Transcript Slide 1

T1. DESIGN OF STEEL BEAMS
Floor plan
Steel framed building
+ bracing
Beam: linear member subjected to bending and shear (N=0).
Example: Design of secondary girder F1 and beam G1.
page 1.
T1. Design of steel beams
I. Design of secondary girder F1
I.1. Geometry, model, loads
Cross-sectional data
I.1.1. Model, Geometry:
section tables (ST)
simple supported beam
leff =
I.1.2. Loads: floor
Dead load
-Self-weight:
Floor layers:
 kN 
gK  2 
m 
 g ,sup  1.35
1.5 cm parquet
1 layer PE foam underlay
4 cm composition layer
5 cm Rockwood insulation
10 cm monolithic reinforced concrete slab
5 cm steel trapezoid sheet
HE 180 secondary girder (spacing 1.2 m)
2 layer plasterboard
g Kfloor 
T1. Design of steel beams
Σ
page 2.
- Variable load: qKfloor 
 q  1.5
(for balcony: qKbalc 
)
Load of partition walls (substitute load which can be added to variable load):
floor
pEd
  g  g K   q  qKfloor 
Design value of the total load on one secondary girder:
sg  kN 
floor  kN 
pEd
 m   t m pEd  m 2  
t=
I. 2. Calculation of internal forces
VEd 
pEd leff
2
M Ed 

2
pEd leff
8

I. 3. Ultimate limit state: strength analysis
Idealized - diagram
I.3.0. Material properties
Steel:
homogenous, izotropic, linear-elastic/perfectly plastic material model
Grade of material:
S235 (Steel, fy [N/mm2])  fy =
T1. Design of steel beams
page 3.
Study Aid for Steel Structures (S.A.S)
I. 3.1. Classification of section
I.3.2. Bending
Force equilibrium:
N  0
Moment equilibrium: limit state
M c, Rd  Wpl , y
Wpl , y 
fy
c , Rd
 M 0  1.0
 M0
plastic section modulus (ST)
M c,Rd 
I.3.3. Shear
M  M
M Ed 
Avz 
Vc, Rd  Avz
Vc,Rd 
the area of shear
fy
3 M 0

VEd 
I.3.4. Bending combined with shear
VEd

Vc , Rd
T1. Design of steel beams
page 4.
(ST)
I.4. Stability analysis:
-
Lateral-torsional buckling (between the supports against buckling)
-
local plate buckling under axial compression:
-
local plate buckling under axial compression:
-
web buckling under shear (AS. 5.5.1)
-
web buckling under shear:
-
Effect of transverse concentrated force:
-
Effect of transverse concentrated compressive force:
(S.A.S.)
grading of cross-section
I.5. Servicebility limit state: Deflection
Quasi permanent load combination 2 =0.3
pKfloor  g K  2  qK 
 kN 
 kN 
For the considered secondary girder: pKsg    t m pKfloor  2  
m
m 
sg
4
5 pK l
E=
Iy =
wmax 
384 EI y
wmax 
(ST)
allowed deflection:
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T1. Design of steel beams
II.
Design of beam G1
II.1 Loads, Geometry, model
Model:
leff =
Cross-section:
Load of secondary girders (assumed uniformly distributed):
Self-weight of beam:
(ST)
Masonry infill (height. 3.0 m):
considering openings:
beam
pEd

II.2. Internal forces
VEd 
pEd leff
2

M Ed 
2
pEd leff
8

II.3. Strength analysis
II.3.0. Material properties
Grade of material:
S235 (Steel, fy [N/mm2])  fy =
II.3.1. Cross-section classification
(S.A.S)
page 6.
T1. Design of steel beams
II.3.2. Bending:
M c , Rd  Wel, y
fy
M0
Wel, y 
elastic section modulus
M c,Rd 
(ST)
M Ed 
II.3.3. and II.3.4. Shear and bending combined with shear
(S.A.S)
Avz 
Vc, Rd  Avz
the section in shear (ST)
fy
3 M 0

VEd

Vc , Rd
II.4. Stability analysis
- lateral-torsional buckling:
- local analyses – grading of cross-section
II.5. Deformation analysis: Deflection
page 7.
T1. Design of steel beams
 M 0  1.0