APPLICATIONS OF FIELD TESTING TO BRIDGE EVALUATION

Bridge testing is rapidly becoming a major tool in evaluation. Despite improved structural analysis there are numerous cases in which field testing may be the best way to help ensure future safe performance. Th e reasons for testing include uncertainties in material and structural modeling and concerns for serviceability limit states. Switzerland ha s long experience in testing new bridges before allowing them to go in to service. The general testing plan, the responses that are modeled, and an example are described. The aim in this paper is to extend these bridge-testing methods to strength-evaluation activity. The Swiss app roach in testing offers a compromise between a diagnostic performance test and a proof-loading check on capacity. The level of test loading is normally about 80-85% of the code-specified serviceability or unfac tored load, which is still significantly above the expected lifetime m aximum traffic loading. The paper describes in detail a risk model app ropriate to modeling the risks during the testing as well as the benef its in higher safety indices gained after the testing. An example is d escribed in the paper.