MAXIMUM STRESSES IN BRIDGE MEMBERS. 
L. M. HOSKINS, 
Professor of Applied Mechanics, Leland Stanford Junior University. 
INTRODUCTION. 
1. Object of Discussion .— It is proposed to consider in as gen¬ 
eral a manner as possible, the problem of determining what posi¬ 
tion of a given series of moving loads will produce the greatest 
stress in any member of a bridge truss. The truss is assumed 
to be simply supported at the ends, and may be of any form sub¬ 
ject only to the restriction that it shall be possible to take any 
‘member as one of three through which a section may be passed 
dividing the truss into two parts. 
For such a truss it is found that a general rule can be stated, 
applicable to any member of the truss, which gives the position 
of the moving loads causing maximum stress. Moreover, the 
rule deduced is quite simple and easy of application in all 
special cases. 
Various particular cases of the rule have been deduced and 
discussed by several writers. I am not aware, however, that 
the principle in its general form has been before stated, nor that 
the problem has been discussed by the method employed in this 
paper. 
Before proceeding to the demonstration, the statement of the 
principle will be given. 
2. Statement of General Principle .— Let A and B be the projec¬ 
tions on a horizontal line of the points of support of the truss. 
Let the truss be divided into two parts by a section cutting 
three members, one of which necessarily belongs to that chord 
at which the moving loads are supported; let C D be the pro¬ 
jection of this member upon A B. 
Choosing one of the three members cut as that whose stress 
is to be discussed, let F' be the point of intersection of the 
