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Title |
Tension Estimation of External Tendons in PC Bridges Using Vibration Measurement Method
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Keywords |
텐던의 긴장력 ; 진동측정방법 ; 고유진동수 ; 휨강성 ; 현의 공식 Tendon tension ; Vibrational measurement method ; Natural frequency ; Flexural stiffness ; String equation |
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Abstract |
In this study, vibrational tendon tension measurement methods are applied to estimate tension of external tendons used in segmental post-tensioned bridges. The acceleration of various length type of tendons is measured and natural frequencies are obtained using FFT (Fast Fourier Transform). The obtained natural frequencies are within 1% error regardless of sensor direction and location. On the basis of natural frequency of tendon, estimation of the tendon tension is performed by using many types of solutions such as string theory equation, multi mode estimation, practical formula estimation and stiff string with clamped-clamped boundary conditions. The results are compared with each other and have shown that the flexural stiffness is not negligible in tendons of this type causing the vibration mode to be inharmonically related. The results have shown that the method using stiff string equation with clamped-clamped boundary conditions is more accurate than the other methods. Application example of in-service bridges has shown that force distribution effects from friction at deviation blocks can be effectively detected.
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