Section 1 General

1.1.1 This Chapter indicates the general outline of the structural requirements which apply to the various elements which may be included in a linkspan namely, pontoons, bridges, ramps, walkways and supporting steelwork.

1.2.1 The structural requirements for the basic hulls of pontoons are highly prescriptive and are generally the same as those for pontoons covered by Pt 3 Construction, Design and Test Requirements and Pt 4 Engineering Systems of the Rules and Regulations for the Classification of Ships (hereinafter referred to as the Rules for Ships).

1.2.2 Pontoon designs complying with these basic hull requirements may be deemed to safely accommodate inter alia:

• hydrostatic loads on the hull resulting from heeling and trimming operations whilst the pontoon is freely floating up to the point of deck edge immersion, and
• any direct hydrodynamic loads on the hull which might occur at the geographic location for which class has been assigned,
• any additional loading from the effects of propeller or thruster wash from the berthing ship.

1.2.3 For greater pontoon immersions than deck edge immersion, see Pt 3, Ch 4, 1.1 Application 1.1.6.

1.2.4 Any further loads on the basic pontoon structure which arise as a result of vehicular traffic and/or of support given by the pontoon to associated bridges, vehicle ramps, and walkways or other applied loadings due to vehicle or pedestrian transfer are to be transmitted to the hull by suitable structural appendages fixed to the basic pontoon structure. These appendages are to comply with the load and design criteria given in Pt 3, Ch 5 Bridge/Vehicle Ramp Strength or Pt 3, Ch 6 Passenger Walkway Strength, as appropriate.

1.2.5 Structural reinforcement of the basic hull in way of these appendages is to be provided and suitably connected into the pontoon structure. The composite structure is also to comply with the load and design criteria given in Ch 5, Pt 3, Ch 5, 3 Design loads and combinations and Pt 3, Ch 5, 4 Design criteria as appropriate.

1.2.6 For pontoons with length to depth ratios exceeding six additional longitudinal strength calculations should be carried out.

1.3.1 The structural requirements for bridges and vehicle ramps are less prescriptive than those for basic pontoon structures. They are determined from an allowable stress approach, using factored loads and other requirements given in Pt 3, Ch 5 Bridge/Vehicle Ramp Strength.

1.3.2 Specific details of the structural requirements for bridges and vehicle ramps are given in Pt 3, Ch 5 Bridge/Vehicle Ramp Strength.

1.4.1 The structural requirements for walkways are less prescriptive than those for basic pontoon structures. They are determined from an allowable stress approach, using factored loads, and other requirements given in Pt 3, Ch 6 Passenger Walkway Strength.

1.4.2 Specific details for the structural requirements for walkways are given in Pt 3, Ch 6 Passenger Walkway Strength.