If the connection is not standard, it must be noted and detailed as in Fig. 59, second view, and if it were not in the center of the web, its distance from the bottom should be given as in the ease of the standard connection. In case there are holes in the outstanding leg, they should be shown as in Fig. 62. Where the leg against the web is standard and the outstanding leg is of the same punching, no dimensions need be shown, but the outstanding leg mast be shown and the material notation of the angle put on as in Fig. 59, first view, right end.
When beams are on a slight beret, it is desirable to hare the bevel taken up in the connection angles and th,e holes in the web of the beam at right angles to the center line. The bevel should be indicated, see third view, Fig. 58, right end.
In case field connections to the web arc made, as in cases where other beams are riveted to it, it is unnecessary to give the vertical spacing of the holes if the connection is standard. The horizontal distances and their number will designate which connection is required.
For example, in the first view, Fig. 5S, the six holes 58-inch centers show this to be a standard for 12-inch beams, while the four holes centers indicate the standard connection for a 7-inch, S-inch, 9-inch, or 10-incli beam. In all cases the vertical spacing will be 2-1- inches. It should be noted that in all cases of standard connections of S holes or less in a vertical row the rivet spacing is 2-1 inches, while all over S have a spacing of 3 inches.
The centers of all groups of field holes above the bottom of the beam should be given.
Tie rods are pill in in case no beams are riveted to the webs, to keep the beams from lateral ?notion. The holes for these are 4 inches apart, and they are referenced as in Fig. 59, second view.
Where two beams are placed close together; they should be connected by "sep arators" to prevent lateral motion. When such is the case the holes are indicated as shown in Fig. 60. The various kinds of wall anchors are shown in the handbooks and in Fig. 20. Care should be taken to provide for their connection to the beams when required.
When beams are used in building work, it is usually required that either the upper or the lower flanges of part or all of the beams hr at the same elevation. When the girder or main beams are deep enough, the joist top or bottom flanges may be brought to the some elevation as shown in Fig. 63 which shows a 12-inch and a 7-inch beam. The connection angles are in all cases arranged so that the rivets through the girder web and the smaller connection angles go through the connection of the larger beam also.
In case it is desirable to have beams so as to have all their tops or bottoms at the same elevation, it may be accomplished by an operation known as "coping" the beam. By coping is meant that the flange is cut back for a certain distance depending on the size of the beam which is to join the beam under consideration and the web is then cut down a distance X and sloped back on a. bevel of 3 inches in 12 inches, see Fig. 64.
Fig. 64 shows a beam coped top and bottom to fit into another beam of its own depth. A beam may be coped on top only, Fig. 65a, or on bottom only, Fig. 65b. Other conditions of coping are shown in Fig. 65c—f, together with the ways of indicating them. Fig. 58 shows some indicated in the beam sketches.
JJ'hen a beam is to be coped on a bevel, the flanges are not cut to a bevel, but are cut as in Fig. 66. The distances a and b should be given allowing a clearance, and the portion of the beam coped is to be shown crosshatched. This method of cutting to a bevel should be used whenever possible, whether the beam is coped to fit another or is simply cut to a bevel.
When a single beam or a girder formed of two beams having a cover plate riveted thereto is cut to a bevel, the corer plate should be sheared to the line of bevel and the beam should be cut as shown in Fig. 66.
When an I-beam of a channel is cut to a bevel across the depth, the cut should be -made as shown in Fig. 67, and the distance "a" should be given.
Detailing of Roof Trusses. The first thing to determine in this respect is the outline of the outer line of the roof and the end, and the center depths. The chords should now be located by center lines corresponding to the gauge lines of the angles, or the center of gravity lines of the pieces, as the case may be. The above mentioned deter minations may be obtained from the architect's drawing and from the stress sheet; and in many, if not most all cases, the center lines of the chords are shown on the stress sheet. The stress sheet may be an outline with the stresses and the sections on it, or it may and in fact should be as shown on Plate I. Here the designer, who is an experienced man, has shown the general details. It now remains for the draftsman to draw this up so that the shopmen can make it. After he has finished, the results will be as shown on Plates II and III, which will now be discussed in detail.