• Structural Engineering and Mechanics
• /
• 제69권3호
• /
• pp.347-359
• /
• 2019

This paper aims to evaluate the behavior of Dorim-Goh bridge in Seoul, Korea, under static and dynamic loads effects by ambient trucks. The prestressed concrete (PSC) girders and reinforcement concrete (RC) slab of the bridge are evaluated and assessed. A short period monitoring system is designed which comprises displacement, strain and accelerometer sensors to measure the bridge performance under static and dynamic trucks loads. The statistical analysis is used to assess the static behavior of the bridge and the wavelet analysis and probabilistic using Weibull distribution are used to evaluate the frequency and reliability of the dynamic behavior of the bridge. The results show that the bridge is safe under static and dynamic loading cases. In the static evaluation, the measured neutral axis position of the girders is deviated within 5% from its theoretical position. The dynamic amplification factor of the bridge girder and slab are lower than the design value of that factor. The Weibull shape parameters are decreased, it which means that the bridge performance decreases under dynamic loads effect. The bridge girder and slab's frequencies are higher than the design values and constant under different truck speeds.

• Steel and Composite Structures
• /
• 제32권4호
• /
• pp.467-478
• /
• 2019

Running safety and ride comfort of high speed railway largely depend on the track geometry that is dependent on the bridge deformation. This study presents a theoretical study on mapping the bridge vertical deformations to the change of track geometry. Analytical formulae are derived through the theoretical analysis to quantify the track geometry change, and validated against the finite element analysis and experimental data. Based on the theoretical formulae, parametric studies are conducted to evaluate the effects of key parameters on the track geometry of a high speed railway. The results show that the derived formulae provide reasonable prediction of the track geometry change under various bridge vertical deformations. The rail deflection increases with the magnitude of bridge pier settlement and vertical girder fault. Increasing the stiffness of the fasteners or mortar layer tends to cause a steep rail deformation curve, which is undesired for the running safety and ride comfort of high-speed railway.

• PNF and Movement
• /
• 제18권3호
• /
• pp.315-321
• /
• 2020

Purpose: Recent studies have indicated that applying different inclination angles and suspension devices could be a useful way of performing exercises that include the co-activation of the trunk muscles. Present study was to examine the influences of changes in the inclination angle during trunk muscle activity while engaging in a bridge exercise with a suspension device. Methods: 18 healthy, physically active male volunteers completed three trunk inclination angles (15°, 30°, and 45°) for bridge exercise variations. The surface electromyography responses of the rectus abdominis, internal oblique (IO), erector spinae (ES), and rectus femoris (RF), as well as the subjective difficulty (Borg RPE score), were investigated during these bridge exercises. Results: The bridge with a 45° inclination angle suspension significantly increased the muscular activities of the RA and RF and increased the Borg RPE scores (p<0.05). The bridge with a 15° suspension significantly elevated the ES activities when compared to the other conditions. Conclusion: The present study demonstrated that a higher inclination angle could not activate the overall trunk muscles during the bridge exercise. The RA and RF produced greater activation during the bridge exercise with the higher inclination angle. On the other hand, the activities of the erector spine were greater during the bridge exercise with the lower inclination angle. The present study suggests that applying a low trunk inclination angle for the supine bridge exercise is suitable for activating the erector spine muscles.

• Structural Engineering and Mechanics
• /
• 제82권3호
• /
• pp.369-383
• /
• 2022

In this study, an equivalent boundary conditions (BCs) determination method is developed numerically for a panel reinforced concrete (RC) slab to realistically analyze the deformation and fatigue behaviors of a bridge RC slab. For this purpose, a finite element analysis of a bridge RC slab is carried out beforehand to calculate the stiffness of the bridge RC slab, and then the equivalent BCs for the panel RC slab are determined to achieve the same stiffness at the BCs to the obtained stiffness of the bridge RC slab at the corresponding locations of the bridge RC slab. Moreover, for the simulation of fatigue behaviors, fatigue analysis of the panel RC slab is carried out employing a finite element method based on a numerical model that considers the bridging stress degradation. Both the determined equivalent BCs and the BCs that have been typically applied in past studies are employed. The analysis results confirm that, in contrast to the panel RC slab with typically used BCs, the panel RC slab with equivalent BCs simulate the same bending moment distribution and deformation behaviors of the bridge RC slab. Furthermore, the equivalent BCs reproduce the extensive grid crack pattern in the panel RC slab, which is alike the pattern normally witnessed in a bridge RC slab. Conclusively, the panel RC slab with equivalent BCs behaves identical to the bridge RC slab, and, as a result, it shows more realistic fatigue behaviors observed in the bridge RC slab.

• Smart Structures and Systems
• /
• 제32권1호
• /
• pp.49-59
• /
• 2023

A bridge transportation network supplies products from various source nodes to destination nodes through bridge structures in a target region. However, recent frequent earthquakes have caused damage to bridge structures, resulting in extreme direct damage to the target area as well as indirect damage to other lifeline structures. Therefore, in this study, a surrogate model-based comprehensive framework to estimate the seismic resilience of bridge transportation networks is proposed. For this purpose, total system travel time (TSTT) is introduced for accurate performance indicator of the bridge transportation network, and an artificial neural network (ANN)-based surrogate model is constructed to reduce traffic analysis time for high-dimensional TSTT computation. The proposed framework includes procedures for constructing an ANN-based surrogate model to accelerate network performance computation, as well as conventional procedures such as direct Monte Carlo simulation (MCS) calculation and bridge restoration calculation. To demonstrate the proposed framework, Pohang bridge transportation network is reconstructed based on geographic information system (GIS) data, and an ANN model is constructed with the damage states of the transportation network and TSTT using the representative earthquake epicenter in the target area. For obtaining the seismic resilience curve of the Pohang region, five epicenters are considered, with earthquake magnitudes 6.0 to 8.0, and the direct and indirect damages of the bridge transportation network are evaluated. Thus, it is concluded that the proposed surrogate model-based framework can efficiently evaluate the seismic resilience of a high-dimensional bridge transportation network, and also it can be used for decision-making to minimize damage.

• 한국음향학회지
• /
• 제25권5호
• /
• pp.197-206
• /
• 2006

비올족 현악기에서 현의 진동은 브릿지에 의해 전판에 전달되어서 악기 몸통을 공명시킨다. 따라서 브릿지의 재질, 기하학적 형상, 설치 위치 등이 음색에 영향을 미치게 된다. 본 연구에서는 첼로에서 현에 의해 변위가 가해질 때 브릿지 내부의 변형, 응력, 그리고 브릿지 다리에 의해 전판에 미치는 힘을 탄성학적으로 해석하고, 브릿지의 고유진동모드와 고유진동주파수 등을 구하였다. 또, 브릿지의 형상이 음색에 미치는 영향을 주파수 응답의 관점에서 측정하였다. 본 연구의 결과는 첼로에서 브릿지의 진동특성은 대단히 복잡하고, 그 재질, 형상 등이 음색에 큰 영향을 미치며, 따라서 브릿지의 형상을 변화시킴으로써 첼로의 음색을 조정하는 것이 가능함을 실험적으로 보였다.

• 한국강구조학회 논문집
• /
• 제28권6호
• /
• pp.449-458
• /
• 2016

강박스거더교의 온도하중을 위한 유효온도를 산정하기 위하여, 강박스거더교의 시험체와 실교량에서 온도 데이터가 2년간 측정되었다. 이 실험체와 실교량의 온도 측정결과를 바탕으로 대기온도에 대한 최고 및 최저 유효온도를 2014년, 2015년, 그리고 연속 2년간 산정하였다. 산정된 최고, 최저 유효온도는 EURO code, 그리고 현행 도로교 설계기준과 서로 비교 평가되었다. 2년간(2 year) 측정한 데이터 기준으로 최대 유효온도와 Euro code의 결정계수는 교량 시험체에서 R=0.894, 실교량에서 R=0.927이 산정되며, 최저 유효온도는 교량 시험체에서 R=0.992, 실교량에서 R=0.813이 산정되었다. 또한 연구 결과는 도로교설계기준(한계상태설계법)의 최고온도와 유사하든가 약간 초과하는 것으로 평가되었다.

• Earthquakes and Structures
• /
• 제6권5호
• /
• pp.495-514
• /
• 2014

The performance of passive control system for the seismic protection of a multi-tower cable-stayed bridge with the application of partially longitudinal constraint system is investigated. The seismic responses of the Jiashao Bridge, a six-tower cable-stayed bridge using the partially longitudinal constraint system are studied under real earthquake ground motions. The effects of the passive control devices including the viscous fluid dampers and elastic cables on the seismic responses of the bridge are examined by taking different values of parameters of the devices. Further, the optimization design principle of passive control system using viscous fluid dampers is presented to determine the optimized parameters of the viscous fluid dampers. The results of the investigations show that the control objective of the multi-tower cable-stayed bridge with the partially longitudinal constraint system is to reduce the base shears and moments of bridge towers longitudinally restricted with the bridge deck. The viscous fluid dampers are found to be more effective than elastic cables in controlling the seismic responses. The optimized parameters for the viscous fluid dampers are determined following the principle that the peak displacement at the end of bridge deck reaches to the maximum value, which can yield maximum reductions in the base shears and moments of bridge towers longitudinally restricted with the bridge deck, with slight increases in the base shears and moments of bridge towers longitudinally unrestricted with the bridge deck.

• 한국철도학회논문집
• /
• 제16권3호
• /
• pp.217-225
• /
• 2013

본 연구에서는 교량 단부의 레일지지점 간격, 교량과 교대사이 거리(유간) 및 교량 단부 회전각을 고려하여 콘크리트 궤도가 부설된 교량 단부 궤도의 거동을 분석하였다. 궤도구조가 고려된 교량 및 교대 시험체를 이용한 실내시험 결과, 동일한 유간(레일지지점 간격)에서 교량 단부 회전각이 증가함에 따라 레일의 변위가 선형적으로 비례하는 것으로 나타났다. 또한 이러한 레일의 변위는 레일 및 체결구의 발생응력에 직접적인 영향을 미치는 것으로 분석되었다. 실험결과를 바탕으로 다중 회귀분석을 수행하여 레일지지점 간격 및 교량의 단부 회전각을 매개변수로 하는 철도교량 단부 궤도의 궤도-교량 상호작용력 예측식을 도출하였다.

• 한국조경학회지
• /
• 제35권5호
• /
• pp.82-91
• /
• 2007

Currently, bridges are regarding as the structure with formative, scenic and environmental values more than their function as simple passageways. Because an attempt to work on the diversity of the bridge types and installation of the large structures on bridge are part of the project of the regional amenity enterprises, a study that harmonizes bridges with landscape is needed at this point in time. This background can influence the direction of bridge landscapes that considers local features by analysis of visual preferences on a bridge simulated scene. The results were as follows: analyzing the change of the simulated landscape image, forest landscape are damaged by the input of a bridge which was natural, harmonic and intimate. On the other hand, when a bridge was inserted into the ocean landscape, it was thought to improve the ocean landscape, especially, upper part form of arch bridge various or suspension bridge were improved in polished and various image. The insertion of a bridge into an urban landscape change from a negative image to a beautiful, harmonic and attractive image. The intimate, harmonic and natural image of a rural landscape was damaged by inserting a bridge. As analysis result about change of landscape preference by input of bridge, there is difference between before and after as input the bridge, and bridge influences as main object in the simulated scene. Visual preference was the highest in the ocean landscape, and the lowest in the suspension bridge in the rural landscape. The complicated shape of bridge follows on the background type difference certainly appear. Thee simulated scene preference except the urban landscape of the simulated scene fell generally Especially, fall of preference of girder bridge in the forest and ocean landscape, suspension bridge in the rural landscape appeared notedly.