This document discusses the design of composite slabs with profiled steel sheeting. It covers general requirements for the slab thickness, connection systems, and analysis for forces and moments. It also provides an example calculation for checking the flexure, shear, and deflection of a composite slab with profiled steel sheeting. The slab is found to have sufficient strength for bending but is not strong enough for longitudinal shear based on the m-k method calculations in the example.

1. concrete structures
ES EN 1994-1-1:2015
Section 9,Composite slab with
profiled steel sheeting for
Buildings

2. 1.0 General
• Profiled sheeting has three uses
• First as working platform
• Second as a shuttering for the in situ casting of concrete
• Third as the bottom tensile reinforcement of the composite slab
• The size of webs is limited to br/bs≤0.6
Where br is rib width and bs is center to center width of ribs
1.1 Connection system,9.1.2.1
• Mechanical interlock
• Frictional interlock
• End anchorage

5. 1.2 Slab thickness,9.2
• h≥80mm,depth of composite slab
• hc≥40mm,thickness of concrete above ribs
• Aggregate size limits
• o.4hc or bo/s
• 31.5mm
• Where bo =mean width of ribs

6. 1.3 Action and action effects,9.3
1.3.1 Design situations
• As shuttering
-Loading shall be: weights of concrete and steel deck; construction
loads, storage loads and ponding(increased depth of concrete due to
deflection of sheeting) ;ponding can be neglected if deflection,δ, of
slab is less than 1/10 of slab depth otherwise concrete thickness will be
increased by o.7δ.
• As composite slab
• Loading shall be in accordance with EN-ES1991-1-1:2015

7. 1.4 Analysis for forces and moments,9.4
1.4.1 Effective width of point or line loads
• bm=bp+2(hc+hf)
• If bp/bh<0.6 then use equation 9.2,9.3 and 9.4
• Transverse reinforcement shall be not less than 0.2% when imposed loads:
-Concentrated load:7.5kn
-distributed load:5kn/m2
Otherwise the moments due to the concentrated loads should be calculated
and the reinforcement determined accordingly.

9. 1.5 Verification of profile sheeting,9.5 and 9.6
• For ultimate limit state :the provisions of ES-EN1993-1-3:cold formed
structures
1.6 For serviceability limit state: the deflection δs ,of the sheeting under
self weight and wet concrete, shall not exceed δs,max=L/180

10. • 1.7 Verification of composite slabs,9.7
• Flexure
• Sagging bending
-For full shear connection MRd should be determined as follows:
a)Neutral axis above the sheeting
Nc,f=Ap fyp,d
Xpl=Nc,f/o.85fcdb
For Xpl<hc
MRd=Nc,f(dp-o.5Xpl)

12. b) Neutral axis in the sheeting
Nc,f=0.85fcd bhc
Npa=Ap fyp,d
Mpr=1.25Mpa(1-(Ncf/Npa))≤Mpa
MRd=Nc,f z+Mpr
Z=h-0.5hc-ep+(ep-e)Nc,f/Apefyp,d

14. • C) hogging bending ;For hogging bending contribution of steel
sheeting is neglected

15. 1.7.1 Longitudinal shear without end anchorage
• Equation 9.7 is used ;
• Values of m and k are determined from tests for every profile
• Ls=shear span=l/4 for uniform loads
• For continuous composite slabs the span can be reduced to:
-0.8L for internal spans
-0.9L for external spans
• For Partial connection MRd is calculated as earlier but with
Ncf replaced by Nc=τu,Rd bL≤Ncf
Where τu,Rd is design shear strength , τu,Rd /γvs (γvs =1.25)

16. 1.7.2 longitudinal shear for slabs with end anchorage
--unless shear devices are used sheet should be designed for the tensile
forces
-the design resistance of headed stud is the smaller of equation 9.10
and that given in 6.6.4.2
1.7.3 Vertical and punching shear shall be checked as in concrete. For
punching shear critical perimeter is as in figure 9.8

17. • Punching shear area

18. • 1.8 Verification for serviceability state
-crack width shall be calculated as in concrete
-anti-crack reinforcement above rib should be 0.2% and 0.4% of the cross
sectional area above the rib for un-propped and propped construction
respectively.
1.8.1 Deflection
-deformation affecting appearance/comfort
-causing damages to finishes
-vibrations
-ES-EN 1993 applies to deflection of sheeting

19. -For composite member elastic analysis can be used after adjusting
moment areas to average values
-deflection calculations may be omitted if span to depth ratios of ES-EN
1992,7.4 are satisfied and slip requirements are met.

20. Profiled steel sheeting
• Example

21. Material data
• Guaranteed minimum yield strength, fyp = 350 N/mm2
• Design thickness, allowing for zinc coating, tp = 0.86 mm
• Effective area of cross-section, Ap = 1178 mm2/m
• Second moment of area, Ip = 0.548 × 106 mm4/m
• Characteristic plastic moment of resistance, Mpa = 6.18 kN m/m
• Distance of centroid above base, e = 30 mm
• Distance of plastic neutral axis above base, ep = 33 mm
• Characteristic resistance to vertical shear, Vpa = 60 kN/m (approx.)
• For resistance to longitudinal shear, m = 184 N/mm2
• k = 0.0530 N/mm2
• Volume of concrete, 0.125 m3 per sq. m of floor
• Weight of sheeting, 0.10 kN/m2
• Weight of composite slab at 19.5 kN/m3,
• gk = 0.10 + 0.125 × 19.5 = 2.54 kN/m2

22. • Profiled steel sheeting as shuttering
• In EN 1991-1-1, the density of ‘unhardened concrete’ is increased by
• 1 kN/m3 to allow for its higher moisture content, and the imposed load during construction is 1.0 kN/m2, so the design loads for the
sheeting are:
• • permanent:
• gd = (2.54 + 0.125) × 1.35 = 3.60 kN/m2
• • variable:
• qd = 1.0 × 1.5 = 1.5 kN/m2
• The top flanges of the supporting steel beams are assumed to be at least
150 mm wide. The bearing length for the sheeting should be at least
50 mm. Assuming that the sheeting is supported 25 mm from the flange tip (Fig.) gives the effective length of each of the two spans as
• Le = (4000 − 150 + 50)/2 = 1950 mm

23. Fig.1.0

24. • Flexure and vertical shear
• The most adverse loading for sagging bending is shown in the figure, in which the weight of the sheeting alone in span BC is
neglected. Elastic analysis gives the maximum design bending moments as:
• • sagging:
• MEd = 0.0959 × (3.6 + 1.5) × 1.952 = 1.86 kN m/m
• • hogging (both spans loaded):
• MEd = 0.125 × 5.1 × 1.952 = 2.42 kN m/m
• With γA = 1.0, the design resistance is MRd = Mpa = 6.18 kN m/m, which is ample.
• Vertical shear rarely governs design of profiled sheeting. Here, the maximum value, to the left of point B in Fig. 1.0, is
• VEd = 0.625 × 5.1 × 1.95 = 6.2 kN/m
• which is far below the design resistance of about 60 kN/m.

25. a p
Deflection
The characteristic permanent load for the sheeting is 2.66 +1.0 =3.66
kN/m2
. It is assumed that the prop does not deflect. The maximum deflec-
tion in span AB, if BC is unloaded and the sheeting is held down at C, is
4 4
δ =
wLe
=
max
185E I
3.66 × 1.95
185 × 0.21 × 0.548
= 2.5 mm
This is span/784, which is
satisfactory.

26. • Composite slab – flexure and vertical shear
• This continuous slab is designed as a series of simply-supported spans. For bending, the
reactions from the beams are assumed to be located as in
• Fig. 1.0, so Le = 3.90 m. For vertical shear, the span is taken as 4.0 m, so
that the whole of the slab is included in the design loading for the beams.
The characteristic loadings are:
• • gk = 2.54 (slab) + 1.3 (finishes) = 3.84 kN/m2
• • qk = 5.0 (imposed) + 1.2 (partitions) = 6.2 kN/m2

27. • The design ultimate loadings are:
• • permanent:
• gd = 3.84 × 1.35 = 5.18 kN/m2
• • variable:
• qd = 6.2 × 1.5 = 9.30 kN/m2
• The mid-span bending moment is
• MEd = 14.48 × 3.92/8 = 27.6 kN m/m
For the bending resistance, from the Equation , Nc,f=Ap fyp,d
• Nc,f = 1178 × 0.35/1.0 = 412 kN/m

28. • The design compressive strength of the concrete is 0.85 × 25/1.5 =
14.2 N/mm2 so, from the equation, x = xpl = Nc,f /(0.85fcdb) , the
depth of the stress block, for full shear connection, is
• x = 412/14.2 = 29.0 mm This is less than hc (which can be taken as 95
mm for this profile ,see drawing of profile.
so from Figure 9.5 of ES EN 1994 with dp = 120 mm,
• MRd = 412(0.12 − 0.015) = 43.3 kN m/m
• The bending resistance is sufficient, subject to a check on longitudinal
shear.

29. • The design vertical shear for a span of 4 m is
• VEd = 2(5.18 + 9.3) = 29.0 kN/m
• For the shear resistance, from Equation 6.3N with dp taken as 200 mm,
• vmin = 0.035 × 23/2 × 251/2 = 0.49 N/mm2 , vmin = 0.035[1 + (200/dp)1/2]3/2 fck
½
ES EN 1992-1-1 , (eq 6.3N )where 1+√(200/d)≤2,d in mm
• with b0 = 162 mm, b = 300 mm (drawing of profile),
• VRd = (162/300) × 120 × 0.49 = 31.7 kN/m , VRd = (b0 /b) dpvmin per unit width
• which is just sufficient.

30. • Composite slab – longitudinal shear
•
• Longitudinal shear will be checked by the ‘m–k’ method. From Equation 9.7
of ES EN 1994, the m–k method gives the vertical shear resistance as
•
• V l , Rd = bdp[m Ap /(bLs) + k]/γVs = 25.9 kN/m The values
used are:
• b = 1.0 m m = 184 N/mm2
• dp = 120 mm k = 0.0530 N/mm2
• Ap = 1178 mm2/m γVs = 1.25
• Ls = L /4 = 1000 mm

31. • where γVs is taken from ES EN 1994-1-1:2015,9.7.33,Note 1 and the
other values are explained above. The design vertical shear is 29.0
kN/m so the slab is not strong enough, using this method.