2. In the above problem, if the 7-in. beams frame at the other end to a 12-in., 311-lb. beam along a wall, both being flush on top. and it is 11 ft. center to center of girders, make shop details covering both 7-in. beams.
3. Given a 15-in., 33-lb. channel framed to a column at each end, the distance being 16 ft. 5} in. between faces, and the channel having a 31 X 21 X Fin. angle on the back side, with the long leg vertical and 1 in. from the bottom. A 10-in., 25-lb. beam frames flush with bottom of the channel 5 ft. 4} in. from face of each column. Make detail of above.
This column has a bracket for a crane track girder with a dia phragm bracing the crane girder to the column. The roof column, as shown by Fig. 186, is a plate and angle column and sets down between the channels, as the web runs at right angles to the web of the channels. It is always better to avoid re-entrant angles in a plate if possible. In a case like this where a bracket plate comes into the lines of the column at the top and there is a plate the width of the flanges above this point, it is better to make this a separate plate. If this plate is necessary for the effective area of the column the joint can be faced. The bracket and shelf angles on the plate are for a beam framed between columns.
The student should be able to follow this detail and understand all the points without further explanation.
Fig. 224 shows another type of column made of a web plate and four angles with channels across the flange the flanges being turned in.
There are various reasons for turning the channels with flanges in; here it is desirable to have a 10-in. arch for stiffness, and the thick ness of the wall in which this column comes makes it necessary to turn the flanges in; this also allows the column to set flush with the inside face of the wall and gives a smooth surface. Then again,
this gives good connection for the cranes girder bracket and for the wind strut below, at N and 0.
The top of this column receives a heavy floor girder and another column; the latter column is made of a smaller web so as to provide a seat over the main column members for the girder. Fig. 225 gives a detail of the wind strut which frames between the columns.
In columns of the type shown in Fig. 224, the dimensions must be such as to give room between the flanges of channels, and between the flanges and web, to rivet up the different members.
For light building construction columns are sometimes made of hollow iron pipe fitted with a cast iron cap and base. The dimen sions, weights, etc., of standard steam, gas, and water pipe, as manu factured by the American Tube and Iron Co., will be found on page 344, Cambria Handbook. Fig. 234 gives a diagram giving the "strength of wrought iron pipe in compression" according to the formula in which L = length of column in feet r = least radius of gyration.
For example, suppose we wish to select a size of pipe suitable for supporting a load of 25,000 pounds, and having a length (or height) of fifteen feet. Along the left hand side of the diagram, under "thousands of pounds" find 25 (i.e. 25 thousands), and then find the length ( = 15 feet) along bottom line of the diagram. Fol low the vertical line at 15 feet until it intersects the horizontal line through 25 thousands, and the nearest inclined line above that point will give the diameter of the pipe to be used. In this case a 5-in. diameter will be 'required.
1. Fig. 220 shows a framing plan on which is all the informa tion necessary to detail the different members. Make a detail of column No. 4, assuming that the bottom of the column rests on a cast iron web base 12 ft. below the top of the 15-in. beam No. 9, and that the column is arranged to receive another column of the same size, the joint being 1 ft. 6 in. above the top of the 15-in. beam.