. Details of riveted railroad truss bridges . of gravity being far from the centre ofthe webs making an unsymetrical section which is to be section is not deep but nevertheless the pin at L has 0 to be thrown off the centre of the webs in order to eliminateeccentric stresses. On account of the upper end being rivetedthe fact that the pin is off centre makes a difficult problem inexactly computing stresses. The lov/er part of the post can notbe held rigid unless lacing is used. A heavy section sometimesused is shown in Pig. 33. This section is not in common use. The method of laci
. Details of riveted railroad truss bridges . of gravity being far from the centre ofthe webs making an unsymetrical section which is to be section is not deep but nevertheless the pin at L has 0 to be thrown off the centre of the webs in order to eliminateeccentric stresses. On account of the upper end being rivetedthe fact that the pin is off centre makes a difficult problem inexactly computing stresses. The lov/er part of the post can notbe held rigid unless lacing is used. A heavy section sometimesused is shown in Pig. 33. This section is not in common use. The method of lacing might be taken up here. There aretwo general kinds of lacing, namely; single and double the function of lacing is to keep the two sides of the postapart and cause equality of stresses in the two sides of themember the double lacing is to be prefered except in lightsections. -22- The form of lacing shown in is the most this the post is held solid and the stresses equally distribut-ed between the two ^^ There are two common forms of single lacing. These are shown and 26. The first requires more lacing and unless thelattice bars are of such a thickness to make a riyet to long,this form is prefered to the second. The form of requiresalmost twice as many rivets as and is no more fact the appearance is not as desirable. Por medium length bridges, posts with sections such asare shown in and 30 are the best and the lacing of Pig,35is prefered. Two details of heavy end post sections are shown These post sections are only economical in very largebridges, on account of the difficulty found in riveting theinside members. There are three general methods of fastening the endpost to the lower chord, vis., where the end post is placedout side of the lower chord and is riveted directly to it; or -23- wiiere the lower chord is outside and the end post is riveted onthe inside; or both a
Size: 2654px × 942px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookiddetails, booksubjecttheses
