IRON BRIDGES AND GIRDERS.
16
DESCBIPTION OF PLATES.
PLATE i.
SEVERAL GIRDERS USED FOR CARRYING THE RAILWAY OVER COMMON ROADS.
GREAT NORTHERN RAILWAY.
JOSEPH CUBITT, ESQ., ENGINEER.
EXECUTED BY MESSRS. FOX, HENDERSON, & CO .
These girders are of parobolie form, and of the ordinary section; the dimensions and sectional areas beinggiven in each particular case. They are bedded on oak plates, 15 inches by 9 inches thick, which runthe whole breadth of the abutment, and are notched to receive the bottom flange. The girders are placedat a distance of 10 feet 6 inches, inside of the vertical flange; the roadway is formed of 7-inch Memel firplanks, the chairs being fastened on these, and the rails fixed in the usual manner.
Figs. 1,2, 8.— Girder for Bridge over Turnpike Road at Wymondley.
Ft.
In.
Total length of girder .......
Clear span .........
Total depth of girder at centre ......
Width of bottom flange . .
Do. of top flange . . . .
Thickness of flanges
Do. of vertical rib.
Sectional area of bottom flange .....
Do. do. of top flange ......
Do. do. of girder at centre .....
Calculated breaking weight at centre by Formula 4 .
Maximu m load, say one ton per foot run, or half a ton foreach girder, equal to ......
Strain per sectional inch .......
Weight of each girder .......
48 9
44 3
3 9
2 0
0 7
0 21
0 2
60 superficial inches.171
1 t 2 99 5)
1471 „
132 tons.
44 ,. at centre.6 cwt.
10 „ 2 „
Figs. 4, 5, 6.—Girders for Bridge over Parish Road at Welwyn .
Total length of girder ..••••'■'
Clear span.
Total depth of girder at centre ..••••■’
Width of bottom flange.
Do. of top flange.•
Thickness of flanges.■
Do. of vertical rib ...•••••*’
Ft.
30
25
2
1
0
0
0
In.
0
6
6
6
5
2
2