The present invention relates to a method of building a structure and also to a method to strengthening, or reducing the deflection of, a built structure.
The invention has been primarily developed for use in relation to portal frame structures that use materials other than steel, such as: aluminium and other alloys; carbon fibre; plastics; ceramics; timber; or glass and will be described hereinafter with reference to these applications. However, the invention is not limited to this field of use and is also to applicable for other non-steel structural and architectural works.
When designing a structure or building, consideration must be given to, amongst others requirements, the requirements of strength, deflection and dynamics. It is common for additional material to be required in a structure to satisfy deflection requirements, when compared to the material required to satisfy strength requirements. The additional material increases material and construction costs and can also adversely affect the building's dynamic response (particularly to earthquakes) and also requires a corresponding increase in the building's foundations.
It is important that the amount of materials used in building structures is minimised from a cost and environmental standpoint. It is an object of the present invention to reduce the material required in a building whilst still satisfying deflection criteria.
Accordingly, in a first aspect, the present invention provides a method of building a structure, the method including the steps of:
In a second aspect, the present invention provides a method of building a structure, the method including the steps of:
In a third aspect, the present invention provides a method of strengthening, or reducing the deflection of, a built structure, the method including the steps of:
The cable retainers are adapted to follow the tensile line of resistance the sub-structure is subjected when loaded during use.
Preferably, the method includes assembling at least two sub-structures into a structure.
Preferably also, the method includes inserting at least two cables into the cable retainer.
The cable is preferably bonded to the cable retainer by any one of the following: welding, gluing (including grouting, most preferably with cementitous grout), or by expanding the cable retainer relative to the cable or shrinking the cable relative to the cable retainer (for example by heating the cable retainer and/or by cooling the cable and thereafter allowing them to shrink and/or expand into engagement with one another) prior to inserting the cable into the cable retainer.
The tensile force is preferably applied to the cable by jacking.
The structure is preferably a steel portal frame structure, more preferably produced from I or T section beams or from tubular truss assemblies.
When the sub-structure is in the form of an I or T section beam, the cable retainer are attached to the web of the beam and, most preferably, passes through the flange of the beam. When the sub-structure is a truss assembly, the cable retainer is in the form of one of the tubular members integral with the truss.
The sub-structure is preferably utilised in the centre span of the structure. However, the sub-structure can also be used in the columns or walls of the structure.
In one form, the cable retainer extends within the boundaries of its associated sub-structure. In another form, the cable retainer is attached to the sub-structure external the boundaries of sub-structure.
Preferred embodiments of the present invention will now be described, by way of examples only, with reference to the accompanying drawings, wherein:
The centre span 22 has a first cable retainer 28 attached thereto, by welding in the regions 30 and via the struts 32 in the region 34. Each of the columns 24 also have cable retainers 36 attached thereto by welding.
Cables, represented by double headed arrows 38 and 40, are passed through the cable retainers 28 and 36 respectively. The cables 38, 40 are tensioned relative to the cable retainers 28, 36 respectively then bonded to the cable retainers 28, 36 respectively, prior to releasing the tension in the cables. The tensioning, bonding and releasing steps shall be described in more detail below.
The cable retainers 28, 36 extend generally along the longitudinal direction of their associated centre span (sub-structure) 22 or column (sub-structure) 24. More particularly, the cable retainers 28, 36 are positioned to follow the tensile line of resistance of their associated sub-structure when the structure 20 is subjected to its intended load during use.
For example, the portal frame structure 20 shown in
The resulting structure is able to better resist deflection under its designed load conditions as the tension applied to the cables relative to their associated sub-structure stores strain energy in the resulting sub-structure. Accordingly, as forces are applied to structure, the counter strain stored in the sub-structure resists the application of that load.
The resulting structure can, within certain boundaries, accept load with reduced strain and thus has an increased load carrying capacity for a given deflection. A 50-100% reduction in deflection can result compared to a similar sized existing structure.
The portal frame structures shown in
The structure 50 shown in
The structure 60 shown in
The structure 70 shown in
The structure 80 shown in
The structure 90 shown in
The structure 100 shown in
The structure 110 shown in
The structure 120 shown in
The structure 130 shown in
The structure 140 shown in
As an alternative, one, or more of the sub-structures can be assembled and tensioned according to the method described above, and then subsequently attached to the sub-structures. For example, the centre span sub-structure can be assembled on the ground and, after tensioned cables have been bonded thereto, be raised into its final position and connected to the column sub-structures.
As a further alternative, cable retainers can be added to a pre-existing structure, or a new structure built without them, which are then tensioned and bonded in the manner described above. This finds particular application in improving the strength and/or is deflection performance of an existing built structure or structure whose design is complete.
The structures described above can be designed to meet strength and dynamic requirements, whilst reducing the need to increase the material added to the structure to satisfy deflection requirements. The embodiments described previously advantageously enable the span of a structure to be increased whilst using the same amount of materials to thus provide a larger structure for the same material cost. Conversely, a structure with a like span to an existing structure can be produced using a reduced amount of materials. The structures described above are also lighter and cheaper than existing comparable structures, particularly when foundation saving are taken into account.
Although the invention has been described with reference to specific embodiments, it would be appreciated by those skilled in the art that the invention can be embodied in many other forms. For example, the cable retainers can be of any shape and any number of cables can be inserted therein.
Number | Date | Country | Kind |
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2004904033 | Jul 2004 | AU | national |
This application is a continuation application of U.S. patent application Ser. No. 11/572,406, filed Jan. 19, 2007, which is a national phase application of International Application No. PCT/AU2005/001078, filed Jul. 21, 2005, designating the United States and claiming priority to Australian Patent Application No. 2004904033, filed Jul. 21, 2004, both of which are incorporated by reference herein in their entirety.
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Number | Date | Country | |
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20100257813 A1 | Oct 2010 | US |
Number | Date | Country | |
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Parent | 11572406 | US | |
Child | 12821902 | US |