• Journal of Korean Society of Steel Construction
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• v.26 no.4
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• pp.251-262
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• 2014

It has been considered that factors affecting accuracy of the estimated weight of moving vehicle by BWIM system are vehicle and bridge characteristics, and measurement conditions which is related to the strain curve. In this study, theoretical review and field test were performed to evaluate effect of these factors in BWIM system. From these evaluations, we proposed a way to improve accuracy of the estimated vehicle information in BWIM system. As the results, it was known that girder type and continuity of spans in bridge are not governing factor, but its plane shape gives large influence on accuracy of the estimated vehicle information. In addition, running speed of vehicle has also large effect on the estimated accuracy of axle distance if the distance between second and third axles is short. However, weight sum of the two axles can be estimated reasonably by assuming them as one axle.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.3
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• pp.193-210
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• 1991

For the deckhouse or superstructure, attention is directed to the reduction of vibration from a human susceptibility point of view. The two basic requirements for obtaining a low vibration level in the accommodation are to ensure that excitation forces from propeller and/or main engine are small and to avoid resonance excitation of the hull and superstructure. In recent years increased attention has been directed towards the problems of vibration and noise in deckhouse, which have caused major problems with regard to the environmental quality in the living quarters for crews. Accordingly, in this paper, the characteristic of the vibration of deckhouse of fishing boat, of which the length/height ratio is also relatively high, are studied systematically with regard to the shape and modelling of deckhouse based on finite element method of 1-dimensional, 2-dimensional and 3-dimensional model. This study is divided into 4-part. 1st part is the global deckhouse vibration, 2nd part is the local deckhouse vibration, 3rd part consists of the estimation for stiffness of foundational support and 4th part is the application to TUNA LONG LINER of 416 ton class. For the global vibration analysis, the severity of the vibration depends on the longitudinal shear and bending stiffness of the deckhouse, on the vertical deckhouse support(fore, aft and sides). However, even if the design is technically sound, vibration problems may arise due to vertical or longitudinal hull girder or afterbody resonances. Author applied the method of this study to the analysis of, deep-sea fishing vessel of G.T. 416 ton class with relatively low height and long deckhouse, and investigated the vibrational characteristic of the fishing vessel with earlier structural feature. According to this investigation, the vibration, response of above vessel was confirmed of which main hull and deckhouse behave as one body. It is at the bottom of vibrational trouble which a accommodation part of the fishing vessel is raised, that is the local vibration for side wall, fore-aft wall and deck plate of deckhouse rather than thief fect of fore-aft vibration of deckhouse for above fishing vessel. and the resonance of main hull, deckhouse and driving system such as the main engine, propeller in exciting source is mainly brought up as the trouble.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.123-128
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• 2018

Girder bridges and slab bridges are equipped with a system consisting of a flexible joint unit, support, inverted T shaped abutment, and a separate connecting slab structure. These systems have problems such as an increase in cost due to frequent breakage of the expansion joints and a decrease in durability due to a structure with low moment redistribution. To improve these problems, propose Inegral and Semi-Integral Hybrid Slab Bridge and examine the safety through structural analysis. As a result of the review, Inegral and Semi-Integral Hybrid Slab Bridge was the section stiffness is small. but it is confirmed that the structural safety, ductility and flexibility are higher than existing bridges because the moment redistribution and the force transmission are surely performed.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.6
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• pp.11-15
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• 2009

Recently, a new PSC (Prestressed Concrete) bridge system, which is supported by Concrete-filled fiber-reinforced polymer (CFFRP) strut, has been introduced. This bridge is able to reduce self-weight and increase the width of traditional PSC bridges. However, no relevant research has been reported on local behavior of CFFRP strut in the bridge system. The purpose of this study is to investigate local behavior of CFFRP struts using fiber Bragg grating (FBG) sensors. Field tests were performed to examine the hoop strains and longitudinal strains of the FRP strut under various lateral positions and velocities of a test truck. It has been observed that CFFRP strut is under compression regardless of vehicle speed and location. However, the CFFRP strut is sensitive to the lateral position of vehicles in terms of strain magnitude. Results also indicated that the FBG sensors can faithfully record the hoop and longitudinal strains of the FRP strut without electro-magnetic interference.

• Journal of Korean Society of societal Security
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• v.1 no.3
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• pp.51-57
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• 2008

The long-term behaviors of prestressed concrete cable-stayed bridges are considerably influenced by the time dependant material characteristics such as creep and shrinkage. This study investigated the influences of the change of relative humidity by application of the CEB-FIP model and ACI model, which are generally used in the prediction of long-term behavior of concrete structures. In case of the moment of girder, CEB-FIP model predicted a bigger effect of relative humidity change than the ACI model. Furthermore, the effect was significant. Also, the long-term behaviors between these models were different each other even under the same material condition. Therefore, the prediction of the long-term behavior should be compensated after comparative analysis with the results of material tests of each construction site and between the different models.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.67-73
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• 2017

This study has addressed to evaluate the effects of radius of curvature and skew angle on the negative reaction in a plate girder bridge with LRB (Lead Rubber Bearing) supports. As analytical parameters, various radius of curvatures and skew angles were selected and two seismic loads of El-Centro and artificial earthquakes were applied to the bridge in the longitudinal and transverse directions. As results of 3D analysis, the possibility of negative reaction is shown at the part of acute angle and inner side of the curved bridge, and becomes increased when seismic load is applied in the transverse direction. In addition, the occurrence of negative reaction is found to be increased as both radius of curvature and skew angle decrease, which means that curved bridge has higher possibility of negative reaction than straight one. Conclusively, all of earthquake wave, gradient, radius of curvature and skew angle should be considered together to investigate the possibility of negative reaction at the bridge support subject to seismic load.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.108-113
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• 2018

Researches on strengthening and rehabilitation methods are being widely conducted due to the deterioration of existing concrete structures. Use of externally bonded Carbon Fiber Reinforced Polymers (CFRP) strips for the rehabilitation is a cost-effective and time-saving method. Generally, the CFRP layout for the shear strengthening was a uni-directional layout. Many researches have focused on the variables of the uni-directional CFRP layout such as the amount of material, angle, and spacing. Pilot tests indicated that the effective confinement of the concrete member can be provided with the bi-directional CFRP layout than the uni-directional layout. Therefore, the test was carried out after the uni- and bi-directional strengthening work using the same amount of CFRP material. CFRP anchors were installed to prevent unexpected premature CFRP delamination failure before reaching CFRP fracture strain. The effectiveness of the CFRP anchor and bi-directional CFRP layout for shear strengthening was verified based on the principal tensile strain contours.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.541-544
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• 2001

PC Box Girder was constructed by PSM(Precast Span Method) to solve the shortage of the construction period. The site case study was used in the PSM to find the construction productivity improvement. In this case study, main reasons of low productivity were founded unskilled technical engineers and insufficient equipment management winter season concrete curing condition. Productivity improvements are presented by assigning production personnel appropriately, motivation which increased by providing incentives for technical engineers, strictly cooperation of each participant, organizational teamwork, and Promoting productive work condition. Additional method of productivity improvements are continuous improvement of the work methods by considering the feedback on previous work, and continuous training to best handle the site conditions. This study of productivity improvement will help to use the most advantage of the PSM method and desire to successfully plan the future construction performance.

• Korean Journal of Construction Engineering and Management
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• v.10 no.2
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• pp.102-110
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• 2009

The cost for maintenance of bridge structures such as repair or reinforcement is increasing. In addition, the efforts for inspection of bridge structures is becoming more important since the proper repair or reinforcement should be performed to save the maintenance cost and ensure the safety for public infrastructure. Therefore, it is studied on this paper to estimate the repair or reinforcement cycles using probabilistic approach for the steel-box girders of bridge superstructure. In addition, a computer simulation program is uniquely developed based on probabilistic approach to calculate the cycles derived from the function of age of bridge and performance rating curve which were previously studied. In order to ensure the reliability of results and appropriateness of the model, statistical analyses were performed. Also, the results were compared and proved to be similar with ones from previous statistical data related to the repair or reinforcement cycles. The results from this study is expected to be useful for the determination of proper time to repair or reinforce the bridge structure and raise the safetyness of bridge structure in advance.

• Structural Engineering and Mechanics
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• v.43 no.5
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• pp.637-655
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• 2012

In this study, stochastic responses of a cable-stayed bridge subjected to the spatially varying earthquake ground motion are investigated by the finite element method taking into account soil-structure interaction (SSI) effects. The considered bridge in the analysis is Quincy Bay-view Bridge built on the Mississippi River in between 1983-1987 in Illinois, USA. The bridge is composed of two H-shaped concrete towers, double plane fan type cables and a composite concrete-steel girder deck. In order to determine the stochastic response of the bridge, a two-dimensional lumped masses model is considered. Incoherence, wave-passage and site response effects are taken into account for the spatially varying earthquake ground motion. Depending on variation in the earthquake motion, the response values of the cable-stayed bridge supported on firm, medium and soft foundation soil are obtained, separately. The effects of SSI on the stochastic response of the cable-stayed bridge are also investigated including foundation as a rigidly capped vertical pile groups. In this approach, piles closely grouped together beneath the towers are viewed as a single equivalent upright beam. The soil-pile interaction is linearly idealized as an upright beam on Winkler foundation model which is commonly used to study the response of single piles. A sufficient number of springs on the beam should be used along the length of the piles. The springs near the surface are usually the most important to characterize the response of the piles surrounded by the soil; thus a closer spacing may be used in that region. However, in generally springs are evenly spaced at about half the diameter of the pile. The results of the stochastic analysis with and without the SSI are compared each other while the bridge is under the sway of the spatially varying earthquake ground motion. Specifically, in case of rigid towers and soft soil condition, it is pointed out that the SSI should be significantly taken into account for the design of such bridges.