I. IX, 



Table*. The important 

 Figs. 7, 8, and are mimmariaed in Fig. II. If a uniform 

 1m load is used, the shaded areas in Fig. 1 la, b and e mul- 

 tiplied i,y the intensity of the uniform land will gjv. 

 maxiinuin live-load stresses. The algebraic value of any one 

 of the>e triangular areas b conveniently exprewed a* thr 

 base of th.- tnangli- times ' _, ,f the given algebraic ordi- 

 nate. The lengths of the bases of the shaded area* in Flp. 

 llu and b may be readily determined by one of thr con- 

 ^ructions shown in Fig*. 12a and 121), which ghre thr j-- 

 MtiMh of the unit l.>ad t"..r /ero stress in the mffTflm* indi- 

 cated. The proofs that these constructions locate nrutral 

 point- are not ui\.-n. for they are generally known, and 

 (I in numerous texts on bridges. (See Marburg'* 



- andC.ir.le. \ I ,igr 392.) 

 The application ,,f the preceding formulas will now be 

 made to the calculation of the live-load treases in thr two 

 HhLil'- track through Pratt trusses shown in Ft**. 13 and 

 11. \ convenient procedure is as follows: 



1 1 ). -tennine the lengths of all inclined membeni 

 write their values on the tniv. outline. 



2. Determine the \alue> of the intercepts a 



by Fig. 11 and write their value- on the truss outline, 



3. Write on the truss outline the distances of the 

 eral panel points from the right end of the span. 



l -own the reciprocal* of the span, panel length. 



and lengths of vertical members, 



5. Make a form for tabulating calculations and fist 

 members in some convenient form as is done b F%L 13 

 and 1 1. 



6. Calculate the numerical values of the rnofficimU O 

 and // tor the several member* by use of the formulas 



ly clerr 

 7 I ><-r ermine the position of the loading for 



stress by finding the position of loading cauiong ( jp IF H , ) 



