Using portable/in-situ stress-strain microprobe system to measure mechanical properties of steel bridges during service

摘要

Abstract: There are 590,232 federally reported bridges in the US with 186,733 or 31.6 percent being defined as substandard. Developing new methods for inspection and evaluation of bridges has recently received considerable attention. The characterization of aging responses in structural materials entails establishing the fundamental relationships between service and environmental exposure and material properties. Service failures due to inaccurate characterization of aging responses might result in costly repair or premature component replacement. A novel portable/in-situ stress- strain microprobe (SSM) system was developed to use an automated ball indentation technique to nondestructively measure yield strength, true-plastic-strain curve, strength coefficient, strain-hardening-exponent, and to estimate fracture toughness. Example test results on metallic structural components and samples are given in this paper and a video demonstration will be presented at the conference. The SSM technology will allow: 1) establishing current key mechanical properties which are needed as input for various damage prediction models as well as to re- evaluate the safety factors used for bridges, and 2) periodic monitoring of aging bridges to develop correlations between the SSM-measured mechanical properties and the damage accumulation as a function of bridge service usage. !16