As the flange plates on this section are not as thick as those on the lower section, it is necessary to ship filler plates bolted to the column.
There are two beams framed to each flange of this column so that the shear angles are spread to come as nearly as practicable under the web of the beams. These angles cannot always be made to come directly under the web on account of the relation between the spacing of beams and the spacing of rivets through flanges of channels of columns. Some variation in size of angles can be made, however, at times to effect this result.
Where box columns are used, it is better to keep the spacing back to back of channel the same throughout all sections. If this is less in the upper sections, it brings the load of this section on to the horizontal splice plate between the sections. The distance between the cap and shelf angles is generally a in. more than the depth of the beam, to allow for clearance. The rivets between the cap and shelf angles are flattened here, as with one beam in position there would not be space to lower the other beam between the rivet heads.
Fig. 215 gives the bill of material for these box columns. Fig. 216 shows the framing of the beams coming on columns No. 1 and No. 2. detailed in Fig. 217. This column has a heavy steel base riveted to it. The load on the section is 265,000 pounds and it will be seen therefore that the rivets in the shear plates are amply suffi cient for the portion of the load coming upon them. The plate W riveted to the web increases the bearing area of the foot of the column and adds somewhat to the efficiency of the base.
In this connection and in such cases where shear angles are used over a shelf angle involving the use of a filler, below the shelf angle and back of the shear angles, as shown by the details of this column, the student should note the difference between a tight and a loose filler.
Fillers G and R are loose fillers. They have no rivets holding them individually to the main members. The stress in the rivets through such a filler does not go into the filler, as there are no extra rivets to take it out again from the filler to the main members. Such
rivets, therefore, are subject to bending if calculated for their full value. They should not be considered for more than one-half the value of rivets directly connecting the main members. Filler W is a tight filler as regards the two rivets through the angles X on the axis of the column. A tight filler has provision by additional rivets for taking the same amount of stress from itself to the main member as it receives.
The open boles shown in the base plate are for anchoring to the footing—such heavy columns are not usually anchored except in special eases; it is well, however, to provide for this if there is any possibility of its being required.
In the connection for floor beams it will be noted that a 10-in. beam comes in on one side of the web and a 12-in. beam on the other side. Such cases often result in special cap angle details in order to provide for riveting without interference on either side. In this case it is impossible to get the upper holes in cap H more than in. from the upper edge of cap M unless these holes are brought nearer the upper edge of H than 1 in., which it is undesirable to do. It is necessary, therefore, to add an extra filler B B to fill out flush with the angle N so as to be able to rivet. The student should follow the detail through and see just why this condition results from the meas urements given.
The four rivets in angles L are countersunk on the side so as to avoid a filler and riveting through angle N.
The 10-in. beam connecting on the flange of the column at one side of the axis, requires a connection similar to that shown. If the load com ing off the axis was very heavy, a deeper shear plate would be used back of the shelf angle, and it would be better to run this shear plate across both angles of the flange, both to provide for the bending on the rivets and also to distri bute the load more uniformly with respect to the axis of the column.
There are no standard details for eccentric and special framings. The draftsman must use his judgment and endeavor to get as simple and effective connections as possible.