CORRUGATED BAR COMPANY, INC. 



steel and concrete. The safe load tables, pages 61 to 106 inclusive, have been prepared 

 on the basis of two different stress combinations and for moments of -^, t7> and 



Y2"* The governing conditions are stated in the heading of each table. 



It is important to note that in the case of ribbed slabs or of T-beams continuous 

 over supports, that the critical compressive stress usually occurs at the supports 

 where the flange is in tension and the stem of the beam is in compression, thereby 

 resolving the problem into that of a beam of rectangular section. However, as only a 

 short section of the beam is under maximum compression at this point it is considered 

 entirely permissible to employ a higher unit stress in the concrete here than at the 

 center of span. This feature has been carefully considered in preparing the tables for 

 continuous or semi-continuous ribbed slabs and T-beams and the maximum fibre 

 stress in the concrete at supports has been held to a value not exceeding 15% greater 

 than the fibre stress noted in the table. This is in accordance with the recommendations 

 of the Joint Committee on Concrete and Reinforced Concrete. 



In the case of T-beams continuous over supports the straight bars in the bottom 

 of the beam are considered to act as compressive reinforcement and should be carried 

 past the face of the support a sufficient distance to develop their stress in bond. 



Shear. After selecting from the tables the proper slab or beam to be used for 

 any particular load, special attention should be given to the shear reinforcement 

 required. For the solid concrete slabs the loads given produce shears of less than 

 forty pounds per square inch on the area bjd. For the concrete ribbed slabs loads 

 to the left of the heavy stepped line produce shears in excess of ninety pounds per 

 square inch on bjd and vertical stirrups should be used in addition to the bent up 

 bars in the ribs. 



In the case of the beam tables, to satisfy the majority of code requirements, stirrups 

 will have to be provided. Particular attention is called to the fact that all loads to 

 the left of the heavy stepped line produce shears in excess of 120 pounds per square 

 inch on bjd. 



Fireproofing. In preparing the tables the depth of fireproofing under the rein- 

 forcement was taken at ^ in. for solid and ribbed slabs and 13^ in. for beams. As the 

 fireproofing determines the effective depth for any given slab or beam it will be nec- 

 essary to increase or reduce the table load should a change be made in the amount of 

 fireproofing. This may be effected by multiplying the sum of the superimposed and 

 dead loads of the table by the square of the ratio of the new effective depth to the 

 given effective depth. This gives the new total load from which should be deducted 

 the dead load in order to obtain the new superimposed load. 



The following examples illustrate the use of the tables: 



Solid Concrete Slabs. Given a floor layout consisting of solid concrete slabs, 

 continuous over beams spaced 12'-0" in the clear. The floor to carry a live load of 150 

 pounds per square foot, a wood finish on sleepers embedded in 2 inches of cinder 

 concrete and a plastered ceiling; the finish and plaster weighing together 25 pounds 

 per square foot, giving a total superimposed load of 175 pounds per square foot. The 

 stress in the steel not to exceed 16,000 pounds per square inch and in the concrete 

 650 pounds per square inch. 



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