MILL CONSTRUCTION BUILDINGS _ 



incorporated in the Revised Building Ordinances of the City 

 of Chicago. 



U. S. Department of Agriculture, Division of Forestry 

 Formula. 



(Bulletin No. 12) 



c(700+15a) 5) 



(700+15a+a 2 ) ' 



Winslow Formula. 



Unit Stress on Column Cross-Sec- 

 tion in Pounds per Square Inch 



L 

 - 



80d 



(16) 



Loads on The amount of load carried by a given column on 

 Columns a top floor is found by adding together the end 

 reactions brought to the bolster or cap by the 

 girders or beams which support the roof and rest on the cap. 

 In the case of uniformly distributed loads, these reactions are 

 each one-half of the load carried by that particular beam or 

 girder. If the loading is not symmetrical on a beam or girder, 

 the end reactions may be found by the principle of moments. 



Columns on lower floors carry a central load from the line 

 of columns above, in addition to the loads from beams and 

 girders supported by the cap of the column in question. 



While it is not probable that all of the floors of a building 

 will be loaded to the capacity of the allowable live load at any 

 time, recommendations in regard to the percentage of this 

 maximum load to use vary in the building codes of different 

 cities. 



A common recommendation in the case of buildings ex- 

 ceeding five stories in height is to use the full live load on the 

 roof and top floor ; for each succeeding lower floor the live load 

 is reduced by 5 per cent until 50 per cent of the live load is 

 reached, then these reduced loads are used for all remaining 

 floors. 



Another recommendation of a more conservative nature is 

 to allow no reduction of live load in buildings where the as- 

 sumed floor load is more than 120 pounds per square foot and 

 is likely to be permanent, as in warehouses, shops, etc. 



Eccentric loads on columns should be avoided if possible. 

 If present, they should be treated by the use of formulas gov- 

 erning such loading. 



Page sixty-five 



