A Treatise On The Principles And Practice Of Dock Engineering

LIVERPOOL SHEDS. 387 principals, and boarded and slated roofs. The front and the back of each shed, for 240 feet of its length, are entirely open, but can be closed at will by steel self-coiling revolving shutters, working between the storey-posts supporting the roof. When these shutters are open, free access is afforded between the quay and the railway in the rear of the sheds, and when they are closed, the requirements of the custom-house for the safe custody of bonded goods are complied with. The ends of each shed, and the small portions of the front and back not closed by the shutters, are covered with corrugated iron supported upon timber framing. Well distributed light for the interior is obtained through 480 large glass slates in the roof of each shed. The floors of the sheds are of pitchpine planking, laid upon sleepers bedded upon a layer of ballast 12 inches thick. Quay sheds, generally similar to those for the branch docks, but of one 60-foot span, are provided for the berths in the tidal basin.” Liverpool Sheds. At Liverpool the sheds are continuons, and their length practically coincides with the length of the quays upon which they stand. They are, however, for working purposes divided up into compartments, of which the average length in the more modern examples is rather less than 300 feet. In width they vary considerably, but the roof spans range generally from 30 to 80 feet, with a few extreme cases approaching 100 feet. Fig. 370 shows a section of a single-storey shed, 150 feet wide, roofed in two spans. The walls are of brickwork, with doorways 20 feet wide by 16 feet and 17 feet 6 inches high. The roof trusses are a combination of wood and iron, the compression members being of wood and the tension members of iron. The intermediate supporting columns are of cast iron, and the roof covering of Vieille-Montagne zinc. The floor is asphalted. Fig. 371 is a section of a double-storey shed, 95 feet wide, roofed in three spans. The upper floor is supported on brick piers, 3 feet square and 26 feet apart longitudinally. It is formed by main and subsidiary girders, the enclosed spaces being covered by buckled plates, upon which is laid a bed of concrete to form a level surface for a layer of l^-inch blue Stafford- shire tiles. The roof trusses are entirely constructed in angle- and bar- iron, with rivetecl joints. The roof covering is Velinheli slates nailed on boarding. Continuous skylights run along each side of the ridge. The lower floor is lighted by windows in the walls and by glazed panels in the upper portion of the sheet-iron doors. In later examples of this type of shed, the width has been divided into two equal spans by means of a central row of cast-iron columns. Upon made ground the column bases are supported by concrete beds, 7 feet square, surrounding and covering the heads of two pitchpine piles, 14 inches square and about 38 feet long, driven to a firm substratum of boulder clay. The fronts of the shed, both to the quay and the roadway, consist of a series of doors closing openings,