safety assesment of a steel frame using current code and sbra method petr konečný, m.s. structural...
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Safety assesment of a steel frame
using current code and SBRA method
Petr Konečný, M.S.
Structural Mechanics Division
Department of Civil Engineering
VŠB – TU Ostrava
Czech Republic
Euro-SiBRAM’2002 Prague June 24 to 26, 2002
Introduction
Summary
Safety Assessment of a steel frame (a) according to the Eurocode (EC)
and (b) according to SBRA method
Comparison of results
Subject of the discussion
Euro-SiBRAM’2002 Prague June 24 to 26, 2002
Steel frame
L = 20,0
10,00 10,00
l8 = 1,00l7 = 1,00
h3 =
3,0
0
H =
12,
00
h1 =
10,
0h2
= 2
,00
VZDÁLENOST PŘÍČNÝCH VAZEB b = 9,0 m
5
8
3 4
1 6
A
C
B
7
22
p
l
pl
1
3
Euro-SiBRAM’2002 Prague June 24 to 26, 2002
Loadings
3g
7
2 5
8
3 4
1 6
A
j8j7
G G
G6
G1
C
B
g4
7
2 5
8
3 4
1 6
A
s
C
B
2,40
2,40
w
7
2 5
8
3 4
1 6
e,H
e,E
w we,I
w
w
A
e,D
e,J
we,G
C
B
7
2 5
8
3 4
1 6
A
C
B
0,5s
7
2 5
8
3 4
1 6
F
A
p8 p7 F
j8 Q j7 Q
B
C
Obr. 6 Mostový jeřáb
Dead load
Wind (from the right or left)
Snow (entire roof, right or left side of the roof)
Crane girder (verticaland lateralhorizontal (forces
Euro-SiBRAM’2002 Prague June 24 to 26, 2002
Eurocode vs. SBRA
SBRA All input random variables are represented by bounded histogram
Reference value is defined by the onset of yielding
The safety function SF = R – S is evaluated using direct Monte Carlo method
The safety is expressed by comparing the calculated probability of failure Pf and target probability Pd, i.e., Pf < Pd
Uses load and resistence factors
Reference values correspond to ultimate (plastic) carrying capacity
Eurocode (EC)
Euro-SiBRAM’2002 Prague June 24 to 26, 2002
Probability of failure Pf (R < ) < Pd = 7.10-5
R - Fy yield stress
- Two component load effects combination expressed by stress
Assessment
N - Axial force
M – Bending moment
SBRA
iiyel
i
ii
ii AW
M
AA
N
var,,.var,
Probability of failure Pf Is calculated using AnthillTM
Computer program
Eurocode (see criteria contained in the code)
Euro-SiBRAM’2002 Prague June 24 to 26, 2002
Inner forces
Scatter axial forces N (kN)
Euro-SiBRAM’2002 Prague June 24 to 26, 2002
Inner forces
Scatter bending moments M (kNm)
Euro-SiBRAM’2002 Prague June 24 to 26, 2002
Comparison of results
In this study the shapes designed according to EC [2] are larger compared to cross-sections resulting from SBRA design.
For details see M.S. Thesis(Konečný, 2002, VŠB - TU Ostrava)
SBRA EC1 100% 121%2 100% 110%3 100% 140%
Cross-sections
Area
Euro-SiBRAM’2002 Prague June 24 to 26, 2002
Summary
Transparent analysis of the multi-component load effects combinations
Rather complicated transformation model
SBRA
Eurocode (EC) Planar frame had to be analyzed considering 144 load effects combinations
Load effects combination analysis was time consuming and not consequente.
Thank you for your attention
Petr Konečný, M.S.
Structural Mechanics Division
Department of Civil Engineering
VŠB – TU Ostrava
Czech Republic