Offshore Structure Platform Design - Offshore Structures: Design, Construction and Maintenance - page 196

3.12 BRIDGES
In cases where two or more platforms are forming a complex or in the case
where separate installations are built to support a helideck or a flair, bridges
may be required to connect the different structures.
The bridge should be designed to resist the following loads:

Self-weight of the bridge.

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Uniformly distributed live load equal to 250 kg/m 2 of the walkway area.

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All piping loads carried by the bridge, if any.

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Wind loads acting directly on the bridge.

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Maximum imposed relative displacement between the bridge ends due to the
environmental-level loads acting on the two structures connected by the bridge.

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Thermal effect due to temperature changes. ●

The bearings of the bridge should be designed to allow for the expected dis-
placements and rotations. Normally, the bearings at one end should be hinged,
allowing only for rotation. The bearings at the other end should be free for sliding
and rotation. Flurogold slide bearings should be adequate to specify the slide
bearing.
The design of the bridge should account for a span tolerance of 1.0 m liable to

result from possible mislocation of the supporting structures. Span length rectifica-
tion should in this case be accounted for by a possible increase or decrease of the
theoretical bridge span or by relocation of the bearings on the structure deck.
The bridge should have an upward camber equal to the deflection supposed
to happen under dead loads.
Figure 3.58 presents the hinge support for the bridge, where it can be seen that
axial movement is prevented, which is opposite to the situation in Figure 3.59 ,
which shows the roller support that permits axial movement.

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FIGURE 3.58 Hinge support for the bridge.