ON THE DESIGN OF GIEDER BRIDGES. 481 



Span in feet . . 8 10 15 20 30 40 50 60 80 100 

 Load in tons 



per foot run . 472 410 3-27 2-85 243 2-23 2-10 2-02 1-91 1-85 



Schedule B. 



Equivalent uniformly distributed load for designing bridges of uniform 

 section and depth, based upon the formulae 



For spans under 12 feet w=~ 



o 



25 

 For spans of 12 feet and upwards iv = 160 + ^ — - 



o + 5 



in which w=load in tons per lineal foot for one track estimated to 

 produce a maximum moment of flexure equal to or greater than that 

 produced by any arrangement of the heaviest engines and boiler tracks. 



Span in feet 8 10 15 20 25 30 40 50 60 



Load in tons per foot run . 4-50 3-60 285 260 243 ii-31 2-16 205 1-99 



Schedule C. 



Table of the greatest ' panel ' or cross-girder loads derived from the 



formula 



25 

 For panels over 6 feet in length ^"=1*60 P + 



2 + 1 



in which W=panel load in tons for one track, and P=length of panel 

 in feet. 



Length of panel in feet . to 5 6 8 10 12 20 25 



Load in tons .... 18-0 18-4 22-3 26-0 296 43-1 51-4 



The above represent the maximum load on a single panel, but the 

 greatest mean load on N consecutive panels might be taken as 



25 



W=l-60 P + 



N + l + l 



Schedule D. 



Admissible stress in wrought iron and steel under varying circum- 

 stances. 



1. In cases where the material is subject to stress of one character only, 

 (a) Limiting working stress under any conditions 



t 



in which a is the greatest stress to which the material may be subject 

 under any conditions of loading ; t is the ultimate tensile strength of the 

 material determined by experiment ; C, product of all the tabular coefficients 

 of safety (Table, p. 483) applicable to the particular case ; N, a coefficient 

 intended to ensure that the greatest actual stress, in the extreme case of 

 the coincidence of all the conditions detrimental to the resistance of the 

 material represented by the tabular coefficients, shall not reach the limit of 

 elasticity. 



1886. I I 



