ESTIMATION OF EXISTING CABLE TENSION OF CABLE-STAYED BRIDGE BY USING WELCH METHOD TO THE VIBRATION METHOD

• Main Author: Murtezza Hasyim, Navid
• Format: Theses
• Language: Indonesia
• Subjects: Teknik sipil
• Online Access: https://digilib.itb.ac.id/gdl/view/71366
• Institution: Institut Teknologi Bandung

Bridge maintenance is a fundamental aspect to conduct during the operational period of a bridge to ensure the soundness and safety of the bridge structure. Measurement of the existing tension on the cable elements of the bridge is one of the methods of cable-stayed bridge maintenance. The lift-off test is a direct method to measure the existing tension in cable elements. However, the implementation of lift-off test requires complex preparations and relatively expensive equipment. Thus, an indirect method was developed to estimate the existing tension of cable elements using the vibration method. The main principle of the vibration method is to use the natural frequency of the cable to estimate the existing tension of the cable elements with the equation of cable motion. In this study, post-processing of the results of dynamic measurements using the Welch method will be carried out to identify the natural frequency of the cable elements. Then the natural frequency will be used to estimate the existing tension of the cable elements using two approaches: a method using multiple mode shapes as a linear regression function and a method that considers the effect of cable sag. The existing tension estimate obtained will be compared with the results of the existing tension estimation using the natural frequency from the FFT method and the results from the previous lift-off test. The results showed that the natural frequency obtained from the Welch method could be used to estimate the existing tension of cable elements, although there is no significant difference between the natural frequency obtained from the Welch method and the FFT method. In addition, it is found that the estimation of the existing tension using an approach that considers the effect of cable sag produces a more accurate estimate of the tension than an approach that uses multiple mode shapes as a linear regression function.