• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.5290-5298
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• 2013

In order to apply a mechanical deck joint to the prefabricated steel grid composite decks, shear resistance of a joint composed of concrete shear key and high-tension bolt is experimentally evaluated by the push-out test. Shear resistance evaluated by the test is compared with resistance estimated by empirical and design equations based on the shear friction theory. Test results show that joint specimens bonded by epoxy have about 10% more shear resistance than specimens with strengthened shear key by steel plates, but in the case of specimens with strengthened shear key there is smaller resistance deviation than specimens bonded by epoxy. In comparison with resistances estimated by empirical and design equations, the deck joint can be safely designed. But because the existed shear resistance of deck joint is underestimated by the ACI-318, application of the LRFD design equation could be more reasonable.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.214-217
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• 2011

두가현수교는 2010년 8월 집중호우로 인해 유실된 교량을 복구하기 위한 과업으로서 향후 재발방지를 위해 중앙 경간장을 증가시켜 통수단면적을 추가확보하고, 교량 여유고를 상향시켜 수해에 대비한 견고한 교량으로 계획하였다. 또한 보행자의 통행을 위한 보도육교의 특성을 고려하여 지역의 관광자원이 될 수 있도록 중앙경간 125m의 V형 주탑 3차원 보도현수교로 설계하였다. 보강거더는 H-Beam을 이용하여 자재 수급 및 취급이 용이하며 강재 바닥판을 적용하여 보다 경량화된 보강거더를 적용함으로써 주케이블의 장력 감소에도 기여하도록 하였으며, 행어정착을 위한 별도의 정착거더를 채택한 ${\pi}$형식을 채택하여 풍동실험을 통해 내풍 안정성을 확인하였다. 주케이블 및 행어는 미관, 구조적 안정성, 유지관리성 및 가설의 용이함을 고려하여 PE를 피복한 PWS케이블을 선정하였다. 경관을 고려한 V형 주탑을 이용한 3차원 케이블을 채택하여 지역의 상징물을 표현하였으며 기초의 규모를 최소화 하였다. 또한 H형 및 A형 주탑과의 비교를 통해 V형 주탑 교량의 특성을 검토하였다.

• Journal of the Korea Concrete Institute
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• v.27 no.6
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• pp.677-685
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• 2015

In a will to subdue the brittleness as well as the low tensile and flexural strengths of ordinary concrete, researches are being actively watched worldwide on steel fiber-reinforced Ultra High Performance Concrete (UHPC) obtained by admixing steel fibers in ultra high strength concrete. For the purpose of maximizing advantage of UHPC, this study removes the upper flange of the steel girder to apply an inverted T-shape girder for the formation of the composite beam. This paper intends to evaluate the behavior of the shear connectors and the flexural characteristics of the composite beam made of the inverted T-shape girder and UHPC slab using 16 specimens considering the compressive strength of concrete, the mixing ratio of steel fiber, the spacing of shear connectors and the thickness of the slab as variables. In view of the test results, it seemed that the appropriate stud spacing should range between 100 mm and 2 or 4 times the thickness of the slab. Moreover, the relative displacement observed in the specimens showed that ductile behavior was secured to a certain extent with reference to the criteria for ductile behavior suggested in Eurocode-4. The specimens with large stud spacing exhibited larger values than given by the design formula and revealed that the shear connectors developed larger ultimate strength than predicted owing to the action of UHPC and steel after non-composite behavior. Besides, the specimens with narrow stud spacing failed suddenly through compression at the upper chord of UHPC before reaching the full capacity of the shear connectors.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.13-17
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• 2004

In recent years, the deterioration of reinforced concrete structures has become a serious problem in civil engineering fields. This situation is mainly due to corrosion of steel reinforcing bars embedded in concrete. Recently, there has been a greatly increased demand for the use of FRP (fiber reinforced plastic) in civil engineering field due to their superior mechanical and physical properties. This paper presents an experimental study on the behavior of concrete bridge deck reinforced with FRP Box, FRP Plate, and FRP Re-bar. In tlIe study, mechanical properties of FRP Box, FRP Plate, GFRP Re-bar, and CFRP Grid have been investigated. Full scale one-way deck slab was tested under four point lateral load (equivalent to actual wheel load of DB-24 including impact). Load-deflection and load-strain data were collected through LVDT's and strain gages attached to the specimen.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.1
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• pp.41-47
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• 2009

Transverse rib web of orthotropic steel decks is highly susceptible to stress concentration due to out-of-plane and oil canning deformation caused by longitudinal rib distortion. In particular, stress concentrations are observed in the crossing point of longitudinal rib-transverse rib-deck plate, and cutout parts of transverse rib. The main objective of this study is to improve structure performance and to reduce the stress concentration of aforementioned susceptible parts. It is known that the installation of diaphragm alleviates stress concentrations between crossing point ant cutout. The influence of transverse rib placement and cutout width on stress concentrations was thoroughly investigated through numerical analyses. The numerical result showed that diaphragms produce the structural details for improved structure performance, when the transverse rib was placed in the same location with diaphragms. In any case, it is certain that the installation of diaphragms has more advantageous than the case without diaphragms in terms of structure performance of orthotropic steel decks. In this study, the distance ratio($y_i/y_{total}$) is defined as the ratio of the distance($y_{total}$) between the deck plate and longitudinal rib bottom to the distance($y_i$) between the deck plate and crossing point of longitudinal rib-transverse rib in cutout part. It has been found that the optimal distance ratio was 0.85 from the numerical simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.2396-2402
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• 2012

In recent years, the use of hybrid fiber reinforced polymer(FRP)-concrete members with a dual purpose of both formwork and reinforcement, has been considered in some structures and has been applied in a small number of bridge decks. Numerical simulations of the beam failure tests were performed using nonlinear finite element program and a parametric study was performed with variables of perfobond shape. The ultimate strength was increased with perfobond shape because of dowel action. It was showed a good performance in case of approximately perforate diameter 25~35mm in this case.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.92-103
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• 2015

Development of new concrete bridge deck system with FRP plank using as a permanent formwork and the main tensile reinforcement recently has been actively conducted. Concurrent use as a reinforcing material and a permanent formwork, it is possible to reduce the construction time and construction costs than the usual concrete slab. In this study, an experiment was carried out for the bond stress between cast-in-place concrete and the type of FRP plank using as a permanent formwork. The interfacial fracture energy that can be one of the most important parameters were evaluated for adhesion performance and bond stress to know the characteristics of the failure mechanism of the adhesion surface. Interfacial fracture energy of normal concrete is 0.24kN/m of GF11 case, in the case of GF21, 0.43kN/m appears, in the case of CF11 and GF31, 0.44kN/m and 0.46kN/m respectively it appeared. In case of RFCON, 0.52kN/m appears from GF12, the CF12 and GF22, 0.51kN/m and 0.36kN/m appeared each case.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.941-944
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• 2008

Various ductile fiber reinforced cement composite(DFRCC) including large quantities of PVA fiber or steel fiber have been developed recently and studies to find applications in diverse domains are currently conducted actively. Regard to economical efficiency, DFRCC becomes competitive when applied as special elements and repair material with small quantities rather than the casting of large volume for the main body of structures in field. The authors have developed FRP-DFRCC composite slab for bridges and a wet spraying repair technique using DFRCC. In case of the application on FRP-DFRCC composite slab, it was found that there was no problems the structure and durability of it after passed 3 months. And in case of the application on the application of the deteriorated sewage box that passed 20 years, it was found that there was no difference the repair performance between domestic PVA fiber and the Japan. Therefore, DFRCC using PVA fiber, the concrete structures can be increased to performance and secured the economical efficiency.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.59-64
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• 2001

The concrete bridge decks are in need of replacement and rehabilitation due to decreasing load carrying capacity. In this study, to extend life cycle of the concrete bridge decks which are reinforced with the glass fiber sheets, the concrete bridge decks are examined on the strengthen effect and the fatigue behavior. The behavior of strengthened slabs is represented by load-displacement relationship, variation of compliance and total released energy. Owing to result of that, the strengthened slabs is modified the elasticity, the compliance and represents to control the crack elongation, to elevate the total released energy, to modify the fatigue life. When the concrete bridge deck is strengthened, the crack propagation nay be controled efficiently.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.221-231
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• 2011

Thinner and lighter structural members can be designed by utilizing the high stiffness and toughness, and high compressive strength of UHPC(ultra high performance concrete), which reaches up to 200MPa. The punching shear capacity of UHPC was investigated in this paper aiming for the application of UHPC to bridge decks. Six square slabs were fabricated and punching shear test was performed under fixed boundary condition. Different thicknesses of test slabs, which were 40mm and 70mm, were selected. The shape ratio of loading plates were ranged between 1.0~2.5. 40mm thickness slabs showed longer softening region after the peak load and, on the other hand, 70mm thickness slabs revealed a more brittle shear failure. Experimental results were analyzed using various existing punching shear predicting equations. Ductal$^{(R)}$ equation and JSCE equation better predicted for 40mm slabs, and Harajli et al. equation and ACI-Ductal$^{(R)}$ equation better suited for 70mm slabs. Nevertheless generally they didn't well predict the test results. A new punching shear equation which was derived based on the actual failure mechanism was proposed. The proposed equation appeared to better predict the punching shear strength of UHPC than other available equations.