What Is Web Crippling?

Web Plate

The amount of steel and the size of the web plate, which is the supporting structure in a girder, beam or truss, is crucial to determining the probability of web crippling. Mathematical design equations must be performed prior to construction to determine the amount of steel to prevent this problem.

Calculations

Six parameters comprise American and Canadian web-crippling capacity calculations. These are thickness of the web, strength of the material, ratio of inside bend radius to web thickness, ratio of flat portion of the web to thickness, ratio of bearing length to thickness and the inclination of the web element. Four different loading conditions--end and interior one-flange loading and end and interior two-flange loading--are also computed.

Localized Failure

Web crippling is a localized, incomplete failure because the steel plate is still able to withstand yield loads even though the structure becomes buckled. This failure, however, can contribute to overall building collapse.