• 한국산학기술학회논문지
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• 제20권4호
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• pp.597-605
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• 2019

IPM Birdge는 경간장 30.0m에서부터 최대 120.0m까지 적용이 가능한 일체식 교량으로, 이러한 교량의 형상 조건은 라멘교에서도 적용가능하다. 교량의 형상조건은 유사하나 거동이 다른 IPM Bridge와 라멘교를 현장에 적용하기 위해, 두 교량의 공학적 우수성을 비교분석하는 과정이 필요하다. 본 연구에서는 라멘교와 IPM Bridge의 구조해석을 수행하여, IPM Bridge와 라멘교의 하중, 모멘트, 및 변위 등의 분포 형태를 비교분석하였다. 입력조건의 차이가 두 교량 형식의 거동에 영향을 미치지 않도록 동일한 조건에서 구조해석을 수행하였다. 구조해석은 경간 30.0m를 기준으로 단경간 교량부터 4경간 120.0m까지로 각 4개의 모델로 구조해석을 수행하였다. 본 연구로부터 도출된 결론은 다음과 같다. 1) 휨모멘트는 라멘교가 크게 산정되었고, 수평변위는 IPM Bridge가 크게 산정되었다. 2) 라멘교는 교량의 연장보다는 경간장에 의해 휨모멘트가 크게 도출되므로, 설계에서 경간장에 대한 허용 휨모멘트가 고려되어야 한다. 3) IPM Bridge의 파일벤트는 120.0m 경간에서도 강관말뚝의 소성모멘트를 초과하지 않았지만, 수축방향의 수평변위가 조인트 교량의 허용기준인 25mm에 근접하므로 설계 시 고려가 필요하다. 4) 실제 설계에서는 부재력에 대한 안정성을 확보하는 것이 중요하므로, 부 모멘트에 대한 검토가 가장 중요한 것으로 나타났다.

• 대한물리의학회지
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• 제10권3호
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• pp.81-86
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• 2015

PURPOSE: Bridge exercises are broadly used to develop trunk co-activation patterns that promote spine stability. This study was to analyze the trunk muscle activity during bridge exercise with various shoulder support surface(stable, sling, Swiss ball). METHODS: The subjects were 20 healthy subjects in their twenties. Subjects were performed bridge exercise on 4 different shoulder support surfaces using stable and labile instruments. 1) Bridge exercise on a stable surface. 2) Bridge exercise with their shoulder on a stable bench. 3) Bridge exercise with their shoulder on a sling. 4) Bridge exercise with their shoulder on a Swiss ball. Rectus abdominis, erector spinae, internal oblique, external oblique muscle activities were measured using electromyography. RESULTS: There were significant differences in RA, EO muscles between performing each of the 4 exercises(p<.05). RA and EO was recorded the highest activity during the bridge exercise with their shoulder on a sling. The lowest activity was recorded during conventional supine bridge on a stable surface. There were no differences found for the EO/RA and IO/RA ratio. The EO/RA and IO/RA ratio was the highest in the bridge exercise with their shoulders resting on a stable bench. CONCLUSION: These findings suggest that change of shoulder support surface during bridge exercise may be useful for enhancing the trunk stability.

• Structural Engineering and Mechanics
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• 제29권4호
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• pp.381-390
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• 2008

This paper proposed a conceptual design of bascule bridge, which is a new kind of movable bridge with an aim of reducing the weight of superstructure. Compared with the traditional bascule bridge, the light bascule bridge chooses cable-stayed bridge with inclined pylon as its superstructure; therefore, the functions of balance-weight and structure will fuse into one. Otherwise, it adopts moving counterweight to adjust its center of gravity (CG) to open or close the bridge. In order to lighten the superstructure, it uses contact springs to auxiliary retract, and intelligent prestressing system (IPS) to control the main girder's deformation. Simultaneously the vibration control scheme of structure is discussed. Starting from establishing the mechanical model of bridge, this article tries to analyze the conditions that the design parameters of structure and attachments should satisfy to. After the design procedure was presented, an example was also adopted to explain the primary design process of this kind bridge.

• Structural Engineering and Mechanics
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• 제39권4호
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• pp.521-539
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• 2011

Jilin highway concrete bridge is located in the center of Jilin City, which is positioned in the middle part in Jilin Province in the east north of China. This bridge crosses the Songhua River and connects the north and the south of Jilin City. The main purpose of damages inspection of the bridge components is to ensure the safety of a bridge and to identify any maintenance, repair, or strengthening which that need to be carried out. The damages that occur in reinforced concrete bridges include different types of cracks, scalling and spalling of concrete, corrosion of steel reinforcement, deformation, excessive deflection, and stain. The main objectives of this study are to inspect the appearance of Jilin highway concrete bridge and describe all the damages in the bridge structural members, and to evaluate the structural performance of the bridge structure under dead and live loads. The tests adopted in this study are: (a) the depth of concrete carbonation test, (b) compressive strength of concrete test, (c) corrosion of steel test, (d) static load test, and (e) dynamic load test. According to the damages inspection of the bridge structure appearance, most components of the bridge are in good conditions with the exception arch waves, spandrel arch, deck pavement of new arch bridge, and corbel of simply supported bridge which suffer from serious damages. Load tests results show that the deflection, strain, and cracks development satisfy the requirements of the standards.

• 한국BIM학회 논문집
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• 제8권4호
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• pp.34-40
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• 2018

As the number of aged bridges increases, the development of efficient bridge maintenance techniques is becoming more important. Particularly, there have been many studies on digital-twin models of bridges for maintenance and SHM (Structure Health Monitering). However, in order to use the digital-twin model for maintenance of the bridge, the model updating process that matches the structural response between the real bridge and the digital-twin bridge model must be done. This study presents a model updating method that adjusts bridge's stiffness and boundary condition with genetic algorithm (GA) using static displacements and verified proposed updating method through field test on PSC girder bridge. This study also proposes a conceptual idea to construct an efficient bridge maintenance system by applying the updated numerical analysis model to the digital-twin model.

• 한국안전학회지
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• 제27권4호
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• pp.50-61
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• 2012

In recent years, various research and developments to introduce composite bridges of new concept have been performed. The types of integral bridge and portal rigid frame bridge are having advantages in bridge maintenance and structural efficiency by eliminating expansion joints and bridge supports. However, the detail of typical girder-abutment connection has problems such as complexity of construction and increase of the construction cost. A new type of bridge, called prestress integral composite girder(PIC girder) bridge, is proposed in this study, which decreases the cost of construction and improves the efficiency of construction by simplifying the detail of construction for girder-abutment connection. PIC girder bridge has the connection detail in which the steel girder and the abutment are integrated by using the PS bar installed in the connection. In this study, finite element analysis and mock-up load test are conducted to evaluate the propriety of design, the effective of fabrication and structural safety for PIC girder bridge. The adequacy of the PIC giredr bridge is verified by the results of static/dynamic load test and finite element analyses.

• Steel and Composite Structures
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• 제29권4호
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• pp.437-450
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• 2018

A bridge comprising of two girders, such as a twin steel box-girder bridge, is classified as fracture critical (i.e., non-redundant). In this study, the various bridge components of the twin steel box-girder bridge are investigated to determine if these could be utilized to improve bridge redundancy. Detailed finite-element (FE) models, capable of simulating prominent failure modes observed in a full-scale bridge fracture test, are utilized to evaluate the contributions of the bridge components on the ultimate behavior and redundancy of the bridge sustaining a fracture on one of its girders. The FE models incorporate material nonlinearities of the steel and concrete members, and are capable of capturing the effects of the stud connection failure and railing contact. Analysis results show that the increased tensile strength of the stud connection and (or) concrete strength are effective in improving bridge redundancy. By modulating these factors, redundancy could be significantly enhanced to the extent that the bridge may be excluded from its fracture critical designation.

• The Journal of Korean Physical Therapy
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• 제34권4호
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• pp.187-191
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• 2022

Purpose: The purpose of our study aimed to identify the effect of static and dynamic bridge exercise with gym ball using gym ball on muscle activation of trunk and lower-limb in healthy individuals. Methods: A total of 20 healthy adults participated in this study. The individuals performed general bridge exercise, static and dynamic bridge exercise using gym ball. During the three methods of bridge exercises, electromyography (EMG) data (% maximum voluntary isometric contraction) of the rectus abdominis, erector spinae, biceps femoris, and gastrocnemius were recorded using a wireless surface EMG system. Results: Rectus abdominis activation showed significantly greater during dynamic bridge exercise compared with general bridge exercise and dynamic bridge exercise. Erector spinae, biceps femoris, and gastrocnemius were greater during static and dynamic bridge exercise compared with general bridge exercise. Conclusion: Based on our results, bridge exercise using gym ball, particularly integrating lower-limb movement, could be a useful method to enhance muscle activation of trunk and lower-limb (rectus abdominis, erector spinae, biceps femoris, and gastrocnemius).

• Interaction and multiscale mechanics
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• 제5권4호
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• pp.347-368
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• 2012

Measuring the bridge frequencies indirectly from an instrumented test vehicle is a potentially powerful technique for its mobility and economy, compared with the conventional direct technique that requires vibration sensors to be installed on the bridge. However, road surface roughness may pollute the vehicle spectrum and render the bridge frequencies unidentifiable. The objective of this paper is to study such an effect. First, a numerical simulation is conducted using the vehicle-bridge interaction element to demonstrate how the surface roughness affects the vehicle response. Then, an approximate theory in closed form is presented, for physically interpreting the role and range of influence of surface roughness on the identification of bridge frequencies. The latter is then expanded to include the action of an accompanying vehicle. Finally, measures are proposed for reducing the roughness effect, while enhancing the identifiability of bridge frequencies from the passing vehicle response.

• Structural Engineering and Mechanics
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• 제59권4호
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• pp.621-652
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• 2016

A new cable-supported bridge model consisting of suspension parts, self-anchored cable-stayed parts and earth-anchored cable-stayed parts is presented. The new bridge model can be used for suspension bridges, cable-stayed bridges, cable-stayed suspension bridges, and partially earth-anchored cable-stayed bridges by varying parameters. Based on the assumption that each structural member is in either an axial compressive or tensile state, and the stress in each member is equal to the allowable stress of the material, the material quantity for each component is calculated. By introducing the unit cost of each type of material, the estimation formula for the cost of the new bridge model is developed. Numerical examples show that the results from the estimation formula agree well with that from the real projects. The span limit of cable supported bridge depends on the span-to-height ratio and the density-to-strength ratio of cables. Finally, a parametric study is illustrated aiming at the relations between three key geometrical parameters and the cost of the bridge model. The optimization of the new bridge model indicates that the self-anchored cable-stayed part is always the dominant part with the consideration of either the lowest total cost or the lowest unit cost. It is advisable to combine all three mentioned structural parts in super long span cable supported bridges to achieve the most excellent economic performance.