AU773310B2

AU773310B2 - A portal frame

Info

Publication number: AU773310B2
Application number: AU59520/00A
Authority: AU
Inventors: Hayden Dagg
Original assignee: Onesteel Trading Pty Ltd
Current assignee: Infrabuild Trading Pty Ltd
Priority date: 1999-09-29
Filing date: 2000-09-20
Publication date: 2004-05-20
Anticipated expiration: 2020-09-20
Also published as: AU5952000A

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): ONESTEEL TRADING PTY LIMITED Invention Title: A PORTAL FRAME The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 A PORTAL FRAME FIELD OF THE INVENTION The present invention relates generally to a portal frame for use in a portal frame shed and relates particularly, though not exclusively, to a portal frame comprising an apex or knee connector. The invention further relates to a method of constructing a portal frame for a portal frame shed.

SUMMARY OF THE INVENTION According to one aspect of the present invention there is provided an apex connector or a knee connector that is adapted for inclusion in a portal frame having two columns and two rafters that are each of a closed hollow section, the apex connector being adapted for connection to one end of both of the rafters to form an apex connection, and the knee connector being adapted for connection to an opposite end of one of the rafters and an end of one of the columns to form a knee connection, the apex connector or the knee e connector being of a closed hollow section, that is adapted for inclusion in a portal frame having two columns and two rafters that are each of a closed hollow section, the apex connector being adapted for connection to one end of both 025 of the rafters to form an apex connection, and the knee connector being adapted for connection to an opposite end of one of the rafters and an end of one of the columns to form a knee connection, the apex connector or the knee connector being of a closed hollow section and being formed and fabricated from a material and in a manner so as to promote plastic failure of the portal frame under a specified design criterion.

According to a further aspect of the present invention there is provided a portal frame comprising: 2a two columns and two rafters, each being of a closed hollow section; and an apex connector to which one end of both of the rafters is connected, and two knee connectors that are each configured to connect to an opposite end of one of the rafters and an end of one of the columns, thereby forming the portal frame, the apex and the knee connectors each being of a closed hollow section, A portal frame comprising: two columns and two rafters, each being of a closed hollow section; and an apex connector to which one end of both of the rafters is connected, and two knee connectors that are each configured to connect to an opposite end of one of the rafters and an end of one of the columns, thereby forming the portal frame, the apex and the knee connectors each being of a closed hollow section, with the columns, rafters and connectors each being formed and fabricated from a S.material and in a manner so as to promote plastic failure 20 of the portal frame under a specified design criterion.

eei eeoc 3 According to another aspect of the present invention there is provided a method of constructing a portal frame, comprising the steps of: providing two columns and two rafters that are each of a closed hollow section; providing an apex connector and two knee connectors that are each of a closed hollow section; connecting one end of both of the rafters to the apex connector, and connecting an opposite end of one of the rafters and one end of one of the columns to each of the respective knee connectors, thereby forming the portal frame, the apex and knee connectors each being a method of constructing a portal frame, comprising the steps of: providing two columns and two rafters that are each of a closed hollow section; providing an apex connector and two knee connectors that are each of a closed hollow section; connecting one end of both of the rafters to the apex connector, and connecting an opposite end of one of the 20 rafters and one end of one of the columns to each of the respective knee connectors, thereby forming the portal frame, the apex and knee connectors each being formed and fabricated from a material and in a manner so as to provide plastic failure of the portal frame under a specified 25 design criterion.

e.

The terminology "specified design criterion" as used herein refers to an approved building or construction standard .0 which allows for plastic failure of a portal frame formed from closed hollow section.

Preferably the apex connector and/or the knee connector comprises an internal sleeve having opposite ends adapted for slidable receipt within the corresponding column or rafter, and an external sleeve formed about an intermediate section of the internal sleeve, the internal and external 3a sleeves together providing a moment connection such that plastic failure of the portal frame occurs within the columns and/or rafters remote from the connectors.

Typically, each internal or external sleeve is formed from two elongate closed hollow sections having adjacent ends welded to one another so as to form the apex or knee connector.

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*o o go *g 4 Preferably the portal frame further comprises two base fixtures each adapted for connection to an opposite end of each of the respective columns, the base fixtures being adapted for location on the ground to anchor the portal frame. More preferably each of the base fixtures comprises a base plate to which a spigot is connected, the spigot configured to be slidably received within the opposite end of the column.

Generally the portal frame is one of a series of portal frames included in a portal frame shed.

Typically the portal frame shed includes a plurality of purlins each connected between and disposed transverse to adjacent rafters of the adjacent portal frames. More typically opposing ends of each of the purlins are connected or coupled to the adjacent rafters via a purlin to rafter coupling being configured to locate upon the rafter and connect to the purlin whereby the purlin is o 20 substantially flush with the rafter.

Preferably the closed hollow section is rectangular hollow section (RHS) such that the apex and knee connectors, columns, rafters, and/or purlins are each in the form of

RHS.

Also disclosed herein is a purlin to rafter coupling comprising a saddle member being adapted to locate upon the C. rafter, the saddle member being configured to temporarily 30 slidably move along the rafter. The coupling further comprises a purlin fixture connected to the saddle member, oo..

the purlin fixture being adapted to secure to or locate one end of the purlin whereby respective upper surfaces of the rafter and the purlin are substantially flush. This purlin fixture can be integrally formed with the saddle member.

In this regard, the purlin to rafter coupling can be fabricated from a single steel sheet. The purlin fixture 5 can be formed as a shoe being shaped internally substantially complementary to the end of the purlin which can thus be seated in the shoe for connection or coupling to the rafter.

BRIEF DESCRIPTION OF THE DRAWINGS In order to achieve a better understanding of the nature of the present invention a preferred embodiment of a portal frame shed together with other aspects of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a perspective view of one embodiment of a framework for a portal frame shed; Figure 2 is a detailed schematic of a portal frame such as that included in the portal frame shed framework of Figure 1; Figure 3 is a schematic of another portal frame; Figure 4 is a detailed partly exploded arrangement of an apex connection such as that of the portal frames of oooo 20 Figures 2 and 3; *Figure 5 is a partly exploded arrangement of a knee connection of a portal frame such as that of Figures 2 and *3; Figure 6 is an exploded perspective view of a purlin to rafter coupling; and Figure 7 is a detailed plan and elevational view of a base fixture of a portal frame shed such as that of Figure 1.

30 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in Figure 1, framework of a portal frame shed is shown generally as 10 and comprises a series of portal frames 12A to 12C which are erected in a vertical orientation and interconnected via roof purlins and wall girts such as 14A to 14D and 16A to 16C, respectively.

6 As depicted in Figures 2 and 3 each of the portal frames such as 12B includes a pair of columns 18A and 18B together with a pair of rafters 20A and 20B. Adjacent ends of the pair of rafters 20A and 20B are interconnected via an apex connector 22 so as to form an apex connection 24. An opposite end of each of the rafters 20A or 20B is connected to an upper end of one of the columns such as 18A via a knee connector 26A or 26B.

A lower end of each of the columns 18A or 18B is anchored to the ground, which is usually a concrete slab or foundation, via a respective base fixture 28A or 28B. The purlins of Figures 1 and 2 such as 14B individually locate between adjacent portal frames such as 12B and 12C whereas 15 the purlin 14C of Figure 3 extends the full length of the portal frame shed 10. In the preferred embodiment of Figures 1 and 2 opposite ends of the purlins such as 14A to 14D connect to corresponding rafters such as 20B via a purlin to rafter coupling 30. Alternatively, the purlin 14C of Figure 3 is anchored to the rafter 20B using a purlin to rafter strap 32.

S. Importantly the portal frames 12A to 12C and purlins such as 14A to 14D are of a closed hollow section, in this example rectangular hollow section (RHS). Preferably the RHS members are those commercially available in Australia under the trade mark DuraGal.

The portal frame shed 10 of this embodiment is designed to permit plastic failure under a specified design criterion.

For example, the Australian standard presently specifies the plastic failure of buildingstructures including portal frame sheds whereby multiple plastic hinges form upon plastic deformation of the portal frame. Although the Australian standard for plastic analysis is directed to open-sections such as universal beams or universal columns, 7 the applicant has been the first to extend this plastic analysis to closed sections such as cold-formed RHS DuraGal in tests conducted at the University of Sydney, Australia.

The inclusion of the apex and knee connectors such as 22 and 26A/26B, respectively, in the portal frame shed 10 is a critical element in allowing formation of the multiple plastic hinges in plastic failure of the portal frame The apex and knee connectors 22 and 26 are designed whereby plastic hinges are formed in the columns 18A/18B and rafters 20A/20B before failure of the connector 22 or 26.

In this example this is achieved by the apex connector 22 and knee connector 26 of Figures 4 and 5, respectively.

The apex connector of Figure 4 comprises an internal sleeve 34 formed in this example from RHS spigots 36A and 36B welded to one another so as to define an obtuse angle at S: which the roof of the portal frame shed 10 is pitched. The apex connector 22 also includes an external sleeve 38 20 located over an intermediate section of the internal sleeve 0 34 to provide a moment connection. The external sleeve 38 e: in this example consists of RHS collars 40A and 40B slid over corresponding spigots 36A and 36B and welded to one another at the juncture of the RHS spigots 36A and 36B.

25 The apex connector 22 thus provides telescopic connection eeo0 for a pair of rafters such as 20A and 20B. The apex connector 22 is configured so that a square cut RHS rafter 00 such as 20A or 20B abuts the corresponding RHS collar or The knee connector 26 of Figure 5 is practically identical in construction to the apex connector 22. For ease of reference like components of the knee connector 26 have been prefixed with the numeral For example, the internal and external sleeves are designated as 134 and 138, respectively. Otherwise, the knee connector 26 is designed at such an angle whereby the column such as 18A is 8 oriented substantially upright. Once again the knee connector 26 is designed so that under plastic failure multiple hinges occur within the columns or rafters 18 or remote from the connectors 22 or 26.

The internal RHS sleeve 34 or 134 of this embodiment is rolled or formed from a steel product commercially available in Australia under the trade mark GALVABOND of a mm or thicker thickness and joined with a full strength butt weld. The external sleeve 38 or 138 is fabricated over the internal sleeve 34 or 134 with a full strength butt weld to provide the moment connection.

The square cut rafters such as 20A and 20B of this embodiment are DuraGal RHS of the dimensions 100 x 50 x or thicker or 150 x 50 x 2.5 or thicker. The square cut columns 18A and 18B are of the same dimension DuraGal RHS.

The particular cross-sectional dimensions may vary depending on the load requirements.

Figure 6 illustrates a purlin to rafter coupling. The purlin to rafter coupling 30 of Figure 2 comprises a saddle member 52 and a pair of purlin fixtures one of which is shown as 54 located on opposing sides and formed integral with the saddle member 52. The saddle member 52 is shaped complementary to the external profile of the rafter 20B and is designed to temporarily slide along the rafter Each of the purlin fixtures 54 is formed as a shoe having a bottom wall 56 and a pair of opposing web elements 58A and 30 58B connected to the saddle 52. The base wall 56 and webs see.

oo 58A and 58B are fabricated so that internally the shoe is shaped complementary to an end of the purlin 14B. Thus, the purlin 14B can be seated in the shoe of the purlin to rafter coupling 30. The base wall 56 is disposed relative to the saddle member 52 wherein an upper surface of the 9 purlin 14B and rafter 20B are substantially flush with one another. Generally the purlin to rafter coupling 30 is fabricated from a single steel sheet and press formed without welding.

The portal frame shed 10 of Figures 1 and 2 includes the base fixtures 28A and 28B such as those shown in detail in Figure 7. Each of the base fixtures 28 includes a base plate 60 upon which a pair of opposing angle-section members 62A and 62B are welded. The angle-section members 62A and 62B are of a DuraGal material and are configured to define a locating spigot on which a lower end of one of the columns 18 locates. The base plate 60 is anchored to in this example the concrete slab 64 via stud anchors 66A and 66B. The base fixtures 28A and 28B may be anchored to the concrete slab 64 with the stud anchors 66A and 66B located along one side, rather than at opposing ends, of the base plate The general steps involved in erection of the portal frame shed 10 described above will now be summarised: the base fixtures such as 28A and 28B are located at the predetermined span apart and secured to the concrete slab for each of the portal frames such as 12B; (ii) the required number of portal frames such as 12A to 12C are prefabricated on site with telescopic connection of the rafters and columns to the apex and knee connectors such as 22 and 26 as described above; (iii) a first of the portal frames 12A is erected upon its corresponding base fixtures and temporarily strutted; (iv) a second of the portal frames 12B is erected upon its corresponding base fixtures 28A and 28B; purlins such as 14A to 14D are interconnected between the adjacent portal frames 12A and 12B to stabilise the structure; 10 (vi) a third of the portal frames 12C is erected and the remaining purlins located between adjacent portal frames 12B and 12C; (vii) wall girts such as 16A to 16C are fixed between adjacent columns 18 of adjacent portal frames such as 12A and 12B; and (viii) the portal frame shed 10 is clad in a conventional manner.

It should be appreciated that fixing or interlocking of the portal frames 12A to 12C is effected using fastenings such as those commercially available in Australia under the trade name of TEK screws. Similarly the columns 18 may be fixed to the base fixtures 28 using TEK screws. Likewise, 15 the purlins 14A to 14D may be secured to the purlin to rafter coupling 30 which is then fixed to the rafter via TEK screws.

Now that preferred embodiments of the various aspects of see 20 the present invention have been described in some detail it will be apparent to those skilled in the art that the described embodiments of the invention have at least the following advantages: a portal frame shed or portal frame can be constructed which permits plastic failure of the portal frame; (ii) the portal frame shed is modular and relatively simple to construct requiring minimal trade skills; (iii) the portal frame shed is constructed in such a manner to eliminate or at least reduces surfaces on which dust and other contaminants can accumulate; and (iv) the portal frame sheds are aesthetically pleasing being constructed of closed section members.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and 11 modifications other than those specifically described. For example, the specific construction of the apex and knee connectors may vary from that described provided they permit plastic failure of the portal frame under the specified design criterion or standard. The rafters, columns and/or purlins may be formed of any closed-section member and are not restricted to DuraGal RHS.

All such variations and modifications are to be considered within the scope of the present invention.

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Claims

1. A portal frame comprising: two columns and two rafters, each being of a closed hollow section; and an apex connector to which one end of both of the rafters is connected, and two knee connectors that are each configured to connect to an opposite end of one of the rafters and an end of one of the columns, thereby forming the portal frame, the apex and the knee connectors each being of a closed hollow section, with the columns, rafters and connectors each being formed and fabricated from a material and in a manner so as to promote plastic failure of the portal frame under a specified design criterion.

2. A portal frame as claimed in claim 1 wherein the apex connector and/or the knee connector comprises an internal sleeve having opposite ends adapted for slidable receipt within the corresponding column or rafter, and an external sleeve formed about an intermediate section of the internal sleeve, the internal and external sleeves together providing a moment connection such that plastic failure of the portal frame occurs within the columns and/or rafters remote from the connectors. 25 3. A portal frame as claimed in claim 2 wherein each internal or external sleeve is formed from two elongate closed hollow sections having adjacent ends welded to one another so as to form the apex or knee connector.

4. A portal frame as claimed in any one of the preceding claims further comprising two base fixtures each adapted for connection to an opposite end of each of the respective columns, the base fixtures being adapted for location on the ground to anchor the portal frame. 13 A portal frame as claimed in claim 4 wherein each of the base fixtures comprises a base plate to which a spigot is connected, the spigot configured to be slidably received within the opposite end of the column.

6. A portal frame as claimed in any one of the preceding claims that is one of a series of frames in a portal frame shed.

7. A portal frame as claimed in any one of the preceding claims wherein the closed hollow section is rectangular hollow section.

8. A portal frame as claimed in any one of the preceding claims wherein the closed hollow section is cold-formed closed hollow section. S

9. A method of constructing a portal frame, comprising 0: the steps of: 20 providing two columns and two rafters that are each of S" a closed hollow section; providing an apex connector and two knee connectors that are each of a closed hollow section; connecting one end of both of the rafters to the apex 0o0o oo 25 connector, and connecting an opposite end of one of the S: rafters and one end of one of the columns to each of the *505. respective knee connectors, thereby forming the portal Os.. frame, the apex and knee connectors each being formed and fabricated from a material and in a manner so as to promote plastic failure of the portal frame under a specified design criterion. A method as claimed in claim 9 wherein the closed hollow section is rectangular hollow section. 14

11. A method as claimed in claim 9 or 10 wherein the closed hollow section is cold-formed closed hollow section.

12. An apex connector or a knee connector that is adapted for inclusion in a portal frame having two columns and two rafters that are each of a closed hollow section, the apex connector being adapted for connection to one end of both of the rafters to form an apex connection, and the knee connector being adapted for connection to an opposite end of one of the rafters and an end of one of the columns to form a knee connection, the apex connector or the knee connector being of a closed hollow section and being formed and fabricated from a material and in a manner so as to promote plastic failure of the portal frame under a specified design criterion.

13. An apex connector or a knee connector as claimed in claim 12 that comprises an internal sleeve having opposite ends adapted for slidable receipt within the corresponding column or rafter, and an external sleeve formed about an intermediate section of the internal sleeve, the internal and external sleeves together providing a moment connection such that plastic failure of the portal frame occurs within the columns and/or rafters remote from the connectors.

14. An apex connector or a knee connector as claimed in claim 12 wherein each internal or external sleeve is formed from two hollow elongate closed hollow sections having adjacent ends welded to one another so as to form the apex or knee connector. A connector as claimed in any one of claims 12 to 14, wherein the closed hollow section is rectangular hollow section. 15

16. A connector as claimed in any one of claims 12 to wherein the closed hollow section is cold-formed closed hollow section.

17. A portal frame substantially as herein described with reference to the accompanying drawings.

18. An apex connector or a knee connector substantially as herein described with reference to the accompanying drawings. Dated this 30th Day of January 2004 15 ONESTEEL TRADING PTY LIMITED .By its Patent Attorneys GRIFFITH HACK o*