Floor and ceiling structures

A composite floor or ceiling structure which comprises a profiled steel deck supported by a plurality of I-section steel beams each having an upstanding web bordered by upper and lower flange plates and covered in situ with concrete. The deck comprises a plurality of side-by-side elongate profiled deck members each including an upper generally horizontal surface bordered by downwardly and outwardly inclined side surfaces. The upper flange plate of each beam has formed in its upper surface a plurality of grooves in a pattern to increase bonding between the beam and its covering of concrete. Preferably, each supporting beam is rolled as a single piece with the width of its lower flange plate greater than that of its upper flange plate to define a supporting platform for the steel deck.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to floor and ceiling structures and more especially 
to composite floor and ceiling structures of concrete and steel. 
2. Description of Related Art 
Composite floor and ceiling structures which comprise a profiled steel deck 
supported on the lower flange of steel beams and covered in situ with a 
concrete layer are known. Advantages of such structures include reductions 
in floor thickness and weight, ease and speed of construction and savings 
in labour and cranage costs during assembly. 
SUMMARY OF THE INVENTION 
One problem associated with existing composite structures concern the need 
to ensure the adequacy of the shear bond between the concrete layer and 
the supporting steel beams. 
It is an object of this invention to provide enhanced keying between the 
support beams and the concrete layer to ensure lasting connection 
therebetween. 
It is also an object of this invention to provide improved servicing 
capabilities for buildings by including ducting in the steel decking and 
through the support beams to act as air plenums, and using the 
ceiling/floor structure to form either a full air-conditioning duct or as 
a thermally transparent surface to enhance thermal efficiency and air flow 
thereby reducing air-conditioning costs. 
According to the present invention in one aspect, there is provided a 
composite floor or ceiling structure which comprises a profiled steel deck 
supported by a plurality of I-section steel beams each having an 
upstanding web bordered by upper and lower flange plates and covered in 
situ with concrete, the deck comprising a plurality of side-by-side 
elongate profiled deck members each including an upper generally 
horizontal surface bordered by downwardly and outwardly inclined side 
surfaces, the upper flange plate of each beam having formed in its upper 
surface a plurality of grooves in a pattern to increase bonding between 
the beam and its covering of concrete. 
Preferably, each supporting beam is rolled as a single piece with the width 
of its lower flange plate greater than that of its upper flange plate to 
define a supporting platform for the steel deck. 
Preferably the grooves of the pattern extend across the full width of the 
upper surface of the upper flange of each beam and are inclined to the 
longitudinal axis of the beam. The grooves may define a generally 
symmetrical diamond-shaped pattern. 
Edge laps may extend outwardly from the edge of one or both inclined side 
surfaces of one or more deck members. 
The upper surface of each deck member and/or edge lap may be formed with a 
dove-tail groove. 
The profiled deck members may be supported at their ends on shaped 
diaphragms secured to the lower flange plate of the respective beam. 
Concrete may be pumped, poured onto or otherwise applied to the upper 
surface of the steel deck and the supporting beams. 
A steel anti-crack mesh may be supported by the beams and/or the steel deck 
before concrete is applied to the structure. 
The shape of the steel deck may be such as to provide between the 
undersurfaces of its inclined side surfaces passageways for receiving 
ducting for the flow of heating and/or cooling medium, specifically air 
conditioning ducting. The installed floor structure may act, in use, as a 
heat reservoir. 
The invention will now be described by way of example only with reference 
to the accompanying diagrammatic drawing

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
As will be seen from the drawings, each support beam 1 is of asymmetrical 
I-section and has a lower flange plate 2 whose width is greater than that 
of its upper flange plate 3. This increased width enables the flange plate 
2 to define a support platform for one end of a profiled steel deck 4 and 
steel diaphragms 5 (see FIG. 1) on which the individual deck members 
locate. The diaphragms 5 are secured to the flange plate 2 before the deck 
members are offered to the beams. Typically, the deck 4 is fixed at 600 mm 
centres using either shot fired pins or self drilling/tapping fasteners. 
The diaphragms minimise concrete leakage and provide precise alignment of 
the deck profile. 
Each support beam 1 is rolled as a single piece with the lower and upper 
flange plates 2, 3 formed integrally with the central web section 6 of the 
beam. Preferably, the beams are formed from S355 or Fe 510 (Grade 50) 
steel. Alternatively, Fe 430 (Grade 43) steel may be employed especially 
where deflection criteria control the design. 
Typical specifications of these asymmetrical beams are set out in Table A 
below. 
TABLE A 
______________________________________ 
Nominal Steel Beam Beam Imposed 
Section 
Weight (mm) Thickness 
Span Spacing 
Load 
Size (kg/m) Flange Web (m) (m) (kN/m.sup.2).dagger. 
______________________________________ 
280 ASB 
100 16 19 6 6 5.0 
280 ASB 
135 22 25 7.5 6 3.5 
or 135 22 25 6 7.5 5.0 
300 ASB 
150 24 27 7.5 7.5 3.5 
______________________________________ 
.dagger.In addition to a partition toad of 1kN/m.sup.2 
A pattern of groves 7 is formed in the upper surface of the upper flange 
plate 2 of each beam to aid keying of the concrete layer of the structure 
to the support beams and to produce an effective composite structure. The 
grooves 7 extend across the full width of the flange and define a 
diamond-like pattern. Typically, the depth of the grooves approximate to 1 
mm to 2 mm and are the grooves are rolled into the upper surface of the 
upper beam flanges during production of the same. 
As will be seen from FIGS. 2 and 3 the steel deck 4 comprises a plurality 
of side-by-side elongate profiled deck members each having a ribbed upper 
surface 8 bordered by downwardly and outwardly extending ribbed side 
surfaces 9, the upper surfaces of the side surfaces 8 defining troughs for 
receiving concrete. The solidified concrete layer is indicated by 
reference numeral 10. One side surface 9 of each deck member terminates in 
an outwardly extending lap 11 which overlies and may be joined by, for 
example, stitching, to the side or an adjoining lap of the neighbouring 
deck member. Typically, the side laps 11 are stitched at 350 mm centres 
with self-drilling fasteners which also connect through shear bond clips 
of the deck. The individual deck members are typically of a span of up to 
6 m. The upper surface 8 of each deck member includes a dovetail groove 12 
to aid keying of the concrete to the decking. Each lap 11 may also include 
such a dovetail groove. 
As will be seen from FIG. 2, holes are formed in the central wall sections 
of the beams to receive service ducting 14. Between the beams, this 
service ducting passes through three-sided conduits defined by the under 
surfaces of the deck upper and side surfaces 8,9. Typically, the geometry 
of the ribbed surfaces allows for up to 160 mm diameter or oval service 
openings for service runs. Typically, the holes formed in the beams are at 
600 mm spacing in the middle third of the respective beam. 
With the steel deck in place, a steel anti-crack mesh is supported by the 
beams and over the upper surface of the deck before lightweight or normal 
concrete 10 (see FIG. 3) is pumped or poured onto the structure completely 
to cover the deck and the beams, and then levelled. Reinforcement rods are 
provided within the troughs defined between the inclined side surfaces 9 
of the individual deck members. The concrete is used primarily for 
stiffness to increase inertia and to provide lateral restraint to the 
floor at its ultimate limit state. 
Typically, the floor will comprise a 60 mm or 70 mm layer of concrete 
covering the steel deck, with a minimum of 30 mm of this layer over the 
support beams 1. 
The steel of the deck is preferably galvanised and is typically of 1.25 mm 
thickness. The ribs are typically at 600 mm centres and the depth of the 
deck is typically 225 mm. The deck acts as permanent formwork to the in 
situ concrete slab and develops composite action with the concrete. 
Propping of the beams or decking is normally not necessary for the average 
plan grid, e.g. a 9 m beam span at 6 centres. However, for longer deck 
spans (up to 7.5 mm) a central line of props may be needed. If the deck is 
propped it is possible to achieve economies in the beam sections when 
construction loads dictate the design. 
As will be seen from the drawings, elongate voids are defined below the 
steel deck between the inclined side surfaces 9 and the upper surfaces 8. 
These voids can, in use, be employed as ducting for conveying heated 
and/or cooled media to locations within the ducting in which the floor 
structure is installed. To this end, valves, distributors, closure 
floor/ceiling pieces and other necessary components can be installed such 
that these voids defined in the structure can be employed as distribution 
ducting for conditioned air, and from the ceiling finish to the 
compartments above or below. 
The composite floor structure can also be employed as a heat reservoir. 
Thus, air rising through a thermally transparent ceiling below the floor 
structure during the day heats the concrete layer which in turn heats 
cooler air drawn into the building at night. 
Advantages offered by floor structures in accordance with this invention 
include speed and ease of construction, and a lightweight structure when 
compared to either reinforced concrete or pre-cast structures thereby 
providing savings in steel and cranage costs. Also, because the deck 
members can arrives on-site in bundles already cut to length, they can 
readily be lifted into place and manhandled to form the required platform, 
erection can be speedily achieved. Furthermore, the deck provides a safe 
working platform in the construction stage and a dry working area for 
apparatus, and the stiffened upper surfaces of the deck members allow for 
flexibility in detailing of openings and vertical services. Also, when 
fixed, the deck acts as a diaphragm to resist in-plane forces. The 
structure in its entirety acts as a service plenum thereby reducing costs 
of service installations and operating costs for heating and cooling of 
the respective building. 
It will be appreciated that the foregoing is merely exemplary of flooring 
structures in accordance with this invention and that modifications can 
readily be made thereto without departing from the scope of the invention 
as set out in the appended claims.