AU2021103539C4

AU2021103539C4 - A flooring panel, system and method for constructing a fire-rated suspended floor

Info

Publication number: AU2021103539C4
Application number: AU2021103539A
Authority: AU
Inventors: warrick hancock
Original assignee: Shape Australia Pty Ltd
Current assignee: Shape Australia Pty Ltd
Priority date: 2021-06-22
Filing date: 2021-06-22
Publication date: 2022-12-15
Anticipated expiration: 2029-06-22
Also published as: US20220403647A1; AU2021103539A4; AU2021103539B4

Abstract

A fire-rated flooring panel for use in forming a suspended floor, comprising: a bottom metal sheet layer; an upper re-enforced concrete layer overlaying the bottom layer; and a structural steel frame enclosing circumferential walls of the upper and lower layers.

Description

A FLOORING PANEL, SYSTEM AND METHOD FOR CONSTRUCTING A FIRE RATED SUSPENDED FLOOR TECHNICAL FIELD

The present invention relates to a flooring panel which is particularly configured for the rapid construction of a fire-rated suspended concrete floor in a building. Embodiments of the present invention find application in the fields of passive fire protection and building construction.

BACKGROUNDART

Any discussion of documents, acts, materials, devices, articles or the like which has been included in this specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia or elsewhere before the priority date of this application.

It is imperative that large scale commercial buildings are rapidly built to be commercially feasible. It is also imperative that such buildings comply with the relevant fire safety standards and regulations.

Concrete slabs are commonly used in commercial buildings for constructing floors and ceilings. Conventionally, concrete slabs were formed on site. However, in-situ slab formation is time consuming due to the time required to form the slab and wait for the concrete to sufficiently cure. As such, the industry has moved toward using pre-cast concrete slabs that are formed off-site (and often in advance of the build) and shipped when ready to be installed. Pre-cast slabs are thus well suited for rapid construction, significantly reducing the time from project approval to occupancy.

Pre-cast slabs are recognised by the Building Code of Australia (BCA) as part structure and part sacrificial form work. Thus, they need to be compliant with the relevant fire safety standards. To meet these standards, floors comprising pre-cast slabs will often require a "topping slab" to be formed there over. In general terms, the topping slab operates not only to increase the structural depth and strength of the underlying base concrete, but also to cover non-fire rated elements of the floor (thus rendering them compliant). However, since topping slabs are necessarily formed in-situ, the forming and curing step significantly adds to the time taken to install the floor, thus increasing the cost of the build. Another limitation of pre-cast concrete slabs is that they result in a thick floor system and are not suitable for long spans.

Bondek metal sheets are a form of sacrificial form work that is increasingly being used in forming pre-cast concrete slabs. This method of construction involves pouring concrete over a layer of Bondek, which operates to provide an additional degree of slab flexibility allowing increased slab spans. However, the BCA does not recognise Bondek as part of the fire rating between floors since the underside of the sheet can be compromised by fire and fail. Thus, the fire rating is determined based on a depth of the concrete to the satisfaction of a structural engineer.

It would be advantageous if there was provided a fire rated flooring system that addressed the above limitations associated with suspended floors formed of pre-cast concrete slabs.

SUMMARY OF THE INVENTION

In one aspect of the present invention there is provided afire-rated flooring panel for use in forming a suspended floor, comprising: a bottom metal sheet layer; an upper re enforced concrete layer; and a structural steel frame enclosing circumferential walls of the upper and lower layers.

In an embodiment the frame comprises three or more side walls that enclose the respective circumferential walls.

In an embodiment at least one side wall of the structural steel frame comprises an inwardly extending upper flange. The at least one side wall may also comprise an inwardly extending lower flange connected to the upper flange by a web and wherein the upper and lower flanges form a parallel flange channel. An intermediate inwardly extending lower flange may be disposed between the upper and lower flanges and wherein the intermediate flange is configured to support an edge of the bottom metal sheet layer.

For rectangular shaped panels opposite side walls of the structural steel frame may comprise inwardly extending upper and lower flanges thereby forming facing parallel flange channels.

In an embodiment the concrete layer extends above each of the side walls thereby forming a stepped circumferential upper edge for receiving a fire-rated material.

In an embodiment the upper re-enforced concrete layer comprises a plurality of lifting points. An upper surface of the frame may also comprise a plurality of lifting points.

In an embodiment the panel further comprises one or more threaded bolt ends extending upwardly from the upper re-enforced concrete layer for use in securing a column to the panel.

In accordance with a second aspect there is provided a modular system for forming a fire rated suspended floor, the system comprising: a plurality of preformed panels, each panel comprising: a bottom metal sheet layer; an upper re-enforced concrete layer; and a structural steel frame enclosing circumferential walls of the upper and lower layers; and wherein, in use, a first panel is positioned adjacent a second panel such that an outer wall of the first panel bears against an outer wall of the second panel and such that an upper surface of the upper re enforced concrete layers lie generally flush with one another.

In an embodiment the panels are rectangular panels with opposing structural steel side walls and wherein the panels are positioned such that outer surfaces of adjoining side walls but against one another.

In an embodiment the system further comprises a fire rated material that sits within a channel defined between adjacent stepped edges of adjoining side walls and such that an upper surface of the fire rated material sits generally flush with the adjacent upper surfaces of the re-enforced concrete layers. The fire rated material may comprise, for example, Promat board, Vermiculite spray, Fyrecheck and/or Vermiculate paint.

In accordance with a further aspect there is provided a method of constructing a fire rated flooring panel for use in forming a suspended floor, comprising: fabricating a structural steel frame comprising a pair of parallel side walls and a pair of parallel end walls, the walls each formed of PFC steel and wherein the frame is fabricated such that flanged channels of each PFC steel wall face inwardly and wherein two or more of the flanged channels comprise inwardly extending sheet seating portions; seating a bottom metal sheet layer on the sheet seating portions; pouring concrete over the bottom metal sheet layer and allowing the concrete to set thereby form a re-enforced concrete layer that overlays the bottom layer.

The features and advantages of the present invention will become further apparent from the following detailed description of preferred embodiments, provided by way of example only, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Figure 1 is a perspective view of a panel in accordance with an embodiment of the invention; Figure 2 is a process flow outlining steps for fabricating the panel of Figure 1; Figure 3 is an isometric view showing a pair of side walls with angles fastened thereto; Figure 4 is a perspective view of a complete frame assembly, in accordance with an embodiment; Figure 5 is a perspective cutaway view of a completed panel, showing the various layers formed by the fabrication method outlined in Figure 2; Figure 6a is a partial section view of the panel of Figure 1 showing a stepped upper panel edge, in accordance with an embodiment; Figure 6b is the same partial section view as Figure 6a additionally illustrating bolted assembly of a column, in accordance with an embodiment; Figure 7 is a process flow outlining steps for panel assembly, in accordance with an embodiment; Figure 8 is a schematic showing a formation of panels that form a suspended floor, in accordance with an embodiment; Figure 9a is a partial isometric cutaway showing connection of adjacent panel sidewalls; and Figure 9b is a partial sectional view showing connection of adjacent panel sidewalls.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Embodiments described herein relate to a flooring panel and system for forming a fire-rated suspended concrete floor in a building. As will be discussed in subsequent paragraphs, the unique configuration of the panel as described herein allows it to be prefabricated offsite and readily shipped to any location for modular assembly with other panels to rapidly construct a suspended floor that adheres to the stringent Australian fire safety standards.

Referring to the Figures there is shown a fire rated prefabricate flooring panel 1 according to an embodiment of the invention. The panel 1 has a layered construction consisting of a bottom metal sheet layer la and upper re-enforced concrete layer lb. A circumferential structural steel frame 2 surrounds the upper and lower layers la, lb, thus forming a structural steel perimeter. The structural steel frame 2 is configured to butt up against, and be directly fastened to, an adjoining panel frame for forming a suspended floor as will be described in more detail in subsequent paragraphs.

As stated above, the flooring panel 1 is typically pre-fabricated off site and a general method of fabrication will now be outlined. The method will be described in the context of forming a four sided rectangular panel 1 configured for securing to a correspondingly shaped panel (i.e., so as to form a partial section of a suspended concrete floor). A rectangular panel 1 fabricated using this method may span 3m wide by 13 m long, thus allowing it to be transported by road without exceeding wide load transport constraints. A depth of the panel (dictated primarily by a thickness of the upper layer lb) may vary depending on the desired application and subject to engineering specifications. However, a typical thickness range is between 120 and 200mm. It will be understood that other regular and irregular panel shapes may equally be fabricated using this general methodology, depending on the flooring configuration and engineering specifications.

With reference to Figure 2, the method commences with the fabrication of the structural steel frame 2. More particularly, at step Si, a pair of side perimeter walls 3a, 3b for the frame 1 are selected and, if necessary, cut to specified length using any suitable cutting tool. The side walls 3a, 3b take the form of parallel flange channel (PFC) steel beams having upper and lower flanges connected by a web. The walls are of the same channel height, width and length. Typically, the height will range between 150mm to 380mm, the width between mm to 100m and the length varying as required for specific installation. At step S2, holes are drilled in the upper flange of each channel with bolts 17a extending upwardly therethrough for subsequent use in securing floor columns (i.e., with the bolt head underlying or recessed within the upper flange). This is best shown in Figure 6b. During fabrication of the panel, each bolt 17a may be held in place by a nut 17b secured over the upper flange. The hole spacings and sizes, as well as the specification for the bolts/nuts, will vary depending on the floor configuration (and as per engineering specifications). Still at step S2, a length of shelf steel angle 4 is installed on a channelled face of each side wall 3a, 3b. The angles 4 span substantially the length of the corresponding wall 3a, 3b and are used to support the bottom metal sheet layer la, as will be described below. The angles 4 may, for example, be welded, bolted or otherwise securely fastened. The location of the angle 4 on the channelled face can vary depending on the PFC dimensions, requisite thickness of the upper layer lb and thickness of fire rated material used to cover the frame (as will be described in more detail in subsequent paragraphs). A side wall 3a with angle attached thereto is shown in Figure 3.

At step S3, a pair of end perimeter walls 3c, 3d are fabricated. The end walls 3c, 3d also take the form of PFC steel beams, however need not be as large as the side walls 3a, 3b since they are not as structurally integral. A typical PFC end wall height is 150mm. Once cut to length (if necessary), at step S4, one of the end walls 3c is welded between corresponding ends of the side walls 3a, 3b such that the upper faces of each wall 3a, 3b, 3c lie flush so to as to allow a flat form edge for the concrete. The three-sided (partial) frame assembly is configured such that the channelled faces of each frame wall 3a, 3b, 3c face inwardly.

At step S5, the metal sheet layer la is slid into the partial frame assembly from the open end with edges thereof seated on the opposing angles 4. The metal sheet layer la has substantially the same internal length and width as the partial frame and, according to embodiments described herein, is formed of Bondek (manufactured by Lysaght Australia, see URL: https://www.lysaght.comproducts/bondek). The metal sheet layer la provides a permanent formwork for formation of the upper concrete layer lb. At step S6 re enforcement 7 is placed over the layer la in a conventional manner. The final step of fabricating the steel frame 2 comprises securing the remaining end wall 3d to the free ends of the partial frame assembly (i.e., in the same manner as for end wall 3c), thus forming a closed rectangular perimeter formed of structural steel. This is best shown in Figure 4.

Once the structural steel frame 2 has been assembled, at step S7 formwork having an inner profile corresponding to that of the frame 2 is seated on the upper flanges of the assembly (i.e., with the opening of the formwork in registration with the opening of the frame assembly). According to the illustrated embodiment, the formwork has a depth of 20mm and can be formed of any suitable material, such as timber, aluminium, etc. As will become evident from subsequent paragraphs, the formwork is used to create a stepped upper edge profile (concrete lip 19) for the panel 1 that, in use, creates a channel for receiving a fire rated material 13 that covers the exposed upper flange of the side and end walls 3a, 3b, 3c, 3d. According to the illustrated embodiment, the fire rated material may comprise a fire rated board, such as Promat Systempanel 2G (manufactured by Promat Australia Pty. Ltd., see URL: https://www.promat.com/en-au/construction/products systems/systems/compartmentation/promat-systempanel-2g-fire-rated-floor-ceiling-system). The depth of the channel (i.e., formed by adjacent concrete lips 19) is determined by the desired fire rating. It will be understood that various fire rating product have different criteria and depths. In the example case of Promat Systempanel 2G, a 20mm board thickness gives min of fire protection.

Still at step S7 lifting points 9 are tied to the reinforcement 7 to allow for lifting of the panel 1. Additional lifting points 11 may be provided in the upper flanged wall of the side walls 3a, 3b, 3c, 3d. The lifting point locations are determined by the structural engineer.

Step S8 involves pouring concrete into the internal space defined by the metal layer la, frame 2 and rectangular formwork. Once cured and finished the formwork is removed, resulting in a completed panel 1 ready for transportation. At this point the nuts 17b used to retain the bolts 17a may be removed (since the head of the bolt 17a is now cast into the panel). Figure 5 is a partial cut-away view illustrating the formation of layers of the completed panel 1. Figure 6a is a sectional view showing the stepped edge created by the formwork. Figure 6b shows a partial cross section taken along a portion of the panel 1 that is configured to support a column 12.

Figure 7 is a process flow outlining the steps for panel assembly. At step S9, a crane is used to lift a panel 1 into place using either the lifting points 9 cast into the face of the concrete upper layer lb, or the structural steel lifting points 11. Typically, a panel 1 is seated over four columns 12 extending from the floor below. Once seated in place bolts may be used to secure the panel I to each column 12 (step S10). In a particular embodiment, a hole drilled in the lower flange of the panel 1 aligns with a hole in an upper flange of the column 12 for receiving a bolt used to secure the two parts together. Similarly, for mounting a column 12 to an upper face of the panel 1, holes in a lower flange of the column will align with the threaded bolt ends extending upwardly out of the upper flange of the panel side wall 3a, 3b. The column 12 is then seated over the panel as shown in Figure 6b, with nuts used to fasten the two parts together. It will be understood that the holes in the panel 1 and column flanges may be predrilled for suitable alignment. Typically, the suspended floor will be formed of multiple panels 1 located in a grid like fashion, as is best shown in Figure 8. At step Sl l, adjacent panels 1 are bolted together. More specifically, this involves locating panels 1 such that adjacent side walls butt up against one other (i.e., with the PFC side walls 3a, 3b in a back-to-back orientation). This is best shown in Figure 9a. Bolts 21 are subsequently passed through holes (typically pre-drilled) through adjacent side walls under the angles 4. Nuts 23 are then fastened to the bolts thus preventing separation of the adjoining side walls 3a, 3b. At step S12, a fire rated material 13 is installed (e.g., glued, nailed, or otherwise suitablyfixed) in a channel created by the adjacent stepped upper edges 19 of adjoining panels 1. This operates to fire rate the upper metal surface of the assembled frame 2. This is best shown in Figure 9b. As shown, an upper surface of the fire rated material 13 sits flush with the upper surface of the panel 1. Returning to Figure 9a, at step S13 the underside of the connected frame walls 3a, 3b, 3c, 3d are cladded, coated or otherwise protected with a fire rated material 15 using one of the various fire rating options common in the industry, such as Vermiculite spray, Promat Board, Fyrechek, or Vermiculite paint.

One or more of the following advantages may arise from the embodiments as afore described:

Panel configuration readily provides fire rating between floors and the modular system can be configured to meet the requirements of any floor dimension;

Panel lengths and widths can be adopted to any permutation with the intent to maximise the floor area and minimise the transport that is required to site;

The trafficable and sturdy panel configuration obviates the need for a topping slab and adjacent panels can be readily bolted together from underneath. Columns can be fixed from above using traditional methods;

Panels can be efficiently fabricated off site and before any works on site commence.

While a number of preferred embodiments have been described, it will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A fire-rated flooring panel for use in forming a suspended floor, comprising: a bottom metal sheet layer; an upper re-enforced concrete layer; and a circumferential structural steel frame comprising three or more side walls that at least partially surround the bottom and upper layers and wherein at least one of the structural steel side walls comprises inwardly extending upper and lower flanges connected by a web thereby forming a parallel flange channel and wherein a portion of the web connected to the lower flange extends beyond the bottom metal sheet layer thereby creating a panel joining portion for abutment against, and securing to, a corresponding joining portion of an adjacent fire-rated flooring panel, and wherein the panel is pre-formed prior to installation of the suspended floor.

2. A fire-rated flooring panel in accordance with claim 1, wherein the panel further comprises an intermediate inwardly extending flange disposed between the upper and lower flanges and wherein the intermediate flange is configured to support an edge of the bottom metal sheet layer.

3. A fire-rated flooring panel in accordance with claim 1 or 2, wherein the concrete layer extends above each of the structural steel side walls thereby forming a stepped circumferential upper edge for receiving a fire-rated material.

4. A modular system for forming a suspended floor, the system comprising: a plurality of prefabricated fire-rated flooring panels as defined in any one of claims 1 to 3; and wherein, in use, a first of the panels is positioned adjacent a second of the panels such that an outer wall of the first panel bears against an outer wall of the second panel and such that an upper surface of the upper re-enforced concrete layers lie generally flush.

5. A modular system in accordance with claim 4, wherein the panels are the panels according to claim 3 and wherein the system further comprises a fire rated material that sits within a channel defined between adjacent stepped edges of the side walls and such that an upper surface of the fire rated material sits generally flush with the adjacent upper surfaces of the re-enforced concrete layers, and wherein the fire rated material comprises one or more of Promat board, Vermiculite spray, Fyrecheck and Vermiculate paint.