Nondestructive bridge cable tension assessment using laser vibrometry

The hanger cables of the I-470 Vietnam Veteran Memorial Bridge in Wheeling, West Virginia, were tested to assess the feasibility of using a Laser Doppler Vibrometer for tension measurements on large structures and to show the potential of laser technology in civil engineering applications. For each hanger, at least two strands were measured to ensure that the vibration measurements are a true representation of the actual cable behavior. Except for one incident, where a strand was known to be loose, all cables of the same hanger had the same vibration frequencies. Results show that the current state of the bridge is stable due to the acceptable tension levels within the hanger cables, and that LDV has great potential in civil structure applications.