STRENGTH AND ELASTICITY OF REINFORCED CONCRETE. 161 



(1) may be simplified thus : — 



Using the same data as before and applying the results 

 in a similar manner we obtain : — 

 x = 0*4 

 c = 2835 lbs. per square inch. 



Professor Hatt, however, uses data which differs con- 

 siderably from that obtained by the writer, and if these 

 had been inserted in his equations the results would not be 

 the same. For instance, he gives -— - == 7*5 instead of 12. 



Professor Hatt has given equations for the determination 

 of x, M and c for loads less than those which produce a 

 crack on the tension side, and points out very clearly the 

 necessity of using the correct values of the coefficients of 

 elasticity for the particular stresses developed in tension 

 and compression in a reinforced beam. The real difficulty 

 in obtaining correct results for steel-concrete work consists 

 in knowing accurately the strength and coefficients of 

 elasticity of the various materials employed under the 

 conditions existing. 



SHEARING STRESSES IN STEEL-CONCRETE BEAMS AND THE 

 METHODS EMPLOYED TO RESIST THEM. 



When a steel-concrete beam reinforced in a horizontal 

 plane only is subjected to a uniformly distributed load, it 

 tends to fail near the ends by cracking on the tension side 

 in a direction inclined towards the centre of the beam, 

 following the full lines in Fig. 13. The inclination of the 

 cracks is 45°. To prevent this cracking, the beam should 

 be reinforced in a vertical plane by means of bars arranged 

 vertically or inclined at 45° sloping away from the centre 

 of the beam. 



E— Sept. 7,1904. 



