NORTHAM RAILWAY BRIDGE - AN UNUSUAL BRIDGE IN SOUTHAMPTON

Northam Bridge in Southampton dates from 1908, It has an unusual layou t, with one main girder on one side and two on the other, Its structur e is also unusual, consisting of twin lattice girder webs with members of varying size. The history of the bridge in the context of the Lond on and South Western Railway is presented together with a detailed bre akdown of its structure. A finite element analysis of the structure wa s carried out to examine the load path through the highly redundant we b. The structural response was compared with the behaviour of a simple truss and a plate girder, It was shown that the bridge is generally s ound even for 40 t vehicle loading, although the deck supports give so me cause for concern.