This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
(9) The rivet spacing curve should be constructed if it is not given on the stress sheet.
In addition to the above the following rules which apply directly to the detailing should be followed. They are:
Fig. 70. Method of Locating End Holes for Laterals and Diagonals so that They May be Sheared by a Single Operation.
(5) The girder detailed is always the far girder and is looked at from the inside.
(6) If a span has no lower lateral bracing, only sufficient of the ends of the girder arc to be shown in order that the detail of the base plate and its connection to the flange may be shown.
(8) When the ends of two girders meet on the same pier the masonry plate should be made continuous, that is, one plate to extend under both spans. Never make the base plates continuous since they could not be riveted up in the field.
(9) Detail the bed (masonry) plate separately, never show it in connection with the base plate.
At least two sheets are necessary to complete the detail drawings of any girder span, viz, (1) the Floor, Masonry, and Erection Plan, Plate VII, and (2) the Girders and Bracing, Plate VIII, although in many cases the information on this sheet is put on two sheets, the girder on one and the bracing on the other. The first sheet should show:
(1) A cross-section of the floor.
(2) A longitudinal view of the floor.
(3) A side elevation of the floor.
(4) The angle of skew and the width of the bridge seat.
(5) The elevation of the bridge seats and the grade of base of rail.
(6) The marking diagram.
(7) All clearances.
(8) Other essential information.
In the marking diagram all members which are entirely alike should be given the same mark. It may be, and usually is a fact, that all marks can not be put on the marking diagram until the detail drawing is done since then and only then is it possible, especially with the plates, to determine all members which are alike. Only those members which are shipped loose are given a mark. Thus it is seen that while each connection plate has a mark, only the entire cross-frames are given one mark since the members which compose them are all shop-riveted together. "Other essential information" is seldom required. In this special case there is shown another track which it is proposed will be put in in the future. Another case is where each end of the span has a different height from the base of rail to the masonry. In such cases this should be shown.
On this sheet should be shown the masonry plates, and if the ends are supported on cast-steel bases the height of these and also the dimensions of the base should be given.
The following general rules apply to the second sheet, Plate VIII.
(1) At the top of the sheet show a top view of the span with cross-frames, laterals, and their connections complete, the girders being placed at their proper distances apart.
(2) Below this show the elevation of the far girder from the inside, with all field holes in the flanges and stiffeners indicated and blackened in.
(3) If the span has lower lateral bracing, show below the elevation a horizontal section of the span just above the tops of the lower flange angles. On this drawing show the lower lateral bracing.
(4) Cross-frames shall, whenever possible, be detailed on the right hand of the sheet in line with the elevation. The frame shall be of such a depth as to permit it being swung into place without interfering with the heads of the flange-rivets in the girders. (5) Always use a plate, not a washer, at the intersection of the diagonals of cross-frame.
Plate VII. Floor, Masonry, and Erection Plan for Plate-Girder Span.
Plate VIII. Detail Drawing of Girders and Bracing for Plate-Girder Span.
The various parts of Sheet 2, Plate VIII, will now be taken up in detail and described and commented upon.
The Webs. As a usual thing webs are never specified in fractions of an inch. If so, the next inch in width must be ordered and then after the flange angles are riveted on, the projecting portion is cut off - an expensive operation. Webs are ordered in even inch widths and the distance back to back of angles is made 1/4 inch or 1/2 inch greater than the width of the web plate. This is sufficient to prevent any irregularities in rolling from projecting above the flange angles. Some engineers favor the web planed down from the greater width and claim that the bearing of the web on the sole or base plate thus obtained is a great advantage. The advantage is slight, however, and unless specially instructed to detail it that way, it should not be done. The web splices should, as before mentioned, be at a panel point of the lateral system. In some cases the web plates butt up against each other, being planed to an even bearing. In most cases, however, the ends of the webs are sheared off and the customary 1/4-inch clearance is allowed. In this case the sum of the lengths of the webs as given is 2 (25'-3/4)+23'-5 3/4"=75'-9 1/4", while the "overall" distance is 73'-10" or 3/4 inch less, which is taken up by the distance between webs at the splice and by the small amount, 1/8 inch, which web is below the backs of the angles at the ends. This shows the webs to be 1/4 inch apart at the splices. It is unnecessary to place any dimensions or notes on the drawing calling attention to this fact since the shop will make this allowance unless instructed otherwise. In case the webs are to be close together, a note must be placed on the drawing at the splice, reading "Webs planed to even bearing."