Development of a Portable Stress Measurement Instrument

This report documents the results of IDEA project 179, Development of a Portable Stress Measurement Instrument. An ultrasonic stress measurement (USM) instrument has been developed that provides bridge engineers with quantitative measurements of the in-situ stresses in bridge members. The instrument is very unique because there are no other practical total stress measurement methods for in-service steel bridges. The total stress measured includes dead load, residual, and live load stresses. This new technology is a significant improvement over other stress measurement technologies such as strain gages, which are not capable of measuring the in-situ residual or dead load stresses in a bridge member. The total stress measurement provided by the USM instrument can be used to analyze the structural adequacy of bridge members in ways not possible using conventional technologies.  The full report is available from TRB at http://www.trb.org/Main/Blurbs/176966.aspx