• Title, Summary, Keyword: full scale measurements

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Design and characterization of a compact array of MEMS accelerometers for geotechnical instrumentation

  • Bennett, V.;Abdoun, T.;Shantz, T.;Jang, D.;Thevanayagam, S.
    • Smart Structures and Systems
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    • v.5 no.6
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    • pp.663-679
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    • 2009
  • The use of Micro-Electro-Mechanical Systems (MEMS) accelerometers in geotechnical instrumentation is relatively new but on the rise. This paper describes a new MEMS-based system for in situ deformation and vibration monitoring. The system has been developed in an effort to combine recent advances in the miniaturization of sensors and electronics with an established wireless infrastructure for on-line geotechnical monitoring. The concept is based on triaxial MEMS accelerometer measurements of static acceleration (angles relative to gravity) and dynamic accelerations. The dynamic acceleration sensitivity range provides signals proportional to vibration during earthquakes or construction activities. This MEMS-based in-place inclinometer system utilizes the measurements to obtain three-dimensional (3D) ground acceleration and permanent deformation profiles up to a depth of one hundred meters. Each sensor array or group of arrays can be connected to a wireless earth station to enable real-time monitoring as well as remote sensor configuration. This paper provides a technical assessment of MEMS-based in-place inclinometer systems for geotechnical instrumentation applications by reviewing the sensor characteristics and providing small- and full-scale laboratory calibration tests. A description and validation of recorded field data from an instrumented unstable slope in California is also presented.

The effect of small embankments on wind speeds

  • Quinn, A.D.;Robertson, A.P.;Hoxey, R.P.;Short, J.L.;Burgess, L.R.;Smith, B.W.
    • Wind and Structures
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    • v.1 no.4
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    • pp.303-315
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    • 1998
  • Full-scale measurements have been made to determine the increase in wind speed over two exposed embankments, one of $23^{\circ}$ slope and 4.7 m in height, the other of $24^{\circ}$ slope and 7.3 m in height. Measurements were made at heights of 5, 10 and 15 m above the upper edge of each embankment and at the same heights approximately 100 m upwind in the lower-level approach fetch. Despite the modest sizes of the embankments, the maximum recorded increase in mean wind speed was 28% and the minimum was 13%; these increase relate to increases in wind loads on structures erected at the top of the embankments of 64% and 28% respectively. The associated increases in gust speeds are estimated at 33% and 18%, which imply increases in gust loading of 77% and 39% respectively. These experimental results are compared with predictions obtained from a computational fluid dynamics (CFD) analysis, using three high Reynolds number eddy-viscosity models and estimates from the UK wind loading code, BS 6399: Part 2. The CFD results are generally in agreement with the experimental data, although near-ground effects on the embankment crest are poorly reproduced.

Evaluation of Hydraulic Behavior within Parallel arranged Upflow Sedimentation Basin Using CFD Simulation (I) - The influence of feed water inequity- (CFD를 이용한 병열 배열형 상향류식 침전지 수리해석에 관한 연구(I) - 침전지 내 유입유량 불균등 영향 조사 -)

  • Park, No-Suk;Kim, Seong-Su;Choi, Jong-Woong;Sung, Youl-Boong;Kang, Moon-Sun
    • Journal of Korean Society of Water and Wastewater
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    • v.27 no.4
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    • pp.469-477
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    • 2013
  • In order to investigate the influence of feed water inequity on the settling performance for parallel arranged upflow sedimentation basin in domestic G_WTP(Water Treatment Plant), CFD(Computational Fluid Dynamics) simulation were employed and ADV(Acoustic Doppler Velocimeter) measurements were carried out. From the results of both CFD simulations and ADV measurements, the differences among inlet flow rates to each inlet structure make turbulent energy dissipation uneven overall sedimentation basin. Especially local velocities in the near of both side wall were observed over the design overflow rate(74.4 mm/min). Also, it was confirmed that this inequity of inlet flow would exert an serious influence on the turbidity of settled water which is out from 8 troughs. Even though experimental velocities in full scale basin about 20% higher than the simulated, the results of ADV measurement were in good accordance with those of CFD simulations.

Performance evaluation of in-service open web girder steel railway bridge through full scale experimental investigations

  • Sundaram, B. Arun;Kesavan, K.;Parivallal, S.
    • Structural Monitoring and Maintenance
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    • v.6 no.3
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    • pp.255-268
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    • 2019
  • Civil infrastructures, such as bridges and tunnels are most important assets and their failure during service will have significant economic and social impact in any country. Behavior of a bridge can be evaluated only through actual monitoring/measurements of bridge members under the loads of interest. Theoretical analysis alone is not a good predictor of the ability of a bridge. In some cases, theoretical analyses can give less effect than actual since theoretical analyses do not consider the actual condition of the bridge, support conditions, level of corrosion and damage in members and connections etc. Hence actual measurements of bridge response should be considered in making decisions on structural integrity, especially in cases of high value bridges (large spans and major crossings). This paper describes in detail the experimental investigations carried out on an open web type steel railway bridge. Strain gages and displacement transducers were installed at critical locations and responses were measured during passage of locomotives. Stresses were evaluated and extrapolated to maximum design loading. The responses measured from the bridge were within the permissible limits. The methodology adopted shall be used for assessing the structural integrity of the bridge for the design loads.

Local Buckling and Inelastic Behaviour of 800 MPa High-Strength Steel Beams (800MPa급 고강도강 보 부재의 국부좌굴 및 비탄성 거동)

  • Lee, Cheol-Ho;Han, Kyu-Hong;Kim, Dae-Kyung;Park, Chang-Hee;Kim, Jin-Ho;Lee, Seung-Eun;Ha, Tae-Hyu
    • Journal of Korean Society of Steel Construction
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    • v.24 no.4
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    • pp.479-490
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    • 2012
  • Flexural tests on full-scale H-shaped beams, built up from high-strength steels (HSB800 and HSA800) with a nominal tensile strength of 800 MPa, was carried out to study the effect of flange slenderness of high-strength steel on flexural strength and rotation capacity. The primary objective was to investigate the appropriateness of extrapolating current stability criteria (originally developed for ordinary steel) to high-strength steel. The performance of high-strength steel specimens was very satisfactory from the strength, but not from the rotation capacity, perspective. The inferior rotation capacity of high-strength steel beams was shown to be directly attributable to the absence of a distinct yield plateau and the high yield ratio of the material. Residual stress measurements reconfirmed that the magnitude of the residual stress is almost independent of the yield stress of the base metal.

Amplitude dependency of damping of tall structures by the random decrement technique

  • Xu, An;Xie, Zhuangning;Gu, Ming;Wu, Jiurong
    • Wind and Structures
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    • v.21 no.2
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    • pp.159-182
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    • 2015
  • This study focuses on the amplitude dependency of damping of tall structures by the random decrement technique (RDT). Many researchers have adopted RDT to establish the amplitude dependency of damping ratios in super-tall buildings under strong wind loads. In this study, a series of simulated examples were analyzed to examine the reliability of this method. Results show that damping ratios increase as vibration amplitudes increase in several cases; however, the damping ratios in the simulated signals were preset as constants. This finding reveals that this method and the derived amplitude-dependent damping ratio characteristics are unreliable. Moreover, this method would obviously yield misleading results if the simulated signals contain Gaussian white noise. Full-scale measurements on a super-tall building were conducted during four typhoons, and the recorded data were analyzed to observe the amplitude dependency of damping ratio. Relatively wide scatter is observed in the resulting damping ratios, and the damping ratios do not appear to have an obvious nonlinear relationship with vibration amplitude. Numerical simulation and field measurement results indicate that the widely-used method for establishing the amplitude-dependent damping characteristics of super-tall buildings and the conclusions derived from it might be questionable at the least. More field-measured data must be collected under strong wind loads, and the damping characteristics of super-tall buildings should be investigated further.

Stability analysis of shield tunnel segment lining by field measurement and full scale bending test (실대형 하중재하 시험 및 현장계측을 통한 쉴드터널 세그먼트 안정성 분석)

  • Lee, Gyu-Phil;Chang, Soo-Ho
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.21 no.5
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    • pp.611-620
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    • 2019
  • The shield tunnel was mostly applied to cable tunnel with a diameter of 3~4 m, recently 7.8 m diameter shield tunnel was constructed in the lower section of the Incheon International Airport runway and is planning or under construction to roads and railway tunnels in the lower section of the Han River. Segments are also becoming larger as the shield tunnel cross-section increases, which causes a number of problems in the design, construction, and performance evaluation of segments. In this study, segment lining structural safety, criteria for serviceability check considering axial forces and quality control method for approximately 8 m in diameter shield tunnel were reviewed by field measurements and full scale bending test.

Effects of Cyclic Loading Rate on response of Reinforced Concrete Structures (철근콘크리트 구조물에 대한 반복하중속도의 영향에 관한 연구)

  • Chung, Lan;Park, Hyun-Soo
    • Computational Structural Engineering
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    • v.2 no.3
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    • pp.77-84
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    • 1989
  • Small-scale models of reinforced concrete beam-column joints and anchorage-bond specimens were subjected to large cyclic displacements at two rates. To assess damage, free vibration tests were conducted. The reliability of the modeling techniques was established by comparison of the results for the slower rate with those obtained from the full-scale tests on prototype. The higher rate of loading caused a greater damage than that at the slower rate. This was evidenced by the measurements of the stiffness obtained from the free-vibration test. The relatively greater extent of damage appears to result from the different bond behavior at different rates of loading.

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Self-propulsion Test and Analysis of Amphibious Armored Wheeled Vehicle with Propulsion System of POD Type Waterjet (전투 차량용 포드형 물 분사 추진장치의 모형시험 및 해석)

  • Byun, Tae-Young;Kim, Moon-Chan;Chun, Ho-Hwan;Kim, Jong-Hyun
    • Journal of the Society of Naval Architects of Korea
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    • v.42 no.3
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    • pp.197-204
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    • 2005
  • A waterjet propulsion system has many advantages compared with a conventional screw propeller especially for amphibious armored wheeled vehicles because of a good maneuverability at low speed, good operation ability at shallow water, high thrust at low speed to aid maneuverability and exit from water, etc. The POD type waterjet is adequate for the present wheeled vehicle because the weight is lighter and L/B is longer than the conventional armored amphibious vehicle. Resistance and self-propulsion tests with a 1/3.5-scale model are conducted at PNU towing tank. Based on these measurements, the performance is analyzed according to ITTC 96 standard analysis method and also according to the conventional propulsive factor analysis method. Based on these two methods, the full-scale effective and delivered powers of amphibious armored wheeled vehicle are estimated. This paper emphasizes the analysis method of model test of the waterjet propulsion system for a amphibious armored wheeled vehicle and the model test technique together with the comparison of the two analysis methods.

Finite element modelling of transmission line structures under tornado wind loading

  • Hamada, A.;El Damatty, A.A.;Hangan, H.;Shehata, A.Y.
    • Wind and Structures
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    • v.13 no.5
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    • pp.451-469
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    • 2010
  • The majority of weather-related failures of transmission line structures that have occurred in the past have been attributed to high intensity localized wind events, in the form of tornadoes and downbursts. A numerical scheme is developed in the current study to assess the performance of transmission lines under tornado wind load events. The tornado wind field is based on a model scale Computational Fluid Dynamic (CFD) analysis that was conducted and validated in a previous study. Using field measurements and code specifications, the CFD model data is used to estimate the wind fields for F4 and F2 full scale tornadoes. The wind forces associated with these tornado fields are evaluated and later incorporated into a nonlinear finite element three-dimensional model for the transmission line system, which includes a simulation for the towers and the conductors. A comparison is carried between the forces in the members resulting from the tornadoes, and those obtained using the conventional design wind loads. The study reveals the importance of considering tornadoes when designing transmission line structures.