THE WRITER’S DESIGN
The site for the warehouse has been taken at New Orleans, Louisiana, on the property of the Illinois Central fronting the gulf known as Stuyvesant Docks. The design, however, is adapted to any sea-board town where a great deal of heavy freight is received from railroads for shipment by water, or vice versa. It might also with a few variations be suitable for an inland town.
The warehouse will be 600 ft. long. This length is chosen because it represents the length of wharf available for that purpose. The width of the building will be 148 ft., of which 20 ft. in the center will be occupied by two tracks spaced fifteen feet center to center, which allows an ample passage-way between the tracks and also between the floor and the track.
Load. The size of warehouse having been decided upon, the next thing is to select the proper floor load to be allowed for. This depends upon the class of freight to be expected and also upon the manner of storing it. Passage-ways will at most times be left in the freight for accessibility, which will make some difference in the loading; but as the passageways are likely to be omitted at some time, the unit load should be on the side of safety and cover all contingencies. A load of 250 lbs per. sq. ft. on both the upper and lower floor has been taken in this design, which it is believed will be ample as iron ore, lead, etc., will not be stored here.
Support of Upper Floor. The columns will be spaced 20 ft. apart in the direction of the length of the building, and 15 ft. in the other direction. The girders will run parallel to the length of the building and therefore the girders will be 20 ft. long and the joists 15. The economic length of the girder is somewhat less than 20 ft. but by this spacing of the columns more clear room will be obtained, which is a thing worthy of some consideration.
Roof Trusses. The vertical load on the roof will be taken as 35 lbs. per. sq. ft. of horizontal projection, of which 20 lbs. is supposed to cover the weight of the roof itself, and 15 a possible load due to wind. The horizontal effect of the wind is taken as 30 lbs. per. sq. ft. of the vertical projection. A design was first made in which it was intended to span 60 ft. with one Fink truss, but this required such heavy construction in the truss members, that the span of the trusses was reduced to 30 ft. and a column was projected up through the second story to carry one end of the trusses.
For an elevation of the trusses see Plate III, page [23]. The stresses in the several members of the trusses were found by graphical resolution. In many cases a stress was found smaller than would be safely carried by a 2 × 2–inch angle, but on account of riveting a smaller section could not be used. For details of the trusses see Plate III, page [23].
Purlins. The purlins are spaced 7 ft. apart and have a span of 20 feet. This requires rather a heavy purlin, and on account of the length there will be more or less deflection in it; but this will not be in the least detrimental. Five-inch nine-pound channels will be used, and on these will be bolted the nailing pieces.
Roof Covering. Over the purlins will be laid 1½–inch fine sheathing covered with tin. Tin is used in preference to corrugated iron, as it may be soldered so as to be absolutely water-tight. On the underside of the sheathing will be nailed a layer of asbestos to prevent sparks from the engines below setting fire to the woodwork.
Flooring. The flooring for the upper story will be 3–inch well-seasoned long leaf yellow pine surfaced to a thickness and laid with square joints. The floor can safely carry the required load with a span of 4 feet, and therefore the joists will be spaced 4 feet center to center. The joists will be supported by girders which are in turn supported by the columns. The joists will be 15–inch 42 lb. I beams, and the girders 20–inch 65–lb. I beams.