This document discusses the behavior of composite slabs with profiled steel decking. It presents information on:
1) Composite slabs that use profiled steel sheets as permanent formwork and tensile reinforcement, allowing for 30% reduced concrete and lower structural weight.
2) The profiled steel decking used which is thin-walled, cold-formed sheets meeting ASTM and IS standards with a galvanized coating.
3) Three slabs - plain concrete, bar reinforced, and steel fiber reinforced - were tested for negative bending capacity, with the fiber reinforced slab showing over a 2.5x increase in load capacity compared to plain concrete.
1. BEHAVIOUR OF COMPOSITE SLABS
WITH PROFILED STEEL DECKING
PRESENTED BY
SHEIK FARHAN(271298)
SANDIPAN SINHA(271316)
MANIVEL S(271324)
KARTHIKEYAN V(271342)
2. INTRODUCTION
• The composite slabs have now become a
common form of construction of floor
decks in major buildings.
• In composite slabs, the profile sheet is
used as permanent formwork and as
tensile reinforcement.
• In this composite slab, there is 30% saving
in concrete material, resulting in reduced
structural weight.
• It favours fast and easy construction and
also it proves to be economical
3.
4. Profiled Deck steel
• Thin-walled cold-formed profiled steel decks
• Quality steel sheets conforming to ASTM A653
(2008) and IS 1079 (1994)
• A galvanized surface coating with an average
thickness of 0.0254 mm is finished on each face
of the steel deck
• Yield strength of sheet = 250 N/sq.mm
As per EN 1993-1-1, 3.2.6.
• Shape= Trapezoidal type sheeting
• Embossments= Oval and concave
5. Size of sheeting = 1.8mx0.830m
Thickeness = 1.1mm
(a min. of 0.7 mm ie recommended)
6. Thickness of slab
• Based on the satisfactory performance of floors
that had previously been constructed in a wide
range of countries, EN 1994-1-1 specifies the
following minimum slab thicknesses that should
be used in design:
• Where the slab acts compositely with a beam, or
is used as a diaphragm:
o the overall depth of the slab h ≥ 90 mm; and
o the thickness of concrete above the top of the
ribs of the sheeting hc ≥ 50 mm.
7. Where the slab does not act compositely with a
beam, or has no other stabilising function:
o the overall depth of the slab h ≥ 80 mm; and
o the thickness of concrete above the top of the
ribs of the sheeting hc ≥ 40 mm.
8. • Here the depth of deck alone is 52mm and so
40mm to 50mm is the minimum thickness of
concrete above deck sheet.
• Hence over all slab thickness will be 110mm.
• This is much less than conventional rcc slab
• As per Euro code 4 (part 2) a slab thickness of
110mm will have a fire resistance of 90 minutes
10. TEST CRITERIA
• Three slabs with different reinforcement
conditions are to be tested for negative bending.
• Negative bending is very essential in deck slab
design as it is laid as continuous slab at site.
• Usually positive bending tests will be carried out
and they give least importance to negative
bending.
11. • Here in deck slab, the deck sheet is at the
bottom and hence during negative bending, it
will be subjected to compression and top flange
to tension.
• 1st slab - Plain concrete with no reinforcement
• 2nd slab - Concrete with bar reinforcement
• 3rd slab - Concrete with steel macro fibre
reinforcement
12. Properties of Fibre
S.no Fibre Properties
Steel Fibre
1.
Length (mm)
30
2.
Shape
Wavy
3.
Size/Diameter (mm)
0.5
4.
Aspect Ratio
60
5.
Density (Kg/cubic m)
7850
6.
Youngs Modulus
210 GPa
7.
Tensile strength
532 MPa
13. • As per Euro code 4 (Part 2) the dosage of steel
macro fibres is 20kg/m3 to 30 kg/m3 for
increasing the flexural strength and crack control
• Here, we have chosen 20kg/m3
• Also beyond 30kg/m3, increase in fibre content
does not have any effect in the strength of
composite slabs
20. CONCLUSION
• The use of fibres in the composite slab
increased its load carrying capacity to nearly
2.5 times of the capacity of plain concrete
composite slab.
• Also the fibres played an important role in
crack control.
21. Code books & Refernces
1. For steel sheet properties - ASTM & IS codes
2. For Composite slab design and experiment
inference - Euro code 4 (Part 1)
3. ASCE portal
LITERATURE:
1. Composite Slab behaviour and strength
analysis, Part I: Calculation procedure, Byton j.
Daniels and Michel Crisinel.
2. The use of profiled steel sheeting in Floor
Construction, H.D. Wright, H.R. Evans and
P.W.Harding, University College, South Wales, UK