Civil Engineering Reference
In-Depth Information
3600
1500
4500
S
2700
S
1
S
1
S
1800
1800 1800 1800 1800
L
= 6 × 4500 = 27,000 mm
9000 mm
Elevation
Cross-section
S
-
S
9000
27,000
Plan of lower wind bracing (section
S
1
-
S
1
)
Figure 4.126 General layout of a double track open-timber floor plate girder pony
railway steel bridge (the fourth design example).
plate girders) is 9 m as shown in
Figure 4.126
.
It is required to design the
bridge components adopting the design rules specified in EC3 [1.27].
The steel material of construction of the double-track railway bridge con-
formed to standard steel grade EN 10025-2 (S 275) having a yield stress of
275 MPa and an ultimate strength of 430 MPa. The bridge has only a lower
wind bracing of K-shaped truss members as shown in
Figure 4.126
. In addi-
tion, the bridge has lateral shock (nosing force) bracing for the stringers as
well as braking force bracing at the level of the lower wind bracing as shown
in
Figure 4.127
.
The lateral shock bracing eliminates bending moments
around the vertical axis of the stringers, while braking force bracing elimi-
nates bending moments around the vertical axis of the cross girder. The plate
girder web is stiffened by vertical stiffeners, to safeguard against shear stresses
and web buckling, spaced at a constant distance of 1.5 m. The expected live
loads on the bridge conform to Load Model 71, which represents the static
effect of vertical loading due to normal rail traffic as specified in EC1 [3.1].
The bolts used in connections and field splices are M27 high-strength
pretensioned bolts of grade 8.8.
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