The stress developed at specific details of multi-girder steel bridges under repeated loading (fatigue) is a concern. The majority of the details that are prone to fatigue are identified and classified in the design specifications. Whether the detail is classified or not, there are certain configurations which lead to unintended distortion. As a result, the stresses developed at such details are not accounted for the design. Even though these secondary stresses are not accounted for in the design, some of these details develop high stress under fatigue leading to cracking. Hence, it is vital to instrument such waves that are generated due to fatigue leading to cracking. Hence, it is vital to instrument such waves that are generated due to fatigue crack initiation and growth.

This article discusses the state-of-the-art technologies available for developing a monitoring system to achieve the above stated objectives related to distortion-induced fatigue, simulation of web gap strains using laboratory specimens, and developing a strain gage configuration for measuring web gap strains as part of a structural health monitoring (SHM) system.