Cable Force Transferring Mechanism and Construction Monitoring of Suspender Replacement in Tied Arch Bridge

This article takes a tied arch bridge with a service life of over 20 years as the engineering background. In response to the common problems of PE sheath cracking and steel wire corrosion in bridge suspension rods, the construction plan of cutting the old suspension rod in situ and installing a new one is discussed. Using finite element numerical calculation and actual bridge engineering construction monitoring data, the transmission law of cable force near the suspension rod during the suspension rod cutting process is studied. To ensure the stress safety of the structure during the cable replacement process, a two-stage force system conversion method of "temporary suspension rod graded tensioning+old suspension rod steel wire graded cutting" and "new suspension rod graded tensioning+temporary suspension rod graded releasing" is adopted to achieve smooth cable force transmission from the old suspension rod to the new suspension rod. Numerical analysis was conducted using the finite element software ANSYS, and vibration string strain gauges and total station monitoring systems were installed at key sections of the solid bridge. Strain gauges were attached to the old suspension rods to collect key parameters such as arch rib stress, suspension rod tension, and bridge deck displacement in real-time. Through mutual verification with the monitoring data of the actual bridge, it was found that the proportion of cable force transmitted from the suspension rod to the adjacent two and four suspension rods was 61.0% and 92.2%, respectively. However, the cable force of the old suspension rod was mainly transmitted to the temporary suspension rod, and the proportion of cable force transmitted to the adjacent suspension rod had a large variability but did not exceed 20%. The displacement and stress of the arch rib can be ignored. During construction, special attention should be paid to the displacement of the bridge deck to provide technical support for the construction monitoring plan, thereby ensuring the smooth transmission of cable force during the replacement of suspension rods and the safety of structural stress.