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Patent Searching and Data


Title:
LOAD BEARING STRUCTURES
Document Type and Number:
WIPO Patent Application WO/2014/127401
Kind Code:
A1
Abstract:
A structure (1), for load bearing. Three or more bars (3) are arranged about, to run along an elongate volume EV. There are walls (5) between the bars such that, in cross- section transverse to the elongate volume, the elongate volume is surrounded. At least one of the walls is a corrugated wall.

Inventors:
HEIDARPOUR AMIN (AU)
ZHAO XIAO-LING (AU)
SONG QIAN-YI (AU)
Application Number:
PCT/AU2014/000103
Publication Date:
August 28, 2014
Filing Date:
February 11, 2014
Export Citation:
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Assignee:
UNIV MONASH (AU)
International Classes:
E04C3/04; E04B1/30; E04C3/20; E04C3/30; E04C3/32; E04C3/34; E04G13/02; E04H12/08; E04H12/12
Foreign References:
SU1668587A11991-08-07
US2068022A1937-01-19
GB448178A1936-06-02
EP1251217A12002-10-23
US3256671A1966-06-21
US4047354A1977-09-13
Attorney, Agent or Firm:
WADESON (Melbourne, Victoria 3001, AU)
Download PDF:
Claims:
CLAIMS

1. A structure, for load bearing, including three or more bars arranged about, and to run along, an elongate volume; and walls between the tubes such that, in cross-section transverse to the elongate volume, the elongate volume is surrounded; wherein at least one of the walls is a corrugated wall.

2. The structure of claim 1 wherein each of the walls is a corrugated wall.

3. The structure of claim 1 or 2 wherein each of the corrugated wall(s) has

corrugations in substance running along the elongate volume. 4. The structure of claim 1 , 2 or 3 wherein the bars are tubes.

5. The structure of any one of claims 1 to 4 wherein the bars are in substance straight bars.

6. The structure of any one of claims 1 to 5 wherein the bars are in substance parallel to each other. 7. The structure of any one of claims 1 to 6 wherein the bars are in substance cylindrical bars.

8. The structure of any one of claims 1 to 7 wherein the bars are in substance spaced about a pitch circle.

9. The structure of claim 8 wherein the bars are in substance equi-spaced about the pitch circle.

10. The structure of any one of claims 1 to 9 including exactly three of the bars.

1 1. The structure of any one of claims 1 to 10 including exactly four of the bars.

12. The structure of any one of claims 1 to 1 1 wherein the walls are energetically bonded to the bars. 13. The structure of any one of claims 1 to 12 further including a filling material within the elongate volume, wherein at least the walls define an outer periphery of the filling material.

14. The structure of claim 13 further including an elongate cavity within the filling material and running along the elongate volume. 15. The structure of claim 14 further including a tubular structure defining an inner periphery of the filling material about the elongate cavity.

16. The structure of claim 13, 14 or 15 wherein the filling material includes aggregate and the corrugations are configured to define at least one recess dimensioned to wholly receive a typical portion of the aggregate. 17. The structure of claim any one of claims 1 to 16 wherein the corrugated wall(s) are formed of material having a lower yield stress than the material of which the bars are formed.

18. The structure of any one of claims 1 to 17 wherein the corrugated wall(s) are formed of mild steel. 19. The structure of any one of claims 1 to 18 wherein the bars are formed of very high strength steel.

20. The structure of any one of claims 1 to 18 wherein the bars are formed of stainless steel. The structure of any one of claims 1 to 20 when placed at least in axial pression.

Description:
LOAD BEARING STRUCTURES

FIELD

The invention relates to load bearing structures. BACKGROUND A range of competing concerns are relevant to the design of load bearing structures. Generally speaking, load bearing structures should be light, strong, low cost and fire resistant. By way of example, use of lighter materials in the upper storeys of a building reduces the load applied to (and in turn, requisite strength of) the load bearing members in the lower storeys. A wide range of load bearing members have previously been proposed, yet the present inventors have recognised that further improvement is possible.

It is not admitted that any of the information in this patent specification is common general knowledge, or that the person skilled in the art could be reasonably expected to ascertain or understand it, regard it as relevant or combine it in any way at the priority date.

SUMMARY

One aspect of the invention provides a structure, for load bearing, including three or more bars arranged about, and to run along, an elongate volume; and walls between the bars such that, in cross-section transverse to the elongate volume, the elongate volume is surrounded; wherein at least one, and preferably each, of the walls is a corrugated wall. Each of the corrugated wall(s) preferably has corrugations in substance running along the elongate volume.

In preferred forms of the invention, the bars are tubes. The bars may be in substance straight bars, and may be in substance parallel to each other. Preferably the bars are in substance cylindrical bars. The bars may be in substance spaced, and preferably equi- spaced, about a pitch circle.

There may be exactly three, or exactly four, of the bars. Preferably the walls are energetically bonded to the bars.

The structure optionally includes a filling material within the elongate volume, wherein at least the walls define an outer periphery of the filling material. If so, there may be an elongate cavity within the filling material and running along the elongate volume. The structure may further include a tubular structure defining an inner periphery of the filling material about the elongate cavity. The filling material may include aggregate, in which case preferably the corrugations are configured to define at least one recess

dimensioned to wholly receive a typical portion of the aggregate.

Preferably the corrugated wall(s) are formed of material having a lower yield stress than the material of which the bars are formed. By way of example, the corrugated wall(s) may be formed of mild steel, and/or the bars formed of very high strength steel or stainless steel. Another aspect of the invention provides the structure when placed at least in axial compression.

BRIEF DESCRIPTION OF DRAWINGS

Figures 1 , 2 and 3 are perspective views of exemplary load bearing structures. DESCRIPTION OF EMBODIMENTS

Figure 1 illustrates a load bearing structure 1 consisting of four bars 3 and four walls 5. In this example of the invention, the bars 3 are tubular bars.

Each tube 3 is a straight cylindrical tube. The tubes 3 are arranged in parallel such that when viewed in transverse cross-section they define the vertices of a square. Put another way, the tubes 3 are equi-spaced about a common pitch circle.

The tubes 3 are spaced about an elongate volume EV surrounding that volume in the manner of a cage.

Each tube 3 is connected to each of its neighbouring tubes by a respective one of the walls 5. The tubes 3 and walls 5 together define a tubular structure about the volume EV. Each wall 5 has a planar "fundamental shape" (or linear fundamental shape in transverse cross-section) such that this tubular structure is fundamentally square in cross-section. Each wall 5 includes, imposed on this fundamental shape, a set of corrugations running along its length. In this example, each wall 5 includes three trapezoidal corrugations in the form of inwardly directed table formations spaced across its width. Each table formation has inclined sides. Of course, other forms of corrugation are possible. By way of example, the corrugations could take the form of a continuous sinusoidal pattern or of spaced narrow ribs between wide planar sections.

In the example of Figure 1 , the walls 5 are energetically bonded to the tubes 3 by welding. The walls 5 are seam welded along their long edges to the tubes 5 such that the walls 5 project radially from the tubes 3. Other forms of fastening, and energetically bonding such as brazing, are contemplated. Indeed, the structure 1 may well be integrally formed.

Whilst integral formation is possible, it is preferred that the walls be attached to the tubes in that this readily allows for the tubes and the walls to be formed of differing materials. Most preferably the tubes are significantly stronger than the walls. In this way the materials are most effectively utilised. In particular the walls serve to stay the tubes to resist buckling under compressive loads. In this example the tubes are formed of a very high strength steel and the walls formed of mild steel. Very high strength steel is steel having a yield stress in the vicinity of 1350 MPa or more, whereas mild steel typically has a nominal yield stress in the vicinity of 350 MPa. Alternatively, the tubes may be formed of a stainless steel such as Grade 316L stainless steel.

Figure 2 illustrates another exemplary load bearing structure 1 ' identical to the structure 1 but further including a filling material 9. The filling material 9 takes the form of concrete. Concrete, and other settable materials, are convenient filling materials in that they can be supplied to the structure 1 in liquid form, to fill the structure and conform to the interior boundaries of the walls 5 and then set. In this manner the structure 1 constitutes a permanent formwork about the filling material 9.

The concrete in this example of the invention includes an aggregate in the form of crushed rock. "Aggregate" as used herein refers to a particulate dispersed within a continuous phase of the filling material. Whilst crushed rock is non-homogenous, the corrugations of the walls 5 are dimensioned and spaced to define elongate recesses wide and deep enough to wholly receive a typical piece of aggregate. In this way the aggregate can be suitably positioned within the filling material to reinforce the projecting ribs of the filling material defined by the corrugations. Figure 3 shows yet another load bearing structure 1 " which is identical to the structure V but further includes an inner skin 1 1 in the form of a square sectioned tube running along the elongate volume EV. The tube 1 1 forms another piece of permanent formwork defining the internal boundary of the filling material 9 to define an elongate cavity EC running along the elongate volume. In this example the tube 1 1 , and in turn the elongate cavity EC, has a square profile concentrically arranged within the walls 5 and running parallel to those walls. The described examples of the invention have been found to be stronger, lighter and more fire resistant than simple square profiled tubes and square profiled tubes having corrugated side walls. In particular, tests have shown that when subjected to the same degree of utilisation (the ratio of an applied load to an ultimate load capacity), variants of the structure 1 having stainless steel tubes 3 last longer than these two alternatives under fire. This extended time to failure is of course advantageous in that it extends the time in which firefighters may safely extinguish a blaze before a catastrophic collapse.

Whilst various examples of load bearing structure have been described, many other examples are possible. The scope of the invention is defined by the claims. In particular, whilst the described variant includes four tubes 3 arranged in a square array and running parallel to each other, other arrangements are possible and may well be advantageous in particular applications. In particular, triangular load bearing structures are contemplated. The tubes 3 may not be linear - they may be curved to produce a curved load bearing member. It is also contemplated that the tubes may not be parallel - e.g. downwardly divergent tubes may be desirable when the load bearing structure is used as a tall load bearing column.