http://www.documentbays.org/89984-bs-en-15512-2009.html

6.3.4.2 Effects of operational methodsThe following operational methods shall be used to determine the horizontal placement load.a) Where goods are placed with manually operated mechanical equipment (e.g. forklift trucks).1) For racks up to 3 m in height, Qph shall be a load of 0,5 kN applied at any height up to the top of therack.2) For racks over 6 m in height, Qph shall be the worst case of either a load of 0,25 kN applied at the topof the rack or a load of 0,5 kN applied at any height up to 3 m.3) For racks with heights between 3 m and 6 m, Qph shall be the worst case of a load at the top of therack whose magnitude is determined by linear interpolation between 1) and 2) or a load of 0,5 kNapplied at any height up to 3 m.b) Where goods are placed by automatic storage and retrieval equipment, Qph and its position shall bespecified by the materials handling equipment supplier. However, it shall never be less than 0,25 kN.c) Where backstops are used it shall be clearly defined whether these are safety backstops or bufferingbackstops and the design load Qph shall be defined by the specifier. For manually operated mechanicalequipment this shall be subject to a minimum value of 0,25 Qu in the plane of the upright frame, where Quis the weight of unit load.Buffer back stops and pick and deposit stations with positioning devices shall be considered to give riseto variable actions whereas safety backstops shall be considered to give rise to accidental actions. Theactions arising from both of these shall be used with the relevant load factors.NOTE 1 Buffering backstops are considered to be undesirable because they encourage misuse. In somecircumstances they are specified for adjustable pallet racking to help the driver with positioning however the forcesresulting from these operations are of a high magnitude and are very difficult to quantify precisely.NOTE 2 Safety backstops might be specified for automated systems (crane racking) to fulfil the requirements ofEN 528.d) Qph as specified above shall be taken into account when designing the following rack components in thedirect vicinity of the backstop. These effects are all local.1) The backstop device itself.2) The connection of the backstop with the rack component concerned (beam or upright).3) The part of the upright to which the backstop or the beam to which the backstop is directly connected.4) The upright frame bracing in the direct vicinity of this upright part.

6.3.4.3 Application of the horizontal placement load in the down-aisle directionIn the down-aisle direction, the horizontal placement load arises at the beam levels and amplifies the down-aislesway caused by frame imperfections.In order to avoid creating unnecessary load cases, the concentrated load Qph may be replaced by a total loadof 2Qph distributed uniformly over all beam levels.6.3.4.4 Application of the horizontal placement load in the cross-aisle directionIn the cross-aisle direction, the most unfavourable location for the placement load shall be either:a) the top of the upright frame in order to maximise the forces in the bracing system, midway between twobracing nodes of the upright frame lattice in order to maximise the cross-aisle bending moment. In thiscase, the critical load location is generally in the lowest length of upright between bracing points. If thespacing of bracings is non-uniform, other locations shall also be investigated.NOTE In order to determine the design bending moments, a global analysis of the complete upright frame need notbe carried out. It is sufficient to add positive and negative bending moments of magnitude Qph ℓ/6.b) The mid-span of a beam in the horizontal plane in order to provide the maximum minor axis bendingmoment. This case need not be incorporated in the global cross-aisle analysis and a load of 0,5 Qph shallbe considered to be carried by a single beam in the horizontal plane through the neutral axis. It ispermissible to ignore the interaction with the vertical load causing Qph..