Fig. 25
52. Planning for Traveling Cranes.—In designing factories or mill buildings in which traveling cranes are to be installed, it is important to observe that the track of the crane can be properly supported, and also that there is sufficient headroom under the floor or roof construction to permit the trolley of the crane and the traveling mechanism of the crane girder to move underneath.
In [Fig. 25], there is shown the upper portion of a steel-mill building. The columns a support the girder carrying the runway of the crane. A convenient means of supporting the roof is to splice to this column a similar column b, which is incorporated in the design of the roof truss and rigidly braced with the truss by means of a knee brace at c. In the design of such a building, it is very important to determine the distances x and y required by the makers of the traveling crane. These distances x, y depend on the size of the crane, that is, whether it is designed to carry 5, 10, 15, or more tons. Usually from 9 to 12 inches is sufficient for the measurement x, while the measurement y varies from 5 to 8 feet.
53. Cranes Supported on Reinforced-Concrete Walls.—Frequently, in the latest types of construction, the runway for the crane is supported on reinforced-concrete walls, which construction is shown in [Fig. 26 (a)]. It will be observed that the pilasters supporting the crane are strongly reinforced in all directions from which stresses are likely to be created from the eccentric load imposed by the crane track.
Where cranes are supported on reinforced-concrete columns, as in [Fig. 26 (b)], it would be good practice to put additional rods in the far side of the column as at a, in order to supply a greater resistance to bending, and thus counteract the effect of the eccentric load produced by the reaction from the crane track. Where cranes handle heavy rails or cumbersome material that might, by swinging, impose a blow on the reinforced-concrete columns, it is good construction to protect the edge of the columns with an angle iron as indicated at b. This angle iron may be fastened in the forms and anchored by means of pronged anchors back into the concrete when it is tamped.
Fig. 26
Fig. 27