Monorail runway beams for hoist blocks

Specific rules for the justification of running girders are currently set out in standard NF EN 1993-6. The running girders covered by this text are those designed to support overhead travelling cranes, suspended cranes or simple carts.

Overhead travelling cranes are those which run on the upper flange of the running girders, transmitting the loads from the rollers, generally via rails. Suspended overhead travelling cranes run on the bottom flange of the running girders, with the rollers acting directly on them.

A cart is a cart, equipped with a hoist, suspended under a beam and running on the beam's lower flange. When the cart runs on a single fixed beam, it is referred to as a monorail cart beam, or, more synthetically, a monorail beam.

These monorail girders have a number of special features in comparison with overhead travelling cranes, linked on the one hand to the nature of the loads induced by the cart, and on the other to the determination and consideration of the local stresses induced in the bottom flange.

This article deals with monorail beams, and will successively summarize the actions due to cart cars, discuss the design principles and examine the justification methods for this type of beam.