Fig. 203 shows the detail of the lintel beams to which beam No. 11 connects. The table on page 44, Cambria Handbook, gives the standard spacing for double beams. These spacings cannot always be followed. In this case the beams are spread more so as to bring the flanges nearer to the outside faces of the wall which rests upon them. Separators are always placed at ends over the bear ings and at varying distances, center to center, as noted in Part II.
Fig. 204 shows the detail of No. 15. Observe the difference in details of two ends; one coming on the cast iron column and one on the steel column.
As the beam is a 15-in. beam, while on one side is a 12-in. terra cotta arch, it is necessary to provide an angle on this side. The bottoms of the 9-in. beams are 3 in. above the bottom of this 15-in. girder, and if the connections were central with the 9-in. beams, the first hole would be in. from the bottom of the 15-in. beam. In order'to get clearance between this hole and the tipper edge of shelf angle sufficient to drive the rivet, and to avoid cutting the angle at each connection, the shelf angle is dropped, making the upper side of the outstanding leg flush with the bottom of the 12-in. beams, and the connection on the 9-in. beams raised •1,- in.
Fig. 205 gives the detail of beam No. 12. In this case, the length of beam cannot be obtained directly from the framing plan, as the beam No. 1 is not perpendicular to beam No. 12. The difference in measurement of the ends of No. 1 from the wall line is 1 ft. 10 in., and the length parallel to this wall and square with beam No. 12 is 12 ft. S in. from the center of the column. As No. 12 is 4 ft. 2", in. from the center of the column, the bevel from the column to No. 12 is X 22 = 7.31 inches, or 7 in., to the nearest sixteenth.
12.67 The length of No. 12 from the face of wall to center of No. 1 on this line, therefore, is 14 ft. 10H in. The bearing on wall being S in., and the clearance at the other end 4 in., the total length of beam is 15 ft. in.
The girder No. 1 coming under the sidewalk is 4 in. lower than beam No. 12. This is not enough to get a shelf angle on the girder, or to get angles over the top of the girder, as in the case of beam No. 11. It is necessary, therefore, to drop the connection on No. 12 and notch the beam over the top flange of No. 1. This notching is not figured on as reducing the required number of rivets in the con nection, but does give an added element of strength and of stiff ness. In order to get the connection in, it is necessary to go within
1 in. of the bottom flange of No. 12 and the top flange of No. 1; thus encroaching somewhat on the fillet in each case. As the required number of rivets can not be obtained in two lines, as is generally the case, it is necessary to use special spacing as shown. The connection specifies bent plates rather than angles; where the bevel is over 1 in. to the foot, it is customary to use plates.
Fig. 206 gives the detail of channel No. 17. This channel has a single angle framing. This is a case where the channel comes into a wall so that a connection angle on the back side cannot be reached. In order to get the necessary number of rivets in the outstanding leg, therefore, a 6 X 6-in. angle must be used. The holes at the left hand end in the web are for the connection of a channel similar to what is shown in the end view.
These holes are located from a line which in turn is located from the end of the channel; this axis is the back of the channel framing in.
Fig. 207 gives a schedule of tie rods and of field bolts, and of bearing plates for the framing as shown on Fig. 199.
Note the over-all lengths of the tie rods is 3 in. longer than the length, center to center of beams. This al lows 11 in. for the two nuts, about in. for half the thickness of the two webs and about in. pro jection of rod beyond the nut.
The length of field bolts is always given from the underside of the head to the end of the bolts. The grip is the thickness of the metal between the underside of the head and the nut; that is, the thickness of the connection angles and the web. A projection of in. or 1 in. beyond nut should be allowed for.
Fig. 208 shows the setting plan of another floor, a part of which the student will be required to detail as problems.
Fig. 209 shows the detail of the beam girders, Nos. 2 and 3. As•the beams are spaced close together, connections can be used only on the outside of the webs. The same number of rivets in the out standing legs must, of course, be used, as would be required for a double-angle connection, and more rivets must be used through the web, as these are in single shear instead of bearing or double shear. In the case of the beams shown, seven rivets are all that are necessary, although the standard connection requires eight.