The use of continuous crane runway girders should be discouraged because they are subject to many problems and a short fatigue life (see 4.8.4). However, if such girders must be made continuous, three alternatives are available in the literature: (1) from ANSI (2003), the unbraced length should be taken as twice the cantilevered distance or the distance between the supports, whichever is greater; (2) Tanner (1985) gives an alternative and possibly less conservative solution that considers the ratio of overhanging span to the adjacent interior span in the developed equations; and, (3) for doubly symmetric cross-sections, Galambos (1998) gives cantilever unbraced lengths for use in a corresponding equation for nominal lateral torsional buckling strength.

American National Standards Institute, 1996, Specifications for Patented Underhung Cranes and Monorail Systems, MH27.1, ANSI, New York, NY. MH 27.1-2003

Tanner, N.S., 1985, “Allowable Bending Stress for Overhanging Monorails,” Engineering Journal, Vol. 22, No. 3, (3rd Qtr.), pp. 133-138, AISC, Chicago, IL.

Galambos, T.V., 1998, Guide to Stability Design Criteria for Metal Structures, 5th Edition, John Wiley & Sons, New York, NY.

last modified 1 January 2006