LE PONT VIERENDEEL." 



A New Type of Bridge, 



By J. I. Haycropt, m.i.c. 



[Bead before the Engineering Section of the Royal Society of N.S.- 

 Wales, September 20, 1899.] 



Professor Vierendeel, of the University of Louvain, who w 

 also Engineer-in-Chief and Director of Technical Service in 

 Western Elanders, has recently written a work called 

 "Longitudinals with trellis, and Longitudinals with arcades,"" 

 which presents some novelties in Bridge design. 



The writer proposes to extract from that work sufficient to 

 explain the method of calculation and peculiar properties of a 

 bridge, shown by Fig. 1, which, to all intents at first sight, is a 

 plate girder with portions of the web removed between the 

 vertical stiffeners. 



Prof. Vierendeel, hereafter referred to as the Professor, 

 states that the metal trellis owes its origin to the American 

 wooden truss, and that, whilst the Americans have preserved the 

 articulation which existed in these trusses in their present 

 practice with pin connections, European engineers have 

 abandoned the articulation in favour of rigid rivetted connec- 

 tions. 



Whilst the bad effect of rivetting lattice bars is great, still 

 the Professor says the bad effect of pin connections is greater 

 still. It is in the nature of things that there should be rigidity 

 in metal structures and articulation in wooden ones. Originally 

 trellis girders had multiple systems, but during the last 25 years 

 the systems have been reduced by only employing the bars,, 

 actually necessary, and so the triangular trellis has eventuated. 



