GB2394465A - Containers having reduced section deck beams - Google Patents

Abstract

An open sided container (31) has base deck support beams (33) of progressively reduced - say waisted or stepped - cross-section towards the longitudinal centre relative to opposite beam ends, to accommodate beam deflection braced by end frame attachment.

Description

GB 2394465 A continuation (74) Agent and/or Address for Service: Chris J

Tillbrook 1 Mill Street, WARWICK, CV34 4HB, United Kingdom

Waisted Container Deck Beam Section Background

In the field of so-called 'shipping' (ie transport and storage) containers there is an

open sided configuration - with a rectangular platform base, opposite end walls and a 5 roof - but open sides for cargo (un) loading access.

Open sides forgo the structural benefit of rigid side wall infill panels as in a general purpose shipping container of enclosed shell configuration.

More specifically, the base is of necessity strong and rigid in its own right, in order to support a typical 30 tonne payload, in transi\t over land and sea.

10 The base is thus necessarily somewhat heavier than one supported by a side panel.

Scope for base deflection is limited by a requirement for overall container stacking one upon another.

The roof of containers is generally not load bearing to a large degree.

So any container placed upon another must be able to support its own payload, 15 without deflecting down so far as to make contact with the roof of an underlying container and so causing it damage.

In contemporary open side container construction, a base features '1' beams or box beams, with top (upper) flanges substantially parallel to bottom (lower) flanges.

Open side container operators seek a maximum height or depth availability between 20 base and roof, to maximise cargo height which can be (side) (un)loaded.

Thus an open sided container floor surface is typically closely horizontal when unladen, so that initial cargo loading has maximum open side height.

The deflection problem could be overcome by adding more (steel) material, to make the structure more rigid.

25 Although the most common method of overcoming the deflection problem, additional structure tends to reduce available payload, because of roadway upper loading constraints. It also adds build and operating costs, because of the extra material used and carried.

Increased beam depth, for greater rigidity without increased weight penalty, might be 30 considered.

However this would reduce side access height of any given fixed height of container.

An alternative would be to camber deck beams, or raise entire deck beams upwards but again access height would be reduced, since the roof height would remain fixed.

A light-weight structure affording maximum access height, without exceeding 5 deflection limits, would represent something of a breakthrough in this field.

Statement of Invention

The present invention provides an open sided container having a platform base, with opposite end frames, 10 surmounted by a roof, the base having a longitudinal support beam, between end frames, characterized in that the base beam is progressively reduced in cross-section, 15 from a full depth at or toward the ends, to a reduced depth at or toward a longitudinal centre.

The term 'beam' embraces extruded continuous sections and pre-fabricated assemblies of multiple discrete elements.

Desirably, a platform deck floor is substantially horizontal when unladen.

20 A continuously tapered beam cross-section may be employed.

Multiple longitudinal base support beams may be employed.

An 'I' section deck support beam cross-section may be employed.

A 'Z' section deck support beam cross-section may be employed.

A 'C' section deck support beam may be employed.

25 A box section deck support beam may be employed.

Mixed deck beam sections may be employed.

End structures could be contrived to exert an upwardly concave or 'hogging' pre bending moment upon the base, to counter cargo load deflection.

In a particular construction, a container cold be configured with a fully laden beam 30 stress of some 1.8 times gross capacity less tare weight, and which, if generated in a conventional open sided container base, through application of uniformly distributed load, would cause downward base deflection substantially more than 6mm below a

ground reference line.

A staggered or stepped cross-sectional profile could be employed.

A deck support beam could be pre-stressed, to reconfigure internal stresses and impart a desired bending predisposition.

5 Embodiments There now follows a description of some particular embodiments of the invention, by

way of example only, with reference to the accompanying diagrammatic and schematic drawings, in which: Figure 1 shows a side elevation of a typical known open sided container 11; 10 Figure 2 shows a side elevation of a container according to the invention, with progressively waisted longitudinal beam cross-section; Figure 3 shows a side elevation of a variant container of the invention with stepped beam cross-section incremental reduction; Figure 4 shows a variant of Figure 3; 15 Figures 5A through 5D show variant base or deck support beam cross-sectional forms. Referring to Figure 1, a base 12 comprises side beams 13, supporting a floor 14, typically of plywood, with a top surface which is substantially horizontal and level with the top surface of top flanges 15 of side beams 13.

20 A bottom flange 16 is depicted raised up by an amount 'B' - typically some 30mm or so above a ground surface reference line 17 upon which the container 11 rests through bottom corner fittings 18.

The base 12 might be cambered upwards toward a longitudinal centre datum, by a distance 'C' above the ground plane.

25 However the amount of camber is limited by the need to maximise side opening access height 'A'.

At each end of the container 11 is a frame structure 19 comprising corner end posts 20 capped by corner handling and stacking fittings 21.

At one (rear) end are a pair of hinged access doors 22 - opened to allow end 30 (un)loading of cargo.

At the opposite front end is a wall panel 23 secured to corner end posts 20.

A roof structure 24 is fitted between the tops of end frames 19, and comprises a side rail 25 typically welded to top corner fittings 21 and closed by a corrugated steel infill panel 26.

When cargo knot shown) is loaded upon base 12, it deflects downward - as indicated 5 by broken line 16' - representing the underside of bottom flange 16, which may pass notionally below a ground reference line 17 near the longitudinal centre of base 12.

The amount that base 12 can deflect downward is limited by the need to avoid contact damage of an underlying container, under dynamic handling conditions as might be experienced when lowering one container clumsily down upon another by crane.

1 0 International regulators have agreed that this downward deflection limit should be set at a maximum of 6mm below the ground reference line or plane.

Figure 2 shows a corresponding view to Figure 1, but for an embodiment of the present invention with a progressively waisted longitudinal base or deck support beam cross-sectional profile.

1 5 For clarity, the taper is exaggerated somewhat in relation to the drawing scale.

An open side container 31 has base 32, with longitudinal side beams 33 supporting a floor 34 - typically of plywood - with a top surface substantially horizontal and level with top surface of top flanges 35 of those side beams 33.

A bottom flange 36 of side beams 33 is depicted raised up a distance 'B' say, some 20 30mm or so above a ground line or plane 37 adjacent to bottom corner fittings 38 upon which the container 31 rests.

However, unlike prior art container of Figure 1, bottom flange 36 is profiled to bow or

taper' progressively and continuously upward - to a somewhat greater height 'D' above ground reference line 37, toward the longitudinal centre of base 32 - in this 25 example to a maximum of some 70mm above ground for an unloaded container 31.

At each end of the container 31 is an end frame structure 39, comprising corner end posts 40 capped by corner handling and stacking fittings 41.

At a rear end are a pair of hinged doors 42, opened to allow cargo end (un)loading access, and at the front end there is a wall infill panel 43 fitted to posts 40.

30 A roof structure 44 is secured between top of opposite end frames 39, and comprises a longitudinal side rail 45, typically welded to corner fittings 41 and closed by a corrugated steel infill wall panel 46.

When cargo (not shown) is loaded upon the container 31, its cargo support base 32 deflects downward, as indicated by broken line 36'- representing the underside of

the bottom flange 36 when deflected.

In this example, 'upward' taper of bottom flange 36 provides extra ground clearance for deck beam 33 loading deflection.

Thus bottom flange 36 can deflect - not just an amount 'B' - of, say, some 30mm 5 adjacent corner casting 38, plus an allowance of say 6mm 'below ground' allowance, but by a supplementary amount ('head space') of some 40mm.

Overall, base 32 can be made substantially less rigid, and lighter in weight than in the prior art - without exceeding industry norms and yet also provide the same internal

side loading access height 'A' es in Figure 1.

1 0 Because the base 32 deflects more than conventional deck beams, it develops a greater bending moment in posts 40 - with the potential of utilising end frame structure more optimally and allowing potential weight saving.

In designs of open sided containers where side doors, short wall sections, diagonal struts and stays can be fitted, further improvements in end frame bending restraint 1 5 can be achieved.

Generally, a progressively reduced deck support beam cross-sectional profile allows the required scope for loading deformation, without underlying contact interference.

Aside from a continuously tapered waisted cross-sectional profile, an abrupt incremental stepped profile, such as of Figures 3 or 4, may be employed.

20 This affords intermediate transition blocks 51 at the step junction transition between successive base flanges 52.

The term 'open sided' embraces both or only single open sides.

A longitudinal side infill wall panel (not shown) provides supplementary deck bracing on that side, relieving the burden upon longitudinal deck beam profiling.

25 Thus a waisted deck beam cross-sectional profile may be differentiated (not shown) between opposite deck sides.

Beam cross-sectional size variation may be applied to a diversity of beam sections, such as shown in Figures 5A through ED, from minimal 'I' (Figure 5A), 'Z' (Figure 5C) or C' (Figure 5D) to enclosed box (Figure 5B) sections.

30 In each case, for top surface alignment reference, a deck platform floor 34 is shown juxtaposed with a deck support beam upper flange 35.

In practice, a deck platform may rest upon transverse rails (not shown) and/or upon longitudinal side rail top flanges 35.

Beam pre-stressing according to the Applicants' co-pending UK patent application GB0322254.4 can be employed to control longitudinal deck beam deflection.

Thus, excess pre-camber profiling, through such pre-stressing may be applied allowing progressive settling recovery to a more permanent long term profile, with 5 attendant re-aligned internal stresses.

Features may be selectively mixed and matched to suit particular construction and operational criteria - albeit it is not feasible to illustrate every workable permutation or combination. Component List 10 11 container 12 base 13 side beam 14 floor 15 top flange 15 16 bottom flange 17 ground reference line 18 bottom corner fitting 19 end frame structure 20 corner end post 20 21 corner handling/stacking fitting 22 access door 23 wall panel 24 roof 25 side rail 25 26 corrugated infill panel 31 container 32 base 33 side beam 34 floor 30 35 top flange 36 bottom flange 37 ground reference line 38 bottom corner fitting 39 end frame structure 35 40 corner end post 41 corner handling/stacking fitting 42 access door 43 wall panel 44 roof

45 side rail 46 corrugated infill panel 51 intermediate transition block 52 base flange

Claims (13)

Claims In the claims, bracketed items, vis {...}, alongside claim numbering are for ease of reference only and as such form no part of claim content or scope.

1. {waisted deck beam} 5 An open sided container (31) having a platform base (32), with opposite end frames (39) surmounted by a roof (44), the base having a longitudinal support beam (33), between end frames, 10 characterized in that the base beam is progressively reduced in crosssection, from a full depth at or toward the ends, to a reduced depth at or toward a longitudinal centre.

2. {horizontal deck} 15 An open sided container, as claimed in Claim 1, in which a platform deck floor is substantially horizontal when unladen.

3. {continuous tapered beam} An open sided container, 20 as claimed in either preceding claim, with a continuously tapered beam cross-section.

4. {multiple beams} An open sided container, as claimed in any preceding claim, 25 with multiple longitudinal base support beams.

5. {'I' section beam} An open sided container, as claimed in any preceding claim, with an 'I' section deck support beam.

6. { 'Z' section beam} An open sided container, as claimed in any preceding claim, with a 'Z' section deck support beam.

5

7. {'C' section beam} An open sided container, as claimed in any preceding claim, with a 'C' section deck support beam.

8. {box section beam} 10 An open sided container as claimed in any preceding claim, with a box section deck support beam.

9. {hogging} An open sided container, 15 as claimed in any preceding claim, with end structures exerting a 'hogging' or pre-bending moment upon the base, to counter cargo load deflection.

10. {laden beam stress} An open sided container as claimed in any preceding claim, 20 configured with a fully laden beam stress of some 1.8 times gross capacity less tare weight, and which, if generated in a conventional open sided container base, through application of uniformly distributed load, would cause downward base deflection 25 substantially more than 6mm below a ground reference line.

11. {stepped section} An open sided container, as claimed in any preceding claim, with a staggered or stepped cross-sectional profile 30 longitudinal deck beam.

1 2. {pre-stressing} An open sided container, as claimed in any preceding claim, with a pre-stressed deck support beam, 5 to reconfigure internal stresses and impart a desired bending predisposition.

13. {one open side} A container, with one or more open sides, 10 having a platform base, with opposite end frames surmounted by a roof, the base having at least one longitudinal support beam with narrowing crosssectional depth 15 from each end towards the longitudinal centre.