13 



hoops of flat steel with bolts to draw up tight. 



Every column boxl must have a hand hole left in 

 the bottom, at least 6 in. high, by which to remove 

 shavings or other refuse which might work its way 

 down into the form. This is imperative. 



There are three general types of form construction 

 for reinforced concrete floors. They may be called 

 the Core-Box type, the Panel type and the Loose Piece 

 type. They will be taken up in order. 



By the Core-box type is meant the construction in 

 a rigid unit, of the floor sheeting and supporting joists 

 for one panel of a floor together with the sides of the 

 beam and girder boxes confining that panel. It is, 

 when in place, like a shallow box inverted. It is prac- 

 ticable to employ only when there are several typical 

 floors in the building under construction, so that the 

 whole unit for one floor panel may be lowered from 

 underneath the floor where last used, and then raised 

 to some other floor by a derrick, and set in place to 

 be used over again. To use this type of construction 

 makes necessary a very decided chamfer in the sides 

 of the beams or girders. Otherwise the panel could 

 not be removed without great difficulty and probable 

 damage to the lumber owing to -the well known wedg- 

 ing action of the concrete. The beam and girder bot- 

 toms are loose, and in this instance could be placed 

 either before or after the core forms are in place and 

 lined up. Aside from the suggestion that the joists 

 ought to run the short way of the panel, that is, be- 

 tween the beams, and the sheeting the long* way (to 

 save cutting as much as possible), the economical con- 

 struction of one of these units ought to present no 

 great problem. The sheeting and beam sides could 

 well be made of y%-\r\. matched stuff, and the joists 

 as hereafter mentioned. 



The Panel and Loose Piece types of floor form work 

 differ only in that the former contemplates the build- 

 ing of the floor sheeting into a rigid panel, sometimes 



