Fig. 189.

It is very important to show on all shop drawings the diameter of rivets to be used in the work, and if different sizes of rivets or rivet noles for field rivets occur in the same member, then these must be indicated on the drawing by a note prominently displayed so that the shop men may readily find it and avoid error. The sizes of rivets generally used for structural steel and bridge work are 5/8 in., 3/4 in., or 7/8- in. in diameter, although special work may require smaller sizes, and occasionally rivets 1 in. in diameter are used for very heavy work.

RETAIL STORE OF MARSHALL FIELD & CO., CHICAGO, ILL.

The Largest Retail Store in the World.

WHOLESALE WAREHOUSE OF MARSHALL FIELD & CO., CHICAGO, ILL. A Modern Warehouse Building.

Rivets are made with one head formed, and the shank of the rivet must be long enough to project through the parts to be joined, and far enough out on the other side to form a full perfect head when subjected to the pressure of the machine. After the rivet has been heated to a cherry red it is inserted in the rivet hole and the riveter is placed so that the cap fits over the head already formed, and the other jaw of the machine presses against the protruding shank of the rivet and forms the head. It is desirable that riveting machines be made to hold on to the two ends of the rivet with the full pressure until the rivet partially cools.

The terms "rivet pitch" and "rivet spacing" refer to the distances center to center between rivets. For example, if the rivets are spaced 3 in. apart for a certain distance along a member of a structure, we refer to the rivets for this portion of the member as being of three-inch pitch. Fig. 190 gives the lengths of rivets required for a given "grip".

## Problems

1. Given an 18-in., 55-lb. I-beam with a 4 X 4 X 1/2-in. shelf angle riveted on one side; what length of 3/4-in. rivet should be ordered for riveting this angle on in the field?

2. In Fig. 187 of Part II, is shown a 12-in. beam girder bolted to a cap angle on a column; what length of bolts should be ordered for this connection?

3. If the beams shown in Fig. 187 are 6 1/2 in. center to center, and are bolted up, using standard cast iron separators, what lengths should be ordered for these separator bolts?

4. Suppose a 12-in., 40-lb. beam and a 7-in., 15-lb. beam are framed opposite each other on a 15-in., 60-lb. girder; if standard connection angles are used, what length of 7/8-in. field rivets should be ordered for the connection of the beams to the girder?

 Length of field rivets for holes punched or drilled 1/16" larger than diameter of rivets dia. rivet 7/8 3/4 5/8 1/2 Length of Countersunk Rivets Grip length length length length 3/8 1 7/8 1 3/4 1 5/8 1 1/2 1/2 2 1 7/8 1 3/4 1 5/8 5/8 2 1/8 2 1 7/8 1 3/4 3/4 2 1/4 2 1/8 2 1 7/8 1/8 2 3/8 2 1/4 2 1/8 2 1 2 1/2 2 3/8 2 1/4 2 1/8 1 1/8 2 5/8 2 1/2 2 3/8 2 1/4 1 1/4 2 3/4 2 5/8 2 1/2 2 3/8 1 3/8 2 7/8 2 3/4 2 5/8 2 1/2 1 1/2 3 1/8 3 2 7/8 2 5/8 1 5/8 3 1/4 3 1/8 3 2 7/8 1 3/4 3 3/8 3 1/4 3 1/8 3 1 7/8 3 1/2 3 3/8 3 1/4 3 1/8 2 3 5/8 3 1/2 3 3/8 3 1/4 2 1/8 3 3/4 3 5/8 3 1/2 3 3/8 2 1/4 3 7/8 3 3/4 3 5/8 3 1/2 2 3/8 4 3 7/8 3 3/4 3 5/8 2 1/2 4 1/8 4 3 7/8 3 3/4 d 2 5/8 4 1/4 4 1/8 4 3 1/2 2 3/4 4 3 7/8 3 3/4 3 5/8 2 7/8 4 1/2 4 3/8 4 1/4 4 1/8 c 5 2 1/2" 2 1/4" 2 1 3/4 3 4 3/4 4 3/8 4 1/4 4 1/8 3 1/8 4 7/8 4 3/4 4 5/8 4 1/2 3 1/4 3 4 7/8 4 3/4 4 5/8 3 3/8 5 1/8 5 4 7/8 4 3/4 3 1/2 5 1/4 5 1/8 5 4 7/8 b 5 2 1/2 2 1/4 2 1 3/4 3 5/8 5 3/8 5 1/4 5 1/8 5 3 3/4 5 1/2 5 3/8 5 1/4 5 1/8 3 7/8 5 5/8 5 1/2 5 3/8 5 1/4 4 5 3/4 5 5/8 5 1/2 5 3/8 L 1 1/8 1 7/8 3/4 111/16 4 1/8 5 7/8 5 5/8 5 1/2 5 3/8 a 4 1/4 6 5 7/8 5 3/4 5 5/8 4 3/8 6 1/4 6 5 7/8 5 3/4 _ 4 1/2 6 1/2 6 1/4 6 minimum dia rivet 1 7/8 3/4 5/8 1/2 4 5/8 6 5/8 6 3/8 4 3/4 6 3/4 6 1/2 4 7/8 6 7/8 6 5/8 5 7 6 3/4 "a must not be less than 1/4 in.+1/2 h.

Fig. 190.

5. If it is necessary to drive two rivets of 5/8 in. diameter exactly opposite in the two legs of an angle 3 X 3 1/2 X 7/16 in.; how close to the back of the angle can the rivets be spaced?

Strength of Joints. The student should now become familiar with the method of calculating the strength of joints and connections. We will take first the connection of one beam framed to another. The rivets in the connection, of course, are the only means of transmitting the load from the beam to the girder. There are two sets of these rivets, one set through angles on the end of the beam to be carried and the other set through the outstanding legs of these angles and through the web of the girder. The load must go from the beam through the first set of rivets into the connection angles, and then from the angles through the second set of rivets into the girder.

The rivets through the angles securing them to the web of the beam are subject to failure in two ways. (1) The rivet might break along the two planes coincident with the faces of the web of the beam, thus allowing the beam to drop between the two angles - this method of failure is called "shearing" of the rivets. (2) The rivets might crush the metal of the web of the beam on the upper semi-circumference of the rivets; this is called failure by "bearing."

In designing a connection, the number of rivets is determined by whichever provision against these two methods of failure gives the greatest required number. The strength of a rivet as regards shearing and bearing is called its value, and in order to determine the number of rivets to carry a given load in connections of this character, it is only necessary to determine the value to be used for one rivet. This value is determined in the following way: