AU2263200A - Composite steel decks - Google Patents

Description

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AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION

ORIGINAL

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Name of Applicant: Actual Inventor: Address for Service: Invention Title: SUNTISUK PLOOKSAWASDI SUNTISUK PLOOKSAWASDI H.R. HODGKINSON CO.

Patent Trade Mark Attorneys Level 3, 20 Alfred Street MILSONS POINT NSW 2061 COMPOSITE STEEL DECKS The following statement is a full description of this invention, including the best method of performing it known to me BACKGROUND OF THE INVENTION The invention relates to a cold-formed corrugated steel deck, in particular a composite deck slab. The present invention pertains to the improvement of mechanical bond between concrete and steel deck resulting in increasing ultimate strength of composite deck slab, yielding more economic use of the slab and increasing shear resistance of the composite panel.

Composite steel deck is fabricated from coiled, usually galvanised, sheet formed into a 10 corrugated panel. During the forming process, sets of rolls are pressed on the panel to form •rows of embossment of indentation on bottom and/or top flanges and on webs of the panel, .depending upon manufacturers (see figure This embossment or identification is used as g.

:steel permanent form for concrete slab and at the same time served as positive bending reinforcement of the slab. It also acts as working platforms and provides stability of structural frame during construction.

ooo The ultimate load carrying capacity of composite deck slabs is found to vary for each type of cold formed panels, but shear bond slip, a breakdown at the interface between steel panel •oo• and concrete, is the predominant cause of failure in composite deck slabs. The shear bond S 20 capacity of all slabs, regardless of types of mechanical bond devices used, increases with increase in slab depth, decreases with decrease in shear span, and increases with increased compressive strength of concrete.

Mechanical bond devices may include:a Wire welded across flute tops of the steel deck.

b Holes which will permit small amounts of concrete to flow into them and, when set, to create a positive interlock, and c Embossment or indentation on the steel form d Geometrical shape of the form with combinations of the above.

For steel decks with embossment types, which are more popular design than others, shear bond slip is caused by loosing of adhesive force between steel panel and concrete and can be detected at the ends of concrete slabs. After the slip, the composite deck slab strength will depend mainly on mechanical bond of the embossment. This embossment is similar to lugs of deformed reinforced bar in the sense that it creates a development bond between steel and concrete. At time of slab failure, profile of steel panel will be deformed and lessened the effectiveness of shear resisting between concrete and steel panel. The embossments will slide away from their seats in concrete. Normally the maximum strength of steel panel will not be reached and this failure slip limits higher potential of steel strength to develop. If this shear bond slip can be prevented or prolonged to a higher stage of steel strength, the composite deck slab can withstand higher load resulting in more fully utililized capacity and S* 10 yields more economical design to this type of structure.

SUMMARY OF THE INVENTION The objective of this invention is to provide means to improve performance of composite deck slab. The improvement lies on increasing shear bond resistance to the steel deck. At least a wire or bar or steel strip is used for the purpose. A wire is referring to cold drawn round or indented wire. A bar is referring to hot rolled round or deformed bar such as ones used in reinforced concrete. A steel strip is referring to that which is slit from cold rolled coil or cold rolled plate.

The present invention employs at least said wire or said bar or said strip to be welded to the steel deck. Said wires or bars or steel strips shall be horizontally disposed parallel along the longitudinal length of steel deck and are preferably extended in full length of the flute. For embossed steel deck, they shall be welded along contour line of row of the embossments.

Said wires or bars or steel strips will increase mechanical bond between embossment and concrete at the same time strengthen bending capacity of the deck during installation. After the concrete has been poured, said wires or bars or steel strips will be embedded into concrete and enhance interlocking force to the embossments. As a composite member of the concrete slab, said wires or bars or steel strips will act as a positive reinforcement additional to that deck which will either result in reducing thickness of steel deck or increasing bending and shear capacity of the slab.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a perspective view showing a section of a typical composite steel deck and its cross section.

FIGURES 2 to show various types of embossment or indentations commercially available in construction.

FIGURES 3 to 5 show wires or bars welded in different positions on different types of 10 embossments. They are preferably welded on every crest of embossments.

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FIGURE 6 shows steel strips welded to the crests of the embossments. The free edges are •bent to increase the bond to concrete.

FIGURE 7 shows steel strips profiled to fit contour line of row of embossments. Multiple of holes are punched in the strip to increase bond to the concrete.

FIGURE 8 shows embossed steel strip with bend profiled edge welded to the steel deck.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Figure 1 shows typical composite steel deck Label 2 shows its cross section. j Label 3 and 4 are bottom and top flanges respectively. Label 5 shows web of the steel deck with embossment (label 6) on its web. Line 7 is the longitudinal line of row of embossments.

Cross section X-X in figure lb shows flat surface of the web (label 8) and crest of embossment (label Contour line of the row of embossments (label 10) is also shown in the figure. Figure 2(a) to show various types of embossments or indentations commercially available in construction.

Referring to the drawings of figure 3 to 5, wires or bars are horizontally placed parallel along the fluted deck. They will be welded on every crest of embossments along the longitudinal length of steel deck. Number and size of bars will depend on bending capacity required. After pouring concrete, the wires or the bars will be fully embedded in concrete.

At high level of load, adhesive force between steel deck and concrete will be broken and profile of steel deck will begin to deform. Embossments at this stage will be the main shearing resistance between concrete and the steel deck. Welding spots between wires or bars and embossments will limit movement of both deck profile and embossments resulting in extending the failure of composite deck slab to a higher stage of load.

To further improve the bonding effect, wires or bars can be crimped. The wave of crimping shall match with crests of embossments. The crimped wires or bars will have their bowed parts deeper into concrete and increase their embedment length. This modification is made •to insure that the wires or bars will not be pulled out of concrete during failure of composite deck slab.

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Figure 6 shows steel strips welded in the same manner as wires and bars. The steel strip has two longitudinal edges. One is an attached edge which is the edge welded to the steel deck.

Another is a free edge which extends into concrete. The steel strip attached edge shall be divided in two alternatives. Firstly straight edge (figure the edge shall be welded to the crests along the longitudinal line of row of embossments. Secondly profiled edge to fit contour of the embossments (figure the edge shall be welded along the contour line of row of embossments. In case of unfitted profiled edge (picture not shown), only the remaining straight edge shall be welded to the flat surface of the steel deck. Figure 8 shows bent leg of an attached edge. The bent leg will increase welding area between the steel strip and the deck.

On the other hand, the free edge or free portion of the strip shall be modified to increase bond between the strip and concrete and shall be divided into 3 alternatives. First alternative, bending of longitudinal part of the free edge into inverted L-shaped strip as shown in figure 6. Second alternative, in figure 7, multiple holes are punched into the steel strip. The holes can be in any shape as long as the perforated strip can keep its strength and shall not be torn out under tension. After pouring concrete, the filled holes will provide interlocking force needed to bond development. Figure 8 shows the third alternative where embossments are pressed on body of the steel strip. The difference between steel deck embossment and steel strip embossment is the latter is embedded firmly into concrete and should give full bond development for strip with adequate width. The attached edge of steel strip is then placed perpendicular to the surface where contour line of row of embossments is located. It shall be welded to the surface along the full length of the steel deck.

Combination of the attached and free edges mentioned above can be chosen for each design of steel strip. For example one can replace embossed steel strip, in figure 8, with multiple holes steel strip from figure 7 and then the steel strip will become bent leg attached edge with multiple holes. Another example is to double bent leg attached edges, in figure 8, to form U-shaped steel strip. This combination will ensure holding force between embossments and concrete.

As shown in figure 2, the embossments can be formed on any locations either flanges or web S.:i depending upon manufacturers. The wires or the bars or the steel strips shall be welded to the line of row of embossments in the same matter. The selection of this invention to match with shapes and locations of embossments can be determined by test results.

Page(s) is the abstract page.

Claims (14)

1. A composite steel deck having at least one wire or bar or steel strip welded to inner surface of the deck, said wire or said bar or said steel strip shall be horizontally s placed parallel along length of the deck and are preferably extended in full length of the flute.

2. A composite steel deck in accordance with claim 1 wherein at least one said wire or said bar is welded to crests of embossments.

3. A composite steel deck in accordance with claim 2 wherein at least one said wire or S. 10 said bar is crimped and the wave of crimping shall match with crests on the line of embossments.

4. A composite steel deck in accordance with claim 1 wherein said steel strip, having one longitudinal attached edge and one longitudinal free edge, is horizontally placed, on said attached edge, perpendicular to surface of steel deck.

5. A composite steel deck in accordance with claim 4 wherein said steel strip shall have said attached edge welded to crests of embossments.

6. A composite steel deck in accordance with claim 4 wherein steel strips have said e attached edge, profiled to fit to contour line of row of embossments.

7. A composite steel deck in accordance with claim 6 wherein said attached edge of said steel strip shall be welded along contour line of row of embossments. S:

8. A composite steel deck in accordance with claim 4 wherein said steel strip shall have said attached edge, profiled over contour of embossments.

9. A composite steel deck in accordance with claim 8 wherein said attached edge of said steel strip is welded to the flat surface along line of row of embossments.

10. A composite steel deck in accordance with claim 6 wherein said steel strip shall have said attached edge, bent in angle with said steel strip.

11. A composite steel deck in accordance with claim 10 wherein said bent attached edge of said steel strip is welded to the flat surface along line of row of embossments.

12. A composite steel deck in accordance with claim 4 wherein said steel strip shall have said free edge, bent in angle with said steel strip.

13. A composite steel deck in accordance with claim 4 wherein said steel strip shall be embossed in plurality within its surface.

14. A composite steel deck in accordance with claim 4 wherein said steel strip shall be punched to form multiple holes within its surface. A composite steel deck in accordance with claim 4 wherein combine the attached edge either in claim 6 or 8 or 10 with either free edge in claim 12 or steel strip arrangement in claim 13 or 14. Dated this 2 8 th day of March, 2000 SUNTISUK PLOOKSAWASDI 10 BY: H. R. HODGKINSO CO. Patent Attorneys for the Applicant o a a 0•