In pin-connected steel truss bridges, flame shortening has long been used as a means to re-tension eyebars that have become unacceptably slackened over time. During this procedure, eyebar stress is estimated by converting the measured fundamental natural frequency to the corresponding tension through a simple analytical model. Recent studies have developed new models that more closely reflect the actual end conditions present in many situations, allowing for more accurate tension measurements. These enhancements offer potential utility for endeavors beyond flame shortening, such as rating and condition assessment. This paper reviews the analytical models and examines the fixed-end case in greater depth, considers field tests, and discusses possible applications.