314 FOUNDATIONS 



Where a test is made of the sustaining power of the soil, 

 the Commissioner of Buildings shall be notified so that he 

 may be present in person or by representative. The record 

 of the test shall be filed in the Department of Buildings. 



SPREAD FOOTINGS 



DESIGN AND CONSTRUCTION 



The term spread footings is applied to either wall or column 

 footings that have a considerable projection beyond the 

 upper tier of the footing, wall, or column base, as the case 

 may be. 



The usual type of spread footing for the support of a 

 column is illustrated in Fig. 1. This footing was designed 

 to be used with a structural-steel column core, and is one that 

 would ordinarily be used for a ten- or twelve-story building 

 that is to be erected on unstable soil. 



Placing Reinforcement in Column Footings. The rein- 

 forcing rods, or bars, are placed from 2 to 4 in. from the 

 bottom of the footing, and are arranged so as to cross each 

 other at right angles. No attempt is made to interlace the 

 bars or rods. It is good practice, however, to wire them, 

 together, for by so doing, any danger of misplacing the bars 

 is avoided. Several tiers of bars, or rods, are used in heavy 

 footings, although spread footings that support light loads 

 are sometimes reinforced with expanded metal or woven- 

 wire fabric. 



In designing column footings in reinforced concrete, so 

 steel reinforcement is often placed in the upper part of the 

 footing directly under the base of the column. This rein- 

 forcement acts as a mattress to distribute the concentra 

 load from the column and also as a bond to tie the concrete 

 together. 



Two other methods of arranging the reinforcing rods in 

 concrete column footings are shown in Fig. 2. In (a), the 

 rods and bars are crossed at right angles; every other bar is 

 made short so as to save metal. 





