Basis of 

 design. 



Conclusions 

 from tests. 



" Steelcrete" can be laid more quickly and more satisfactorily than any other type or system of 

 reinforcement yet devised. 



(12) Last but not least is the long list of successful and notable sewers and like structures in 

 which this material has been used. These structures, because of their importance, have neces- 

 sarily commanded the highest talent in the engineering profession. The use of "Steelcrete" 

 mesh in this work is the highest endorsement this material could have. 



CONDITIONS IN PRACTICE. 



On account of the uncertain nature and material of the foundations of ordinary sewers and 

 the varying conditions of the point of application, as well as the direction and the amount of the 

 loads, the design of sewers is rarely susceptible to a rigid mathemetical investigation. Our table 

 of sizes and reinforcement, found elsewhere in this pamphlet, is not based on a mathematical 

 analysis, but on good modern practice. For a more complete discussion of the design of rein- 

 forced concrete sewers we would refer you to an article by Mr. Ernest McCullough in Engineer- 

 ing Record of Feb. 27, 1909, and Bulletin No. 22, University of Illinois April 29, 1908. 



The following article is reprinted by permission of Mr. Arthur N. Talbot from Bulletin No. 22, 

 University of Illinois, dated April 29, 1908 on reinforced concrete culvert pipe, etc. 



CONDITIONS OF BEDDING AND LOADING FOUND IN PRACTICE. 



"If the layer of earth immediately under the pipe is hard or uneven, or if the bedding of the 

 pipe at either side is soft material or not well tamped, the main bearing of the pipe may be 

 along an element at the bottom and the result is in effect concentrated loading. The result is to 

 greatly increase the bending moment developed and hence the tendency of the pipe to fail. This 

 condition may be aggravated in the case of a pipe with a stiff hub or bell where settlement may 

 bring an unusual proportion of the bearing at the bell and the distribution of the pressure be far 

 from the assumed condition. In bedding the pipe in hard ground it is much better to form the 

 trench so that the pipe will surely be free along the bottom element, even after settlement occurs, 

 so that the bearing pressure may tend to concentrate at points say under the one third points of 

 the horizontal diameter (or even the outer quarter points). This will reduce the bending 

 moments developed in the ring. 



76 



