Pallet Racking Glossary
Automated Storage and Retrieval Systems (ASRS)
A rack structure in which loading and unloading of the racks is accomplished by a stacker crane, or similar vehicle, without the aid of an on-board operator.
ASD (Allowable Strength Design)
Method of proportioning structural components such that the allowable strength equals or exceeds the required strength of the component under the action of the ASD load combinations.
ASD load combination
Load combination in the applicable building code intended for allowable strength design (allowable stress design).
Typically, a horizontal structural member that has the primary function of resisting bending moments.
Beam locking device
A pin, bolt, or other mechanism that resists disengagement of the beam connector from the column.
An essentially vertical truss system that provides resistance to lateral forces and provides stability for the structural system.
Limit state of sudden change in the geometry of a structure or any of its elements under a critical loading condition.
Nominal strength for buckling or instability limit states.
A rack structure comprised primarily of vertical columns, extended bases, horizontal arms projecting from the face of the columns, and down-aisle bracing between columns. There can be shelf beams between arms depending on the product being stored. Cantilever columns may be free-standing or overhead tied.
A test designed and conducted to determine the connection momentresisting capacity and the rotational rigidity of a beam-to-column connection. The test set-up employs one column segment and one beam segment connected to one another with a beam-to-column connector, with a load applied downwardly in the plane of the frame at the cantilever end of the beam segment.
Case flow rack
A specialized pallet rack structure in which either the horizontal shelf beams support case-flow lanes or case-flow shelf assemblies are supported by the upright frames. The case-flow lanes or shelves are installed at a slight pitch permitting multiple-depth case or box storage with loading from one service aisle and unloading or picking from another service aisle.
Exterior covering of structure.
Cold-formed steel structural member
Shape manufactured by press-braking blanks sheared from sheets, cut lengths of coils or plates, or by roll forming cold- or hotrolled coils or sheets; both forming operations being performed at ambient room temperature; that is, without manifest addition of heat such as would be required for hot forming.
Structural member that has the primary function of resisting axial force.
Limit state of compressive failure in concrete having reached the ultimate strain.
Two or more forces acting in conjunction with one another at a single location.
A test designed and conducted to determine the connection moment-resisting capacity and rotational rigidity, along with energy-dissipation properties, of beam-to column connections when those connections are subjected to cyclic loading conditions. The test set-up employs one column segment and two beam segments connected to one another, using two beam-to-column connectors, as a double cantilever. Two parallel loads are applied, in opposing reversing cyclic fashion, in the plane of the frame at the ends of, and normal to, the cantilevered beam elements.
Applied load determined in accordance with either LRFD load combinations or ASD load combinations, whichever is applicable.
Resistance factor multiplied by the nominal strength
Design strength divided by the appropriate section property, such as section modulus or cross section area.
Inclined structural member carrying primarily axial force in a braced frame.
A mode of buckling involving change in cross-sectional shape, excluding local buckling.
When a shelf is loaded with loads stacked one on top of another in a pallet position.
A rack structure comprised primarily of vertical upright frames, horizontal support arms, and horizontal load rails typically used for one-wide by multiple-depth storage. This structure includes an 'anchor section' with horizontal beams supporting the load rails. Loading and unloading within a bay must be done from the same aisle. A two-way drive-in rack is a special case where back-to-back rows of drive-in racks are combined into a single entity with a common rear post.
A rack structure comprised primarily of vertical upright frames, horizontal support arms, and horizontal load rails typically used for one-wide by multiple-depth storage. This structure lacks the 'anchor section' found in drive-in racks; therefore, loading and unloading can be accomplished from both ends of a bay.
Length of an otherwise identical column with the same strength when analyzed with pinned end conditions.
Effective length factor
Ratio between the effective length and the unbraced length of the member.
Effective section modulus
Section modulus reduced to account for buckling of slender compression elements.
Reduced width of a plate or slab with an assumed uniform stress distribution which produces the same effect on the behavior of a structural member as the actual plate or slab width with its nonuniform stress distribution.
Product of a load factor and the nominal load.
Buckling mode in which a compression member deflects laterally without twist or change in cross-sectional shape.
Buckling mode in which a compression member bends and twists simultaneously without change in cross sectional shape.
Resultant of distribution of stress over a prescribed area.
Load such as that produced by dead and live loads, acting in the downward direction.
A vertical plate (angle or barrier) that is installed at the edge of an elevated floor that is intended to prevent loose items from sliding off the edge of the floor.
Factor that accounts for deviations of the nominal load from the actual load, for uncertainties in the analysis that transforms the load into a load effect and for the probability that more than one extreme load will occur simultaneously.
Limit state of buckling of a compression element within a cross section.
LRFD (Load and Resistance Factor Design)
Method of proportioning structural components such that the design strength equals or exceeds the required strength of the component under the action of the LRFD load combinations.
LRFD load combination
Load combination in the applicable building code intended for strength design (load and resistance factor design).
A rack structure comprised primarily of vertical upright frames and horizontal shelf beams and typically used for one-deep pallet or hand-stack storage.
Strength of a structure or component (without the resistance factor or safety factor applied) to resist load effects, as determined in accordance with this specification.
Maximum horizontal distance (in.) from the centerline of the column at the floor to a plumb line that extends downward from the centerline of the column at the top shelf elevation divided by the vertical distance (ft.) from the floor to the top shelf elevation.
Maximum horizontal distance (in.) from the centerline at any point on the column to a plumb line from any other point on the column divided by the vertical distance (ft.) between the two points.
An applied force that causes a structure to turn over.
The front and back shelf members that bear the weight of the load and transfer the load to the upright frames.
Pallet flow rack
A specialized pallet rack structure in which the horizontal shelf beams support pallet-flow lanes. The pallet-flow lanes are typically installed on a slight pitch permitting multiple-depth pallet storage with loading from one service aisle and unloading from another service aisle.
Pallet load support member
Any load bearing member with the long axis on the horizontal plane and intended for use as support of unit loads in direct contact. (pallet and shelf supports and beams, not bracing).
A rack structure comprised primarily of vertical upright frames and horizontal shelf beams and typically used for one and two-deep pallet storage.
A rack structure comprised primarily of vertical frames and horizontal beams typically having one or more platform levels of selective, case-flow, or pallet-flow bays feeding into a central pick aisle(s) [work platform(s)] supported by the rack structure.
Portable rack (stacking frames)
An assembly, typically with four corner columns, that permits stacking of one assembly on top of another without applying any additional load to the product being stored on each assembly.
A test designed and conducted to determine the connection moment-resisting capacity and the rotational rigidity, F, of a beam-to-column connection. The test setup employs two column segments and one beam segment connected to one another using two beam-to-column connectors forming a portal frame, with the load applied laterally in the plane of, and to the corner of, the portal frame in the direction parallel to the beam segment.
The weight of the item(s) placed on the rack.
A specialized pallet rack structure in which the horizontal shelf beams support push-back lanes comprised of tracks and carts. The push-back lanes are installed on a slight pitch permitting multiple-depth pallet storage. Loading and unloading are done from the same service aisle by pushing the pallets back.
Rack supported platforms
A decked working surface supported by a rack structure.
Rack supported structure
A rack structure similar to other rack structures; however, this structure also includes wall girts and roof purlins or equivalent components used to support wall and roof cladding. This structure is designed to carry, wind, snow, and rain loads in addition to the normal storage rack loads.
Factor that accounts for unavoidable deviations of the nominal strength from the actual strength and for the manner and consequences of failure.
Factor that accounts for deviations of the actual strength from the nominal strength, deviations of the actual load from the nominal load, uncertainties in the analysis that transforms the load into a load effect, and for the manner and consequences of failure. The nominal load divided by the safety factor results in the allowable load for an allowable Strength Design.
A surface that is provided in areas where order picking personnel may need to step off the normal walking area or pick module walkway to dislodge loads that may not have properly flowed to their correct position.
Seismic response modification coefficient
Factor that reduces seismic load effects to strength level.
Limit state of lateral buckling of the tension flange opposite the location of a concentrated compression force.
Single plate elements used to stiffen a compression flange.
Site class definition
A classification assigned to a location based on the types of soils present.
Condition reached in the loading of a structural component, frame or structure in which a slight disturbance in the loads or geometry does not produce large displacements.
See Portable rack.
A rack structure similar to one of the other rack structures; that is serviced by an automated storage and retrieval machine.
Resistance to deformation of a member or structure, measured by the ratio of the applied force (or moment) to the corresponding displacement (or rotation).
Force per unit area caused by axial force, moment, shear or torsion.
An assemblage of load-carrying components that are joined together to provide interaction or interdependence.
Stub column test
Concentric compression testing of members not affected by column buckling used to determine the column effectiveness.
Buckling mode in which a compression member twists about its shear center axis.
Buckling mode in which compression members bend and twist simultaneously without change in cross section shape.
Trussed-braced upright frame
Upright frames having two columns similar to the chords of a truss and diagonal and horizontal bracing attached to and located between the columns. The diagonals and horizontals become the web members of the truss. (It is referred to as a vertical truss.).
Distance between braced points of a member, measured between the centers of gravity of the bracing members.
The total weight expected to be positioned in the rack consisting of the product load and pallet weight.
The main members that carry the vertical and horizontal loads to the floor. They are usually made up of two columns and bracing members between the columns. The beams of the rack are attached to the columns of the frames and carry the loads to the columns.
Vertical impact load
Additional downward force added to the beams produced during loading of the rack.
First stress in a material at which an increase in strain occurs without an increase in stress as defined by ASTM.
Stress at which a material exhibits a specified limiting deviation from the proportionality of stress to strain as defined by ASTM.