• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.45-52
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• 2020

An open-spandrel arch bridges, which consists of slab deck, arch rib, and vertical members, shows a various level of moment and axial forces according to the supporting boundary condition of arch rib and vehicle speeds. Also, the definition of impact factor accepts any kind of response parameters, not only displacement response at slab deck. The present study considers concrete open-spandrel arch bridges constrained with fixed conditions at the ends of arch rib and investigates the impact factor variation due to moving load speeds, response parameters, measuring locations, and vertical member spacing ratio of the bridges. The results of Reference model show that the impact factor is biggest when the reactive moment resulted at the vehicle-inducing opposite end of the arch rib is applied. The peak impact factor is a similar level obtained for the middle of the span adjacent to the slab deck center, but it is 19% higher than the peak impact factor calculated using the axial force developed at the same location. Reducing the spacing ratio of the vertical members as half as the reference model whose ratio is 1/9.375 produces a similar level of the moment-based peak impact factor compared to the reference model. However, when the spacing ratio is doubled, the peak impact factor is 4.4 times greater than the reference model.

• Journal of Korean Society of Steel Construction
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• v.9 no.2 s.31
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• pp.259-267
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• 1997

Wind tunnel test results and their interpretations focused on the behavior of girder, which were performed to study the aerodynamic stability of a self-anchored suspension bridge with lateral sag of main cable, are presented in this paper The shape of the girder which has the best aerodynamic stability was selected based on the section model test under uniform and turbulent flow conditions. Good performance of the selected section was confirmed in the full bridge model test. Measured flutter derivatives are presented for further study. Buffeting response was investigated to check the fatigue problem and serviceability of the bridge but it was found to be acceptable from the engineering point of view. Even though the drag coefficient of the girder had high value, the amplitude of the lateral vibration was found to be very low. This may be due to the restraint provided by the lateral sag of the cables.

• Journal of the Korean Society for Railway
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• v.13 no.4
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• pp.440-446
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• 2010

This paper was investigated on the laminated rubber bearing, which mitigates damages of bridges from threat of earthquakes. Laminated rubber bearing can bear large loads for long periods of time and be capable of large deformations during an earthquake. To evaluate seismic isolation with laminated rubber bearing on several earthquake waves, we performed a shaking table test. In this test, deck acceleration was measured by accelerometers and shear force on piers was surveyed by load cells. Furthermore, seismic capacity of isolated systems with laminated rubber bearing was compared with non-isolated systems through shaking table test. The results show that deck acceleration and shear force were relatively reduced by laminated rubber bearing.

• The Journal of the Acoustical Society of Korea
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• v.25 no.5
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• pp.197-206
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• 2006

Vibration of string is transmitted to the front plate through bridge to cause resonance of the instrument body in viol family string instruments. Therefore. the properties. geometrical shape. and positioning of the bridge are expected to have some effect on the sound color. In this study the strain and the stress in the bridge. and the force exerted on the top plate by the bridge as the string vibrates the bridge in cello are calculated through simulation based on the theory of elasticity. The modes of vibration and the characteristic frequencies are also found. Furthermore. the effect of geometric shape of bridge on sound color is studied in terms of frequency response. The results of this study show that the vibration characteristics of bridge is quite complex and the properties and the geometrical shape of bridge have significant effect on sound color, and therefore. the sound color of a cello can be controlled by changing the geometrical shape of bridge.

• Journal of the Society of Disaster Information
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• v.19 no.4
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• pp.851-858
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• 2023

Purpose: A study was conducted to ensure the structural safety of a raised girder bridge with improved cross-sectional efficiency compared to the conventional PSC girder. For this purpose, the cross-sectional specifications such as girder length, height, and width were determined, the arrangement of the tendons was designed, and the practical performance of the raised girder under static and dynamic loads was verified. Method: The static performance experiment examined the serviceability limit state by measuring behavioral responses such as deflection and cracking to primary and secondary static loads. In addition, the dynamic load loading experiment measured the acceleration and displacement behavior response over time to calculate the natural frequency and damping ratio to examine the usability limit state. Result: As a result of the static performance test, the deflection value based on the maximum applied load showed stable behavior, and the crack width measured at the maximum applied load level was very small, satisfying the serviceability limit state. In addition, a natural frequency exceeding the natural frequency calculated during the design of the dynamic loading experiment was found, and a damping ratio that satisfies the current regulations was found to be secured.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.87-94
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• 2019

Recently, the advance of accurate dynamic displacement measurement devices, such as GPS, computer vision, and optic laser sensor, has enhanced the structural monitoring technology. In this study, the dynamic displacement data was used to verify the applicability of the structural physical parameter estimation method through subspace system identification. The subspace system identification theory for estimating state-space model from measured data and physics-based interpretation for deriving the physical parameter of the estimated system are presented. Three-degree-freedom steel structures were fabricated for the experimental verification of the theory in this study. Laser displacement sensor and accelerometer were used to measure the displacement data of each floor and the acceleration data of the shaking table. Discrete state-space model generated from measured data was verified for precision. The discrete state-space model generated from the measured data extracted the floor stiffness of the building after accuracy verification. In addition, based on the story stiffness extracted from the state space model, five column stiffening and damage samples were set up to extract the change rate of story stiffness for each sample. As a result, in case of reinforcement and damage under the same condition, the stiffness change showed a high matching rate.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.97-105
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• 2010

The displacements of steel deck bridge due to construction step are measured, and three dimensional analysis with full modeling is carried out to compare with the measured results. Three dimensional structural analyses considering construction step by large block construction method are accomplished with verified model. The conclusions are as follows. 1. Comparing the data of grid analysis with the result of 3D full modeling in steel deck bridge, the design method using grid analysis has a limit for describing the displacements of curved bridge. The analysis of 3D full modeling has been proved as more accurate method. The differentiation of results in two methods is about 10%~20%. 2. It is verified that the maximum displacement of during construction is 1.7 times larger than the displacement of final construction. 3. The bridge behavior considering the construction step is somewhat different from that of final stage in whole structure and the displacement and stress during construction is larger than that of final construction. Therefore, it needs the reasonable structural design considering the construction step to get economical efficiency and a high competitive construction.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.189-194
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• 2001

This paper presents a mew design of an inductive position sensing system with high sensitivity. The designed system consists of the driving coils, position-detecting coils, and closed loop formed magnetic blocks. To obtain high sensitivity we design a symmetric and closed loop type measuring system with small air-gaps. The elements that affect the system characteristics are turn ratio, excitation frequency, air-gap size, capacitance effect, and load resistance. By experimental investigation, the influences of these elements are examined and the system parameters are selected. The sensitivity of the newly designed system is greater than 2800mV/(V mm) and the linearity error is below${\pm}0.01%; in; the; range; of; {\pm}200{\mu}m$.

• Proceedings of the Korea Contents Association Conference
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• 2016.05a
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• pp.195-196
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• 2016

본 연구는 건설된 구조물의 주요 구조부재에 각종 계측 Sensor를 설치하여 이로부터 다양한 정보를 제공받아 Monitoring하는 계측 System은 대형구조물의 구조적 응답을 계측하여 분석하고, 구조물의 위험요소를 사전에 발견하고 분석하여 적절한 대책을 수립함으로써 대형 시설물의 수명연장 및 유지관리 비용의 효율성을 높이고, 구조물의 사용성 및 안전성을 확보하고, 그 설계수명을 유지할 수 있는 것이다. 계측전 초기치와의 비교 및 시간 경과에 따른 추이 분석을 통해 이상상태를 발견하는 신호 기반 감시 수행하고 있고, 상태판정 및 손상도 추정이 가능하므로 향후 계속해서 발전시켜 나갈 수 있는 지식기반 감시시스템이 필요하므로 본 연구에서는 공간 정보기반의 정보를 재생하여 GNSS/USN기술을 접목시켜감으로 대형시설물 안전관리가 매우 용이하게 적용할 수 있도록 하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.114-122
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• 2018

This study presents the emergency assessment method about seismic safety of cable-supported bridges using seismic acceleration sensors installed on the primary structural elements of them. The structural models of bridges are updated iteratively to make their dynamic characteristics to be similar to those of real bridges based on the comparison of their natural frequencies with those of real bridges estimated from acceleration data measured at ordinary times by the seismic acceleration sensor. The displacement at the location of each seismic acceleration sensor is derived by seismic analysis using design earthquake, and the peak value of them is determined as the disaster management criteria in advance. The displacement time history is calculated by the double integration of the acceleration time history which is recorded at each seismic acceleration sensor and filtered by high cut(low pass) and low cut(high pass) filters. Finally, the seismic safety is evaluated by the comparison of the peak value in calculated displacement time history with the disaster management criteria determined in advance. The applicability of proposed methodology is verified by performing the seismic safety assessment of 12 cable-supported bridges using the acceleration data recorded during Gyeongju earthquake.