IES970938A2 - Steel structures - Google Patents

Abstract

A steel structure formed from steel sub-assemblies, each steel sub-assembly having a unique erection identification stamp for correctly locating the steel sub-assembly in a desired orientation and position with respect to surrounding steel sub-assemblies within the steel structure and indicating sequence of assembly.

Description

The present invention relates to steel structures and in particular to the fabrication of a steel structure to facilitate its erection.

Currently, steel structures are produced by fixing together a wide variety of steel sub-assemblies. The number, size and complexity of these assemblies presents a variety of problems, both in their fabrication and their subsequent assembly.

O $ : s -j Steel structures of this type are most frequently used as the skeletal frame for large buildings. Typically, the scale of these buildings is such that a great deal of skill and experience is required during the construction phase. This is particularly so given that building designs are rarely repeated and given the number, size and complexity of the relationships between the various sub-assemblies involved.

In an attempt to overcome the constructional difficulties associated with such structures, a variety of techniques and methodologies have been developed. For example, US 3,863,418 shows a method and means for executing such a building. While this method overcomes many of the problems associated with using cables and winches to move pre-fabricated units such as housing units into position within a vertical structure, it does not overcome the problems associated with erecting the structural steel frame on which the buildings are based.

Additionally, US Patent No. 5,577,362 shows a modular construction method for use in the construction of a steel structure. This disclosure also refers to a variety of previously known construction methods namely the pile up method in which sub-assemblies are transported to the construction site and lifted into position as a single item and reference is also made to the push up method in which, after completion of the 5970939’ - 2 roof and top floor the completed section is jacked up using hydraulic equipment, etc. to produce a space into which the next floor may be installed.

While the modular construction method illustrated in US 5,577,362 overcomes many of the problems associated with these construction methods, namely the weight, space limitations and work-flow problems associated with the inter-relationship between constructional elements and floors, it does not overcome the significant cost overhead in construction of such a building associated with the experience and skill of the work force.

Similarly, while the construction method described allows for the construction of buildings of any height, or shape by using jacks in place of cranes, to move the modular constructions into position, it does not address the problems of ensuring prefabricated elements are delivered in sequence for efficient assembly.

Those involved in the erection of steel structures and in particular the erection of steel sub-assemblies to form part of the structures, will be aware that quite often, the sub-assemblies are made without any consideration whatsoever to their eventual erection. Thus, in many instances, there are a large number of sub-assemblies on site which cannot be used, either because they are waiting for other parts to be erected or because they require the use of specialised direction or other fitting and fixing equipment whether they be for the pouring of concrete for foundations, the attachment of other members thereto or simply their carrying and transporting or lifting.

Everybody appreciates that the correct way to overcome the problem is to ensure that, rather in the same way as just-in-time manufacturing has become the desired way of producing many a product that such assemblies are correctly sequenced and delivered. Heretofore, nobody has been able to devise a satisfactory way of applying the principles of just-in-time manufacturing to the erection of steelwork. The explanation given for not 59709381 - 3 doing this has been that since all or almost all large steelwork assemblies are generally one-off jobs that are specifically designed for the particular structure in mind, thus the techniques that are applied to more continuous or even batch production cannot be applied to steelwork assembly. However, the advantages of being able to apply these techniques to structural steel erection would be far reaching and particularly advantageous. The advantages would start not simply on the site but would carry over into the manufacturing operation where costly assemblies would not be manufactured until required for erection.

On the erection site, there is nothing that causes more confusion and delay than having a large number of subassemblies present, which sub-assemblies have to be continually checked and monitored to find the next subassembly required. The ideal situation would be to ensure that the various sub-assemblies and structures required for erection arrived on site immediately before they were required by the particular piece of equipment for that erection. Ideally, what will arrive on site is the one load of structure steel which one load of structure steel would be the next load that had to be erected. This seems to be relatively simple and obvious, however, heretofore it has not been achieved.

The second requirement in any good erection site is to have clear instructions for those carrying out the erection as to the mating parts and to where particular parts fit. The least number of parts on site or at least parts on site which are placed on site in the order of which they need to be erected will ensure that mistakes are not made in the erection sequence and that further parts are located correctly on other portions of the structure in the correct location and orientation. It is almost impossible to overemphasise the need to ensure that all the various sub-assemblies do interlock in the correct position and in the correct orientation. What is often forgotten by those designing such subassemblies is that it is very easy on site to make mistakes and to position sub-assemblies in the wrong 7 0 9 3 8 position or orientation.

It is an object therefore of the present invention to provide an improved steel structure which will overcome these problems .

Statements of Invention Accordingly, there is provided a steel structure formed from a plurality of steel sub-assemblies, each steel sub-assembly comprising a plurality of rigidly interconnected steel strut members and having fixing means for engaging associated adjacent steel subassemblies, forming on assembly a rigid structure, and having unique erection identification means adjacent one of said fixing means for correctly locating the steel sub-assembly in a desired orientation and position with respect to surrounding steel sub-assemblies within the steel structure and indicating sequence of assembly.

This greatly accelerates the speed at which the structure may be erected as each steel sub-assembly has a unique identifier which will allow construction personnel to rapidly identify the steel sub-assembly and determine its correct orientation and position within the steel structure. It also reduces the skill levels required on site to position the sub-assembly within the structure.

Furthermore, as the identification means provided is unique to each steel sub-assembly it ensures that component elements of the steel structure are delivered to a site in the correct sequence to minimise both the lead time required to complete the building and simultaneously minimising the on-site storage requirements for steel sub-assemblies.

Ideally each steel strut member has a unique fabrication identifier for indicating a desired relative position and orientation for each steel strut member with respect to adjacent steel strut members within a steel subassembly of the steel structure. 5970938 - 5 This greatly reduces the lead time in assembling structures of this kind as raw unprocessed steel members used in the fabrication of steel sub-assemblies are delivered to a fabrication area in sequence to allow fabrication in its entirety of a given steel subassembly. Heretofore the unprocessed steel struts were more commonly batch processed so that a number of steel strut elements forming common component elements of a number of steel sub-assemblies were prepared at the same time and used as a reservoir supply of such steel strut members. It will be immediately apparent that the provision of a unique fabrication identifier in this way ensures that the number of work pieces in progress at any given time is minimised as materials are provided for the efficient assembly and dispatch of entire steel sub-assemblies .

According to one aspect of the invention there is provided a process for producing a steel structure comprising the steps of: receiving a cut steel strut member; stamping the received steel strut member with a unique fabrication identifier for indicating a desired relative position and orientation within a steel sub-assembly; rigidly fixing a plurality of stamped steel strut members in accordance with the fabrication identifier to form the steel sub-assembly; stamping the assembled steel sub-assembly with a unique direction identification tag for correctly locating the steel sub-assembly in a desired orientation and position; and rigidly interconnecting a plurality of stamped assembled steel sub-assemblies in a desired relative orientation and position to form the steel structure.

T9709 3 β This greatly reduced the lead time in fabricating and erecting such a steel structure and consequently reduces costs .

Preferably the process further comprises the steps of: delivering each stamped assembled steel subassembly to a dispatch area; grouping delivered steel sub-assemblies into a dispatch group in accordance with the unique identification tag, the dispatch group containing adjacent and interdependent steel sub-assemblies of the steel structure; and delivering each dispatch group in a desired sequence to an erection site.

Thus, it will be readily apparent that by grouping the inter-dependent sub-assemblies in this way for delivering together the number of steel sub-assemblies stored on site is reduced if not altogether eliminated. Furthermore, by dispatching the associated steel subassemblies of the structure in groups the fabrication of costly steel sub-assemblies can be delayed until required for positioning within the steel structure. A further advantage is obtained in that correctly ordering and sequencing the sub-assemblies in this way allow for construction to begin at an earlier stage as care and attention is paid to ensure that the necessary steel sub-assemblies are obtained and dispatched as soon as possible.

Ideally the step of: receiving a steel sub-assembly specification; and retrieving a steel section from a supply and repeatedly cutting the steel section to a desired length in accordance with the steel sub-assembly specification to produce all cut steel strut members necessary to produce the steel subSg7 Ο» 3 β assembly.

In this way all of the pieces required to complete a given sub-assembly are delivered to the fabrication area in a similar just-in-time manner. This greatly facilitates the work throughput of the fabrication facility and reduces the production cost overhead associated with structures of this type. This is particularly so in that many of the delays causing excessive lead time in erecting such structures are associated with fabrication and very few of the delays are associated with cutting component struts.

According to a further aspect of the invention there is provided a steel sub-assembly for use in construction of a steel structure formed from a plurality of rigidly interconnected steel struts, each strut having a unique fabrication identifier for indicating a desired relative position and orientation to adjacent steel struts with the steel sub-assembly.

Ideally the steel sub-assembly has a unique erection identification means for correctly locating the steel sub-assembly in a desired orientation and position with respect to surrounding steel sub-assemblies within the steel structure.

For the purposes of this invention the term steel strut is taken to include all forms of structural steel member, such as rolled steel joists, angle irons, T beams, I beams and channel sections, etc.

Detailed Description of the Invention The invention will be more clearly understood from the following description thereof given by way of example only with reference to the accompanying drawings in which :Fig. 1 is a perspective view of a steel structure produced in accordance with the invention; 5970938 - 8 Fig. 2 is an exploded view of a portion of the steel structure of Fig. 1 illustrating a plurality of steel sub-assemblies; and Fig. 3 is a perspective view of a steel subassembly forming part of the invention.

Referring to the drawings and initially to Fig. 1 there is illustrated a steel structure produced according to the invention indicated generally by the reference numeral 1. The structure 1 is formed from a large number of interconnected steel sub-assemblies 2. Each of the steel sub-assemblies 2 is formed by a number of rigidly interconnected steel strut members 3.

In more detail and referring now particularly to Figs. 2 and 3 there is illustrated one such steel sub-assembly 2. The steel sub-assembly 2 has fixing means provided by four projecting rails 4 formed for engaging corresponding recesses or rails on adjacent steel subassemblies. The steel sub-assembly 2 also has an erection identification stamp 5 in one corner for correctly locating the steel sub-assembly 2 in a desired orientation with respect to surrounding steel subassemblies within the steel structure 1. The erection identification stamp 5 indicates a unique part number associated with the particular steel sub-assembly together with a part number to which the particular steel sub-assembly is to be attached and an alignment tag for indicating when the correct orientation and relative position between steel sub-assemblies has been achieved.

Each of the steel strut members 3 at the sub-assembly 2 has a unique fabrication identification tag 8 adjacent one end to facilitate and position the strut members 3 within the steel sub-assembly 2. In this way , adjacent steel strut members 3 are delivered in the correct sequence to facilitate the fabrication of the steel subassembly 2 ensuring that the minimum of steel subassemblies 2 are under construction at any given time.

I ι According to another aspect of the invention there is provided a process for producing a steel structure 1. The process begins when a steel sub-assembly specification is received and a steel section is retrieved from a supply area. The retrieved steel section is then cut into the cut steel strut members necessary to produce the steel sub-assembly in accordance with the steel sub-assembly specification received. Thus, delays in fabrication of each of the required steel sub-assemblies are minimised as all of the component parts are readily available when the piece is ready for fabrication.

The process continues as each of the cut steel strut members is stamped in accordance with the steel sub15 assembly specification with a unique fabrication identifier. This unique fabrication identifier indicates the desired relative position and orientation of the given steel strut member within the steel subassembly. When the steel strut members are rigidly fixed again in accordance with the steel sub-assembly specification the steel sub-assembly itself is stamped with a unique direction identification tag for correctly locating the steel sub-assembly in a desired orientation and position within the steel structure. This allows for the implementation of just-in-time like manufacturing and management systems in that the steel sub-assemblies having the unique direction identification taps stamped on are delivered to a dispatch area where they are grouped in accordance with the identification tag into dispatch groups. These dispatch groups are made up of steel sub-assemblies which will ultimately be interconnected and interdependent within the steel structure when rigidly connected. Obviously, the advantages of this are many in that it reduces the lead time associated in producing such a steel structure by allowing initial steel subassemblies to be delivered to the site for initial erection before beginning fabrication of subsequent steel sub-assemblies.

In addition, the on-site storage of steel sub-assemblies -V 5970938 - 10 may be eliminated and thus identification of component parts to be used in the steel structure is greatly facilitated.

In addition, the unique erection identification stamp 5 5 of each steel sub-assembly 2 ensures that adjacent steel sub-assemblies are delivered to a construction site in the correct sequence. This advantageously minimises the number of such steel sub-assemblies on site at any give time.

Additionally, as each steel sub-assembly is clearly identified and thus its relative position within the steel structure 1 is also clearly indicated, the skill level of the construction personnel on site is significantly decreased as the necessity for the skill required to identify the given components within the structures is obviated.

It will be appreciated that while steel is referred to throughout the specification that any other suitable material may be used and that the invention is not limited to the embodiments hereinbefore described, but may be varied in both construction and detail.

Claims (5)

1. A steel structure formed from a plurality of steel sub-assemblies, each steel sub-assembly comprising a plurality of rigidly interconnected steel strut members and having fixing means for engaging associated adjacent steel sub-assemblies, forming on assembly a rigid structure, and having unique erection identification means adjacent one of said fixing means for correctly locating the steel subassembly in a desired orientation and position with respect to surrounding steel sub-assemblies within the steel structure indicating sequence of assembly.

2. A steel structure as claimed each steel strut member has a identifier for indicating a position and orientation for member with respect to adjacent within a steel sub-assembly. in claim 1 wherein unique fabrication desired relative each steel strut steel strut members

3. A process for producing a steel comprising the steps of: structure receiving a steel sub-assembly specification; retrieving a steel section from a supply and repeatedly cutting the steel section to a desired length in accordance with the steel sub-assembly specification to produce all cut steel strut members necessary to produce the steel sub-assembly; receiving a cut steel strut member; stamping the received steel strut member with a unique fabrication identifier for indicating a desired relative position and orientation within a steel sub-assembly; rigidly fixing a plurality of stamped steel $970939» - 12 strut members in accordance with the fabrication identifier to form the steel subassembly; stamping the assembled steel sub-assembly with a unique direction identification tag for correctly locating the steel sub-assembly in a desired orientation and position; rigidly interconnecting a plurality of stamped assembled steel sub-assemblies in a desired relative orientation and position to form the steel structure; delivering each stamped assembled steel subassembly to a dispatch area; grouping delivered steel sub-assemblies into a dispatch group in accordance with the unique identification tag, the dispatch group containing adjacent and interdependent steel sub-assemblies of the steel structure; and delivering each dispatch group in a desired sequence to an erection site.

4. A steel sub-assembly for use in construction of a steel structure formed from a plurality of rigidly interconnected steel struts, each strut having a unique fabrication identifier for indicating a desired relative position and orientation is adjacent steel struts within the steel subassembly, the steel sub-assembly having a unique erection identification means for correctly locating the steel sub-assembly in a desired orientation and position with respect to surrounding steel sub-assemblies within the steel structure .

5. A steel structure as with reference to the accompanying drawings.