Assessing the Damage Potential in Pretensioned Bridges Caused by Increased Truck Loads Due to Freight Movements Abstract:
Due to the aging and deterioration of bridges, the evaluation of the existing conditions of their structural elements becomes vital to engineers and public officials when deciding upon how to repair or replace these structures. The ability to obtain necessary information on these conditions is often expensive and time consuming, especially in the case of concrete bridges where the reinforcement is not available for inspection. Employing the surface-strain relief method could allow for accurate evaluation of aged or damaged prestressed members.
The surface-strain relief method was developed to measure initial or pre-existing strains in a concrete member. It involves relieving the strain in the member and measuring the change in strain. Two methods were tested in this study—the first used a linear electrical-resistance strain gage and a three-inch-diameter diamond concrete core bit to cut around the gage, and the second used a laser-speckle imaging device and a diamond cutting wheel to create notches perpendicular to the axis of maximum strain. Both methods measured the change in strain and related it to within 10 percent of the actual fse. The method of cutting notches and the laser-speckle imaging device provided a simpler method to be implemented in the field, while the coring method achieved a higher level of accuracy and precision. In light of these research findings, selection of transportation modes are provided and promising future research tasks are suggested.