Prof. Talbot made 32 tests. 



Prof. Talbot's Tests on Resistance of Bars. 



Prof. W. II. Warren, Sidney University. See table page 31. 



It seems well to use bars slightly rusted. 

 COLUMNS. 



Concrete columns unreinforced or reinforced with* longi- 

 tudinal rods only will break suddenly with very slight de- 

 formation. Failures occur in hooped columns when the 

 deformation amounts to a value as high as 3% of the 

 original length. A plain column does not give a warning 

 of its failure; a reinforced one does by beginning to flake. 

 The resistance of hooped concrete can be considered con- 

 stant after it has reached a maximum. The elastic limit 

 Is raised when a load is placed on a hooped column. 

 Hoops, according to Considere, begin to act when the 

 longitudinal bars have passed their elastic limit and al- 

 most reached their ultimate strength. 



Concrete elongates under water and contracts in air, 

 according to the following deductions of Considere. (For 

 detailed description, see Marsh.) Tables on page 32. 



The deformation is less for reinforced than for plain 

 prisms. The metal contracted when in air and the con- 

 czete Just the reverse. 



SLABS. 



Slabs fail generally by the cracking of the concrete on 

 the tension side and slipping of reinforcement through the 

 concrete caused by the rods stretching locally. With ex- 

 panded metal both fail at the snme time. The compres- 

 sion side begins to flake at failure, 



