34 BULLETIN" 801^ U. S. DEPARTME]SrT OF AGEICULTUEE. 



The ordinary beam system of reinforced concrete design is illus- 

 trated b}^ tile x^hotograph, Plate XVI, which shows the interior of 

 a compartment similar to those of the warehouse design in figure 2. 

 In this last design the distance between the line of columns and the 

 division wall is 25 feet, the compartment being 50 feet wide. The 

 story height is 8J feet, which permits the storage of cotton to a height 

 of only one bale on end, and consequently a limitation in load of 

 from 50 to 75 pounds per square foot. This extremely light floor load 

 in combination with the rather long span of 25 feet between the 

 column and wall are distinctly favorable to the beam system of con- 

 struction.^ 



The combination of clay tile with reinforced concrete has not 

 the advantages for warehouse construction that it has in ordinary 

 domestic building. Its onlj^ advantage for the warehouse is that of 

 reducing the amount of concrete and steel required for a given 

 strength of floor or roof. In the case of the most economical design 

 for the warehouse floor there is no advantage in the use of tile.^ 



FAILURE OF POORLY CONSTRUCTED FLOORS AND ROOFS FROM 



FIRE. 



It is interesting to note the degree of success with which the 

 tyjjes of construction here described have withstood the tests of 

 fire. A view of a building which successfully withstood one of the 



^ 111 this instance tlie columns are located under alternate beams, while the 

 intervening beam is carried by a cross beam, or girder. The beams are spaced 

 8 feet apart, which is a very effective spacing with this light load, considering 

 the proportions necessary for both the beam and slab. The best fire resistance 

 for beams is secured when the beam is no thinner than necessary, a good pro- 

 I»ortion being secured when the breadth, or thickness, of the beam is not 

 more than half the drop, or distance from the bottom of the slab to tlie bottom 

 of the b<?am ; but in no case should the thickness of the beam be less than 6 

 inches, while 8 inches is to be preferred as a minimum thickness. 



^ For the roof slab, economy may sometimes be effected by the use of the 

 tile, depending entirely on the local cost of materials. When it is used the 

 blocks should be arranged end to end in a single row and with a space be- 

 tween rows of not less than 6 inches for the concrete joists, which are cast 

 between. The whole top surface should be troweled over with cement mortar 

 after casting to receive the roofing material. Even with the best of work- 

 manship this construction is not as good as solid concrete, and the chances 

 of poor workmanship are much greater than with the latter. Only a sub- 

 stantial saving in cost would justify a departure from the solid concrete for 

 this particular character of building. The semi-porous clay tile is best for 

 this use. 



For all of these designs, columns should receive very careful attention. 

 '3'hey may be round, octagonal, or square. The round is the best shape, but 

 usually requires the use of metal forms. The octagonal shape is practically as 

 good and is readily secured by use of wooden forms, The square column, 



