Section 3 Design loads and combinations

3.1.1 When loaded, walkways are to be considered for the worst possible combination of inclinations and support arrangements arising from the following forces:

1. Self-weight.

2. Specified loading.

3. Static and dynamic forces due to inclination and movement of the pontoon or other buoyant support.

4. Operational environmental loads.

5. Loads due to ship movement transmitted to the walkway through any ship to linkspan connection.

3.1.2 When unloaded and out-of-service, walkways are to be considered for the worst possible combination of slope, twist angles and support arrangements arising from the following forces acting on the whole linkspan:

1. Self-weight.

2. Static and dynamic forces due to inclination and movement of the pontoon or other buoyant support.

3. Extreme environmental loads appropriate to the location (e.g. wind, wave or current).

3.2.1 The self-weight load, L _w, is to be taken as the weight of the walkway for all design conditions except when it is being mechanically raised or lowered in which case it is to be multiplied by a factor of 1,1.

3.2.2 The applied load, L _c, is the load on the walkway from passengers. This is usually expressed as a UDL and need not be increased by a dynamic factor as sufficient allowance has been incorporated for the effects of pedestrian movement, unless otherwise stated.

3.2.3 Environmental loads, L _e, need not be increased by any factor.

3.3.1 Walkways are to be designed to operate safely and efficiently when accommodating any inclination or dynamic movement of the pontoon or other buoyant structure from which they derive their support.

3.4.1 Walkways are to be considered for the design loadings resulting from the following load cases:

Case 1: The walkway is to be considered with respect to self-weight plus applied load, together with any horizontal, vertical and rotational forces resulting from pontoon movement and slope of the walkway, together with any loads imposed by the ship and any environmental loading. This is represented by the following expression:

where the above loads are added vectorially, and where

Case 2: The walkway is to be considered with respect to the direct forces resulting from the extreme environmental conditions (generally 1 in 50 year return case) and from the corresponding forces acting on the self-weight resulting from the accelerations due to pontoon motions and static inclination resulting from the same severe environmental conditions.

Case 3: The walkway is to be considered with respect to its self-weight multiplied by 1,1, together with any additional horizontal forces resulting from pontoon motions (see Pt 3, Ch 6, 3.3 Forces due to motion of the pontoon or other buoyant support 3.3.1), and environmental forces. This is represented by the following expression:

where the above loads are added vectorially.