The present invention relates to the field of construction, and more specifically relates to the elaboration of a floor deck structure and of a composite floor deck. The present invention also relates to a process for assembling such a floor deck structure and such a composite floor deck.

Composite floor decks are well known in the field of construction, and they typically comprise a corrugated / profiled metallic sheet, a wire mesh and concrete encompassing the wire mesh and fastened to the profiled metallic sheet by chemical bonding and/or mechanical or frictional interlocking.

The composite floor decks are particularly interesting because the metallic sheet acts as a working platform before concrete pouring and, after concrete hardening, gets incorporated to the concrete slab, working as full or part of tension reinforcement of the slab. As such, the composite floor decks reduce the amount of propping during concrete pouring.

The floor deck resistance depends on the height of the corrugations, and the higher the corrugations are, the more resistant the deck is. However, in some circumstances, the height of the deck has to be limited due to construction specific needs / requirements / National Standards. For example, there are locations where decks are limited in height to 75 mm, limiting their use to short spans. This leads to a limited composite floor deck resistance and span and the deck needs to be propped up during the concrete pouring phase.

The aim of the present invention is therefore to remedy the drawbacks of the prior art by providing a floor deck structure and a composite floor deck which can reach sufficient spans without the need for propping up.

The present invention also provides a process for assembling the floor deck structure and the composite floor deck of the invention.

For this purpose, a first object of the present invention consists of a floor deck structure, comprising:

- a profiled metallic sheet comprising at least a first, a second and a third upper portion separated by a first and a second longitudinal groove comprising a base, a first lateral wall linking the base to one of the upper portions and a second lateral wall linking the base to an adjacent upper portion;

- a first and a second rebar truss each extending longitudinally in and/or above, respectively, the first and second longitudinal groove and,

- a plurality of connectors fastening the first and the second rebar trusses to the profiled metallic sheet.

The floor deck structure according to the invention may also have the optional features listed below, considered individually or in combination:

- The plurality of connectors is fastening the first and second rebar trusses respectively to the first and second longitudinal groove.

- The connectors comprise a first and a second side, respectively fastened to the first lateral wall and the second lateral wall.

- The shape of each connector matches at least partially the shape of the corresponding longitudinal groove.

- The profiled metallic sheet has a unique transverse shape.

- The distance called height dimension between the base of any groove and the adjacent upper portion is comprised between thirty millimeters and eighty millimeters.

- The floor deck structure comprises at least one longitudinal plate, said plate comprising a longitudinal side which is fastened to the base of the first or second longitudinal groove and that is extending substantially perpendicularly to said base.

- Each rebar truss comprises a plurality of longitudinal metallic rebars.

- Each rebar truss has a triangular transverse section.

- Each connector is designed for, and capable of, being clipped on the corresponding rebar truss.

- The plurality of connectors fastens the first and the second rebar trusses to the profiled metallic sheet so that the relative movement of the first and the second rebar trusses with respect to the profiled metallic sheet is prevented. - each connector is unmovingly fastened to the profiled metallic sheet.

- Each connector is bolted on the profiled metallic sheet.

- Each connector is screwed on the profiled metallic sheet.

- Each connector is welded to the profiled metallic sheet.

- The first and second rebar truss are unmovingly fastened to the plurality of connectors.

- Some nodes of the first and second rebar truss are put in contact with a plurality of connectors so that they cannot move with respect to the connectors.

- The first and second rebar truss are welded to the plurality of connectors.

A second object of the invention consists of a composite floor deck, comprising:

- a floor deck structure comprising at least a first, a second and a third upper portion separated by a first and a second longitudinal groove comprising a base, a first lateral wall linking the base to one of the upper portions and a second lateral wall linking the base to an adjacent upper portion, a first and a second rebar truss each extending longitudinally in and/or above, respectively, the first and second longitudinal groove, and connectors fastening the first and the second rebar trusses to the profiled metallic sheet, and,

- a concrete structure embedding the rebar trusses and anchored to the metallic sheet.

A third object of the invention consists of a process for assembling a floor deck structure, wherein the process comprises at least the following steps:

(i) providing a profiled metallic sheet comprising at least a first, a second and a third upper portion separated by a first and a second longitudinal groove comprising a base, a first lateral wall linking the base to one of the upper portions and a second lateral wall linking the base to an adjacent upper portion,

(ii) providing at least a first and a second rebar truss, (iii) respectively positioning the rebar trusses in and/or above the first and second longitudinal grooves, and

(iv) fastening the first and the second rebar trusses to the metallic sheet using connectors.

A fourth object of the invention consists of a process for assembling a composite floor deck, wherein the process comprises at least the following steps:

(i) providing a floor deck structure according to the invention and

(ii) pouring concrete on the metallic sheet of the floor deck structure in order to encompass the rebar trusses.

Other characteristics and advantages of the invention will be described in greater detail in the following description.

The invention will be better understood by reading the following description, which is provided purely for purposes of explanation and is in no way intended to be restrictive, with reference to:

- Figure 1 , which represents a perspective view of the floor deck structure of the invention;

- Figure 2, which represents a perspective view of the corrugated / profiled metallic sheet of the floor deck structure of figure 1 ;

- Figures 2a to 2c, which represents various transverse shapes of the corrugated / profiled metallic sheet;

- Figure 3, which represents a perspective view of the rebar truss of the floor deck structure of figure 1 ;

- Figure 3a, which represents a perspective view of the rebar truss of the floor deck structure of figure 1 unmovingly fastened to connectors of Figure 5;

- Figure 4, which represents a perspective view of a connector in a first variant;

- Figure 4a, which represents a cross section view of a rebar truss linked to the connector of figure 4; - Figure 5, which represents a perspective view of a connector in a second variant;

- Figure 6, which represents a perspective view of the composite floor deck of the invention;

- Figure 7, which represents a graphic showing deflection of the composite floor of the invention versus deflection of the profiled metallic sheet alone of said composite floor;

- Figure 8, which represents a graphic showing stiffness versus span of the composite floor of the invention versus that of the profiled metallic sheet alone of said composite floor;

- Figure 9, which illustrates the results of numerical simulation on two variants of the invention.

It should be noted that the terms “lower”, “upper”, “above”, “bottom”... as used in this application refer to the positions and orientations of the different parts of the floor deck structure and composite floor deck when they are lying down on the ground. The terms “substantially perpendicularly” define an angle of 90° +/- 15° and the terms “substantially parallel” define an angle of 0° +/- 15°.

The invention relates to a floor deck structure 1 . According to figures 1 to 2c, the floor deck structure 1 comprises a profiled metallic sheet 2, preferentially a profiled steel sheet 2. In a known manner the profiled metallic sheet 1 can be made of galvanized steel. In this case, the metallic coating covering the metallic sheet can be made of a zinc-based alloy, optionally comprising Al and/or Mg and/or Si.

This profiled metallic sheet 2 comprises a plurality of upper portions 7 separated by a plurality of grooves 3, thus forming a corrugated metallic sheet. As an example and as depicted in figure 2, the metallic sheet 2 comprises five upper portions 7 and four grooves 3. Each groove 3 comprises a base 5 and a first and a second lateral walls 13, 14 respectively linking two adjacent upper portions 7 to the base 5 of said groove 3. The succession of grooves 3 and upper portions 7 improves rigidity and stiffness of the metallic sheet 2 while its thickness remain low, typically between 0,75 and 2 millimeters. Further in the description, the combination formed by an upper portion 7 and the two opposite lateral walls 13, 14 linked to said upper portion 7 will be further called a longitudinal element 6.

The distance H between the base 5 of any groove 3 and the adjacent upper portion 7, which will be further called groove height H, is for example and preferentially comprised between 30 millimeters and 80 millimeters. Preferably, the ratio of the distance between the first and the second lateral walls 13, 14 of a groove 5, further called width of the base 5, to the groove height H is lower than 5 and is more preferably comprised between 0.5 and 3.5. In addition, the ratio of the width l of the profiled metallic sheet 2 to the groove height H is preferably lower than 25 and more preferably comprised between 10 and 20, said width l of the profiled metallic sheet being its transverse dimension. Typically, the width l of the profiled metallic sheet 2 is comprised between 0.5 meters and 1.5 meters, preferentially around 0.75 meters. Thanks to these ratios, the rigidity of the profiled metallic sheet and thus the resistance of the composite floor deck is further increased.

Advantageously and in order to further improve the rigidity of the profiled metallic sheet 2, said profiled metallic sheet may comprise additional stiffeners 15 arranged in the base 5 of the principal grooves 3 of the metallic sheet 2, and optionally along the lateral walls 13, 14 and along the upper portions 7. These stiffeners are preferably in the form of longitudinal ribs. Their height is small compared to the groove height H and the ratio of the groove height H to the stiffener height is preferably above 4 and more preferably between 5 and 100.

Regarding figures 2a and 2c, the metallic sheet 2 also advantageously comprises a plurality of embossment 16a, 16b protruding from the surface of the profiled metallic sheet 2 and at least located on the upper portions 7 and/or the lateral walls 13, 14 of the profiled metallic sheet 2. Those embossments 16a, 16b may also be located on the lateral walls 13, 14 of the grooves 3, and optionally on the base 5 of the grooves 3. They differ from the stiffeners is that they are episodic, i.e. they do not extend along the length of the metallic sheet but are positioned at regular intervals. They can be in the form of squared buttons, rounded buttons, oval buttons, oblong buttons, chevrons. The function of those embossments 16a, 16b will be explained later.

Finally, the profiled metallic sheet 2 may comprise one or several longitudinal plates (not depicted), each plate comprising a longitudinal side that is fastened to the base 5 of the corresponding groove 3 and extending substantially perpendicularly to said base 5. The plates enhance the mechanical resistance of the floor deck structure 1 and improve the interlocking of the profiled metallic sheet with concrete.

The profiled metallic sheet 2 may have different transverse shapes, as depicted in figures 2a to 2c.

According to figure 2a, the width of each longitudinal element 6 of the profiled metallic sheet 2 decreases towards the bases 5 at least locally along the lateral walls 13, 14. In other words, each groove 3 is dovetail shaped. In addition, each groove 3 comprises two additional stiffeners 15 arranged in the base 5 of said groove 3, and each longitudinal element 6 comprises at least one embossment 16a arranged in its upper portion 7.

Figure 2b represents a second variant of a profiled metallic sheet 2 wherein the width of each longitudinal element 6 decreases towards the bases 5 at least locally along the lateral walls 13, 14. In other words, each groove 3 is dovetail shaped. In particular, the two lateral walls 13, 14 are S-shaped in order to create a re-entrant profile 30 of the longitudinal element 6. In addition, each groove 3 comprises one additional stiffener 15 arranged in the base 5 of said groove 3.

Figure 2c represents another variant of a transverse shape of a profiled metallic sheet 2. In this embodiment, the shape of the longitudinal element 6 is trapezoidal, but the groove 3 is not dovetail shaped. As it will be explained further, the profiled metallic sheet 2 in this embodiment have embossments 16b at least located on the lateral walls 13, 14. In addition, each groove 3 comprises one additional rib 15 arranged in the base 5 of said groove 3, and each upper portion comprises two additional grooves 15. The profiled metallic sheet 2 may have a transverse shape that is not depicted in the figures and still stays within the scope of the invention. As an example, each longitudinal element 6 may be cylindrical with an opened circular transverse shape.

Generally speaking, the profiled metallic sheet 2 has a unique transverse shape.

Regarding figures 1 and 3, the floor deck structure 1 also comprises at least two rebar trusses 10 each extending longitudinally in and/or above, respectively, two of the longitudinal grooves 3 of the profiled metallic sheet 2. By “in and/or above”, it is meant that, in cross-section, the rebar truss 10 can either fit completely in the groove 3, or fit partially or can be positioned higher than the upper portions 7.

The number of rebar trusses 10 can be adjusted depending on the desired mechanical resistance of the composite deck 11. According to a preferred embodiment, a rebar truss 10 extends in each and every groove 3. According to another embodiment, rebar trusses 10 extend in every other groove 3. According to another preferred embodiment, the rebar trusses extend at least over the entire length of the profiled metallic sheet. They can extend over the length of the profiled metallic sheet. Alternatively, they can extend over several profiled metallic sheets or over internal supports of the building. This further improves the strength and stiffness of the composite floor deck.

Typically, each rebar truss 10 comprises a plurality of substantially parallel metallic rebars 10a, 10b, 10c, typically a first 10a, a second 10b and a third metallic rebar 10c. The first and the second longitudinal rebars 10a, 10b are assembled with a first corrugated rod 17, while the first 10a and the third longitudinal rebars 10c are assembled with a second corrugated rod 17 having a periodic triangular pattern, so that the rebar truss 10 has a triangular transverse shape. Other shapes of rebar trusses are possible as long as the base of the rebar truss is designed so that it can be connected to the connector and as long as its upper part can be embedded in concrete. An example of other shape is a rebar truss having four longitudinal rebars and a rectangular transverse shape. More preferably the shape of the rebar truss is such that some parts of it can block the relative movement of the rebar truss with respect to the connectors described below.

Regarding figures 1 and 4 to 5, the floor deck structure 1 comprises a plurality of connectors 9a, 9b positioned transversally in a groove 3 and fastening each rebar truss 10 to the profiled metallic sheet 2. The distance between two connectors 9a, 9b fastened to the corresponding rebar truss 10 is adapted case by case to optimize the connection between the rebar truss 10 and the profiled metallic sheet 2. Preferentially, the distance between two connectors 9a, 9b is comprised between 20 and 120 centimeters and more preferably between 30 and 70 centimeters.

Overall, each connector 9a, 9b comprises fastening means to the profiled metallic sheet 2 and fastening means to the rebar truss 10.

In a first embodiment depicted in figure 4 and 4a, the connector 9a is an elongated element comprising a main body 19 whose shape is compatible with the base 5 of the considered groove 3 (figures 1 and 6) and two opposite edges 20.

Each edge comprises, as fastening means to the rebar truss 10, a notch 21a whose shape matches the cross-sectional shape of one of the metallic rebar 10b, 10c of the rebar truss 10. As depicted in figure 4a, the second and third metallic rebars 10b, 10c of the rebar truss 10 are then located inside the opposite notches 21a of said connector 9a. More precisely, the connector 9a is clipped on the corresponding rebar truss 10.

The edges 20 are designed so that they form fastening means to the profiled metallic sheet 2. In particular, the edges at least partially match the shape of the groove 3 in which the connector 9a is inserted. More precisely, while the connector 9a is located inside the groove 3, with its lower face above the base 5 of the groove

3, the external face 25 of each edge 20 is in contact with the considered lateral wall 13, 14 of the groove 3 and thus matches the shape of said lateral wall 13, 14. The external face 25 of each edge 20 is thus curved. Thanks to this design and in combination with a re-entrant transverse shape of the profiled metallic sheet 2, the connector 9a is maintained in place along the Z axis (vertical) and Y axis (transversal). Consequently, the profiled metallic sheet 2 and the connector 9a form an assembly and one piece will not move relative to the other along the Y and Z axes during the use of the composite deck floor 11. In this embodiment, the external faces 25 of the edges 20 of each connector 9a are pressed against the considered lateral walls 13, 14 of the grooves 3. The rebar trusses 10 are thus fastened to the considered grooves 3 of the profiled metallic sheet 2 thanks to the connectors 9a. The connector 9a is preferably unmovingly fastened to the profiled metallic sheet. By “unmovingly fastened”, it is meant that a first piece cannot move with respect to a second piece in any direction. In particular, the connector cannot move with respect to the profiled metallic sheet in any direction. In other words, an unmoving fastening prevents the relative movement of the connector with respect to the profiled metallic sheet. Accordingly, the connector 9a can further comprise means for unmovingly fastening the connector to the profiled metallic sheet. These means for unmovingly fastening can comprise holes in the connector, through which fastening means, such as screws or bolts, can be inserted so that the connector is screwed or bolted to the profiled metallic sheet. Alternatively, the connector 9a can be welded to the profiled metallic sheet to prevent its relative movement with respect to the profiled metallic sheet. Any other type of bonding is also possible.

Similarly, the rebar trusses are preferably unmovingly fastened to the connectors. In that case, the rebar trusses cannot move with respect to the connectors in any direction. In other words, the unmoving fastening prevents the relative movement of the rebar trusses with respect to the connectors. Accordingly, some parts of the rebar truss can block the relative movement of the rebar truss with respect to the connectors, and thus with respect to the profiled metallic sheet. In the example of Figure 3, the nodes formed by the connection of the first and second corrugated rod 17 on the second and third longitudinal rebars 10b, 10c can be locked in a connector. Some nodes can also be put in contact with a plurality of connectors so that they cannot move with respect to the connectors. In particular, and as illustrated on Figure 3a, a first node can be positioned adjacent to the right side of a first connector while a second node is positioned adjacent to the left side of a connector. Alternatively, the rebar truss can be welded to the connectors. Any other type of bonding is also possible.

In a second embodiment depicted in figure 5, the connector 9b is an elongated element comprising a main body 19b extending in a plane intended to be perpendicular to the base 5 of the considered groove 3 (figures 1 and 6) in which said connector 9b is inserted. The connector 9b also comprises two opposite lateral edges 20b and two lateral legs 24 respectively extending from the two opposite lateral edges 20b. In addition, the two opposite legs 24 are extending in opposite directions, both perpendicular to the main body 19b, in order to ensure stability of the connecter 9b while inserted inside the groove 3.

The connector 9b also comprises two opposite lateral notches 21b respectively managed in each lateral extremity of the main body 19b, said notches 21b forming fastening means to the rebar trusses 10. More precisely, the shape of each notch 21 b matches the cross-sectional shape of one of the metallic rebar 10b, 10c of the rebar truss 10.

The second and third metallic rebars 10b, 10c of the rebar truss 10 are thus located inside the opposite notches 21 b of said connector 9b. The edges 20b are thus designed so that they form fastening means to the profiled metallic sheet 2. In particular, while the connector 9b is located inside the groove 3, with its lower edge 23 above the base 5 of the groove 3, the external face of each leg 24 is in contact with the considered lateral wall 13, 14 of the groove 3 and thus matches the shape of said lateral wall 13, 14. In particular, the external face of each leg 24 forms an acute angle with the lower edge 23 of the connector 9b. Thanks to this design and in combination with a re-entrant transverse shape of the profiled metallic sheet 2, the connector 9b is maintained in place along the Y and Z axes.

Consequently, the profiled metallic sheet 2 and the connector 9b form an assembly and one piece will not move relative to the other along the Y and Z axes during the use of the composite deck floor 11. In this embodiment, the external faces of the legs 24 of each connector 9b are pressed against the considered lateral walls 13, 14 of the grooves 3. The rebar trusses 10 are thus fastened to the considered grooves 3 of the profiled metallic sheet 2 thanks to the connectors 9b. The connector 9b is preferably unmovingly fastened to the profiled metallic sheet. Accordingly, the connector 9b can further comprise means for unmovingly fastening the connector to the profiled metallic sheet. These means for unmovingly fastening can comprise holes in the connector, in particular in the legs 24, through which fastening means, such as screws or bolts, can be inserted so that the connector is screwed or bolted to the profiled metallic sheet. Alternatively, the connector 9b can be welded to the profiled metallic sheet to prevent its relative movement with respect to the profiled metallic sheet. Any other type of bonding is also possible.

Similarly, the rebar trusses are preferably unmovingly fastened to the connectors, as described above with reference to the first embodiment of the connectors.

Other shapes of connectors are possible as long as part of the connector is designed for, and capable of, fastening the connector to the profiled metallic sheet 2 and as long as part of the connector is designed, and capable of, fastening the rebar truss 10 to the connector. In particular, other shapes of connectors designed for, and capable of, preventing the relative movement of the connector with respect to the profiled metallic sheet are possible. Also, other shapes of connectors designed for, and capable of, preventing the relative movement of the connector with respect to the rebar truss are possible.

Overall, the connectors are preferably fastening the rebar trusses to the profiled metallic sheet so that the relative movement of the rebar trusses with respect to the profiled metallic sheet is prevented. It has been observed by the inventors that the unmoving fastening of the rebar trusses on the profiled metallic sheet significantly improves the performances of the composite floor deck. This unmoving fastening provides a full shear connection, which increases the bending resistance (strength) and the displacements under serviceability (stiffness), which allows for larger unpropped spans.

A process for assembling a floor deck structure 1 according to the invention will now be described.

In a first step, it is provided a profiled corrugated metallic sheet 2 comprising at least a first, a second and a third upper portion 7 separated by a first and a second longitudinal groove 3 comprising a base 5, a first lateral wall 13 linking the base 5 to one of the upper portions and a second lateral wall 14 linking the base 5 to an adjacent upper portion 7. In the example illustrated on figure 1 , the profiled metallic sheet 2 comprises four grooves 3 and five upper portions 5. In a second step, at least a first and a second rebar truss 10 as described above are provided. In a third step, they are respectively positioned in and/or above at least the first and second longitudinal grooves 3. In a fourth step, the first and second rebar trusses are fastened to the profiled metallic sheet using connectors 9a, 9b.

According to one variant of the invention, in-between the first and second steps, a plurality of connectors 9a, 9b are provided and fastened to the profiled metallic sheet. In particular, they are inserted inside the first and second grooves 3, in particular above the bases 5 of said grooves 3. If the connectors 9a are those depicted in figure 4a, the opposite edges 20 of each connector 9a are respectively brought into contact with the first and second lateral walls 13, 14 of the considered groove 3. If the connectors 9b are those depicted in figure 5, the lateral sides 24 of each connector 9b are respectively fastened to the first and second lateral walls 13, 14 of the considered groove 3. The number of grooves 3 equipped with the connectors 9a, 9b can be adapted case by case to optimize the mechanical resistance (strength) and stiffness of the composite floor deck 11. Preferably, the connectors are unmovingly fastened to the profiled metallic sheet. As described above, it can be done notably by screwing, bolting or welding the connectors on the profiled metallic sheet. This further improves the strength and stiffness of the composite floor deck.

According to this variant, the fourth step consists in fastening the first and the second rebar trusses to the connectors. In particular it consists in inserting the rebar truss 10 in the notches 21a, 21 b of each connector 9a, 9b. In particular, two metallic rebars 10b, 10c of each rebar truss 10 are respectively inserted in the opposite notches 21 a, 21 b of each connector 9a, 9b, in order to fasten said rebar truss 10 to the profiled metallic sheet 2. Preferably, the rebar trusses are unmovingly fastened to the connectors. As described above, it can be done notably by positioning some nodes of the rebar truss in contact with a connector so that the relative movement of the rebar truss with respect to the connectors is prevented. This further improves the strength and stiffness of the composite floor deck.

According to another variant of the invention, the fourth step comprises providing a plurality of connectors 9a, 9b and inserting them between the rebar truss 10 and the profiled metallic sheet 2. Once inserted, they are fastened both to the profiled metallic sheet 2 and to a rebar truss 10. Preferably, they are unmovingly fastened both to the profiled metallic sheet 2 and to a rebar truss 10. Once the rebar trusses 10 are all fastened to the corresponding connectors 9a, 9b, the floor deck structure 1 is assembled.

Optionally when the metallic sheet 2 comprises longitudinal plates, additional metallic rods (not depicted) may be provided and transversally inserted through openings arranged in said plates. Those additional metallic rods enhance the mechanical resistance of the floor deck structure 1.

Regarding figure 6, a composite floor deck 11 of the invention comprises a floor deck structure 1 described above and a concrete structure 12 poured on the metallic sheet 2 thus embedding the rebar trusses 10 and being anchored to the metallic sheet 2. The anchorage of the concrete structure 12 can be enhanced thanks to the embossment 16a, 16b arranged in the profiled metallic sheet 2 through mechanical interlocking. In addition or alternatively, the re-entrant transverse shape of the metallic sheet 2 depicted in figure 2a and 2b can further improve the anchorage of the concrete structure 12 to said metallic sheet 2 through frictional interlocking.

According to one variant of the invention, the floor deck structure 1 and concrete are assembled on site during building construction to form the composite floor deck 11.

In another variant of the invention, the floor deck structure 1 and concrete are pre-assembled, for instance in a shop, and then transported in anticipation of future work.

The floor deck structure 1 and corresponding composite floor deck 11 of the invention are of particular interest in the field of construction for several reasons.

Firstly, the assembling of the profiled metallic sheet 2, the rebar trusses 10 fastened to the metallic sheet 2 thanks to connectors 9a, 9b, and the concrete structure 12 embedding the rebar trusses 10 and anchored to the metallic sheet provides a composite floor deck 11 that offers good resistance capabilities in tension (due to the metallic sheet 2 and to the rebar trusses 10) and in compression (due to reinforced concrete structure 12). Secondly, the composite floor deck 11 remains thin. This means it can be used with respect to most building regulations. Thirdly, the association of the profiled metallic sheet 2, the rebar trusses 10 and the connectors 9a, 9b increases the self-supporting capabilities of the floor deck structure 1. In other words, during assembling on site, the floor deck structure 1 do not need to be propped up as much as the corresponding profiled metallic sheet alone.

Figure 7 represents a graph showing self-supporting capabilities of a floor deck structure 1 as depicted in figure 2a, comprising four grooves 3, compared to the corresponding profiled metallic sheet 2 alone. The self-supporting capabilities are measured with deflection sensor, for example one or several inductive sensors like linear variable differential transformer positioned half the width of the floor deck structure 1 . In addition, the deflection force is applied against the floor deck structure 1 or the profiled metallic sheet 2 alone in a direction perpendicular to a plane in which the metallic sheet 2 extends, for example with wooden blocks whose first side is in contact with the bases 5 of the profiled metallic sheet 2, and whose second opposite side is in contact with hydraulic actuators applying the deflection force. The deflection force is applied on four different points equally distributed over the width I of the metallic sheet 2 or floor deck structure 1 where appropriate.

More precisely, floor deck structures 1 and profiled metallic sheets 2 of different span have been tested: two meters, four meters and six meters. The graph shows six curves illustrating deflection in millimeters of the structure 1 / sheet 2 measured at midspan versus deflection pressure applied in Kilonewtons. To sum up:

• A first curve 26 represents the deflection of a two meters span L profiled metallic sheet 2, while a second curve 27 represents the deflection of a two meters span L floor deck structure 1 ;

• A third curve 28 represents the deflection of a four meters span L profiled metallic sheet 2, while a fourth curve 29 represents the deflection of a four meters span L floor deck structure 1 ;

• A fifth curve 30 represents the deflection of a six meters span L profiled metallic sheet 2, while a sixth curve 31 represents the deflection of a six meters span L floor deck structure 1 . It appears that when rebar trusses 10 are connected to the profiled metallic sheet 2 in order to form the floor deck structure 1 , the deflection d is lesser. In other words, deflection d is higher for the profiled metallic sheet 2 alone than for the floor deck structure 1 .

Figure 8 shows another graph using results shown in figure 7: stiffness S in kilonewtons per millimeter is calculated for the six profiled metallic sheets 2 and floor deck structures 1 after using a linear regression on curves 26 to 31 , and plotted versus span L in meters. The rounds points represent stiffness of the floor deck structures 1 of different span L, while the triangular points represent stiffness of the profiled metallic sheets of different span L.

The gain in stiffness is calculated for each span L by dividing the stiffness of the floor deck structure 1 by the stiffness of the profiled metallic sheet 2 of same length, and by subtracting 1 to the result. It appears that the gain is:

• 104 % for 2 meters span;

• 144 % for 4 meters span and

• 174 % for 6 meters span.

Those results show that the presence of rebar trusses 10 increases stiffness compared to the profiled metallic sheet 2 alone. In addition, resistance loads are always higher for the floor deck structure 1 than for the profiled metallic sheet 2 alone. It also appears that the floor deck structure 1 is less deformable that the profiled metallic sheet 2 alone having same span L.

Figure 9 shows results of numerical simulation comparing:

- Model A: a composite floor deck comprising a 9cm slab concrete cast on a floor deck structure according to Figure 2c, with a profiled metallic sheet made of steel and having a thickness of 0.75mm, wherein the connectors fasten the rebar trusses to the profiled metallic sheet so that the longitudinal relative movement of the rebar trusses with respect to the profiled metallic sheet is allowed, to

- Model B: a composite floor deck comprising a 9cm slab concrete cast on a floor deck structure according to Figure 2c, with a profiled metallic sheet made of steel and having a thickness of 0.75mm, wherein the connectors fasten the rebar trusses to the profiled metallic sheet so that the relative movement of the rebar trusses with respect to the profiled metallic sheet is prevented.

The deflection calculation took into account dead loads arisen from the profiled metallic sheet, wet concrete and rebar trusses, which represented 1 .20 kN/m of applied load. The connectors were reproduced as rigid elements linking the rebar trusses to the profiled metallic sheet. In model A, they were only transferring vertical forces while, in model B, they were also transferring the shear stress (longitudinal forces).

The maximum unpropped span was calculating knowing that the maximum deflection in serviceability had to respect the following limit, where L is the slab span in millimeters: Results show that the maximum serviceability limit of 20mm is obtained in model B with a maximum unpropped span of 4800mm whereas it is obtained in model A with a maximum unpropped span of 4000mm. By preventing the longitudinal relative movement of the rebar trusses with respect to the profiled metallic sheet, unpropped spans can be increased by 20%.