• Advances in concrete construction
• /
• 제7권3호
• /
• pp.183-189
• /
• 2019

In this study, it has been tried to prepare an analytical fragility curves for isolated straight continues highway bridges by considering different spectral intensity measures. A three-span concrete isolated bridge has been selected and the seismic performance of the bridge has been improved by Lead Rubber Bearing (LRB). Incremental Dynamic Analysis (IDA) is applied to the bridge in longitudinal direction. A suite of 14 earthquake ground motions from medium to sever motions are scaled and used for nonlinear time history analysis. Fragility function considers the relationship of earthquake intensity measures (IM) and probability of exceeding certain Damage State (DS). A full three dimensional finite element model of the isolated bridge has been developed and analyzed. A wide range of different intensity measures are selected and the optimal intensity measure which has the less dispersion is proposed.

• 한국도로학회논문집
• /
• 제19권3호
• /
• pp.19-30
• /
• 2017

PURPOSES : This study proposes the road asset valuation approach using alternative depreciation methods. It has become necessary to have asset management system according to the adoption of accrual basis accounting for governmental financial reporting and the amendment of the road act. Therefore, it is very important to analyze the effect of depreciation methods on road asset value as a basic research for road asset management system. METHODS : The Ministry of Strategy and Finance (MOSF) has mainly performed road asset valuation based on Write down Replacement Cost and Straight Line depreciation method. This study suggests some appropriate asset valuation methods for road assets through case analysis using three depreciation methods: Consumption-based depreciation method, Condition-based depreciation method, and Straight Line depreciation method. A road asset valuation data of national highway route 1 (year 2014) is used to analyze the effect of three depreciation methods on the road asset value. Road assets include land and structures (pavement, bridge, and tunnel). This study mainly focuses on structures such as bridges and tunnels, because according to governmental accounting standards, land and road pavement assets do not depreciate. RESULTS : The main results of this study are as follows. Firstly, overall asset value of national highway route 1 was estimated at 6.97 trillion KRW when MOSF's method (straight-line depreciation method) is applied. Secondly, asset value was estimated at 4.85 trillion KRW on application of consumption-based depreciation method. Thirdly, asset value was estimated at 4.37 trillion KRW when condition-based depreciation method is applied. Therefore, either consumption-based or condition-based depreciation methods would be more appropriate than straight-line depreciation method if we can use the condition data of road assets including land that are available in real time. CONCLUSIONS : Since road assets such as pavements, bridges, and tunnels have various patterns of deterioration and condition monitoring period, it is necessary to consider a specific valuation method according to the condition of each road asset. Firstly, even though road pavements do not depreciate, asset valuation through condition-based depreciation method would be more appropriate when requirements for application of non-depreciation approach are not satisfied. Since bridge and tunnel facilities show various patterns of deterioration and condition monitoring period by type and condition level, consumption-based depreciation method based on deterioration model would be appropriate. Therefore, it is necessary to have a reasonable asset management system to apply condition-based depreciation method and a periodic condition investigation to manage road assets well.

• Steel and Composite Structures
• /
• 제23권5호
• /
• pp.597-610
• /
• 2017

This paper presents a mathematical model for fixed-end moments of I-sections with straight haunches for the general case (symmetrical and/or non-symmetrical) subjected to a concentrated load localized anywhere on beam taking into account the bending deformations and shear, which is the novelty of this research. The properties of the cross section of the beam vary along its axis "x", i.e., the flange width "b", the flange thickness "t", the web thickness "e" are constant and the height "d" varies along of the beam, this variation is linear type. The compatibility equations and equilibrium are used to solve such problems, and the deformations anywhere of beam are found by the virtual work principle through exact integrations using the software "Derive" to obtain some results. The traditional model takes into account only bending deformations, and others authors present tables considering the bending deformations and shear, but are restricted. A comparison between the traditional model and the proposed model is made to observe differences, and an example of structural analysis of a continuous highway bridge under live load is resolved. Besides the effectiveness and accuracy of the developed models, a significant advantage is that fixed-end moments are calculated for any cross section of the beam "I" using the mathematical formulas.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2007년도 정기 학술대회 논문집
• /
• pp.525-530
• /
• 2007

Although just developed in recent years, curved box girder has widely used in modern highway system due to their load resistance capacity as well as aesthetic considerations. According to recent literature reviews on curved box girder designs, distortional load was not considered as much as it deserves to be. In practice, the effect of distributional force is very small in straight bridge systems but yet unknown how it is in curved bridge systems. For the reason, this paper will show up an extensive parametric study on distortional behavior of curved box girder with trapezoidal section. Based on Dabrowski formulas, using finite element method, various bridges were investigated. In this study, following parameters will be included: span length, curvature radius, section height, section width, and internal section angle (web slope). From the obtained results, some initial geometric parameters are proposed for curved box girder bridges.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2005년도 학술발표회 논문집
• /
• pp.380-387
• /
• 2005

Little has been understood about the seismic behavior of curved bridges due to the different structural characteristics compared to straight bridges. In this study, a simple numerical model, widely used for seismic analysis, is modified for a more realistic estimation of the seismic behavior. The seismic response of curved bridges obtained with the modified simple numerical model was compared with the result using a more sophisticated model to verify the feasibility. Seismic analyses were performed on three-span continuous curved bridges, which is a structural system widely used in highway structures. Numerical model of the three-span continuous curved bridges were subjected to seismic loads in diverse directions. From the result of the analysis. it was found that the direction of the seismic load have significant effect of the seismic behavior of curved bridges when the central angle exceeds 90 degrees.

• Steel and Composite Structures
• /
• 제17권5호
• /
• pp.705-719
• /
• 2014

Composite steel-concrete box girders are frequently used in bridge construction for their economic and structural advantages. An integrated metaheuristic based optimization procedure is proposed for discrete size optimization of straight multi-span steel box girders with the objective of minimizing the self-weight of girder. The metaheuristic algorithm of choice is the Cuckoo Search (CS) algorithm. The optimum design of a box girder is characterized by geometry, serviceability and ultimate limit states specified by the American Association of State Highway and Transportation Officials (AASHTO). Size optimization of a practical design example investigates the efficiency of this optimization approach and leads to around 15% of saving in material.

• 한국방재학회:학술대회논문집
• /
• 한국방재학회 2007년도 정기총회 및 학술발표대회
• /
• pp.297-302
• /
• 2007

최근에 빠른 발전을 이루고 있기는 하나, 하중 저항 계수나 미관효과 면에서 박스 거더를 고속도로 분야에 폭넓게 사용하고 있는 실정이다. 최근의 박스 거더 설계를 기반으로 살펴보면 뒤틀림 하중은 그다지 고려되지 않았다. 특히 직선교에서는 뒤틀림 하중의 효과가 작지만 곡선에서는 어떻게 작용하는지 조차 알려진 것이 없었다. 그러한 이유에서 이 연구는 뒤틀림 거동에 미치는 주요한 변수들에 대해 다루었다. 그리고 유한요소법을 사용하는 Dabrowski formula를 바탕으로 하여 다양한 변수의 교량에 대해 연구하였다. 이 연구에서는 다음과 같은 변수들이 사용된다. : 지간장, 곡률반경, 단면높이, 단면폭, 그리고 내부단면각(internal section angle) 연구된 결과로부터 적당한 초기 기하형상에 대한 변수들을 구할 수 있을 것이다.

• 대한토목학회논문집
• /
• 제34권6호
• /
• pp.1731-1741
• /
• 2014

교통수요의 증가에 따른 교통혼잡을 피하기 위하여 고가도로와 고속도로, 경전철 등이 활발히 건설되고 있으며, 이에 따라 접속부 등과 같은 곡률반경이 작은 곡선교 구간의 발생이 증가하고 있다. 초기에는 직선형의 주형을 연결하여 곡선을 이루는 방법을 사용하였으나, 공사비의 증가와 미관성 측면에서 용이하지 않아 강재를 사용한 곡선주형이 개발되어 적용되고 있다. 강재의 특성상 기하학적인 형상을 구현하는데 상대적으로 손쉽기 때문에 대부분의 곡선교에서는 강재를 이용한 강박스 거더교를 주로 사용하고 있다. 그러나 강박스 거더교는 초기 공사비가 고가이고, 도장과 같은 지속적인 유지관리가 필요한 문제점을 가지고 있다. 최근에는 I형 강재 플레이트 거더를 사용하는 방법이 활발히 연구되고 있으나 곡선 I형상의 특성상 개단면이고 얇은 플레이트를 사용하기 때문에 비틀림 강성이 매우 작아 안전성에 문제가 있는 것으로 지적되고 있다. 이러한 곡선강교의 대안으로 경제성과 안전성이 확보되는 프리캐스트 PSC 곡선거더가 제시되고 있다. 이에 본 연구에서는 프리캐스트 PSC 곡선거더를 효율적으로 제작할 수 있는 스마트 몰드 시스템을 개발하고 이를 적용한 2주형 40m 실물교량의 정적 휨 파괴 실험을 통하여 안전성을 확인하고자 한다. 제작단계에서 단일 거더는 곡률반경에 의해 거더의 전도에 대한 안정성이 문제가 있으나 가로보로 연결된 멀티거더는 하중분배가 적절히 이루어지며 안정성이 확보되는 것으로 나타났다. 정적구조 실험결과에서는 균열하중(1,400 kN)이 설계하중(450 kN)의 약 3배 이상 높은 것으로 나타났으며, 허용처짐량에 해당하는 하중은 설계하중의 4배인 1,800 kN에서 발생하여 사용성과 안전성이 모두 확보되는 것으로 나타났다.