| One of the approaches in non-destructive bridge testing is the use of "Diagnostic load testing and instrumented health monitoring". Such technique can provide quantitative, comprehensive, and damage sensitive information about the bridge. Instrumentation that is placed on the structure is composed of static (strain gages, displacement gages, tiltmeters, thermocouples, pressure transducers) and dynamic sensors (accelerometers, velocity transducers). The test duration can vary from a couple of seconds (Crawl speed truck loading, traffic monitoring), to years (continuous monitoring). The loading can be a simple known load pattern (loaded trucks, concrete blocks), environmental loading (wind, temperature, etc.), traffic, earthquake, etc.; Using this technique with extensive instrumentation it is possible to measure all the critical aspects of bridge response and calibrate comprehensive finite element analytical models that accurately simulate the global behavior as well as the localized forces and distortions of a test bridge.; Two typical three-span steel-stringer bridges m Cincinnati were examined by installing monitoring systems for: (1) Demonstrate how the experimental tool of diagnostic load testing & instrumented monitoring may be effective for the condition assessment and evaluation of bridges; (2) Explore a number of less known mechanisms related to the actual behavior and performance of steel stringer bridges.; Reading Road Bridge (HAM42-0992) Cincinnati, OH, was selected for the first prototype bridge monitor to apply the methodology. Over 50 gages were installed for long term and traffic monitoring. Three types of tests were conducted within the two years of monitoring: A static loading test for measuring short-term responses due to controlled loading, a high-speed dynamic test for measuring shot term responses due to moving traffic, and a long-term monitoring test for observing the effects of the daily, seasonal and yearly ambient condition and temperature changes on the bridge.; In addition to above, a damage detection study via instrumented monitoring and diagnostic truck load testing was performed on HAM-561-0583 (Seymour Ave. Bridge), a decommissioned steel stringer bridge. The bridge was subjected to a series of deliberately induced damage, simulating typical deterioration and damage scenarios which may affect steel-stringer bridges. The damage scenarios included, but were not limited to, bearing damages, girder flange cut, girder web cut, crossframe cut. Continuous monitoring as well as diagnostic load testing were performed before and after each damage scenario. |
