FEASIBILITY STUDY FOR SIMPLIFIED LOAD TESTING OF SLAB BRIDGES. FINAL REPORT

The objective of this investigation was to demonstrate the feasibility of obtaining meaningful quantitative structural response data, suitable for rating purposes, from short span reinforced slab bridges by simplified load testing. Such simplified load testing could be carried out by regular inspection personnel, utilizing preweighed vehicles for loading the structures and collecting the resulting deflection data with readily available instrumentation, such as mechanical dial gages, etc. Quantitative in-situ load performance data, combined with conventional visual inspection, would provide a much sounder basis for load rating than visual inspection alone. Before such a rating procedure can be developed, however, it must be verified that useful data can be collected by the "low-tech" instrumentation alluded to. The investigation revealed that measurable deflections, providing data with more than adequate accuracy and resolution, were indeed possible. The "low-tech" dial gages agreed very well with more sophisticated electronic instrumentation, and simple portable fixturing was demonstrated. Load ratings were estimated for the test structures which would appear to be quite reasonable for the test loads utilized. Reasonably heavy loads (axle weights in excess of 30 kips) still did not load the bridges in question beyond the service limit state, defined as steel stresses in the reinforcement estimated at 50% of yield.