Fig. 56. Methods of Determining Number of Rivets in Connection Plate from the Diagonal.

Other problems may be solved in a similar manner. The rivet spacing in the sides and tops is so arranged as to be equal and to fill out the plate, allowing the required edge distance. The plates should be kept rectangular as far as possible.

In many cases, as in roof truss or wind bracing work, the computed number of rivets will be two or less. In such cases three rivets should be put in in order to have a satisfactory joint which will not loosen under vibrations which are liable to occur.

Detailing of Combinations of Structural Shapes. The general methods to be followed are the same as those which have been given together with those which are exemplified in the discussions which

## Table XIV. Thickness Of Lacing Bars

 Single Lacing (t = c/40, ф =30°) Double Lacing (t = c/60; ф =45°) t C t C 1/4" 0'-10" 1/4" 1'-3" 5/16" 1'-0 1/2" 5/16" 1'-6 3/4" 3/8" 1'-3" 3/8" 1'-10 1/2" 7/16" 1'-5 1/2" 7/16" 2'-2 1/4" 1/2" 1'-8" 1/2" 2'-6" 9-16" 1'-10 1/2" 9/16" 2'-9 3/4" 5/8" 2'-1" 5/8" 3'-1 1/2"

follow. In general, the combinations consist of plates or other shapes held together by angles, lacing bars, or tie plates, the size and section of the angles being determined in the design since they are part of the section of the member itself, while the lattice bars and tie or batten plates are chosen in accordance with the specifications employed. The specifications for lacing bars make their size a function of the distance between rivets. Table XIV gives the thickness of lacing bars for any distance between rivets.

Detailing of Beams. This is for the most part done on "Beam Sheets". These sheets are the size of the shop bills, 8 1/2X14 inches, and have a printed heading and footing as on the shop bills. Between the heading and the footing are printed elevations and cross-sections of I-beams, as in Fig. 57, the number on a sheet varying with the number of dimension lines above and material below, i. e., from two to four. In some cases, those blank sketches are printed lengthwise of the sheet and then two only are placed upon a sheet. In case a channel is to be indicated, the draftsman blocks out one half of the section or end view, see Fig. 58, lower cut.

On these blank sketches the draftsman notes the rivets and rivet holes, puts on the connection and other angles, and shows all other information necessary for the complete fabrication of the beam ready for the structure of which it is a part. Figs. 58, 59, 60, and 61 are beam sheets which have been rilled in, and illustrate very nicely the general principles.

The general rules regarding beam sketches are given in the following:

In all possible cases the holes in the end connections to the webs should be according to the standards given in the handbooks. If the connection is standard for that beam, no mention need be made of the fact, and if it is in the center of the web, no dimension is required, see Fig. 58, first view, left end.

Fig. 57. Method of Detailing an I-Beam on Beam Sheets.

If the connection is not in the middle of the web, but it is standard, the location of its center from the bottom should be given, see Fig. 58, first view, right end.

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 case 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 must be shown and the material notation of the angle put on as in Fig. 59, first view, right end.

Fig. 58. Typical Beam Sheet Showing Dimensions Filled in According to Specifications.

Fig. 59. Typical Beam Sheet Showing Dimensions Filled in According to Specifications.

Fig. 60. Typical Beam Sheet Showing Dimensions Filled in According to Specifications.

Fig. 61, Typical Beam Sheet Showing Dimensions Filled in According to Specifications.

When beams are on a slight bevel, it is desirable to have the bevel taken up in the connection angles and the 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.

Fig. 62. Detailing Connection P ate When There Are Holes in the Outstanding Leg.

In case field connections to the web are 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. 58, the six holes 5f-inch centers show this to be a standard for 12-inch beams, while the four holes 5 5/16-inch centers indicate the standard connection for a 7-inch, 8-inch, 9-inch, or 10-inch beam. In all cases the vertical spacing will be 2 1/2 inches. It should be noted that in all cases of standard connections of 8 holes or less in a vertical row the rivet spacing is 2 1/2 inches, while all over 8 have a spacing of 3 inches.