KEINFORCED CONCRETE. 



53 



The arrangement of the fourteen instruments used in 

 the determination of the various deformations is shown in 

 Fig. 1, but the number denoting each instrument was used 

 for convenience in tabulating the results from which the 

 diagrams Figs. 3 to 6 have been plotted, and has no refer- 

 ence to the numbers on these diagrams. Fig. 2 is a photo- 

 graph of the beam removed from the testing machine in 

 order to show more clearly the instruments attached to it. 

 In order to derive the stresses from the strains producing 

 them, recorded in the manner above described, experiments 

 were made, on plain concrete prisms, of the same age and 

 composition as the beams under consideration, subjected 

 to compression, and on briquettes of the same material 

 subjected to tension ; the results obtained have been 

 plotted in Fig. 3, and from these curves the stress can be 

 determined for each inch in the depth of the beam when 

 the corresponding strain is known. 



Fig. 3 — Stress-Strain Curves from Tensile Test of Concrete Briquettes 

 and from Compressive Stress of Concrete Prisms (no reinforcement.) 



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 Extension per inch in units of -00001 inch. 



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