Cable Stay Assessments
Determined resonant frequencies, cable tension, and damping ratios on the cable stays
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The Challenge
- New required inspections led to replacement of cables on the bridge
- The client was in need of ongoing insights into the condition of the bridge overtime for future inspections
The bridge underwent a significant cable replacement project in 2012 due to corrosion and deterioration issues discovered in the original stay cable system. The Louisiana Department of Transportation replaced 72 support cables to extend the life of the structure. The replacement cables use a modern parallel strand system with better durability and maintenance characteristics. The current National Bridge Inspection Standards (NBIS) guidance requires safety inspections for cable stays in public highway bridges at least once every 24 months.
The Solution
As part of the required inspections under the National Bridge Inspection Standards (NBIS), Geocomp assessed the condition of the 72 cable stays on the Hale Boggs Bridge using vibration-based methods. Utilizing our wireless, passive dynamic measurement solution, S-lynks, we determined the resonant frequencies, cable tension, and damping ratios without the need for external excitation.
The S-lynks solution enabled simultaneous data collection from multiple cables in just 20 minutes, minimizing downtime. Data were analyzed using Geocomp’s advanced software, applying both linear taut string theory and a numerical method, accounting for bending stiffness to estimate cable tensions accurately. Repeated measurements allow for monitoring changes over time and detecting potential issues early.
