Authors:  Kevin D. Koch, William T. Riddell, Todd T. Triechel, Christopher P.L. Barkan

Date of Publication:  2000 (?)

Sponsoring Agency:  U.S. Department of Transportation, Federal Railroad Administration, Volpe National Transportation Systems Center; Railway Progress Institute, Association of American Railroads

Abstract:

Under in-service conditions, a railroad tank car is subjected to cyclic loads that can lead to structural damage. Prior to the late 1950s, the construction of a tank car consisted of a tank mounted onto a car structure that incorporated a center beam, or sill, that transferred the in-train buff (compressive) and draft (tension) loads from one end of the car to the other, without directly transferring the loads through the tank shell and heads. Beginning in the late 1950s, the construction of most tank cars consisted of a tank that formed part of the car structure so that the in-train loads passed through the tank and heads. The later become known as “stub-sill” tank cars because the sills consisted of short “stubs” of a full sill that were mounted on each end of the tank. Like most dynamically loaded structures, tank cars and their attached stub-sill structures are subject to fatigue cracking due to cyclic stresses resulting from the in-train loads. Beginning in the late 1970s, the government and industry began research and development and rulemaking initiatives to improve the ability of the tank car structure to withstand these in-train forces. Some of these initiatives included increasing the design requirements for both dynamic and compressive loading of the tank car structure, limiting the maximum weight and capacity of the tank car, and the use of fine-grain and tougher steels.
 

No. of Pages:  12