A loading study of older highway bridges in Virginia. Pt. 1, Steel truss bridge in Allegheny County.

A comprehensive field test was conducted on a highway truss bridge in Allegheny County, Virginia, in July 1974. All typical truss members as well as structural members of the bridge floor system were instrumented and unit strains measured when the structure was loaded with a 3-axle tractor trailer weighting 78,000 lb. placed in incremental positions throughout its length. The purpose of the study was to determine the present capacity of this representative older type design that was used extensively in the. 1920's and 1930's and is represented in many bridges which remain in use today. Although the structure was designed for two 30,000 lb. vehicles passing, it was found that the static loading of the 78,000 lb. test vehicle did not cause serious stresses