Composite concrete slabs include profiled steel decking sheets, concrete that has been poured onto and has set on the decking sheets, and reinforcement (such as mesh or bars) embedded in the concrete.

The present invention relates particularly, but by no means exclusively, to profiled steel decking sheets that are used as formwork in the construction of composite concrete slabs that form the floors of buildings (including car parks).

Conventional profiled steel decking sheets include one upstanding rib or a plurality of upstanding parallel ribs that extend along the length of the sheets and are separated by flat pans. The sheets are usually roll-formed from metal coated, high tensile steel strip in base metal thicknesses of 0.6-1. 0 mm.

The ribs are provided to resist downward deflection of the profiled steel decking sheets in response to the weight of wet concrete poured onto the sheets during on-site construction of composite concrete slabs.

The standard construction procedure for composite concrete slabs includes positioning the decking sheets on an underlying steel or other support frame, positioning suitable side wall formwork around the perimeter of the slabs, and thereafter pouring wet concrete onto the decking sheets.

When the concrete hardens and reaches a sufficient compressive strength, the profiled steel decking sheets provide reinforcement for the composite concrete slabs. In addition, the ribs mechanically interlock the concrete and the profiled steel decking sheets.

A problem with the above-described profiled steel decking sheets during construction of composite concrete slabs is that there is a tendency for wet concrete to flow through the open ends of the ribs of the decking sheets.

In the case of the construction of floors for buildings, the concrete may drop into the lower floors and/or become adhered to the undersurface of the decking sheets in the regions of the open ends of the ribs. In situations where the undersurface of the decking sheets will be exposed, for example in car parks, it is necessary for the concrete to be removed. This can be a time- consuming exercise.

It is known to provide the ribs of decking sheets with plugs for the open ends of the ribs in order to prevent concrete flow via the open ends.

This specification discloses an invention of a method of inserting plugs into the open ends of the ribs of decking sheets, decking sheets having plugged ends produced by the method of the invention, and a roll forming line for manufacturing the decking sheets in accordance with the method.

According to the present invention there is provided a method of manufacturing profiled decking sheets that have at least one open rib separated by pans and are suitable for use as formwork in the construction of composite concrete slabs, the method including the steps

of: uncoiling a steel strip and passing the strip through one or more than one roll-former stand and progressively roll forming the steel strip to form one rib or a plurality of parallel ribs extending from the plane of the strip, and thereafter cutting/shearing the profiled strip into pre-determined lengths and thereby forming a plurality of profiled steel decking sheets, the method being characterised by a step carried out before the cutting/shearing step of inserting lengths of a plug material into at least one rib at locations that coincide with the locations for cutting/shearing the profiled strip so that the lengths span the cutting/shearing locations, whereby when the profiled strip is ultimately cut/sheared at the locations, the plug material plugs both ends of the cut/sheared rib at the locations.

Preferably the method further includes a step of inserting additional lengths of the same or a different plug material into at least one rib at locations that are between the ends of profiled decking sheets ultimately formed by the method. One purpose of such additional lengths of plug material is to provide seals on room walls between adjacent rooms of buildings ultimately made using the profiled decking sheets to address issues of sound attenuation, fire rating/proofing, and heat insulation.

Depending on the circumstances, it may be appropriate to use the same or a different plug material for the additional lengths of plug material inserted between the ends of the profiled decking sheets.

The additional lengths of plug material may be inserted prior to or after the cutting/shearing step.

Preferably the plug material is a compressible material.

Suitable compressible materials include, by way of example, rubber, polyethylene, and polystyrene.

Preferably the lengths of the plug material have substantially the same cross-section profile as that of the rib but have a larger cross-sectional area so that the step of inserting lengths of a plug material into the rib includes compressing the plug material in order to fit the lengths into the ribs.

According to the present invention there is provided a profiled steel decking sheet that has at least one open rib separated by pans suitable for use as formwork in the construction of a composite concrete slab and includes a plug that closes at least one end of at least one of the ribs and is formed by the above-described method.

The profiled steel decking sheet may also include additional lengths of the same or a different plug material in the ribs intermediate the closed ends of the ribs.

According to another invention there is provided a roll forming line for manufacturing profiled steel decking sheets that have at least one open rib separated by pans that are suitable for use as formwork in the construction of composite concrete slabs, the line including : (a) an uncoiler for a coil of strip; (b) one or more than one roll former stand for progressively roll forming the coated strip to form one rib or a plurality of parallel ribs extending from the plane of the strip ; and

(c) a means for cutting/shearing the coated profiled strip into pre-determined lengths of profiled steel decking sheets that include the rib or parallel ribs separated by pans; and the line being characterised by a means for inserting lengths of a plug material into at least one rib at locations that coincide with the locations for cutting/shearing the profiled strip so that the lengths span the cutting/shearing locations, whereby when the profiled strip is ultimately cut/sheared at the locations, the plug material plugs both ends of the cut/sheared rib at the locations.

Preferably the apparatus further includes a means for inserting additional lengths of the same of a different plug material into at least one rib at locations that are between the ends of profiled decking sheets ultimately formed by the method Preferably the plug material is a compressible material.

Suitable compressible materials include, by way of example, rubber, polyethylene, and polystyrene.

Preferably the lengths of the plug material have substantially the same cross-section profile as that of the rib but have a larger cross-sectional area so that the lengths of a plug material are compressed in order to fit the lengths into the ribs.

The present invention is described further by way of example with reference to the accompanying drawings, of which: Figure 1 is a side elevation of one embodiment

of a roll forming line for forming profiled steel decking sheets having plugged ends in accordance with one of the inventions; Figure 2 is a perspective view of a profiled steel decking sheet formed in accordance with one embodiment of the present invention on the line shown in Figure 1 ; and Figure 3 is an underside view of a roll-formed strip immediately after lengths of a plug material have been inserted into the open ribs of the strip on the line shown in Figure 1.

The embodiment of the profiled steel decking sheet shown in Figure 2 includes a series of parallel upstanding open ended ribs 3 separated by flat pans 5 and plugs 7 of rubber or other suitable compressible material in the ends of the ribs.

Each rib 6 has a top wall section 8 and downwardly and inwardly converging side wall sections 10 that define a downwardly facing opening of the rib.

The particular profile of the sheet shown in Figure 2 is a standard profile marketed by the applicant under the Registered trade mark BONDEK.

The sheet is formed from metal-coated, high tensile steel strip.

The profiled steel decking sheet shown in Figure 2 can be manufactured on the high speed roll forming line shown in Figure 1.

The roll forming line shown in Figure 1 includes an uncoiler 23 that holds a coil 25 of metal coated steel

strip so that the strip 71 can be unwound from the coil as a flat sheet and passed successively to and thereafter through a series of conventional roll-former stands 9.

The roll-former stands 9 progressively roll form a series of ribs in the flat strip 71 and thereby form the profile of the-coated profiled decking sheet shown in Figure 2. Each roll-former stand 9 includes a pair of lubricated shaped rolls 21.

Lubricant is applied to the strip 71 via appropriately located sprays 13,15, 17 along the roll- forming line.

The roll forming line also includes a shear station 27 at the end of the line that shears the coated profiled steel strip into pre-determined lengths, thereby to form a plurality of the Figure 2 decking sheet.

The roll forming line is characterised by a plug insertion station generally identified by the numeral 29 that inserts lengths 31 (as shown in Figure 3) of the plug material into the ribs 3 via the downwardly facing openings of the ribs 3 as the coated profiled steel strip moves from the last roll-former stand 9 to the shear station 27.

The roll forming line is controlled so that the plug insertion station 29 inserts the plug lengths 31 at locations that span the locations that are subsequently sheared at the shear station 27.

Consequently, shearing the profiled steel strip formed by the roll former stands 9 separates a downstream sheet from the strip and shears the length 31 of the plug material in each rib 3 into two sections with one section being retained in and plugging the upstream end of the rib

3 of the newly formed sheet and the other section being retained in and plugging the downstream end of the rib 3 of the strip.

As is indicated above, preferably the plug material is a compressible material such as rubber. In such situations, the lengths 31 of the plug material are formed with the same cross-section profile as that of the ribs 3 and have a larger cross-sectional area so that the plug material is compressed as the lengths 31 are inserted into the openings of the ribs 3. This ensures a tight fit of the plugs in the ends of the ribs 3.

The above-described roll forming line and method are a very effective option for inserting plugs of compressible material into the ends of ribs of roll formed profiled decking sheets.

In another, although not the only other, possible embodiment the profiled decking sheet of the present invention includes additional lengths of plug material in the ribs 6 between the ends of the sheet. The locations of the additional plug material are selected to coincide with a wall of a building so that the plug material forms a seal between adjacent rooms separated by the wall. Accordingly, the plug material improves sound proofing, fire proofing and heat insulation between the adjacent rooms.

Many modifications may be made to the preferred embodiments of the inventions described above without departing from the spirit and scope of the invention.

By way of example, the present invention extends to profile decking sheets that have lengths of a suitable plug material inserted in the ribs thereof between open ends of the ribs, with the locations of the material

selected to coincide with a wall of a building so that the plug material forms a seal between adjacent rooms separated by the wall. In this form of the present invention it is not necessary that the ends of the profiled decking sheets be closed by plug material (or other means).