PURPOSES : The objectives of this study are to evaluate the condition of concrete bridge decks using the multi-channel ground penetrating radar (GPR) testing and compare the value of its dielectric constant value with actual concrete condition. METHODS : The reflection coefficient method was used to measure the dielectric properties of concrete bridge decks. Air-coupled step-frequency GPR testing was used to measure the time taken for reflection from the interfaces between the layers. Specimens of the asphalt mixture and concrete bridge-deck were collected by field coring. GPR testing was conducted on two bridges with different concrete bridge deck conditions on national highways. After the GPR tests, the actual conditions of the concrete bridge deck were investigated using specimen coring. RESULTS : GPR testing indicated that the dielectric constants of concrete bridge decks in good condition ranged from 8 to 10, whereas those corresponding to poor condition ranged from 4 to 6. The results of GPR testing can determine the actual condition and degree of distress of concrete bridge decks determined from the specimen coring data. Therefore, GPR testing is appropriate for nondestructively evaluating the condition of a concrete bridge deck. CONCLUSIONS : The analysis results of the dielectric constants of the concrete bridge deck obtained from multichannel GPR testing were consistent with the actual bridge deck conditions. In the near future, an additional verification process for this approach under different bridge conditions will be required to improve its precision and ensure reliability.

교량 인프라는 국민의 경제와 사회적 활동에 반드시 필요한 물리적 기반시설이고, 국민의 안전과 편의성에 직결되는 시설이므로 국민의 입장에서 편익을 고려해야 한다. 교량의 구성요소 중 바닥판은 교량 전체의 생애주기 동안 필연적으로 교체 시기가 도래하고 파손 등으로 인한 부분 교체도 빈번하게 이루어지고 있다. 바닥판 교체공사 시 거더와 바닥판을 합성하는 기 존 용접 전단연결재의 문제점을 해결하기 위한 볼트 접합 전단연결재(DY볼트)는 바닥판 철거 공정에서 파쇄를 최소화하고 교 체공사를 위한 전단연결재 재시공이 용이하여 공사 기간을 기존 대비 단축할 수 있는 것으로 분석되었다. 공사기간 중 도로차 단으로 인해 발생하는 도로이용자비용을 산출하여 기존 공법과 비교하는 방법으로 볼트 접합 전단연결재를 적용한 강합성 교량 의 경제성을 도로이용자(국민) 입장에서 분석하였다.

PURPOSES : Steel deck bridges are the preferred structural type for reducing dead load, and the use of thin-layer asphalt concrete with excellent adhesion to the steel deck and excellent deformation followability is increasing for bridge pavements. However, because these materials are constructed at a high temperature of 240 °C or higher to maintain high fluidity during construction, excessive thermal deformation and stress may be temporarily induced in the steel deck. Therefore, the stability of the structure must be assessed by considering the environmental conditions of the site during pavement construction. Herein, a method is presented for estimating the heat source equation, in which conduction and convection effects are removed using temperature measurement data, for modeling U-rib using plate elements. The validity of the study is assessed by deriving the equivalent heat source equation using the temperature data measured from the underside of the steel deck while constructing a 40-mm-thick goose asphalt concrete pavement layer on a 12-mm-thick steel deck. In addition, the practicality is verified by performing heat transfer and thermal stress analyses. METHODS : By comparing the temperature data measured during the construction of high-fluidity asphalt concrete with the results of repeated heat transfer numerical analysis, heat source data without field conduction and convection conditions are obtained. Subsequently, a heat source equation suitable for the heat source data is derived using the least-squares method. RESULTS : The results of the heat transfer analysis using the equivalent heat source equation calculated using the presented method are almost consistent with the measured temperature data. In addition, the behavioral characteristics of the structure that matches the behavior of the actual structure can be derived through thermal stress analysis, which considers heat conduction and convection to adjacent members. CONCLUSIONS : Even when the steel deck and U-rib member are modeled as plate elements, thermal effect analysis can be performed reasonably while considering field conditions.

PURPOSES : In this study, a method for evaluating concrete bridge deck deterioration using three-dimensional (3D) ground penetrating radar (GPR) survey data and its in situ application are discussed. METHODS : Field surveys are conducted on two bridges in Yongsan-gu (Bridge A) and Seodaemun-gu (Bridge B) in Seoul using 3D GPR. The obtained survey data are used to calculate the dielectric constant map of each bridge using the extended common midpoint method. In addition, random points on both bridges are selected for the chloride content test in accordance with the KS F 2713 standard. The results from the dielectric constant map and chloride content test are compared. RESULTS : For Bridge A, it is discovered that the percentage of sections with a dielectric constant of 5.0 or less is 1.57%, whereas that above 5.0 is 98.43%; this indicates that the percentage of deteriorated sections for Bridge A is low. Meanwhile, for Bridge B, the dielectric constants calculated for the entire bridge exceed 5.0, which suggests no deterioration for Bridge B. Moreover, all the points selected for the chloride content test have less than 0.15% chloride content and have dielectric constants ranging from 5.0 to 7.0, which are favorable condition for the bridge deck. CONCLUSIONS : The analysis results of the dielectric constants of the concrete bridge deck obtained from the 3D GPR system are consistent with the actual chloride content results. Furthermore, additional verification of this method through field surveys on bridge sections with severe deterioration is highly recommended for future improvements.

교면포장이라 함은 교통하중의 반복재하, 충격작용, 우수, 기타 환경하중으로부터 교량의 구조물(상판)을 보호함과 동시에 사용자를 위한 쾌적한 주행성 및 안정성 제공을 목적으로 시공되는 포장체를 의미한다. 이에 따라 교면포장은 높은 내구성, 시공 및 공정관리를 필요로 하며, 우수한 구조적 성능유지를 위해 우선적으로 신・구 콘크리트 간의 완전부착을 통한 일체거동이 확보되어야 한다. 일반적으로 국내 고속도로의 신설 교면포장을 시행함에 있어 신・구 콘크리트간의 부착성능을 향상시키기 위해 바닥판 콘크리트의 레이턴스 제거 공정을 시행하고 있으며, 이에 해당되는 경계면처리 방식에는 인력파쇄, 로드커터, 워터블라스트, 숏블라스트, 샌드블라스트, 평삭기, 워터젯 등 다양한 면처리 방법이 적용되고 있다. 상기 파쇄장비들의 사용목적은 복합 구조체를 형성함에 있어 접합면의 이물질 및 바닥판 콘크리트 표면의 취약부에 의한 부착성능 저하 요소를 제거하고자 함에 있으나, 각 파쇄장비의 적용에 따른 경계면처리 시 높은 파쇄에너지로 인해 바닥판 콘크리트 표면에 손상을 주어 오히려 신・구 콘크리트간의 부착성능이 저하되는 요인이 될 우려가 있다. 따라서 본 연구에서는 신설교면포장의 경계면처리 방식에 사용되는 장비 중 로드커터, 숏블라스트, 평삭기 적용구간을 시험변수로 선정하여 경계면처리 시행구간에 대한 코어채취를 시행, 파쇄장비의 적용에 따른 바닥판 콘크리트의 균열발생 유무 및 균열크기 등에 대해 분석하였다. 파쇄장비 적용에 따른 균열특성을 분석하기 위하여, 장비사용에 따른 4가지 변수(로드커터, 평삭, 블라스팅, 무처리)에 해당하는 현장코어를 사용하여 전자현미경(HT003C)을 통한 표면 균열발생 여부 및 균열크기 분석을 시행하였고, 바닥판 콘크리트에 사용된 쇄석골재(20EA) 또한 표면 균열특성 분석을 시행하였다

FRP composites bridge deck has advantages of structural characteristics and rapid construction in the replacements of the deteriorated bridge deck. Although FRP composites have many advantages, the application in the bridge design has been retarded so far due to the lack of design guidelines. In this paper, the design example for the FRP decked concrete composite girder bridges is presented to verify the proposed design method. The design of connection in the design example is the flexible hybrid shear connection included steel reinforcements and FRP tubes. Finally, this paper may be design guideline for FRP decked concrete composite girder bridges required the composite action.

Recently, the fiber reinforced polymers (FRP) materials have been recognized as advanced materials for bridge construction. The FRP bridge deck system has advantages to construct rapidly, its durability. The FRP bridge decks have accepted as a method of deteriorated reinforced concrete bridge deck replacement. For application, design method details and connections for FRP bridge decks will be provided. In this paper, the design method, deck design and connections details on FRP decked precast, prestressed concrete girder bridges is presented. In this study, the design method of efficient connection between FRP deck and concrete girder is proposed with composite action. The schematic of proposed modular FRP panel deck-to-concrete girder connection is also presented, which is the flexible hybrid shear connection included steel reinforcements and FRP tubes. The FRP deck-to-concrete girder hybrid connection system should be improved with further refinement and experimental program. Finally, it is hoped that this paper will be guideline for research and development on this subject field for researchers and engineers

This paper dealt with the applicability of GFRP materials as reinforcements for a steel box girder bridge deck. The purpose of this study is to provide detailed design procedures with a code-based text for GFRP composites for civil engineering structures. From the example design, the deck was optimized from a serviceability perspective but was quite overdesigned with regard to flexural strength and creep rupture stress, due to its relatively low longitudinal modulus but high strength. We may conclude from these results that it is advisable to check the serviceability limits before optimizing the design for strength or starting the design from the serviceability calculation.

The load-end slip relation of the steel-concrete decks is formulated by Newmark theory. Using the proposed load-end slip relation model, a simple bond model, which can be used to evaluate the behavior of the steel-concrete decks, is proposed. The steel-concrete decks are analyzed by finite element analysis with the aid of the proposed bond model. In the finite element analysis, the shear connectors between the steel plate and the concrete are modeled by a number of spring elements. The results of the finite element analysis with the proposed bond model are fairly correlated with the experimental results of the full-size model. This study furthermore indicates that, if the proposed bond model is properly used in the analysis of steel-concrete composite deck, the behavior of the composite deck can be easily analyzed without the aid of the full-size experiment.

In this study we developed an integrated precast concrete decks for a rapid construction. The structural performance in the integrated precast bridge decks is evaluated by real-scale test bed and detailed finite element analyses. The numerical analysis results were compared with the experimental data from a real-scaled single-span precast/prestressed concrete bridge decks under truck loading. Parametric studies are focused on the various effects of external loads on the structural behavior for different locations and measuring points on the precast bridge decks. The assessment in this study indicates that the integrated precast bridge decks show an excellent structural performance as expected.