the analytical process of reviewing the vibration serviceability during the design of long-span bridges. It involves the comparison of the vibration serviceability of different bridge types by applying the lagging-behind and acceleration amplitude from transient analysis to Meister curve. The result confirms that the process is appropriate.
Durability of GFRP Rebar with Ribs Containing Milled Alkaline Resistant Glass Fibers
Moon, Do Young ; Oh, Hong Seob ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 281~287
DOI : 10.11112/jksmi.2011.15.1.281
GFRP rebars could be deteriorated by concrete alkalinity. This paper focuses on the investigation of durability of GFRP rebars with ribs exposed to alkaline environment of concrete. It has been reported that the milled E-glass fibers in the ribs of GFRP rebar can increase bond strength between GFRP rebars and the concrete. In this study, the effect of milled alkaline resistant glass fibers (milled AR glass) and milled E-glass in the ribs on the durability of GFRP rebar is investigated through ISS tests and moist absorption tests of the bare rebar. To accelerate the effect of the alkalinity, high temperature(
) was applied. According to the test results, mix ratio of milled glass fibers in the ribs by weight had significant effect on durability of GFRP rebars with ribs. It is because that the high mix ratio may leads more voids in the ribs due to lower workability and formability. On the other hand, changing fiber type in the ribs from E-glass to AR-glass had no improvements on ISS strength of the GFRP rebar. Therefore, it is found that determination of proper mix ratio of milled glass fiber in the mixture for the formation of the ribs of the GFRP rebar is important.
Evaluation of the Properties of Absorbent-Pervious Cement Mortar
Lho, Byeong Cheol ; Joo, Myung Ki ; Choi, Jong Yun ;
Journal of the Korea institute for structural maintenance and inspection, volume 15, issue 1, 2011, Pages 288~295
DOI : 10.11112/jksmi.2011.15.1.288
The objective of this study is to develop a proper absorbent-pervious pavement. By using single graded aggregates and SAP, permeability and water absorbability of absorbent-pervious pavement are improved, and also temperature reducing effect is found out. And several tests such as compressive and flexural strength tests, and permeability/water absorption tests of absorbent-pervious pavement are carried out to verify these kind of effects. The compressive and flexural strengths are increased according to decrease of single graded aggregate size, and increase of SAP content. And the volume of water retention and absorbability are increased according to the increase of SAP content and these are also increased in small size of single graded aggregate. And about
of difference is observed in surface temperature between normal asphalt pavement and absorbent-pervious pavement.