Interpretation of field tests in condition assessment of bridge element

Abstract

Mathematical basis of interpretation of data from nondestructive evaluation (NDE) methods in bridge inspection in presented. In bridge inspection with NDE methods, NDE data are not directly used for the condition assessment. Instead, NDE data must be interpreted as condition of bridge element. Interpretation is then assessment. Correct assessments of conditions of bridge elements depend on the inaccuracy and variability in test data as well as on the uncertainty of correlations between attributes (what is measured) and conditions (what is sought in the inspection). Inaccuracy and variability in test data defines the quality of NDE test. The quality of test itself is important, but in view of condition assessment, the significance of uncertainty in correlations of attributes and conditions must be combined. NDE methods that are accurate in their measurements may still be found to be poor methods, if attributes are uncertain indicators of condition of bridge elements. This paper reports mathematical presentation of inaccuracy and variability in test data and of uncertainty in correlation of attributes to element conditions with three examples of NDE methods.