68 CAMBKIA STEEL. 



FIREPROOF CONSTRUCTION. 



Buildings of fireproof construction consist essentially of a steel 

 frame or skeleton to support the floors, and in the case of high 

 buildings, the outside walls also are carried by the steel framing. 

 All parts of the steel work are enclosed and protected by some 

 fire-resisting material, which should be of such quality and 

 arrangement as not to disintegrate or fall away when heated to 

 high temperatures and at the same time exposed to a stream of cold 

 water. The fireproofing for the floors, in addition to its ability to 

 afford a fireproof protection to the steel beams, must be capable of 

 supporting the load and distributing it to the floor beams, which 

 in turn transmit it to the columns and thence to the foundations. 



One of the earlier forms of floors consists of brick arches built 

 between and supported by the bottom flanges and lower portions 

 of the web of iron or steel I-Beams, but this style has considerable 

 dead weight and, as ordinarily constructed, does not provide fire- 

 proof protection for the bottom flanges of the beams. Another of 

 the earlier forms of floor is composed of sheets of corrugated iron 

 arched between the beams, on which a concrete filling is placed, 

 and this also, as ordinarily constructed, does not provide protec- 

 tion for the bottom flanges of the beams, besides, it is quite heavy. 



A later style of floor is the hollow tile system, which is composed 

 of flat or segmental arches constructed of moulded blocks of hard 

 burned clay, specially shaped, and of various depths to suit 

 different loads and the sizes of the I-Beams supporting them. In 

 the hollow tile system, the blocks may also be of porous terra- 

 cotta which is lighter than hard clay. 



Various other systems of fireproofing are now in use, the most 

 usual forms of which consist of cement, concrete or other material 

 used alone or deposited or arranged about a strengthening or sup- 

 porting framework of steel shapes, bars, rods, wire, wire-cloth, etc. 



Column or girder fireproofing may be accomplished by the use of 

 hard clay or porous terra-cotta blocks shaped to fit and enclose the 

 steel work, or the steel may be wrapped with wire, wire-cloth, 

 metal lath, etc., and a concrete or plastered coating applied to it. 



Fireproof partitions may be constructed of hollow tile composed 

 of hard clay or porous terra-cotta to which the plaster finish may 

 be directly applied, or they may be composed of suitable metal 

 studding on which is secured the wire-cloth or metal lath that 

 serves to support the concrete or other fireproofing, the surface 

 then being plastered in the usual manner. 



The dead weights of fireproof floors vary between wide limits 

 dependent upon the system employed, the load to be carried and 

 the distance between the supporting beams. 



