• Title/Summary/Keyword: In-situ vibration

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Bearing capacity Calculation of Displacement in-situ Concrete Pile (비배토 현장타설 콘크리트 말뚝의 지지력 산정에 관한 연구)

  • 박종배;박태순
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.03a
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    • pp.65-84
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    • 2000
  • Europe and US which have more restrictive regulations than Korea about the noise and vibration during construction are using Auger-cast Pile to reduce the problem relating with noise and vibration. However Auger-cast Pile has problems like difficult quality control and low bearing capacity. In Europe, Displacement in-situ concrete Pile has been used to sove that problems since 1990s, and Korea has performed the test construction in 1997 and it has been used as the real structural foundation since 1998. Test and real construction results verified that the allowable capacity of the pile(diameter = 410mm) is between 70 and 100ton. Though De Beer & Van Imps design method utilizing CPT result is used to calculate the bearing capacity of the Displacement in-situ Pile, Korea is dependant upon the SPT as the sounding test, so design method utilizing SPT result is necessary to promote the application of the pile. To find out reasonable design method using SPT result, rearing capacity of the pile constructed in sand and clay in Korea was calculated using Meyerhof, SPT-CPT translation method, Nordlund, Douglas and DM-7 method, and the calculation results were compared to the load test result. Analysis result shows that SPT-CPT translation method is more reliable than others and economical design can be possible because it considers efficiently the friction capacity of Displacement in-situ Pile.

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Development of Error Compensation Algorithm for Image based Measurement System (미세부품 영상 측정시 진동에 의한 오차 보상 알고리즘 개발)

  • Pyo Chang Ryul
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.10
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    • pp.102-108
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    • 2004
  • In this paper, we studied a vibration problem that is critical and common to most precision measurement systems. For micro mechanical part measurements, results obtained from the vision-based precision measurement system may contain errors due to the vibration. In order to defeat this generic problem, for the current study, a PC based image processing technique was used first, to assess the effect of the vibration to the precision measurement and second, to develop an in-situ calibration algorithm that automatically compensate the measurement results in real time. We used a set of stereoscopic CCD cameras to acquire the images for the dimensional measurement and the reference measurement. The mapping function was obtained through the in-situ calibration to compensate the measurement results and the statistical analysis for the actual results is provided in the paper. Based on the current statistical study, it is expected to obtain high precision results for the micro measurement systems.

A simple approach for quality evaluation of non-slender, cast-in-place piles

  • Zhang, Ray Ruichong
    • Smart Structures and Systems
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    • v.4 no.1
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    • pp.1-17
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    • 2008
  • This study proposes a conceptual framework of in-situ vibration tests and analyses for quality appraisal of non-slender, cast-in-place piles with irregular cross-section configuration. It evaluates a frequency index from vibration recordings to a series of impulse loadings that is related to total soil-resistance forces around a pile, so as to assess if the pile achieves the design requirement in terms of bearing capacity. In particular, in-situ pile-vibration tests in sequential are carried out, in which dropping a weight from different heights generates series impulse loadings with low-to-high amplitudes. The high-amplitude impulse is designed in way that the load will generate equivalent static load that is equal to or larger than the designed bearing capacity of the pile. This study then uses empirical mode decomposition and Hilbert spectral analysis for processing the nonstationary, short-period recordings, so as to single out with accuracy the frequency index. Comparison of the frequency indices identified from the recordings to the series loadings with the design-based one would tell if the total soil resistance force remains linear or nonlinear and subsequently for the quality appraisal of the pile. As an example, this study investigates six data sets collected from the in-situ tests of two piles in Taipu water pump project, Jiangshu Province of China. It concludes that the two piles have the actual axial load capacity higher than the designed bearing capacity. The true bearing capacity of the piles under investigation can be estimated with accuracy if the amplitude of impact loadings is further increased and the analyses are calibrated with the static testing results.

Investigation of an in-situ measurement method for Sound Strength in concert halls (콘서트홀의 Sound Strength 현장 측정법 고찰)

  • Jeong, Choong-Il;You, Jin;Jeon, Jin-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.987-990
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    • 2007
  • The accuracy of sound strength (G) measurement method in ISO 3382 has been questioned. One of the main reason is the difficulty in measuring a reference sound level in an anechoic chamber with the same set-up which was applied for the actual hall measurements. In the present paper, an in-situ measurement method for G was proposed by investigating the present G measurement method shown in ISO 3382. In addition, the sound radiation characteristics of typical omnidirectional loudspeakers were investigated and Phi (O) of auto correlation function (ACF) parameters was also calculated from an actual music excerpt to characterize the sound energy distribution in concert halls.

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Using a Micro-flown device to measure acoustical properties of green roof systems (Micro-flown 장비를 이용한 옥상녹화재료 음향 물성치 실험)

  • Yang, Hong-Seok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.870-873
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    • 2014
  • Green roof systems has widely been used on rooftop of buildings by considering environmental benefits in aspects of bio-diversity, storm-water runoff as well as noise reduction. To predict noise reduction effect by green roof systems, it is necessary to measure in-situ acoustical properties of the components by devices enabling in-situ measurements. In this study, Micro-flown, which is the state of the arts device to measure in-situ normalized impedance and absorption coefficient has been used to measure acoustical properties of green roof materials according to different water saturation condition in the materials.

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A Study on Data Analysis of Ground Vibration.Noise Dust Dispersion Measurement for Enhancing Safety at the Construction Sites - Focussed on Blasting and Piling in Sedimentary and Igneous Rocks in the Youngnam Area - (건설 현장에서 안전성 향상을 위한 지반진동.소음.비산먼지 측정자료의 분석에 관한 연구 -영남지역의 퇴적암.화성암층에서의 발파 및 항타작업을 중심으로-)

  • 안명석;류창하;박종남
    • Explosives and Blasting
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    • v.19 no.3
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    • pp.91-104
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    • 2001
  • As in Korean environments with mountainous and hilly areas, the rock generally has to be removed in construction or civil engineering work in tunnelling or excavation for development in urban area. Explosives should be used for blasting, which may cause serious problems on local people for their claim for compensation due to ground vibration, noise. For safe and economic blasting, geology and engineering characteristics of rocks such as discontinuities of rock or weathering are very important factors, together with site characteristics for prediction of ground vibration. In this study, conducted were the detailed study for major rocks most widely distributed in the South-east area, in-situ geological survey, geological and geochemical analysis, and further laboratory uniaxial rock stress, seismic velocity of core samples together with in-situ seismic velocity measurements. Regulations on ground vibration and noise were reviewed for assessing their adaptabilities, and a total of 4,856 measured blasting vibration data were examined for enhancing the confidence level in estimating the predictive formulation using scaled distance statistically.

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A Comparative Study of Wind Speed Spectrum based on the In-Situ Observation at the SeoHae Bridge Site (서해대교 현장계측에 기반한 풍속스펙트럼 모형의 비교인구)

  • Kim, Saang-Bum;Lee, Sung-Jin;Ahn, Sang-Sub
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.417-421
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    • 2006
  • A comparative study of wind speed spectrum based on the in-situ observation at the SeoHae bridge site is conducted. Wind speed and directions of the SeoHae bridge site is measured and analyzed. Mean wind speed and turbulence intensity are estimated. The power spectral density function of the fluctuating component of the wind velocity is estimated. Several wind spectrum models of gust wind turbulence are compared and discussed based on the estimated wind spectrum.

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In-situ test and dynamic response of a double-deck tied-arch bridge

  • Gou, Hongye;Zhou, Wen;Chen, Genda;Bao, Yi;Pu, Qianhui
    • Steel and Composite Structures
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    • v.27 no.2
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    • pp.161-175
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    • 2018
  • In this study, in-situ dynamic tests of the world's longest steel box tied-arch bridge over the Yangtze River, China, are reported. The double deck bridge supports highway and monorail systems at upper and lower levels, respectively. Strain, displacement, and acceleration responses were measured and used to investigate the vibration characteristics of the bridge when excited by running trains and/or trucks at a speed of 5-60 km/h, train braking, and truck bouncing. Impact factors were correlated with the running speed of trains and trucks. A three-dimensional finite element model of the coupled monorail-train-bridge vibration system accounting for track irregularities was established to understand the system behavior and validated by the experimental results. Truck bouncing was the dominant impact factor on bridge responses. The running speed of vehicles determined the riding comfort of traveling trains.

Measurement Errors of Non-contact Type Vibration Sensors Used for Precision Measurement of Shaft Vibration (정밀 축진동 측정에 사용되는 비접촉식 진동센서의 측정오차)

  • 전오성;김동혁;최병천
    • Journal of KSNVE
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    • v.1 no.2
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    • pp.107-113
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    • 1991
  • When non-contact type vibration probes are used for the precision measurement of shaft vibration, they can induce the measurement errors due to the shaft curvature since they have been calibrated for the flat plate. In this study the errors due to the shaft radius and the misalignment between the shaft and probe centerlines are analyzed, and an in-situ calibration tool, which can be conveniently used for calibration independent of the shaft curvature and material, is introduced.

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