38 



(13) Whenever designing a beam and using a T sec- 

 tion do not deviate more than 1-6 the clear span on either 

 side of the slab for your compression, and then the floor 

 steel should be transverse to the beam. Do not exceed 

 one-half the distance between beams. 



(14) Do not specify high carbon steel. It is likely to 

 crack in bending, or being heated have a section of weak- 



(15) That we may consider 60 ib. per sq. in. a safe 

 value to use for shear of concrete. 



(16) That the concrete takes a value of shear equal to 

 the breadth of beam times the effective depth of the 

 beam. 



(17) That longitudinal shear between steel and con- 



V 



crete Is expressed by / 7- 



moq 



V= total vertical shear at the section given. 



M no. of bars, 

 o periphery of bar.. 

 q' effective depth. 

 /' bond developed per unit area of surface of bar. 



When the bars are bent up the value of Q' varies. 



For detailed discussion see Buel & Hill, page 74. 



(18) The distance from center of rods to edge of beam 

 should not be less than 2 diameters of the rod. 



(19 The maximum diagonal tensile unit stress is 



/ /**-{- /JL S 2JL. V 2 (See Merriman 1905). 



s = horizontal tensile stress In concrete. 

 v horizontal or vertical shearing unit stress. 

 The direction of the maximum diagonal tension is 



IJ 



represented by one-half the angle whose cotangent Is 



If there Is no tension In the concrete t r. 



(20) According to M. Considere the percentage of 

 Bteel to use for static loads is 2.5; for moving loads, 1.2. 



(20) That the advantages of reinforcing arches are the 

 following, as given in Buel & Hill's Reinforced Concrete: 



"Almost at the beginning of his work in reinforced con- 

 crete, Mr. Thacher perceived that the shearing stresses 

 In an arch were practically negligible, and that, there- 

 fore, the web of the Melan ribs could safely be omitted 

 with a considerable saving in metal. He secured a patent 



