| Research Abstract |
The purpose of this study was to establish the evaluation method for the properties from fresh to hardened concrete by analyzing the undulation of ultrasonic transversal wave, and in other words to establish the all-age mechanical model of concrete. To achieve above mentioned purpose, properties of Ultransonic transverse wave transfered through concrete specimens were analized by finite element method, and pattern analysis of transfered waveform was accomplshed. Many results were obtained as follows.
1.Finit element analysis by dynamic visco-elastic torsion model
Transmitting of ultrasonic transverse wave through concrete was simulated by finite element method using dinamic visco-elastic model. According to this analysis, waveform, transmitting velocity and absorption coefficient were analyzed accurately. And it was clarified that the optimum size of element was to be decided against individual ages of concrete and frequencies of ultrasonic transverse wave.
2.Pattern analysis of transfered waveform
Effects of coarse aggregate to waveform were analyzed by power spectrum of transferd wave, and it was clarified that maximum size of aggregate affected to the spectrum. It will be applicated as test method of segregation at fresh concrete. And the optimum frequency of wave at non-destractive test using ultrasonic at individual ages were desided by probability density spectrum analysis.
3.All-age mechanical model of concrete
Using dinamic visco-elastic rheology model with moduluses that never depend on time scale, movement of specimens were analyzed and experimented at individual frequency. As results, possibility of evaluation method that can grasp from long time scale phenomena, for example creep, to short time scale phenomena, for instance dynamic movement was shown.
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