Our goal is to guide improvement in construction codes for both rehabilitated and new structures. Destructive and nondestructive data will allow bridge owners to allocate repair funds to the most pressing needs and develop a more accurate representation of the heath of existing structures.
We are rebuilding our capabilities in NDE, specifically in acoustic transmission and acoustic resonators. The acoustic emission calibration block described in ASTM Standard E 1106 is being installed in a new facility, and the calibration equipment is being upgraded. This will allow us to resume primary calibration of AE sensors and move the technology forward. Also, we are developing a MEMS-based shear-mode acoustic resonator that will permit broad-band sensing of strain. This new sensor should be particularly suitable for wireless sensor applications.
We have a mechanical testing project that is developing mechanical test data on old and new components. Since the NIST focus is on measurement technology, we are developing more accurate tests and data to assess the remaining life of existing structures. For example, fatigue crack growth is a common degradation mechanism, but little data exists for older bridges. Another short-term project is to clarify the property changes that occur during flame straightening. Current practice limits the repair of damage by flame straightening to two times. We are studying the onset of brittleness in the steel as a function of thermal cycles and temperature.
Start Date:May 1, 2009
Lead Organizational Unit:mml
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Project Summary (PDF)