full of holes. Such iron should be struck with a heavy hammer or a crowbar enough strong blows to establish beyond question the condition of the thinner metal under the coat of paint. Examine the web also for holes filled in with paint; if there are enough of these holes to materially reduce. the cross-section and weaken the girder the same should be rejected.

3. Separators. Double wall beams should be provided with separators not further apart than five feet. (Section 117, Building Code.) Beams 12 inches and over must have two bolts in each separator. This may be taken to mean that cast iron or steel plate separators must be used for beams 12 inches and over, or else two bolts could not be provided in each separator. Separators are used either for keeping the beams in proper positions at definite distances apart, or for the purpose of equalizing the loads carried by each beam when the load is applied eccentrically. Separators also increase the stability of each beam, lessening the tendency to overturning; they also stiffen the webs and prevent crippling in the web.

I

Fig. 12-Grillage.

Fig. 12 shows a column footing with standard one-inch gas pipe separators in the two lower sets of beams. The 12-inch beams have two pipe separators, one over the other, as required. All these pipe separators keep the grillage

beams in the proper relative position until the grillage is filled in and covered up with concrete.

The most reliable kind of separator is the one built of steel plate and knee angles, as shown under the column. The angles are riveted in the shop to the steel piate, then the other leg of each angle is riveted to one beam when the beams are not too heavy to handle together, otherwise the separator is shipped loose and bolted in the field.

Fig. 13-Gas Pipe and Cast Iron Separators.

Fig. 13 shows the common gas pipe separator used in double wall beams to increase the stability of the iron beams and to prevent them from spreading apart.

Fig. 13 also shows the common or standard type of cast iron separator. Either this separator or a plate and angles separator should be used when the load is applied eccentrically, as in the diagram. The outside beam carries part of the wall load only, while the inside beam carries both wall and floor load. The two wall beams will not act together like one girder unless proper separators are used to tie the beams to one another. Pipe separators should not be used in such cases. The standard cast iron separator must be milled around the edges to fill in closely against the webs and flanges of the beams.

Fig. 14a shows a separator made of 3-inch plate and a steel flat bent to suit and properly bolted.

Fig. 14b shows channel separators.

Fig. 14c shows separators made of 3/4-inch rods with double nuts at each end.

4. Common Defects in Separators:

Separators not provided within 5' 0" center to center

distance.

Using only one bolt in a 12-inch beam separator, instead of two, as required.

Omitting separators.

Using 3/4-inch bolts without pipes.

Using pipes that are too short in length.

Using pipes with rough edges instead of sawing same off to a smooth edge.

Using deceitful short bolts instead of through bolts. Fig. 14d.

Using bolts too short or too long. Fig. 14e.

Using bolts less than 34-inch diameter in 13/16-inch

holes.

Using hook bolts instead of standard head bolts. Fig. 14f. 5. Results of Defective Separators:

In one instance separators have been omitted in 12-inch front wall channels. The channels were about 30 feet long and had shop punched holes for separators. Fig. 14g. Brick work and terra cotta were set for a height of two stories before providing separators. The channels began to spread, as shown dotted. Attempts were made to drive a 1⁄2-inch hook bolt in the inside and to catch the outside channel through a 13/16-inch separator bolt. Two stories of brick work had to be removed, also the terra cotta, and straight separators with sawed off pipes had to be provided. Hook bolts cannot be made sufficiently tight, and they should never be used.

Short bolts may cause leaving out the nut in the threaded ends. Long bolts may not be made tight, due to lack of

thread length. Iron washers may be used with the long bolts, but short bolts should not be allowed. In one case the excess length of some long bolts has been packed up with wooden washers. This is bad construction, as the wood may rot, thus leaving the double beams with loose separators.

6. Strapping of Iron Work. The steel beams supporting the walls of a building should be strapped or tied to the inner parts of the building so as to secure absolute stability. This is usually done by providing steel straps as shown in Fig. 15, under each brick pier between windows, and in all cases not less than three straps for a front of about 25 to 30 feet. Each strap is made of a steel flat 12x3% inches and long enough to catch over four joists and to be bent up will be necessary at the anchored end.

a

b

Fig. 15-Wall Beams and Ties.

Each strap is nailed to each joist at crossing points to prevent the strap from falling down, holes having been provided in the straps for this purpose. Packing should be provided at P, if necessary, to fill in the space between the strap and the last joist. The strap may be made to catch the outside beam or it may be passed in between the beams as shown in the figure. The last method avoids disturbances in the arrangement of the face brick. When the beams are too close together a notch may be made in the flange of one of the beams to make room for the strap.

When the top of the wooden beams is lower than the bottom of the steel beams, the straps may be placed under the steel beams and over the wooden beams with equally good results. Whenever possible the straps should be placed so as to avoid breaking through plastered ceilings which would have been left undisturbed otherwise.

The front beams may also be tied in by means of an angle or channel bolted to such front beams (Fig. 15b) and made to run alongside the floor construction to some interior wall or pier and anchored into same. This arrangement is conveniently used when the wooden floor joists run fore and aft or at right angles to the steel beams supporting the wall.

If the tie beam does not carry any load no template will be necessary at the anchored end.

Another arrangement is given in Fig. 16. It shows. through bolt strapping of a double-beam steel box girder to 8x10 inch wood beams running fore and aft. There are two strap angles, each with two bolts through the timber and one through the girder.

7. Usual Defects in Strapping:

Omitting straps.

Using straps less than 12x3% inch cross-section.

Using short straps which do not catch on four beams. The inner end of each strap is not bent vertically beyond the fourth beam.

Straps are loose and do not fit, no packing being provided. In this case either pack the inner end of the strap with wooden pieces or pack the outer end with iron wedges, or even a piece of a round iron bar or a piece of an angle