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NCCI: Initial Design of Composite Beams
SN022a-EN-EU

NCCI: Initial Design of Composite Beams
Guidance is provided for the selection of simply supported primary and secondary
composite beams

Contents
1. Comparison with non-composite beams 2
2. Use of design graphs 2
3. References 8

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NCCI: Initial Design of Composite Beams
SN022a-EN-EU
1. Comparison with non-composite beams
The bending resistance of a composite beam is typically 60 to 120% higher than that of the
steel beam alone, depending on the proportions of the steel beam and the slab. The stiffness
of a composite beam is typically 150% to 300% higher than that of the steel beam. Therefore,
shallower construction can be achieved.
A typical span/depth ratio for a uniformly loaded composite beam is in the range 18 – 20
(taking the depth as the combined beam and slab depth).
2. Use of design graphs
The Graphs in this NCCI have been taken from ECCS publication 113
(1)
.
2.1 Design Graphs for Uniformly Loaded Beams
In this case, the design graphs are presented for secondary beams as a function of:
Maximum beam span
Slab span (or beam spacing)
Imposed loads of 3,5 or 5 kN/m
2
.
The graphs cover IPE and HEA section sizes and slab depths between 120 and 200 mm.
The assumptions made in preparing these graphs are:
The deck profile has a re-entrant shape and is 50 mm deep with 150 mm rib spacing
The 19 mm diameter shear connectors are pre-welded to the beam flange with one shear
connector in every deck rib.
Normal weight concrete of C25/30 grade is used.
S355 steel is used.
Construction load = 2 kN/m
2
.
Finishes additional to the imposed load are 1,5 kN/m
2
.
Partial factors γ
m
, = 1,0 for steel, and 1,5 for concrete.
The imposed load deflection is limited to span/300, and the total load deflection is limited
to span/250. If the total deflection limit is not satisfied, the beam is precambered.
Note:
(1) In interpreting these design graphs, pre-cambering is generally required for spans longer
than 12 m.
(2) For lighter loads, allowable spans may be increased by the square root of the load
reduction. For example, a 20% reduction in load increases the allowable span by 10%
approximately (actually 11,8%).

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NCCI: Initial Design of Composite Beams
SN022a-EN-EU
2.2 Design Graphs for Primary Beams
In this case, a typical design graph is presented for primary beams as a function of:
Maximum load per unit length of the beam, (taken as an equivalent line load to the point
loads)
Beam span

The graph covers IPE sections.

The common parameters are similar to previously, and include:
S355 Steel
C25/30 concrete
Slab depth = 140 mm
The deck profile has a re-entrant shape and is 50 mm deep with 150 mm rib spacing

In using this design graph, the maximum load per unit length is taken as the sum of all the
point loads acting on the beam divided by the beam span. The loads are calculated using an
average partial factor of 1,5 , and d is the slab depth (in m), g, is the self weight of the beam
(kN/m) and p is the imposed load (kN/m).

2.3 Application to Continuous Beams
Continuous composite beams may be designed using plastic section properties at the ultimate
limit state provided the cross-section is Class 1 or 2. This publication considers only Class 1
sections in which plastic global analysis is also permitted (with some restrictions).
The design of continuous beams is frequently controlled by serviceability criteria. In such
cases, the maximum span of continuous beams may be taken as 12% longer than the
equivalent simply supported beam for the same conditions of loading.
Where strength governs design, the end span of the continuous beam may be taken as 20%,
and an internal span as 40%, longer than the simply supported beam for the same conditions
of loading.
2.4 Software alternative
Software is available as an alternative to the use of the graphs. It may be freely downloaded
from the following web site:
http://www.arcelor.com/sections/en/software/CompositeStructures/default.html

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NCCI: Initial Design of Composite Beams
SN022a-EN-EU

22,0
21,0
20,0
19,0
18,0
17,0
16,0
15,0
14,0
13,0
12,0
11,0
10,0
9,0
8,0
7,0
6,0
5,0 2,5 2,0 3,0 3,5 4,0 4,5
a
a
a
a
a
a
a
a
b


c c c
c
a
c
c
c
c
c
b
B L
L
= 120 mm = 140 mm = 160 mm
(m)
d d d
B
= 180
= 160
= 140
= 120
= 200 d
d
d
d
d
<3 Hz f
IPE 600, = 600 h
h
h
h
h
h
h
h
IPE 550, = 550
IPE 500, = 500
IPE 450, = 450
IPE 400, = 400
IPE 360, = 360
IPE 330, = 330
IPE 300, = 300
d
h
(m)

Figure 2.1 Design curves for composite beams as secondary beams
Imposed load = 3,5 kN/m
2
IPE Sections

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NCCI: Initial Design of Composite Beams
SN022a-EN-EU

23,0

c c c
22,0
21,0
20,0
19,0
18,0
17,0
16,0
15,0
14,0
13,0
12,0
11,0
10,0
9,0
8,0
5,0 2,5 2,0 3,0 3,5 4,0 4,5
c
a
a
a
a
a
a
a
a
a
b
b
c
c
c
L
= 120 mm = 140 mm = 160 mm d d d
= 160
= 140
= 120 d
d
d
<3 Hz f
h
h
h
h
h
h
h
h
d
B L
h
HEA 550, = 540
HEA 500, = 490
HEA 450, = 440
HEA 400, = 390
HEA 360, = 350
HEA 340, = 330
HEA 320, = 310
HEA 300, = 290
(m)

Figure 2.2 Design curves for composite beams as secondary beams
Imposed load = 3,5 kN/m
2
HE Sections

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NCCI: Initial Design of Composite Beams
SN022a-EN-EU

22,0
21,0
20,0
19,0
18,0
17,0
16,0
15,0
14,0
13,0
12,0
11,0
10,0
9,0
8,0
7,0
6,0
5,0 2,5 2,0 3,0 3,5 4,0 4,5
c
a
B (m)
a
a
a
a
a
a
a
a
b
b
L (m)
c c
c
= 120 mm = 140 mm
= 160 mm
d d
d
c
c
c
c
c
= 160
= 140
= 120
d
d
d
d
d
<3 Hz f
h
h
h
h
h
h
h
h
= 180
= 200
IPE 300, = 300
IPE 600, = 600
IPE 550, = 550
IPE 500, = 500
IPE 450, = 450
IPE 400, = 400
IPE 360, = 360
IPE 330, = 330
d
h
B L

Figure 2.3 Design curves for composite beams as secondary beams
Imposed load = 5 kN/m
2
IPE Sections

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NCCI: Initial Design of Composite Beams
SN022a-EN-EU

23,0

22,0
21,0
20,0
19,0
18,0
17,0
16,0
15,0
14,0
13,0
12,0
11,0
10,0
9,0
8,0
5,0 2,5 2,0 3,0 3,5 4,0 4,5
c
a
a
a
a
a
a
a
a
a
b
d
B L
h
b
L (m)
c c c
= 120 mm = 140 mm = 160 mm
(m)
d d d
B
c
c
c
= 160
= 140
= 120
d
d
d
<3 Hz f
HEA 550, = 540 h
HEA 450, = 440
HEA 500, = 490
HEA 400, = 390
h
h
h
HEA 360, = 350
HEA 340, = 330
h
h
HEA 320, = 310
HEA 300, = 290
h
h

Figure 2.4 Design curves for composite beams as secondary beams
Imposed load = 5 kN/m
2
HE Sections

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NCCI: Initial Design of Composite Beams
SN022a-EN-EU


4
5
0
5
0
7
0
9
0
1
1
0
1
3
0
1
5
0
1
7
0
1
9
0
2
1
0
2
3
0
2
5
0
2
7
0
2
9
0
3
1
0
3
3
0
3
5
0
3
7
0
3
9
0
4
1
0
4
3
0
1
3
,
2
6
7
,
2
8
,
4
9
,
6
1
0
,
8
1
2
d
b
a aa
a
a
a
=

1
4
0
b
ca
I
P
E

6
0
0
,





=

6
0
0
I
P
E

5
5
0
,





=

5
5
0
I
P
E

5
0
0
,





=

5
0
0
h
h
h
h
h h
L
dh
B
I
P
E

3
6
0
,





=

3
6
0
I
P
E

4
0
0
,





=

4
0
0
I
P
E

4
5
0
,





=

4
5
0





(
m
)
L





(
k
N
/
m
)

q

Figure 2.5 Design graph for composite beams as primary beams
IPE sections (q
d
= equivalent line loading)

3. References
ECCS. Design Tables and Graphs for Composite Beams to Eurocode 4, Brussels, 2001.
Page 8
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NCCI: Initial Design of Composite Beams
SN022a-EN-EU
Quality Record
RESOURCE TITLE NCCI: Initial Design of Composite Beams
Reference(s)
ORIGINAL DOCUMENT
Name Company Date
Created by Dr Graham Owens SCI
Technical content checked by Tom Cosgrove SCI
Editorial content checked by D C Iles SCI 20/12/05
Technical content endorsed by the
following STEEL Partners:

1. UK G W Owens SCI 29/11/05
2. France A Bureau CTICM 18/1/05
3. Sweden A Olsson SBI 13/12/05
4. Germany C Müller RWTH 16/11/05
5. Spain J Chica Labein 17/11/05
Resource approved by Technical
Coordinator
G W Owens SCI 11/05/06
TRANSLATED DOCUMENT
This Translation made and checked by:
Translated resource approved by:

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