Corrugated steel may be fastened to the girts by barbed roofing nails in case the girts are wood, or by clinch nails in case the girts are angles, or by clips fastened with rivets or 3/16-inch stove bolts stove bolts in a pound is to be found in the handbooks of various manufacturers.

⅜ inch long. Nails and clinch nails should be spaced about 8 to 12 inches apart. Clips are made of

No. 16 gauge steel from f inch to 2 inches wide, and are spaced 8 to 12 inches apart. Fig. 87 shows girts, together with the method of attaching the corrugated steel. The number of nails, rivets, and

Fig. 86. Layout of a Frog and Switch Company's Building.

Fig. 86. Layout of a Frog and Switch Company's Building.

Fig. 87. Methods of Connecting Corrugated Steel to Girts.

Fig. 87. Methods of Connecting Corrugated Steel to Girts.

INTERIOR OF ASSEMBLY BUILDING OF THE GEORGE N. PIERCE COMPANY, BUFFALO, N. Y.

INTERIOR OF ASSEMBLY BUILDING OF THE GEORGE N. PIERCE COMPANY, BUFFALO, N. Y.

Spans under the sawtooth roof are 61-ft., giving the building two unbroken bays, each 61 ft. by 401 ft. Kahn System of Reinforced Concrete.

Courtesy of Trussed Concrete Steel Company, Detroit, Mich.

ALPHA DELTA PHI CHAPTER HOUSE AT CORNELL UNIVERSITY, ITHACA, N. Y.

ALPHA DELTA PHI CHAPTER-HOUSE AT CORNELL UNIVERSITY, ITHACA, N. Y.

Dean & Dean, Architects, Chicago, 111. Ground Floor Split-Faced Bedford Stone; Main Floor of Roman Brick with ⅞-Inch Mortar Joints; Second Floor of Plaster.

Window-frames in mill buildings are, in general, similar to those placed in frame or brick buildings. These frames are fastened either directly to an iron framing or to wood nailing-pieces placed on the . iron framing. The windows may be glazed in the usual fashion by means of putty, or may have the glass held in place by some of the methods shown in Fig. 73, p. 44. Windows in the side of the shop may be so fixed that they may be raised and lowered as the ordinary dwelling window; or they may slide horizontally; or, again, they may be fixed so that they cannot be moved. The windows in the monitors are usually fixed with a swinging sash which can be operated from the floor of the shop (see Fig. 89).

The glass in the windows may be the common window glass, common plate glass, ribbed or corrugated glass, wire glass, or prisms. Of these varieties, the prisms and the ribbed or corrugated are the best, since they give a more uniform light and are not easily broken. Wire glass, which is made of wire netting moulded in the middle of the sheet of glass, gives a very good light, and has the additional advantage that it does not crack and fall out under the action of file and water. It is considered fireproof. Common window glass does not diffuse the light so well as most of the other glasses. It is very liable to fracture, and for this reason the inside of the window should be covered with wire netting. Prisms are made by the American Luxfer Prism Company, of Chicago. They may be obtained up to 84 inches in width and 36 inches in height. The width is parallel to the saw teeth. Figs. 88 and 89 give sections of windows, showing the framing. Attention is called to the fact that the roof on the monitor should overhang sufficiently to prevent the water from dropping upon the swinging window when it is fully opened.

Fig. 88. Section of a Sliding Sash Window.

Fig. 88. Section of a Sliding-Sash Window.

Fig. 89. Section of a Monitor Swing Window.

Fig. 89. Section of a Monitor Swing Window.

Doors may consist entirely of wood, of a frame of angles covered with corrugated steel, or of corrugated steel alone. The first two classes may be so fixed that they will slide, as in the folding doors of residences; open outward like a common door; lift vertically; or, in case they are made entirely of corrugated steel, roll up like a window-shade. This latter door is a patented one. Shop doors are seldom made to open outward or inward, on account of the space required - a space which can be devoted to better purposes. Figs. 90, 91, and 92 show details of the above doors.

Let it be required to design the girt when the trusses are 16 feet apart and the girts are 5 feet center to center. The moment

Fig. 90. Detail of a Wooden Door.

Fig. 90. Detail of a Wooden Door.

is

5

X

16

x

30

X

16

X

12

57 600 pound-inches; and the re-

8

quired section modulus is

57

600

=

3.84. By inspecting the tables

15

000

in the Carnegie Handbook, pp. 97 to 119, it is found that the following shapes will be sufficient:

Shape

Section Modulus

One 5-inch 9 . 75-pound I-beam

4.80

One 6-inch 8. 00-pound channel

4.30

One 41/16 by 3⅛-inch 10.3-pound zee-bar

3.9 1

One 6 by 4 by 7/16-inch 14.3-pound angle

3. 83

From this it is evident that the channel is the most efficient and economical.

23. Columns. Columns may consist of almost any combination of shapes, either latticed or connected by plates. Some of the most common cross-sections are shown in Fig. 93, those illustrated in b and c being used to a great extent. The advantage of these forms is that they give a small radius of gyration about the axis b-b, and a larger one about the axis a-a (see Fig. 94). This is especially desirable, since, in addition to the direct stress due to the weight of the cranes, roof truss, and covering, the column must withstand the moment due to the wind and to the eccentricity of the runway girder. Both of these moments tend to bend the column around the axis a-a. The bending moment due to the eccentricity of the runway girder is equal to the reaction of the girder, times the distance from the center of the column (see Figs. 95 and 96). In case the details of the column are as given in Fig. 96, the direct load due to the reaction of the truss and its covering produces a moment due to its eccentricity. This moment is Rt X e1 Since R1 acts on the opposite side of the center of the column from the point of action of Rg, it tends to counteract the effect of the moment due to the eccentricity of the runway girder. The total moment due to eccentricity is Me= R1 X e1 - Rg X e. If the first term of this equation is less than the last term, the compressive stress on the side of the column with the runway girder is increased, and vice vena. The stress in the column from the runway girder to the roof is that due only to the vertical reaction of the roof and the bending due to the wind. In that part of the column below the crane girder, the stress is that due to the direct action of the weight of the roof; its eccentricity, if there be any; the direct action and eccentricity of the runway girder; and the bending moment due to the wind. The bending moment due to the wind is less in this part of the column than it is at the foot of the knee-bracing, but it is customary to consider it the same.