• Journal of the Korea Concrete Institute
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• v.25 no.4
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• pp.447-455
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• 2013

In this study, reinforced concrete slabs with steps were experimentally studied to analyze their structural performance and to suggest reinforcing details in the step. Because the stepped slabs may behave very poorly in terms of bending strength, stiffness, deflection, cracking, etc., the study is aimed to suggest proper reinforcing details such that the same bending strength is obtained as that without steps. The bending strengths of 12 test specimens with a variety of different reinforcing detail types or other parameters were compared with each other. The specimen without any additional reinforcement in the step had a very low bending strength and significant damage, and the specimens with diagonal reinforcements in the step showed substantial early cracks, experienced hinging of the step, and had a substantial loss of the bending strength. In contrast, the specimens with a combination of U-bars, reversed U-bars, L-bars, and reversed L-bars performed very well and almost reached to 100% of the slab bending strength. The U-bars and reversed U-bars were effective in controling the diagonal cracks, while the L-bars and reversed L-bars were effective in preventing from yielding of slab reinforcement near the step.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.229-237
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• 2011

This study was conducted to investigate the early-age performance of precast pavements constructed by replacing existing asphalt pavements for a bus stop section in urban bus only lanes. The behavior monitoring items included the differences in the levels between asphalt and precast pavements at the entrance and exit of the precast pavement, joint widths and level differences between precast slabs, slab settlement, and skid resistance at the slab surface. The applicability of diamond grinding techniques was also investigated. The results of this study showed that the slab level, joint width, settlement, and skid resistance were not much changed as time passed, which implied that the precast pavements stably sustained vehicle loads. It was also found that employing diamond grinding could much improve the leveling between precast slabs and the surface skid resistance.

• 한국도로학회:학술대회논문집
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• 2009.11a
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• pp.407-412
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• 2009

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.665-670
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• 2009

From the result of preceding study, there is no reinforcement such as dowel bar or etc. in Joint system of floating slab. Length of floating slab in preceding study is short than one of this study. If there is no reinforcement in the joint of long slab span, fracture of slab is predicted by difference between two slabs. Therefore using of dowel bar is demanded. In this study, General characteristic and preceding technology of dowel bar is researched for data of analysis study. And it is considered application of dowel bar in floating slab system.

• Magazine of the Korea Concrete Institute
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• v.2 no.4
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• pp.91-98
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• 1990

Joints are provided in cement concrete pavements to control transverse and longitudinal cracking that occur due to restrained deformations caused by moisture and temperature variations in the slab. But the constuction of joints reduces the load-carrying capacity of the pavement at the joints, and pavements have been deteriorated by cracks at the slab edges along the joints due to traffic loads. Therefore, it is important to analyze the behavior of joints accurately in the design of cement concrete pavements. In this study, the mechanical behavior of cement concrete pavement slabs is analyzed by the plate-finite element model, and Winkler foundation model is adopted to analyze the subgrades. The load transfer mechan¬ism of joints are composed of dowel action, aggregate interlocking, and tied-key action, and the analytical pro¬gram is developed using these joint models. Using this numerical model as an analysis tool, the effects of joint parameters on the behavior of pavements are investigated.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.6
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• pp.41-49
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• 2009

Poor compaction of subgrade soil causes low stiffness and bearing capacity of sublayers so that faulting and differential settlements can be generated between new and old pavement surfaces in case of widening works. However, investigation of verifying the reason of producing the defects in the pavements are not performed in detail. In this study, several in-field tests including PMT and PBT were performed for obtaining stiffness of the sublayers in new and old pavements respectively of an widening project. Then, based on the obtained stiffness values and the measured deformations obtained by specially designed tilt meters, the main reasons of generating different deformations between the old and new pavement sections and the relationship between the deformation and stiffness are verified.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.374-374
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• 2011

Recently the construction of railway sections passing the central area of cities and stations under railway lines are increasing, and then it is urgently required to take the countermeasures against the railway vibration and the second-phase noise radiated from it. The most efficient countermeasure, out of technologies developed up to now, is the floating slab track which is the track system isolated from the sub-structure by springs. In other countries, the source technologies for anti-vibration design and vibration isolator - one of key components - have been developed and many installation experiences have been accumulated. However, in Korea, since the system design technology and technologies for key components are not yet developed, the foreign system are being introduced without any adjustment, and the key component, vibration isolator, depends on imports. In this study, based on the results of previous studies of the dust-control device installation using the slab and go through time after lifting impressive when stepped on power generated by the cross-section of the slab and shear connection re-examined the structural stability.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1303-1313
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• 2013

In this study, the reference values for the internal forces of the rail supports caused by a wheel load, a unit vertical displacement, a unit end rotation in examination of the serviceability of concrete slab track bridge were obtained. In analysis, the analysis models of which the rail was continuously and discretely supported by elastic springs were used. The internal forces of the rail supports from the analysis were compared with the results provided in the DS 804 regulations and agreed with well. In addition, the effects of the space between the rail supports and the stiffness of fastener on the internal forces of the rail supports were investigated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4D
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• pp.593-600
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• 2006

Joint opening of jointed concrete pavement is caused by change in temperature and humidity of adjoined slab. The magnitude of joint opening influences on the load-transfer-efficiency and the behavior of sealant. If temperature or humidity decreases, joint opening increases. Generally maximum joint opening of a given joint is predicted by using AASHTO equation. While different magnitudes of joint opening at the individual joints have been observed in a given pavement section, AASHTO equation is limited to predict average joint opening in a given pavement section. Therefore the AASHTO equation may underestimate maximum joint for the half of joint in a given pavement section. Joints showing larger opening than the designed may experience early joint sealant failure, early faulting. Also unexpected spalling may be followed due to invasion of fine aggregate into the joints after sealant pop-off. In this study, the variation of the joint opening in a given pavement section was investigated based on the LTPP SMP data. Factors affecting on the variation are explored. Finally a probabilistic joint opening model is developed. This model can account for the reliability of the magnitude of joint opening so that the designer can select the ratio of underestimated joint opening.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.792-795
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• 2008

AGT system is a kind of light railway train. AGT system use of concrete track and rubber tire, so it can be reduce the noise and vibration, compare to the normal train system. And, the dynamic responses of normal bridge are influenced by the dynamic characteristics of bridge, the speed of vehicle and the surface roughness of railway. But the AGT system bridge is influenced not only the above facts but also the guiderail unevenness, because, AGT vehicle steered by guiderail. So, in this study, optimized service condition is suggested for the design and operation of AGT system, by the means of experimental study. The experiments are executed for PSC bridge with length of 30m, at the AGT test line in Kyongsan. The test results are compared and investigated according to the prominence. In the test result, the guiderail prominence influenced on the dynamic response of bridge. It shows a increase as compared with no guiderail prominence in the dynamic response value acceleration, displacement, stain.