Bolted Bridge Behavior During Erection and Service

Measurements were made of the movements at connections of a 310-ft railway bridge over a period of 3-1/2 yr. The study was initiated during shop-assembly of a truss and was ended after 3 yr of service loading. As might be expected, substantial relative movements of the bridge joints occurred during erection with the addition of dead load, bracing, and floor systems. The effects of the measured movements on changes in camber are examined and compared with level readings taken during the 3 yr of traffic. In essence, no service movements were found; no evidence of a marked change in camber was found. These findings suggest that a properly designed structure with properly installed high-strength bolts will not slip under normal service loadings.