LIV. J. I. HAYCROFT. 



Verticals. — Column a are the several values of q. Column 

 e is the moment of resistance of the cross section S 2 in kg. metres 

 for a unit stress of 1 kg. per □ inillim. Column / is the direct 



stress divided by the sectional area = — and column g is the 



c 

 bending moment divided by the moment of resistance = — =• 



stress in kilos per square millim. Column k is the English 

 equivalent in tons per square inch of column h. 



Flanges. — Column a are the direct stresses, being cumulative 

 from the outer end to the centre. Column d is equivalent to 



column e in table for verticals. Column e = - ; column f=-y. 



b d 



Professor Yierendeel states that though this exact and 

 complete calculation of the stresses, as just explained, is neither 

 long nor complicated, there still exists a means of considerably 

 simplifying it without unduly sacrificing practical exactitude in 

 the results. This method is as follows : — 



As the diagram of bending moments shows that in each panel 

 (except those near the centre) there is a point of inflexion in each 

 bay of the flanges near their centres, in order to simplify the 

 calculation, as proposed, the Professor acts on the hypothesis 

 that a point of inflection exists at the centre of each bay of the 

 flanges. This certainly is practically the case for the end panels, 

 where the secondary stresses have their greatest effect. The 

 Professor points out that this hypothesis is not so grossly 

 incorrect as that used in the case of rivetted lattice girders.. 

 By utilizing these hypothetical points of inflexion, and the 

 points of intersection of the verticals and the flanges as the 

 origin of the various moments, the abridged calculation is 

 effected. Fig. 8 shows portion of the longtitudinal cut 

 horizontally at centres of the verticals, and the two semi-portions 

 slightly separated. The various vertical stresses in the verticals 

 can be written on at once. The several values of P are got as 

 follows : — Take, for instance the third panel from the left. 



