الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Plate girders became popular in the late 1800’s, when they were used in Construction of railroad bridges. The plates were joined together using angles and rivets to obtain plate gi ders of desired size. By 1950’s welded plate girders replaced riveted and bolted plate girders in developed world due to their better quality, aesthetics and economy. Fig.1 shows :be cross sections of two common types of plate girder bridges. The use of plate girders rather than rolled beam sections for the two main girders gives the designer freedom to select the most economical girder for the structure .
.: large embankment fills are required in the approaches to the bridge, in order to comply
:with the minimum head-room clearance required, the half through bridge is more =r ropriate [Fig.1 (a)]. This arrangement is commonly used in railway bridges where the -”ximum permissible approach gradient for the track is low. In this case the restraint to .z.eral buckling of compression flange is achieved by a moment resisting U-frame _ consisting of floor beam and vertical stiffness, which are connected together with a moment resisting joint. If the construction depth is not critical, then a deck-type bridge, as shown in : -:5.1 (b) is a better solution, in which case the bracings provide restraint to compression flange against lateral buckling.