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Seismic	
  design	
  of	
  steel	
  
building	
  accordance	
  to	
  	
  	
  
Eurocode	
  3	
  and	
  8	
   	
...
Page 2
ABOUT THIS DOCUMENT
This publication provides a concise compilation of selected rules in the Eurocode 8, together
w...
Page 3
List of contents
1.1 DESIGN AND ANALYSIS EXAMPLE OF STEEL FRAME WITH CONCENTRIC
BRACING ..............................
Page 4
2.3.7 TORSIONAL EFFECTS ..............................................................................................
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9.2 DESIGN OF COLUMNS / BEAMS USING ETABS – GRAVITY LOAD ANALYSIS
ONLY ...............................................
Page 6
A1.1:LIMITATION MADE IN THE DESIGN ALGORITHM (MANUAL OF ETABS –
EC3&EC8)..............................................
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1.1 Design and analysis example of steel frame with concentric bracing
1.1 Layout of structure
Figure 1.1: Plan vie...
Page 8
Figure 1.3: Side Elevation (A) & (D)
Table 1.1: Dimensions of the building
Dimensions Symbol Value Units
Storey hei...
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1.2 Preliminary design
Table 1.2: Seismic design data
Data Symbol Value Units
Seismic zone - 3 -
Reference peak gro...
Page 10
Material properties:
Young Modulus of Elasticity
Structural steel (clause 6.1(1) EN 1993 1-1)
Structural steel pro...
Page 11
1.3 Material properties
ETABS: Define > Material properties
1.3.1 Material properties of concrete
Design requireme...
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1.3.2 Material properties of steel
Table 1.4: Material properties of steel
Material Properties Symbol Value Units ...
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1.3.3 Material properties of steel and concrete as define in ETABS
Figure 1.4: Material properties of concrete (C2...
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Table 1.6: Slab properties
Data Symbol Value Units
Slab depth hs 170 mm
Diameter of stud d 19 mm
Height of stud ha...
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1.3.4.1 Modeling requirements of EC8 for concrete members
1. Unless a more accurate analysis of the cracked elemen...
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1.3.4.3 Meshing of slabs
ETABS: Select > Wall/Slab/Deck section > Select Deck
ETABS: Assign > Shell area > Auto Ob...
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1.4 Joint modeling (EN1993-1-1,cl.5.1.2)
(1) The effects of the behavior of the joints on the distribution of inte...
Page 18
Table 1.7: Example of joint types
Simple joint Continuous Fixed joint Semi- continuous joint
ETABS: Pin joint in E...
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ETABS: Fixed joint in ETABS
The fixed-joint in ETABS can be achieved by selecting the members that you assumed to ...
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2.0 Modal Response Spectrum Analysis
2.1 Structural types and behavior factor according to EN1998-1-1,cl.6.3
Table...
Page 21
Dissipative zones in tension and compression diagonals
Frames with K-bracing (CBF)
Not allowed in
dissipative desi...
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αu/ α1 =1.2
dissipative zones in moment frame and tension diagonals
Moment frames with
infills Unconnected concret...
Page 23
Table 2.2: Values of behavior factor for regular and irregular structure
Structural type Regular in plan
and eleva...
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2.2 Define design horizontal response spectrum
2.2.1 Vertical response spectrum (EN1998-1-1,cl.3.2.2.3)
The vertic...
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2.2.3 Parameters of elastic response spectrum (EN1998-1-1,cl.3.2.2.5)
Table 2.3: Parameters of Type 1 elastic resp...
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4. Modify the existing values of elastic response spectrum case in order to change it into
the design response spe...
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Figure 2.2: Amendment Response spectrum (q = 4)
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2.2.3.1 Ground investigation conditions
Table 2.4: Geological studies depend on the importance class (CYS NA EN199...
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CC1: Low consequence for loss of human life, and economic, social or environmental
consequences small or negligibl...
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2.3 Analysis types
2.3.1 Modal Response spectrum analysis
Table 2.7: Requirements of modal response spectrum analy...
Page 32
2.3.1.1 Accidental eccentricity
Accidental eccentricity of each storey cause of uncertainties location of masses h...
Page 33
Define > Response spectrum cases
Note: Add two response spectrum cases: EQX and EQY as showing below (figure 9).
F...
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2.3.2 Lateral force analysis requirements
Table 2.9: Requirements of lateral force analysis according to Eurocode ...
Page 35
2.3.4 Estimation of fundamental period T1
Table 2.11: Estimation of fundamental period T1
Reference structure Peri...
Page 36
2.3.5 Automatic Lateral force analysis using ETABS
ETABS: Define > Static load cases
Figure 2.4: Apply the Equival...
Page 37
Fundamental period (EN1998-1-1,Eq.4.6)
T1=CtH3/4
(For heights up to 40m)
Value of Ct(EN1998-1-1,cl.4.3.3.2.2(3))
C...
Page 38
2.3.6 User loads - Lateral force analysis using ETABS
Geometrical data
Span of the longitutinal direction
Span of ...
Page 39
Dead load
Weight of steel column HE280A
Weight of primary beams IPE240
Weight of secondary beams IPE180
Weight of ...
Page 40
Horizontal design response Spectrum (EN1998-1-1,cl.3.2.2.5)
Behaviour factor q
(EN1998-1-1,cl.6.3)
Lower bound fac...
Page 41
Lower limit of the period, TB
Upper limit of the period, TC
Constant displacement value, TD
Corection factor λ
(EN...
Page 42
Design spectrum acceleration
Seismic base shear
(EN1998-1-1,cl.4.3.3.2.2(1))
Seismic base shear on each bracing
No...
Page 43
Table 2.12: Summary table of the lateral force results
Story
Heigth	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
 ...
Page 44
ETABS: Define > Static load case >
Figure 2.6: Define manually the lateral forces
Figure 2.7: Define manually the ...
Page 45
2.3.7 Torsional effects
FLOW CHART OF TORSIONAL EFFECTS
Carry out Lateral force analysis/
Response spectrum analys...
Page 46
2.3.8 Summary of analysis process in seismic design situation
Importance class/Ductility class
I II III IV
DCL DCM...
Page 47
3.0 Define static loads
Here define as many load cases for your model as you need e.g. dead loads, live loads, win...
Page 48
4.0 Seismic mass requirements according to EC8
Combination of the seismic action with other actions (EN 1998-1-1,c...
Page 49
4.1 Mass Source Option
In ETABS, the user has the option of choosing one of three options for defining the source ...
Page 50
Figure 4.1: Seismic source
Page 51
5.0 Wind loading on structure (EN1991-1-4:2004)
5.1 Calculation of Wind load according to EN1991-1-4:2004
Step by ...
Page 52
Table 5.1: Terrain category and terrain parameters (EN1991-1-4, Tab.:4.1)
Terrain
category
Description z0 (m) zmin...
Page 53
Table 5.3: Values of external pressure coefficient for vertical walls of rectangular plan building
(EN1991-1-4, Ta...
Page 54
5.2 Application of wind loading using ETABS
Table 5.4: Wind load assumptions
Data Symbol Value Units
Basic wind ve...
Page 55
ETABS: Select the area of elevation A-A
ETABS: Assign > Shell/Area loads > Wind pressure coefficients
Figure 5.2: ...
Page 56
Wind pressure coefficient for load case WINDY
Windward load “Area D” Leeward load “Area E”
Side load “Area A & B” ...
Page 57
	
   	
   	
   	
   	
   	
   	
   	
   	
   WIND LOADING ACCORDING TO
EN1991-1-4:2005
Job No.:
	
   	
   	
   	
 ...
Page 58
External	
  Pressure	
  Coefficients	
  Walls	
  Cpe	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
...
Page 59
6.0 Load combination
Table 6.1: Load combination factors and coefficients
Data Symbol Value Reference
Permanent ac...
Page 60
Seismic load combination for “Lateral force Analysis”
SEISMIC 10. DL + 0.3LL + EQXA + 0.3EQYA
SEISMIC 11. DL + 0.3...
Page 61
7.0 Design preferences
ETABS: Options > Preferences > Steel frame design
Figure 7.1: Steel frame design preference...
Page 62
Table 7.1: Steel frame design parameters
Note 1: Reliability class
Class section classification according to EN199...
Page 63
1. Run the design analysis with the Ω=1
2. Find the Npl,Rd and NEd of the bracing member and then overwrite the om...
Page 64
8.0 Analysis and design requirements for Concentrically braced frames according to
EN1998-1-1,cl.6.7.2
Analysis re...
Page 65
8.1 Steps of the design detail of Concentric steel frames
Table 8.1: Detail steel frame design
Design step
number
...
Page 66
8.2 Classification of steel sections
Table 8.2: Section classification (EN1993-1-1,cl.5.5)
Classes Analysis type D...
Page 67
Depth of a part of section for
oustand flange
(I-sections)
EN1993-1-1,Table 5.2
Section classification for
flange ...
Page 68
8.3 Design of composite slab under gravity loads
Table 8.3: Detail design of composite slab (with steel sheeting)
...
Page 69
For holes provided in the sheeting, the diameter of the stud d ≤ 22mm EN1994-1-1,cl.6.6.4.2(3)
Maximum overall hei...
Page 70
Location of neutral axis Neutral axis=if{Np < Nc “Lie above steel sheeting”, “Lie
below steel sheeting”}
EN1994-1-...
Page 71
Serviceability limit state (SLS) – Floor vibration
Floor vibration limits f = 18 / √δa
SCI-P-076 : Design guide
on...
Page 72
8.4 Design of composite beam (with steel sheeting) under gravity loads
Table 8.4: Detail design of composite beam
...
Page 73
Construction
Stage
section Y-Y axis
Check if the verification of
shear buckling resistance
required or not
(EN1993...
Page 74
Composite
Stage
Tensile resistance of steel
section
(EN1993-1-1,cl.6.2.3(2))
Compression resistance of
concrete sl...
Page 75
Composite
Stage
required or not
Design resistance of shear stud connector (cl.6.6.3.1(1))
Upper limit of reduction...
Page 76
Composite
Stage
Design shear resistance of a
headed stud
(EN1994-1-1,cl.6.6.3.1(1))
Degree of shear connection (cl...
Page 77
Longitudinal shear stress (EN1992-1-1,cl.6.2.4(3))
Strength reduction factor
(EN1992-1-1,Eq.6.6N)
Area of transver...
Page 78
Total load on beam is EN1990,A1.4.4
Increase the inertia, Ic by 10% to allow for the
increased dynamic stiffness o...
Page 79
8.5 Detail design of steel columns under gravity loads
Table 8.5: Detail design of composite beam
Partial factor V...
Page 80
Coefficient of interaction vy=VEd / Vpl.Rd,y EN1993-1-1,cl.6.2.8(5)
Reduced yield strength ρ = [(2VEd / Vpl.Rd,y) ...
Page 81
moments making allowance for the presence of
axial forces (Y-Y axis)
MN,y,Rd = Mpl,y,Rd if 0 ≤ c ≤ 1.0
Reduced des...
Page 82
Value to determine the reduction factor χ Φ = 0.5 [1 + α (λ – 0.2) + λ2
EN1993-1-1,cl.6.3.1.2(1)
Reduction factor ...
Page 83
Value to determine the reduction factor χ Φ = 0.5 [1 + α (λ – 0.2) + λ2
EN1993-1-1,cl.6.3.1.2(1)
Reduction factor ...
Page 84
Lateral torsional buckling curves EN1993-1-1,table 6.4
Imperfection factors for lateral torsional buckling curves ...
Page 85
Ratio of end moments EN193-1-1,Table B2)
Equivalent uniform moment factor EN1993-1-1,table B.1&B.2
Interaction fac...
Page 86
Combined bending and axial compression EN1993-1-1,Eq.6.62
Note: This equations is applicable only for I and H sect...
Page 87
8.6 Detail design rules of steel Concentric Braced Frames (CBF) according to Eurocode 8
8.6.1 Detail design rules ...
Page 88
8.7 Detail design rules of steel columns and beams according to Eurocode 8
Description Value References
Overstreng...
Page 89
8.8 Detail design rules of steel composite members according to Eurocode 8
Description Value References
Minimum co...
Page 90
8.9 Detail design rules of steel moment resistance frames (MRF) according to Eurocode 8
8.9.1 Detail design rules ...
Page 91
8.9.3 Detail design rules of steel column for MRF
Description Value References
Overstrength factor used in design ...
Page 92
9.0 Design of steel frames
9.1 Design of steel member overwrites data
Figure 9.1: Steel design result of the membe...
Page 93
Figure 9.2: Steel frame design overwrites for Eurocode 3
3
2
1
4
7
8
9
10
11
12
5
6
Page 94
Table 9.1: Steel frame design overwrites for Eurocode 3
Explanation of Steel frame design overwrites for Eurocode ...
Page 95
3
Bending Coefficient
(C1)
4 Moment coefficient
5
Overstrength factor
used in design1
6
Omega gamma
factor
γov = 1...
Page 96
11
Major shear
capacity, Vc3Rd
12
Minor shear
capacity, Vc2Rd
Notes: 1
Ω is not calculated automatically by the pr...
Page 97
9.2 Design of columns / beams using ETABS – Gravity load analysis only
STEP 1: Analyze > Run Analysis
STEP 2: Desi...
Page 98
Figure 9.4: Gravity load combination at SLS
Figure 9.5: Steel design under gravity load ONLY
Write click on each
m...
Page 99
Figure 9.6: Steel design result of the member
Figure 9.7: Ultimate moment results under worst case combination
ETA...
Page 100
Take the ultimate moment and shear force from the above table and place them into the Excel
spreadsheet or Mathca...
Page 101
Design results of ETABS
ETABS/HAND
Description of
comparison
Results
ETABS
Equation 6.62 in EC3
0.160
HAND (see s...
Page 102
ETABS/HAND N.c.Rd N.t.Rd N.pl.Rd
ETABS 2675.75 2675.75 2675.75
HAND (see section 9.3) 2675.75 2675.75 2675.75
ETA...
Page 103
ETABS/HAND
M.c.Rd M.v.Rd
M.b.rd
y-y z-z y-y z-z
ETABS 305.8 142.45 305.8 142.45 302.05
HAND (see section 9.3) 305...
Page 104
ETABS/HAND
V.c.Rd
V.pl.Rd η
y-y z-z
ETABS 504 1234 504 1.2
HAND (see section 9.3) 504 1156 504 1.0
Page 105
9.3 Design of steel column (Gravity design situation) – Hand calculations
1. Rolled I - section
2. Limit to class...
Page 106
Area of the web
Warping Constant, Iw:
Torsional Constant, IT:
Plastic Modulus, Wply
Plastic Modulus, Wplz
Elastic...
Page 107
For a web element:
Tension resistance (cl.6.2.3)
Design plastic resistance of the cross section
(EN1993-1-1,cl.6....
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8
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ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8

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This publication provides a concise compilation of selected rules in the Eurocode 8, together with relevant Cyprus National Annex, that relate to the design of common forms of concrete building structure in the South Europe. It id offers a detail view of the design of steel framed buildings to the structural Eurocodes and includes a set of worked examples showing the design of structural elements with using software (CSI ETABS). It is intended to be of particular to the people who want to become acquainted with design to the Eurocodes. Rules from EN 1998-1-1 for global analysis, type of analysis and verification checks are presented. Detail design rules for steel composite beam, steel column, steel bracing and composite slab with steel sheeting from EN 1998-1-1, EN1993-1-1 and EN1994-1-1 are presented. This guide covers the design of orthodox members in steel frames. It does not cover design rules for regularities. Certain practical limitations are given to the scope.

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Transcript of "ETABS manual - Seismic design of steel buildings according to Eurocode 3 & 8 "

  1. 1.       Seismic  design  of  steel   building  accordance  to       Eurocode  3  and  8         Valentinos  Neophytou  BEng,  MSc           JULY  2013   -­‐Worked  examples  –  Hand  calculations   ETABS  manual
  2. 2. Page 2 ABOUT THIS DOCUMENT This publication provides a concise compilation of selected rules in the Eurocode 8, together with relevant Cyprus National Annex, that relate to the design of common forms of concrete building structure in the South Europe. It id offers a detail view of the design of steel framed buildings to the structural Eurocodes and includes a set of worked examples showing the design of structural elements with using software (CSI ETABS). It is intended to be of particular to the people who want to become acquainted with design to the Eurocodes. Rules from EN 1998-1-1 for global analysis, type of analysis and verification checks are presented. Detail design rules for steel composite beam, steel column, steel bracing and composite slab with steel sheeting from EN 1998-1-1, EN1993-1-1 and EN1994-1-1 are presented. This guide covers the design of orthodox members in steel frames. It does not cover design rules for regularities. Certain practical limitations are given to the scope. Due to time constraints and knowledge, I may not be able to address the whole issues. Please send me your suggestions for improvement. Anyone interested to share his/her knowledge or willing to contribute either totally a new section about Eurocode 8 or within this section is encouraged. For further details: My LinkedIn Profile: http://www.linkedin.com/profile/view?id=125833097&trk=hb_tab_pro_top Email: valentinos_n@hotmail.com Slideshare Account: http://www.slideshare.net/ValentinosNeophytou
  3. 3. Page 3 List of contents 1.1 DESIGN AND ANALYSIS EXAMPLE OF STEEL FRAME WITH CONCENTRIC BRACING .................................................................................................................................7 1.1 LAYOUT OF STRUCTURE...............................................................................................7 1.2 PRELIMINARY DESIGN...................................................................................................9 1.2.1 PRELIMINARY DESIGN OF COLUMNS AND BEAMS ............................................9 1.3 MATERIAL PROPERTIES ..............................................................................................11 1.3.1 MATERIAL PROPERTIES OF CONCRETE...............................................................11 1.3.2 MATERIAL PROPERTIES OF STEEL ........................................................................12 1.3.3 MATERIAL PROPERTIES OF STEEL AND CONCRETE AS DEFINE IN ETABS 13 1.3.4.1 MODELING REQUIREMENTS OF EC8 FOR CONCRETE MEMBERS...............15 1.3.4.2 MODELING REQUIREMENTS OF EC8 FOR FLOOR DIAPHRAGMS................15 1.3.4.3 MESHING OF SLABS................................................................................................16 1.4 JOINT MODELING (EN1993-1-1,CL.5.1.2) ...................................................................17 2.0 MODAL RESPONSE SPECTRUM ANALYSIS.............................................................20 2.1 STRUCTURAL TYPES AND BEHAVIOR FACTOR ACCORDING TO EN1998-1- 1,CL.6.3 ...................................................................................................................................20 2.2 DEFINE DESIGN HORIZONTAL RESPONSE SPECTRUM........................................24 2.2.1 VERTICAL RESPONSE SPECTRUM (EN1998-1-1,CL.3.2.2.3)................................24 2.2.2 HORIZONTAL RESPONSE SPECTRUM (EN1998-1-1,CL.3.2.2.5)..........................24 2.2.3 PARAMETERS OF ELASTIC RESPONSE SPECTRUM (EN1998-1-1,CL.3.2.2.5)..25 2.2.3.1 GROUND INVESTIGATION CONDITIONS...........................................................29 2.2.3.2 IMPORTANCE FACTOR...........................................................................................29 2.2.3.3 DUCTILITY CLASS...................................................................................................30 2.3 ANALYSIS TYPES ..........................................................................................................31 2.3.1 MODAL RESPONSE SPECTRUM ANALYSIS..........................................................31 2.3.1.1 ACCIDENTAL ECCENTRICITY..............................................................................32 2.3.2 LATERAL FORCE ANALYSIS REQUIREMENTS....................................................34 2.3.4 ESTIMATION OF FUNDAMENTAL PERIOD T1 ......................................................35 2.3.5 AUTOMATIC LATERAL FORCE ANALYSIS USING ETABS................................36 2.3.6 USER LOADS - LATERAL FORCE ANALYSIS USING ETABS.............................38
  4. 4. Page 4 2.3.7 TORSIONAL EFFECTS ................................................................................................45 2.3.8 SUMMARY OF ANALYSIS PROCESS IN SEISMIC DESIGN SITUATION...........46 3.0 DEFINE STATIC LOADS................................................................................................47 4.0 SEISMIC MASS REQUIREMENTS ACCORDING TO EC8.........................................48 4.1 MASS SOURCE OPTION ................................................................................................49 5.0 WIND LOADING ON STRUCTURE (EN1991-1-4:2004)..............................................51 5.1 CALCULATION OF WIND LOAD ACCORDING TO EN1991-1-4:2004....................51 5.2 APPLICATION OF WIND LOADING USING ETABS .................................................54 6.0 LOAD COMBINATION...................................................................................................59 7.0 DESIGN PREFERENCES ................................................................................................61 8.0 ANALYSIS AND DESIGN REQUIREMENTS FOR CONCENTRICALLY BRACED FRAMES ACCORDING TO EN1998-1-1,CL.6.7.2 ..............................................................64 8.1 STEPS OF THE DESIGN DETAIL OF CONCENTRIC STEEL FRAMES ...................65 8.2 CLASSIFICATION OF STEEL SECTIONS....................................................................66 8.3 DESIGN OF COMPOSITE SLAB UNDER GRAVITY LOADS....................................68 8.4 DESIGN OF COMPOSITE BEAM (WITH STEEL SHEETING) UNDER GRAVITY LOADS ....................................................................................................................................72 8.5 DETAIL DESIGN OF STEEL COLUMNS UNDER GRAVITY LOADS......................79 8.6 DETAIL DESIGN RULES OF STEEL CONCENTRIC BRACED FRAMES (CBF) ACCORDING TO EUROCODE 8..........................................................................................87 8.6.1 DETAIL DESIGN RULES OF STEEL BRACING ACCORDING TO EUROCODE 8 ..................................................................................................................................................87 8.7 DETAIL DESIGN RULES OF STEEL COLUMNS AND BEAMS ACCORDING TO EUROCODE 8.........................................................................................................................88 8.8 DETAIL DESIGN RULES OF STEEL COMPOSITE MEMBERS ACCORDING TO EUROCODE 8.........................................................................................................................89 8.9 DETAIL DESIGN RULES OF STEEL MOMENT RESISTANCE FRAMES (MRF) ACCORDING TO EUROCODE 8..........................................................................................90 8.9.1 DETAIL DESIGN RULES FOR MRF - DESIGN CRITERIA....................................90 8.9.2 DETAIL DESIGN RULES OF STEEL BEAM FOR MRF...........................................90 8.9.3 DETAIL DESIGN RULES OF STEEL COLUMN FOR MRF.....................................91 9.0 DESIGN OF STEEL FRAMES.........................................................................................92 9.1 DESIGN OF STEEL MEMBER OVERWRITES DATA.................................................92
  5. 5. Page 5 9.2 DESIGN OF COLUMNS / BEAMS USING ETABS – GRAVITY LOAD ANALYSIS ONLY ......................................................................................................................................97 9.3 DESIGN OF STEEL COLUMN (GRAVITY DESIGN SITUATION) – HAND CALCULATIONS.................................................................................................................105 9.4 DESIGN OF STEEL COLUMN (SEISMIC DESIGN SITUATIONN).........................118 9.4.1 DESIGN OF STEEL COLUMN (SEISMIC DESIGN SITUATION – HAND CALCULATION)..................................................................................................................124 9.5 DESIGN OF COMPOSITE BEAMS - HAND CALCULATIONS................................128 9.5 DESIGN OF STEEL BRACING.....................................................................................145 9.5.1 MAIN CONFIGURATION OF DESIGN OF STEEL BRACING..............................145 9.5.2 SIMPLIFIED DESIGN OF FRAMES WITH X BRACING (EXTRACT FROM DESIGN GUIDANCE TO EC8) ...........................................................................................147 9.5.3 MODEL IN ETABS .....................................................................................................148 9.5.4 DESIGN OF STEEL BRACING (GRAVITY/SEISMIC DESIGN SITUATION) – HAND CALCULATION.......................................................................................................156 10.0 MODAL RESPONSE SPECTRUM ANALYSIS.........................................................170 10.1 SET THE ANALYSIS OPTIONS.................................................................................170 10.2 EVALUATE THE ANALYSIS RESULTS OF THE STRUCTURE ACCORDING TO THE MODAL ANALYSIS REQUIREMENTS ...................................................................171 10.2.1 ASSESS THE MODAL ANALYSIS RESULTS BASED ON THE EN1998...........172 11.0 SECOND ORDER EFFECTS (P – Δ EFFECTS) ACCORDING TO EN1998-1- 1,CL.4.4.2.2 ...........................................................................................................................173 11.1 DISPLACEMENT CALCULATION ACCORDING TO EN1998-1-1,CL.4.4.2.2 .....174 11.2 INTERSTOREY DRIFT................................................................................................174 11.3 CALCULATION OF SECOND ORDER EFFECT USING ETABS...........................175 11.3.1 INTERSTOREY DRIFT DISPLACEMENT .............................................................176 11.3.2 TOTAL GRAVITY LOAD PTOT................................................................................178 11.3.2 TOTAL SEISMIC STOREY SHEAR VTOT...............................................................180 12.0 DAMAGE LIMITATION ACCORDING TO EN1998-1-1,CL.4.4.3 ..........................184 12.1 CALCULATION OF DAMAGE LIMITATION..........................................................185 ANNEX - A ..........................................................................................................................186 ANNEX A.1 - ASSUMPTIONS MADE IN THE DESIGN ALGORITHM (MANUAL OF ETABS – EC3 & EC8) ..........................................................................................................186
  6. 6. Page 6 A1.1:LIMITATION MADE IN THE DESIGN ALGORITHM (MANUAL OF ETABS – EC3&EC8).............................................................................................................................187 ANNEX –B: STEEL DESIGN FLOWCHARTS..................................................................188
  7. 7. Page 7 1.1 Design and analysis example of steel frame with concentric bracing 1.1 Layout of structure Figure 1.1: Plan view Figure 1.2: Side Elevation (4) & (1)
  8. 8. Page 8 Figure 1.3: Side Elevation (A) & (D) Table 1.1: Dimensions of the building Dimensions Symbol Value Units Storey height h 3.0 m Total height of the building H 9.0 m Beam length in X-direction lx 5.0 m Beam length in Y-direction ly 5.0 m Building width in X-direction Lx 15.0 m Building width in Y-direction Ly 15.0 m
  9. 9. Page 9 1.2 Preliminary design Table 1.2: Seismic design data Data Symbol Value Units Seismic zone - 3 - Reference peak ground acceleration on type A ground, agR. agR 0.25 m/s2 Importance class γI 1.0 - Design ground acceleration on type A ground ag 0.25 m/s2 Design spectrum - Type 1 - Ground type - B - Structural system Steel frame with concentric bracing Behavior factor q 4.0 - 1.2.1 Preliminary design of columns and beams Preliminary design of steel beam Design data: Span of beam Bay width Overall depth of slab Loading data: Density of concrete Loads of floor per meter Live load Live load per meter Partial factor for actions: Safety factor are obtain from Table A.1(2)B EN1990 Permanent actions, γ G Variable actions, γ Q Total load Lx 5000mm:= wbay 5000mm:= h 130mm:= γ c 25kN m 3− ⋅:= gfloor γ c h⋅ Lx⋅ 16.25 kN m 1− ⋅⋅=:= qoffice 2kN m 2− ⋅:= qservice qoffice Lx⋅ 10 kN m 1− ⋅⋅=:= γ G 1.35:= γ Q 1.5:= Ed γ G gfloor⋅ γ Q qservice⋅+ 36.94 kN m 1− ⋅⋅=:=
  10. 10. Page 10 Material properties: Young Modulus of Elasticity Structural steel (clause 6.1(1) EN 1993 1-1) Structural steel properties: Yield strength, fy Ultimate strength, fu Yield strength of reinforcement, fyk Deflection limitation: Deflection limit - General purpose Second moment area required Second moment area provided (IPE240) Moment resistance check: Design moment (Fixed end) Plastic modulus required Plastic modulus provided (IPE240) Weak Beam - Strong column -Capacity design: Plastic modulus of column required Plastic modulus of column provided (HE220A) Es 210kN mm 2− ⋅:= γ M0 1.0:= fy 355N mm 2− ⋅:= fu 450N mm 2− ⋅:= fyk 500N mm 2− ⋅:= F Lx 300 := Ireq 300 Ed⋅ Lx 3 ⋅ 384 Es⋅ 1.718 10 3 × cm 4 ⋅=:= Iprov 3892cm 4 := Check_1 if Iprov Ireq> "OK", "NOT OK",( ):= Check_1 "OK"= MEd Ed Lx 2 ⋅ 12 76.953kN m⋅⋅=:= Wpl.y.req MEd fy 216.769cm 3 ⋅=:= Wpl.y 324.4cm 3 := Check_2 if Wpl.y Wpl.y.req> "OK", "NOT OK",( ):= Check_2 "OK"= Wpl.y.c.req 1.3 Wpl.y⋅ 421.72cm 3 =:= Wpl.y.c 515cm 3 := Check_3 if Wpl.y.c Wpl.y.c.req> "OK", "NOT OK",( ):= Check_3 "OK"=
  11. 11. Page 11 1.3 Material properties ETABS: Define > Material properties 1.3.1 Material properties of concrete Design requirement Poisson ratio is equal to v = 0 (cracked concrete) and v = 0.2 (un-cracked concrete) as (EN1992-1-1,cl.3.1.3). Table 1.3: Concrete properties (EN 1992, Table 3.1) Property Data for concrete C16/20 (N/mm2 ) C20/25 (N/mm2 ) C25/30 (N/mm2 ) C30/37 (N/mm2 ) Mass per unit Volume 2,5E-09 2,5E-09 2,5E-09 2,5E-09 Weight per unit volume 2,5E-05 2,5E-05 2,5E-05 2,5E-05 Modulus of Elasticity 29000 30000 31000 33000 Poisson’s Ratio (cracked concrete) 0 0 0 0 Coeff. of thermal expansion 10E-06 10E-06 10E-06 10E-06 Charact. ConcCyl. Strength, fck 16 20 25 30 Bending Reinf. Yield stress, fyk 500 500 500 500 Shear Reinf. Yield stress, fyk 500 500 500 500
  12. 12. Page 12 1.3.2 Material properties of steel Table 1.4: Material properties of steel Material Properties Symbol Value Units References Mass per unit Volume γs 7.85E-09 kg/mm3 EN1991-1-1,table A.4 Weight per unit Volume γs 7.70E-05 N/mm3 EN1991-1-1,table A.4 Modulus of Elasticity Es 210,000 N/mm2 EN1993-1-1,cl.3.2.6(1) Poisson’s ratio ν 0.3 - EN1993-1-1,cl.3.2.6(1) Coeff of Thermal Expansion (Steel structures) α 1.2x10-5 per K (for T ≤ 100o C) K EN1993-1-1,cl.3.2.6(1) Coeff of Thermal Expansion (Composite Concrete- Steel structures) α 1.2x10-5 per K (for T ≤ 100o C) K EN1993-1-1,cl.3.2.6(1) Shear Modulus G ≈81,000 N/mm2 EN1993-1-1,cl.3.2.6(1) Characteristic yield strength of steel profile fy 275 N/mm2 EN1993-1-1,table 3.1 Ultimate strength fu 430 N/mm2 EN1993-1-1,table 3.1 Table 1.5: Strength vales of steel sections (EN1993-1-1,table 3.1) Steel grade Nominal thickness of the element t (mm) t ≤ 40mm 40mm < t ≤ 80mm Grade referencefy (N/mm2 ) fu (N/mm2 ) fy (N/mm2 ) fu (N/mm2 ) S235 235 360 215 360 EN 10025-2 S275 275 430 255 410 EN 10025-2 S355 355 510 335 470 EN 10025-2 S450 440 550 410 550 EN 10025-2 Note: You may use the product standard instead of those given in EN1993-1-1
  13. 13. Page 13 1.3.3 Material properties of steel and concrete as define in ETABS Figure 1.4: Material properties of concrete (C25/30) Figure 1.5: Material properties of steel (S275) 1.3.4 Slab modeling
  14. 14. Page 14 Table 1.6: Slab properties Data Symbol Value Units Slab depth hs 170 mm Diameter of stud d 19 mm Height of stud haw 152 mm Tensile strength of stud fu 430 N/mm2 ETABS: Define > Wall/Slab/Deck Sections/Add new deck Figure 1.6: Deck section properties Press “Set Modifier” in order to modify the slab properties
  15. 15. Page 15 1.3.4.1 Modeling requirements of EC8 for concrete members 1. Unless a more accurate analysis of the cracked elements is performed, the elastic flexural and shear stiffness properties of concrete and masonry elements may be taken to be equal to one-half of the corresponding stiffness of the un-cracked elements (EN1998-1-1,cl.4.3.1(7)). Figure 1.7: Modified “Stiffness Modifiers” 1.3.4.2 Modeling requirements of EC8 for floor diaphragms ETABS: Select > Wall/Slab/Deck section > Select Deck ETABS: Define > Diaphragms ETABS: Select “D1” (Rigid diaphragms) 2. When the floor diaphragms of the building may be taken as being rigid in their planes, the masses and the moments of inertia of each floor may be lumped at the centre of gravity (EN1998-1-1,cl.4.3.1(4)).
  16. 16. Page 16 1.3.4.3 Meshing of slabs ETABS: Select > Wall/Slab/Deck section > Select Deck ETABS: Assign > Shell area > Auto Object Auto mesh option When you have a composite beam floor system, ETABS, by default, automatically meshes (divides) the deck at every beam and girder. This allows ETABS to automatically distribute the loading on the deck to each beam or girder in an appropriate manner. Figure 1.8: Meshing of composite slab Figure 1.9: Meshing of normal slab
  17. 17. Page 17 1.4 Joint modeling (EN1993-1-1,cl.5.1.2) (1) The effects of the behavior of the joints on the distribution of internal forces and moments within a structure, and on the overall deformations of the structure, may generally be neglected, but where such effects are significant (such as in the case of semi-continuous joints) they should be taken into account, see EN 1993-1-8. (2) (2) To identify whether the effects of joint behavior on the analysis need be taken into account, a distinction may be made between three joint models as follows, see EN 1993-1-8, 5.1.1: – simple, in which the joint may be assumed not to transmit bending moments. – continuous, in which the behavior of the joint may be assumed to have no effect on the analysis. – semi-continuous, in which the behavior of the joint needs to be taken into account in the analysis.
  18. 18. Page 18 Table 1.7: Example of joint types Simple joint Continuous Fixed joint Semi- continuous joint ETABS: Pin joint in ETABS The pin-joint in ETABS can be achieved by selecting the members that you assumed to be pinned in the analysis process. This can be done as follow: Select member > Assign > Frame/Line > Frame Releases Partial Fixity Figure 1.10: Pinned joint (both ends)
  19. 19. Page 19 ETABS: Fixed joint in ETABS The fixed-joint in ETABS can be achieved by selecting the members that you assumed to be fixed in the analysis process. This can be done as follow: Select member > Assign > Frame/Line > Frame Releases Partial Fixity Figure 1.11: Fixed joint
  20. 20. Page 20 2.0 Modal Response Spectrum Analysis 2.1 Structural types and behavior factor according to EN1998-1-1,cl.6.3 Table 2.1: Structural types and behavior factor Structural Type q-factor DCM DCH Moment resisting frames (MRF) αu/ α1 =1.1 αu/ α1 =1.2 (1 bay) αu/ α1 =1.3 (multi-bay) dissipative zones in beams and column bases 4 5αu/ α1 Concentrically braced frames (CBF) Dissipative zones in tension diagonals 4 4 V-braced frames (CBF) 2 2.5
  21. 21. Page 21 Dissipative zones in tension and compression diagonals Frames with K-bracing (CBF) Not allowed in dissipative design Eccentrically braced frame (EBF) αu/ α1 =1.2 dissipative zones in bending or shear links 4 5αu/ α1 Inverted pendulum system αu/ α1 =1.0 αu/ α1 =1.1 dissipative zones in column base, or column ends (NEd/Npl,Rd < 0.3) 2 2αu/ α1 Moment-resisting frames with concentric bracing (MRF) + (CBF) 4 4αu/ α1
  22. 22. Page 22 αu/ α1 =1.2 dissipative zones in moment frame and tension diagonals Moment frames with infills Unconnected concrete or masonry infills, in contact with the frame 2 2 Connected reinforced concrete Infills See EN1998-1-1,table 5.1 Infills isolated from moment frame 4 5αu/ α1 Structures with concrete cores or walls See EN1998-1-1,table 5.1 Note: If the building is non-regular in elevation (see EN1998-1-1,cl.4.2.3.3) the upper limit values of q listed above should be reduced by 20 %
  23. 23. Page 23 Table 2.2: Values of behavior factor for regular and irregular structure Structural type Regular in plan and elevation Irregular in plan / Regular in elevation Regular in plan / Irregular in elevation Irregular in plan & elevation Irregular in plan / Regular in elevation Regular in plan / Irregular in elevation Irregular in plan & elevation DCM DCH DCM DCM DCM DCH DCH DCH Moment resisting frame Single storey portal 4.0 5.5 3.2 3.2 3.2 5.25 4.4 4.2 One bay multi-storey 4.0 6.0 3.2 3.2 3.2 5.5 4.8 4.4 Multi-bay, multi-storey 4.0 6.5 3.2 3.2 3.2 5.75 5.2 4.6 Concentrically braced frame Diagonal bracing 4.0 4.0 3.2 4.0 4.0 4.0 3.2 3.2 V-bracing 2.0 2.5 1.6 2.5 2.5 2.5 2.0 2.0 Frame with masonry infill panels 2.0 2.0 1.6 2.0 2.0 2.0 1.6 1.6
  24. 24. Page 24 2.2 Define design horizontal response spectrum 2.2.1 Vertical response spectrum (EN1998-1-1,cl.3.2.2.3) The vertical component of the seismic action should be taken into account if the avg>0.25g (2.5m/s2) in the cases listed below: • for horizontal structural member spanning 20m or more, • for horizontal cantilever components longer than 5m, • for horizontal pre-stressed components, • for beams supporting columns, • in based-isolated structures. 2.2.2 Horizontal response spectrum (EN1998-1-1,cl.3.2.2.5) For the horizontal components of the seismic action the design spectrum, Sd(T), shall be defined by the following expressions: 0 ≤ 𝑇 ≤ 𝑇!: 𝑆! 𝑇 = 𝑎! ∙ 𝑆 ∙ ! ! + ! !! ∙ !.! ! − ! ! (ΕΝ1998-1-1,Eq. 3.13) 𝑇! ≤ 𝑇 ≤ 𝑇!: 𝑆! 𝑇 = 𝑎! ∙ 𝑆 ∙ !.! ! (ΕΝ1998-1-1,Eq. 3.14) 𝑇! ≤ 𝑇 ≤ 𝑇!: 𝑆! 𝑇 = 𝑎! ∙ 𝑆 ∙ 2.5 𝑞 𝑇! 𝑇                                                                                      ≥ 𝛽 ∙ 𝑎! (ΕΝ1998-1-1,Eq. 3.15) 𝑇! ≤ 𝑇 ≤ 4𝑠: 𝑆! 𝑇 = 𝑎! ∙ 𝑆 ∙ !.! ! !!!! !! ≥ 𝛽 ∙ 𝑎! (ΕΝ1998-1-1,Eq. 3.5) Design ground acceleration on type A ground: ag=γIagR Lower bound factor for the horizontal spectrum: β=0.2 Note: the value of q are already incorporate with an appropriation value of damping viscous, however the symbol η is not present in the above expressions.
  25. 25. Page 25 2.2.3 Parameters of elastic response spectrum (EN1998-1-1,cl.3.2.2.5) Table 2.3: Parameters of Type 1 elastic response spectrum (CYS NA EN1998-1-1,table 3.2) Ground Type S TB (s) TC (s) TD (s) A 1.0 0.15 0.4 2.0 B 1.2 0.15 0.5 2.0 C 1.15 0.20 0.6 2.0 D 1.35 0.20 0.8 2.0 E 1.4 0.15 0.5 2.0 Note: For important structures (γI>1.0), topographic amplification effects should be taken into account (see Annex A EN1998-5:2004 provides information for topographic amplification effects). ETABS: Define > Response spectrum function 1. Peak ground acceleration agR=0,25g, 2. Type C or D for building within category of importance I and II, 3. Define two response spectrum cases if the factor q is different in each direction, Select EUROCODE8 Spectrum Add New Function
  26. 26. Page 26 4. Modify the existing values of elastic response spectrum case in order to change it into the design response spectrum. Figure 2.1: Response Spectrum to EC8 PERIOD   ACCELERATION   g  =   9.81   m/sec2     T   Sd(T)   β  =   0.2   -­‐   0.0000   0.2000   SoilType  =   B   -­‐   0.1000   0.1917   q  =   4.00   -­‐   0.1500   0.1875   αgR   =   0.25   -­‐   0.2000   0.1875   S  =   1.20   -­‐   0.4000   0.1875   TB   =   0.15   sec   0.6000   0.1563   TC   =   0.50   sec   0.8000   0.1172   TD   =   2.00   sec   1.0000   0.0938   T  =   0.50   sec   1.5000   0.0625                 2.0000   0.0469     Data  for  soil  type  -­‐  Type  Spectrum  1     2.5000   0.0300     index   Soil  Type   S   TB   TC   TD   3.0000   0.0500     1   A   1   0.15   0.4   2   4.0000   0.0500     2   B   1.2   0.15   0.5   2   5.0000   0.0500     3   C   1.15   0.2   0.6   2   6.0000   0.0500     4   D   1.35   0.2   0.8   2   8.0000   0.0500     5   E   1.4   0.15   0.5   2   10.0000   0.0500                 Convert the existing elastic response spectrum case to design response spectrum case
  27. 27. Page 27
  28. 28. Page 28 Figure 2.2: Amendment Response spectrum (q = 4)
  29. 29. Page 29 2.2.3.1 Ground investigation conditions Table 2.4: Geological studies depend on the importance class (CYS NA EN1998-1-1, NA 2.3 / cl.3.1.1 (4)) Importance class of buildings Ground Type I II III IV A NRGS NRGS RGS RGS B NRGS NRGS RGS RGS C NRGS NRGS RGS RGS D NRGS NRGS RGS RGS E NRGS NRGS RGS RGS NRGS: Not required geological studies RGS: required geological studies if there is not adequate information 2.2.3.2 Importance factor Table 2.5: Importance classes for buildings (ΕΝ1998-1-1,table.4.3 and CYS NA EN1998- 1-1,cl NA2.12) Importance class Buildings Important factor γI Consequences Class I Buildings of minor importance for public safety, e.g. argricultural buildings, etc. 0.8 CC1 II Ordinary buildings, not belonging in the other categories. 1.0 CC2 III Buildings whose seismic resistance is of importance in view of the consequences associated with a collapse, e.g. schools, assembly halls, cultural institutions etc. 1.2 CC3 IV Buildings whose integrity during earthquakes is of vital importance for civil protection, e.g. hospitals, fire stations, power plants, etc. 1.4 CC3
  30. 30. Page 30 CC1: Low consequence for loss of human life, and economic, social or environmental consequences small or negligible. CC2: Medium consequence for loss of human life, economic, social or environmental consequences considerable. CC3: High consequence for loss of human life, or economic, social or environmental consequences very great 2.2.3.3 Ductility class Table 2.6: Requirement for importance class relate to ductility class (CYS NA EN1998- 1-1,cl NA2.16 & cl.5.2.1(5)) Importance class Zone 1 Zone 2 Zone 3 I DCL DCL DCL II DCM/DCH DCM/DCH DCM/DCH III DCM/DCH DCM/DCH DCM/DCH IV DCH DCH DCH DCL: Ductility class low. DCM: Ductility class medium. DCH: Ductility class high.
  31. 31. Page 31 2.3 Analysis types 2.3.1 Modal Response spectrum analysis Table 2.7: Requirements of modal response spectrum analysis according to Eurocode 8 Requirements Values References Regular in plan YES / NO ΕΝ1998-1-1,table 4.1 Regular in elevation NO ΕΝ1998-1-1,table 4.1 Sum of the effective modal masses ≥ 90% EN1998-1-1,cl.4.3.3.1(3) ≥ 5% of total mass Minimum number of modes k ≥3.√n k: is the number of modes n: is the number of storey EN1998-1-1,cl.4.3.3.1(5) Behaviour factor q Tk ≤ 0.20sec Tk: is the period of vibration of mode k. EN1998-1-1,cl.4.3.3.1(5) Fundamental period Tj ≤ 0.9 Ti SRSS EN1998-1-1,cl.4.3.3.2.1(2) Tj ≥ 0.9 Ti CQC Accidental eccentricity See section 2.1.1.1 EN1998-1-1,cl.4.3.2 1. Independently in X and Y direction, 2. Define design spectrum, 3. Use CQC rule for the combination of different modes (EN1998-1-1,cl.4.3.3.3.2(3)) 4. Use SRS rule for combined the results of modal analysis for both horizontal directions (EN1998-1-1,cl.4.3.3.5.1(21)). 5. Modal Combination: “Complete Quadratic Combination” (CQC) can be used if the Tj ≤ 0,9 Ti (EN1998-1-1,cl.4.3.3.3.2(3)P).
  32. 32. Page 32 2.3.1.1 Accidental eccentricity Accidental eccentricity of each storey cause of uncertainties location of masses have been taken into account 5% (EN1998-1-1,cl.4.3.2). Moreover, if there are masonry infills with a moderately irregular and asymmetric distribution in plan, is doubled further in Eurocode 8 (i.e., to 10% of the storey orthogonal dimension in the baseline case, or 20% if accidental torsional effects are evaluated in a simplified way when using two separate 2D models). Table 2.8: Summary of accidental eccentricity Percentage of accidental eccentricity Geometry of model (3D/2D) Asymmetric distribution of mass (Regular/Irregular) Masonry infills (Regular/Irregular) 5% 3D Regular Regular 10% 3D Irregular Irregular 20% 2D - - Note: Accidental eccentricity is automatically included during response-spectrum analysis in ETABS, though equivalent static-load procedures are also available for manual evaluation. Note that floor diaphragms must be rigid, otherwise torsional effects are not substantial. ETABS implements an efficient and practical approach while formulating dynamic response from accidental eccentricity. After the response-spectrum load case is run, the X and Y acceleration at each joint location is determined, then multiplied by the tributary mass and the diaphragm eccentricity along either Y or X. The larger absolute value of these resultant moments (m*Xacc*dY or m*Yacc*dX) is then applied as torsion about the joint location. Static response is then added to response-spectrum output to account for the additional design forces caused by accidental eccentricity.
  33. 33. Page 33 Define > Response spectrum cases Note: Add two response spectrum cases: EQX and EQY as showing below (figure 9). Figure 2.3: Response Spectrum case Data for EQY& EQX
  34. 34. Page 34 2.3.2 Lateral force analysis requirements Table 2.9: Requirements of lateral force analysis according to Eurocode 8 Requirements Values References Regular in plan YES / NO ΕΝ1998-1-1,table 4.1 Regular in elevation YES ΕΝ1998-1-1,table 4.1 Ground acceleration 0.10-0.25g CYS NA EN1998-1- 1:Seismic zonation map Spectrum type 1 EN1998-1-1,cl.3.2.2.2(2)P Ground type A,B,C,D,E Normally type B or C can be used normal condition EN1998-1-1,cl.3.1.2(1) Lower bound factor for the horizontal design spectrum λ = 0.85 if T1 ≤ 2TC and more than 2 storey λ=1.0 in all other case EN1998-1-1,cl.4.3.3.2.2(1Ρ) Behaviour factor q Concrete DCM q= 1.5 – 3.90 EN1998-1-1,cl.5.2.2.2(2) Concrete DCH q= 1.6 – 5.85 EN1998-1-1,cl.5.2.2.2(2) Steel DCM q= 2.0 – 4.00 EN1998-1-1,cl.6.3.2(1) Steel DCH q= 2.0 – 5.85 EN1998-1-1,cl.6.3.2(1) Fundamental period T1≤4Tc T1≤2,0s EN1998-1-1,cl.4.3.3.2.1(2) Accidental eccentricity See section 2.1.1.1 EN1998-1-1,cl.4.3.2 Table 2.10: Equivalent Static Force Case Load case name Direction and Eccentricity % Eccentricity EQXA X Dir + Eccen. Y 0.05 EQYA X Dir – Eccen. Y 0.05 EQXB Y Dir + Eccen. X 0.05 EQYB Y Dir – Eccen. X 0.05
  35. 35. Page 35 2.3.4 Estimation of fundamental period T1 Table 2.11: Estimation of fundamental period T1 Reference structure Period T1 Exact formula for Single Degree of Freedom Oscillator. Mass M lumped at top of a vertical cantilever of height H. Cantilever mass MB = 0. 𝑇! = 2𝜋 𝑀𝐻! 3𝐸𝐼 Exact formula for Single Degree of Freedom Oscillator. Vertical cantilever of height H and of total mass MB. 𝑇! = 2𝜋 0.24𝑀! 𝐻! 3𝐸𝐼 Exact formula for Single Degree of Freedom Oscillator. Mass M lumped at top of a vertical cantilever of height H and of total mass MB. 𝑇! = 2𝜋 𝑀 + 0.24𝑀! 𝐻! 3𝐸𝐼 Approximate Relationship (Eurocode 8). Ct = 0,085 for moment resisting steel space frames Ct = 0,075 for eccentrically braced steel frames Ct = 0,050 for all other structures 𝑇! = 𝐶! 𝐻!/! H building height in m measured from foundation or top of rigid basement. Approximate Relationship (Eurocode 8). d : elastic horizontal displacement of top of building in m under gravity loads applied horizontally. 𝑇! = 2 𝑑
  36. 36. Page 36 2.3.5 Automatic Lateral force analysis using ETABS ETABS: Define > Static load cases Figure 2.4: Apply the Equivalent Static Force Case Figure 2.5: Modify the Equivalent Static Force Case Note: The seismic forces should be applied only above the top of the basement
  37. 37. Page 37 Fundamental period (EN1998-1-1,Eq.4.6) T1=CtH3/4 (For heights up to 40m) Value of Ct(EN1998-1-1,cl.4.3.3.2.2(3)) Ct = 0.085 (for moment resisting steel frames) Ct= 0.075 (for moment resisting concrete frames) Ct= 0.05 (for all other structures) (EN 1998-1-1:2004, cl. 4.3.3.2.2(3)) Ct= 0.075/√ΣAc(for concrete/masonry shear wall structures) (EN 1998-1-1:2004, Eq. 4.7) Ac= Σ[Ai·(0,2+(lwi/H2 ))] (EN 1998-1-1:2004, Eq. 4.8) Fundamental period requirements (EN1998-1-1,Eq.4.6) T1≤4TCT1≤2sec IF this YES LATERAL FORCE ANALYSIS RESPONSE SPECTRUM ANALYSIS Correction factor λ(EN1998-1- 1,cl.4.3.3.2.2(1Ρ)) λ=0.85 if T1≤2TC and more than 2 storey λ=1.0 in all other case Design spectrum Sd(T)(EN1998-1- 1,cl.3.2.2.5) 0≤T≤TB TB≤T≤TcTC≤T≤TD TD≤T Seismic mass(EN1998-1- 1,cl.3.2.4) ΣGk,j/g”+”ΣψE,i.Qk,i/g (EN 1998-1-1:2004, Eq.3.17) Base shear(EN1998-1- 1,cl.4.3.3.2.2) Fb=Sd(T1).m.λ (EN 1998-1-1:2004, Eq. 4.5) Horizontal seismic forces (according to displacement of the masses) F! = F! ∙ s! ∙ m! s! ∙ m! (EN 1998-1-1:2004, Eq. 4.10) Horizontal seismic forces (according to height of the masses) F! = F! ∙ z! ∙ m! z! ∙ m! (EN 1998-1-1:2004, Eq. 4.11) NO
  38. 38. Page 38 2.3.6 User loads - Lateral force analysis using ETABS Geometrical data Span of the longitutinal direction Span of the transverse direction Span of each beam Span of each bracing Height of each column Total heigh of building Area of floor for each storey Number of floors Number of beams IPE240 at each floor Number of beams IPE180 at each floor Number of columns HE280A at each floor Number of TUBE sections D127-4 at each floor Lx 15m:= Ly 15m:= Lb 5m:= Lt 5.831m:= hc 3m:= H 9m:= Af Ly Lx⋅ 225m 2 =:= Nf 3:= Nb 24:= Ns 9:= Nc 16:= Nt 8:=
  39. 39. Page 39 Dead load Weight of steel column HE280A Weight of primary beams IPE240 Weight of secondary beams IPE180 Weight of steel beams TUBE-D127-4 Slab thickness Weigth of concrete Weight of slab Weigth of finishes Total dead load Total dead load Live load Combination coefficient for variable action Live load Total live load Total gravity load per storey (EN1998-1-1,cl.3.2.4(2)P) Total gravity load per storey (EN1998-1-1,cl.3.2.4(2)P) Seismic mass gc 76.4kg m 1− ⋅:= gp 30.7kg m 1− ⋅:= gs 18.8kg m 1− ⋅:= gt 12.38kg m 1− ⋅:= hs 170mm:= γ c 25kN m 3− ⋅:= gslab γ c hs⋅ 4.25 kN m 2− ⋅⋅=:= gfin 1kN m 2− ⋅:= Gk.storey gc Nc⋅ hc⋅ gp Nb⋅ Lb⋅+ gs Ns⋅ Lb⋅+ gt Nt⋅ Lt⋅+( )g gslab Af⋅+ gfin Af⋅+⎡⎣ ⎤⎦ 1.267 10 3 × kN⋅=:= Gk gc Nc⋅ hc⋅ gp Nb⋅ Lb⋅+ gs Ns⋅ Lb⋅+ gt Nt⋅ Lt⋅+( )g gslab Af⋅+ gfin Af⋅+⎡⎣ ⎤⎦ Nf⋅ 3.802 10 3 × kN⋅=:= ψEi 0.3:= qk 2kN m 2− ⋅:= Qk qk Af⋅ 450 kN⋅=:= FEd.storey Gk.storey ψEi Qk⋅( )+ 1.402 10 3 × kN⋅=:= FEd Gk ψEi Qk⋅( ) Nf⋅+ 4.207 10 3 × kN⋅=:= S_mass FEd g 4.29 10 5 × kg=:=
  40. 40. Page 40 Horizontal design response Spectrum (EN1998-1-1,cl.3.2.2.5) Behaviour factor q (EN1998-1-1,cl.6.3) Lower bound factor (EN1998-1-1,cl.3.2.2.5(4)P) Seismic zone (CYS NA EN1998-1-1, zonation map) Importance factor (CYS NA EN1998-1-1,cl. NA2.12) Design ground acceleration on type A (EN1998-1-1,cl.3.2.1(3)) Value of Ct (EN1998-1-1,cl.4.3.3.2.2(3)) Fundamental period of vibration (EN1998-1-1,cl.4.3.3.2.2(3)) Type of soil (EN1998-1-1,cl.3.1.2(1)) Value of parameters describing the Type 1 elastic response spectrum (EN1998-1-1,table 3.2) Soil factor, S q 1.5:= β 0.2:= Seismic_zone "3":= agR 0.15g Seismic_zone "1"if 0.2g Seismic_zone "2"if 0.25g Seismic_zone "3"if 2.452 m s 2 =:= Importance_factor "II":= γ I 0.8 Importance_factor "I"if 1.0 Importance_factor "II"if 1.2 Importance_factor "III"if 1.4 Importance_factor "IV"if 1=:= ag γ I agR⋅ 2.452 m s 2 =:= Value_Ct "OTHER":= Ct 0.085 Value_Ct "MRSF"if 0.075 Value_Ct "MRCF"if 0.05 Value_Ct "OTHER"if 0.05=:= T1 Ct H m ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ 3 4 ⋅ ⎡ ⎢ ⎢ ⎢ ⎣ ⎤ ⎥ ⎥ ⎥ ⎦ s 0.26s=:= Soil_type "B":= S 1.0 Soil_type "A"if 1.2 Soil_type "B"if 1.15 Soil_type "C"if 1.35 Soil_type "D"if 1.2=:=
  41. 41. Page 41 Lower limit of the period, TB Upper limit of the period, TC Constant displacement value, TD Corection factor λ (EN1998-1-1,cl.4.3.3.2.2(1)P) Check the fundamental period of vibration requirements (EN1998-1-1,cl.4.3.3.2.1(2)) Design spectrum for elastic analysis (EN1998-1-1,cl.3.2.2.5(4)P) TB 0.15s Soil_type "A"if 0.15s Soil_type "B"if 0.20s Soil_type "C"if 0.20s Soil_type "D"if 0.15s=:= TC 0.40s Soil_type "A"if 0.50s Soil_type "B"if 0.60s Soil_type "C"if 0.80s Soil_type "D"if 0.5s=:= TD 2.0s Soil_type "A"if 2.0s Soil_type "B"if 2.0s Soil_type "C"if 2.0s Soil_type "D"if 2s=:= λ 0.85 T1 2TC≤ Nf 2>∧if 1 otherwise 0.85=:= Check_1 if T1 4TC≤ T1 2s≤∧ "Lateral force analysis", "Response spectrumanalysis",( ):= Check_1 "Lateral force analysis"= S1e T1( ) ag S⋅ 2 3 T1 TB 2.5 q 2 3 −⎛ ⎜ ⎝ ⎞ ⎟ ⎠ ⋅+ ⎡ ⎢ ⎣ ⎤ ⎥ ⎦ ⋅:= S1e 0( ) 1.961 m s 2− ⋅⋅= S2e T1( ) ag S⋅ 2.5 q ⋅:= S2e TB( ) 4.903 m s 2− ⋅⋅= S3e T1( ) ag S⋅ 2.5 q ⋅ TC T1 ⋅ ag S⋅ 2.5 q ⋅ TC T1 ⋅ β ag⋅≥if β ag⋅( ) β ag⋅ ag S⋅ 2.5 q ⋅ TC T1 ⋅≥if := S3e TC( ) 4.903 m s 2− ⋅⋅= S4e T1( ) ag S⋅ 2.5 q ⋅ TC TD⋅ T1 2 ⋅ ⎛ ⎜ ⎜ ⎝ ⎞ ⎟ ⎟ ⎠ ag S⋅ 2.5 q ⋅ TC TD⋅ T1 2 ⋅ β ag⋅≥if β ag⋅( ) ag S⋅ 2.5 q ⋅ TC TD⋅ T1( )2 ⋅ β ag⋅≤if :=
  42. 42. Page 42 Design spectrum acceleration Seismic base shear (EN1998-1-1,cl.4.3.3.2.2(1)) Seismic base shear on each bracing Note: 2 bracing on each direction S4e T1( ) 72.642 m s 2 = Se T( ) if T TB< S1e T( ), if T TC< S2e T( ), if T TD< S3e T( ), S4e T( ),( ),( ),( ):= T 0.01sec 0.02sec, 4sec..:= 0 1 2 3 4 0 2 4 6 8 Se T( ) T Se S1e 0( ) 0 T1≤ TB≤if S2e TB( ) TB T1≤ TC≤if S3e TC( ) TC T1≤ TD≤if S4e T1( ) TD T1≤ 4s≤if 4.903 m s 2 =:= Fb S_mass Se⋅ T1 s ⋅ λ⋅ 464.519kN⋅=:= Fb.bracing Fb 2 232.259kN⋅=:=
  43. 43. Page 43 Table 2.12: Summary table of the lateral force results Story Heigth                                 zi                                         (m) Mass                                   mi                                     (kN) zi*mi Fb                                   (kN) F=Fb(zi*mi)/ Σzi*mi Moment   M=F*zi   (kNm) Length  of   floor  Lx=Ly Accidental   eccentricity   ei=0.05L Torsional   moment   M=F*ei     (kNm) Moment  due  to   SRSS   MSRS=√Mx^2+My^2   (kNm) STORY1 9 1402 12618 464.52 232.26 2090.34 15 0.75 174.195 246.3489315 STORY2 6 1402 8412 464.52 154.84 929.04 15 0.75 116.13 164.232621 STORY3 3 1402 4206 464.52 77.42 232.26 15 0.75 58.065 82.1163105 TOTAL 4206 25236 464.52 3251.64 Mass per storey Heigth at roof level Heigth at level 2 Heigth at level 1 Total mass: Lateral force at roof level (EN1998-1-1,Eq.4.11) Lateral force at level 2 (EN1998-1-1,Eq.4.11) Lateral force at level 1 (EN1998-1-1,Eq.4.11) Check lateral force per storey mi FEd.storey 1.402 10 3 × kN=:= z3 9m:= z2 6m:= z1 3m:= Σmi_zi FEd.storey z3⋅ FEd.storey z2⋅+ FEd.storey z1⋅+ 2.524 10 4 × kN m⋅=:= F3 mi z3⋅ Σmi_zi Fb⋅ 232.259kN⋅=:= F2 mi z2⋅ Σmi_zi Fb⋅ 154.84kN⋅=:= F1 mi z1⋅ Σmi_zi Fb⋅ 77.42kN⋅=:= F F3 F2+ F1+ 464.519kN=:= Check_2 if F Fb≠ "OK", "NOT OK",( ):= Check_2 "OK"=
  44. 44. Page 44 ETABS: Define > Static load case > Figure 2.6: Define manually the lateral forces Figure 2.7: Define manually the lateral forces/moments per storey
  45. 45. Page 45 2.3.7 Torsional effects FLOW CHART OF TORSIONAL EFFECTS Carry out Lateral force analysis/ Response spectrum analysis 𝑀! = 𝑒! 𝐹! 𝑀! = 𝑒! 𝐹! 𝑒! = −0.05 ∗ 𝐿!𝑒! = +0.05 ∗ 𝐿! 𝑒! = +0.05 ∗ 𝐿!𝑒! = −0.05 ∗ 𝐿! SRSS rule 𝑀!"!! = 𝑀! ! + 𝑀! !
  46. 46. Page 46 2.3.8 Summary of analysis process in seismic design situation Importance class/Ductility class I II III IV DCL DCM DCH DCM DCH DCH Ignore “topographic amplification effects” Consider “topographic amplification effects” IF Slopes <15o Cliffs height <30m Slopes <15o Cliffs height <30m Ignore Consider Regular in plan: YES Regular in elevation YES Regular in plan: NO Regular in elevation YES Regular in plan: YES Regular in elevation NO Regular in plan: NO Regular in elevation NO Type of soil: A , B ,C ,D, E, S1, S2 Type 1 elastic response spectrum 0≤T≤TB TB≤T≤TC TC≤T≤TD TD≤T≤4s LATERAL FORCE MODAL ANALYSIS Displacement ds=qd·de P-Δ effects θ≤0.1 – Ignore 0.1≤θ≤0.2 Consider 0.2≤θ≤0.3 Consider θ≥0.3 Not Permitted Interstorey drift drv≤0.005h - Brittle drv≤0.0075h - Ductile drv≤0.010h - Other Frame joint ΣMRC≥1.3ΣMRB Storey ≥ 2
  47. 47. Page 47 3.0 Define static loads Here define as many load cases for your model as you need e.g. dead loads, live loads, wind loads, seismic loads, thermal loads etc. To be simple define only one dead load with self weight multiplier 1(including finishes, dead, walls etc) and one live load. Figure 3.1: Static load cases
  48. 48. Page 48 4.0 Seismic mass requirements according to EC8 Combination of the seismic action with other actions (EN 1998-1-1,cl.3.2.4): 1. Define the category of building (EN 1991,Table 6.1), 2. Define the reduce factor (EN 1991, Table A.1.1). Combination of seismic mass 𝐆 𝐤,𝐣 + 𝛙 𝐄𝐢 𝐐 𝐤,𝐢 (ΕΝ1998-1-1,Eq. 3.17) Combination coefficient for variable action is: ψ!" = ϕ ∙ ψ!" (ΕΝ1998-1-1,Eq. 4.2) Table 4.1: Values of φ for calculating 𝛙 𝐄𝐢 (CYS NA EN1998-1-1:2004) Type of Variable action Storey φ Categories A-C1 Roof Storeys with correlated occupancies Independently occupied storeys 1,0 0,8 0,5 Categories A-F1 1.0 Table 4.2: Values of ψ coefficients Category Specific Use ψο ψ1 ψ2 A Domestic and residential 0.7 0.5 0.3 B Office 0.7 0.5 0.3 C Areas for Congregation 0.7 0.7 0.6 D Shopping 0.7 0.7 0.6 E Storage 1.0 0.9 0.8 F Traffic < 30 kN vehicle 0.7 0.7 0.6 G Traffic < 160 kN vehicle 0.7 0.5 0.3 H Roofs 0.7 0 0 Snow, altitude < 1000 m 0.5 0.2 0 Wind 0.5 0.2 0
  49. 49. Page 49 4.1 Mass Source Option In ETABS, the user has the option of choosing one of three options for defining the source of the mass of a structure. Click the Define menu > Mass Source command to bring up the Define Mass Source form. The following options appear on the form: 1. From Self and Specified Mass: Each structural element has a material property associated with it; one of the items specified in the material properties is a mass per unit volume. When the ‘From Self and Specified Mass’ box is checked, ETABS determines the building mass associated with the element mass by multiplying the volume of each structural element times it’s specified mass per unit volume. This is the default. It is also possible to assign additional mass to account for partitions and cladding, etc. ETABS adds any additional mass assignments to the element mass to derive a total mass. You cannot have a negative mass in ETABS. 2. From Loads: This specifies a load combination that defines the mass of the structure. The mass is equal to the weight defined by the load combination divided by the gravitational multiplier, g. This mass is applied to each joint in the structure on a tributary area basis in all three translational directions. 3. From Self and Specified Mass and Loads: This option combines the first two options, allowing you to consider self- weight, specified mass, and loads in the same analysis. It is important to remember when using the ‘From Self and Specified Mass and Loads’ option, NOT to include the Dead Load Case in the ‘Define Mass Multiplier for Loads’ box. This will account for the dead load of the structure TWICE.
  50. 50. Page 50 Figure 4.1: Seismic source
  51. 51. Page 51 5.0 Wind loading on structure (EN1991-1-4:2004) 5.1 Calculation of Wind load according to EN1991-1-4:2004 Step by step procedure Figure 5.1: Fundamental Basic wind velocity, vb,0 (CYS NA EN1991-1-4,Fig.1) Season factor (CYS EN1991-1-4,NA 2.4) cseason=1.0 Directional factor (CYSEN1991-1-4,NA 2.4) cdir=1.0 (Conservative value for all direction) Basic wind velocity (EN1991-1-4, Eq. 4.1) vb=cdir.cseasonvb,0 Figure 1 Isotach contours of the fundamental value of the basic wind velocity v c z v z c z c
  52. 52. Page 52 Table 5.1: Terrain category and terrain parameters (EN1991-1-4, Tab.:4.1) Terrain category Description z0 (m) zmin(m) 0 Sea, costal area exposed to the open sea. SEA 0.003 1 I Lakes or area with negligible vegetation and without obstacles. COUNTRY 0.01 1 II Area with low vegetation such as grass and isolated obstacles trees, buildings) with separations of at least 20 obstacle height. 0.05 2 III Area with regular cover of vegetation or buildings or woth isolatd obstacles with seperations of maximum 20 obstacle height (such as villages, suburban terrain, permanent forest). TOWN 0.3 5 IV* Area in which at least 15% of the surface is covered with building and their average height exceeds 15m. 1.0 10 * For buildings in terrain category IV, displacement height hdis should be consider and information can be found in Aneex A.5 of EN1991-1-4:2005. Roughness factor, cr(z) (EN1991-1-4,Eq.4.3-4.5) cr(z)=kr . ln(z/z0) for zmin≤z≤zmax cr(z)=cr . (zmin) for z≤zmin z0: is the roughness length Maximum height, zmax (EN1991-1-4, cl. 4.3.2) zmax=200m Orography factor co(z) co(z)=1 Terrain factor, (EN1991-1-4,cl.4.4) kr=0.19(z0/z0,II)0.07 Mean wind velocity, vm(z) (EN1991-1-4 cl.4.3.1 ) vm(z)=cr(z).co(z).vb Wind turbulence, Iv(z) (EN1991-1-4,Eq.4.7) Iv(z)=σv/vm(z)=kl/co(z)ln(z/z0) for zmin≤z≤zmax Iv(z)=Iv(zmin) for z≤zmin Turbulence factor: kl=1.0 (NA CYS EN1991-1-4, cl. NA 2.10) Note: for co(z)=1 Iv(z) is not important Peak velocity pressure, qpeak(z) (EN1991-1-4 Eq.4.8 ) qpeak(z)=[1+7 Iv(z)]0.5ρ vm 2 (z)=ce(z)·0.5·ρ·vb 2 Air density:ρ=1.25kg/m3
  53. 53. Page 53 Table 5.3: Values of external pressure coefficient for vertical walls of rectangular plan building (EN1991-1-4, Tab.:4.1) ZONE A B C D E h/d cpe,10 cpe,1 cpe,10 cpe,1 cpe,10 cpe,1 cpe,10 cpe,1 cpe,10 cpe,1 5 -1.2 -1.4 -0.8 -1.1 -0.5 +0.8 +1.0 -0.7 1 -1.2 -1.4 -0.8 -1.1 -0.5 +0.8 +1.0 -0.5 ≤0.25 -1.2 -1.4 -0.8 -1.1 -0.5 +0.7 +1.0 -0.3 Note: Values for cpe,1 are intended for the design of small elements and fixings with an element of 1m2 or less such as cladding elements and roofing elements. Values for cpe,10 may be used for the design of the overall load bearing structure of buildings. The external pressure coeffiecient cpe,1 and cpe,10 is using for loadaded area of 1m2 and 10m2 respectively. Key for vertical walls – Flat Roof (EN1991-1-4, Fig.7.5) Key for vertical walls –Mono&dual pitch Roof (EN1991-1-4, Fig.7.5) Pressure on surface &Wind force (EN1991-1-4, Eq. 5.1&5.5) we=qp(ze).(cpe +cpi) & Fw=cscd·Σwe·Aref Table 5.2: Reference height ze, depending on h and b, and corresponding velocity pressure profile (EN1991-1-4, Fig. 7.4)
  54. 54. Page 54 5.2 Application of wind loading using ETABS Table 5.4: Wind load assumptions Data Symbol Value Units Basic wind velocity vb,0 24 m/s Terrain category - II - Structural factor cscd 1 - Turbulence factor kl 1 - Orography factor co(z) 1 - ETABS: Clink on ETABS: Select from first drop-down menu ETABS: Click on select “NONE” and draw rectangular cover all side of plan view Draw walls in plan
  55. 55. Page 55 ETABS: Select the area of elevation A-A ETABS: Assign > Shell/Area loads > Wind pressure coefficients Figure 5.2: Wind load areas Table 5.5: Wind pressure coefficient applied on walls Wind pressure coefficient for load case WINDX Windward load “Area D” Leeward load “Area E” Side load “Area A & B” Side load “Area A & B”
  56. 56. Page 56 Wind pressure coefficient for load case WINDY Windward load “Area D” Leeward load “Area E” Side load “Area A & B” Side load “Area A & B”
  57. 57. Page 57                   WIND LOADING ACCORDING TO EN1991-1-4:2005 Job No.:                       Sheet No.:                       Date: December 2012 Check by: CALCULATION OF WIND LOADING TO EN 1991-1-4:2005. Loading available for rectangular, clad buildings with flat roofs only. Obstruction height, have = 7.5 m Distance to nearest adjacent building, x = 50 m Height of building, h = 9 m Longitudinal length of the building , d = 15 m Transverse length of the building, b = 15 m Edge distance, (Wind direction - θ=90°) e = 15 Basic Wind Velocity, Vbo = 24 m/s ( Figure1) Season Factor, Cseason = 1.0 (cl.NA2.4) Directional Factor, Cdir = 1.0 (cl.NA2.4) Basic Wind Velocity, Vb0=CdirCseasonVb,o Vb = 24 m/s (Eq.4.1) Structural factor, CsCd = 1.0 (cl.6.2) Orography factor, Co(z) = 1.0 cl.4.3.1(1)) Turbulence factor, kI = 1.0 (cl.NA2.10) z0 zmin (Τable 4.1) Terrain Category Define terrain category II 0.05 2 Max heigh, zmax = 200 m (cl. 4.3.2) Height above ground, z = 100 m Dispacement height, hdis = 4.5 m (Annex A.5) Clear height of building, h-hdis = 4.5 Define height z 5
  58. 58. Page 58 External  Pressure  Coefficients  Walls  Cpe                                     Wind  direction   θ=0°                                             Width                              b      =       15   m     Height                              h      =       9   m     Depth                              d      =       15   m     Edge distance, (Wind direction - θ=0°)       e    = 15 m   Actual  h/b  (For  zone  D  -­‐  windward  face)                  h/b      =       0.60                                                         Length  in   Zone  A                         Zones  A  &  B   exist             3   m     Length  in   Zone  B                                         12   m     Length  in   Zone  C                                         0   m                                                       Wind  direction   θ=90°                                             Width                              b      =       15   m     Height                              h      =       9   m     Depth                              d      =       15   m     Edge distance, (Wind direction - θ=90°)       e    = 15 m   Actual  h/b  (For  zone  D  -­‐  windward  face)                  h/b      =       0.60                                                         Length  in   Zone  A                         Zones    A  &  B   exist             3   m     Length  in   Zone  B                                         12   m     Length  in   Zone  C                                         0   m                                                                                                         Table  7.1  values  of  Cpe  for   wind  on                                             Front  (θ=90°)     Front  (θ=0°)             Zones  (θ=90°)     Zones  (θ=0°)           D       0.747         0.747              A     3   m   A   -­‐1.2   m         E       -­‐0.567         -­‐0.567              B     12   m   B   -­‐0.8   m         A       -­‐1.2         -­‐1.2              C     0   m   C   0   m         B       -­‐0.8         -­‐0.8                                     C       0         0                                    
  59. 59. Page 59 6.0 Load combination Table 6.1: Load combination factors and coefficients Data Symbol Value Reference Permanent action γG 1.35 EN1990,cl.6.4.3.2 Variable action γQ 1.5 EN1990,cl.6.4.3.2 Office areas (Type B), ψ0 0.7 CYS NA EN1990:2002, Table A1.1 Roofs ψ0 0.7 CYS NA EN1990:2002, Table A1.1 Wind loads ψ0 0.5 CYS NA EN1990:2002, Table A1.1 Persistent and transient design situation – STR/GEO Equation 6.10 Ed=ΣγG Gk +γQ Qk1 + γQ ψ0,2 Qk2 Ultimate limit state (ULS) Static load combination STATIC 2. 1.35DL + 1.5LL STATIC 3. 1.35DL + 1.5LL + 0.75WINDX STATIC 4. 1.35DL + 1.5LL - 0.75WINDX STATIC 5. 1.35DL + 1.5LL + 0.75WINDY STATIC 6. 1.35DL + 1.5LL - 0.75WINDY STATIC 7. 1.35DL + 1.5WINDX + 1.05LL STATIC 8. 1.35DL - 1.5WINDX – 1.05LL STATIC 9. 1.35DL + 1.5WINDY + 1.05LL STATIC 10. 1.35DL - 1.5WINDY – 1.05LL Seismic load combination for “Modal Analysis” SEISMIC 2. DL + 0.3LL + EQX + 0.3EQY SEISMIC 3. DL + 0.3LL + EQX – 0.3EQY SEISMIC 4. DL + 0.3LL - EQX + 0.3EQY SEISMIC 5. DL + 0.3LL - EQX – 0.3EQY SEISMIC 6. DL + 0.3LL + EQY + 0.3EQX SEISMIC 7. DL + 0.3LL + EQY – 0.3EQX SEISMIC 8. DL + 0.3LL - EQY + 0.3EQX SEISMIC 9. DL + 0.3LL - EQY – 0.3EQX
  60. 60. Page 60 Seismic load combination for “Lateral force Analysis” SEISMIC 10. DL + 0.3LL + EQXA + 0.3EQYA SEISMIC 11. DL + 0.3LL + EQXA – 0.3EQYA SEISMIC 12. DL + 0.3LL - EQXA + 0.3EQYA SEISMIC 13. DL + 0.3LL - EQXA – 0.3EQYA SEISMIC 14. DL + 0.3LL + EQYA + 0.3EQXA SEISMIC 15. DL + 0.3LL + EQYA – 0.3EQXA SEISMIC 16. DL + 0.3LL - EQYA + 0.3EQXA SEISMIC 17. DL + 0.3LL - EQYA – 0.3EQXA SEISMIC 18. DL + 0.3LL + EQXB + 0.3EQYB SEISMIC 19. DL + 0.3LL + EQXB – 0.3EQYB SEISMIC 20. DL + 0.3LL - EQXB + 0.3EQYB SEISMIC 21. DL + 0.3LL - EQXB – 0.3EQYB SEISMIC 22. DL + 0.3LL + EQYB + 0.3EQXB SEISMIC 23. DL + 0.3LL + EQYB – 0.3EQXB SEISMIC 24. DL + 0.3LL - EQYB + 0.3EQXB SEISMIC 25. DL + 0.3LL - EQYB – 0.3EQXB Serviceability limit state (SLS) STATIC 1. DL + LL
  61. 61. Page 61 7.0 Design preferences ETABS: Options > Preferences > Steel frame design Figure 7.1: Steel frame design preferences 2 3 4 1 5 6
  62. 62. Page 62 Table 7.1: Steel frame design parameters Note 1: Reliability class Class section classification according to EN1998-1-1,cl.6.5.3(2) 1. Depending on the ductility class and the behavior factor q used in the design, the requirements regarding the cross-sectional classes of the steel elements which dissipate energy are indicated in table below (EN1998-1-1,cl.6.5.3(2). Ductility class Reference q factor Cross-Section Class Lower limit q factor Upper limit DCM 1.5< q ≤ 2 Class 1, 2 or 3 2.0< q ≤ 4 Class 1 or 2 DCH 4.0< q Class 1 Note 2: Frame type See section 2.0 of this manual Note 3: Gamma factors Partial factors Values Reference Resistance of cross-sections whatever the class γΜ0=1.00 EN1993-1-1,cl.6.1(1) Resistance of members to instability assessed by member checks γΜ1=1.00 EN1993-1-1,cl.6.1(1) Resistance of cross-sections in tension to fracture γΜ1=1.25 EN1993-1-1,cl.6.1(1) Note 4: Behavior factor See section 2.0 of this manual Note 5: System Omega Omega Factor (System Overstrength Factor) axial load member: (𝛀 = 𝑵 𝒑𝒍,𝑹𝒅/𝑵 𝑬𝒅) Omega factor may different for each diagonal member.
  63. 63. Page 63 1. Run the design analysis with the Ω=1 2. Find the Npl,Rd and NEd of the bracing member and then overwrite the omega factor for each diagonal member separately and then re-run the analysis.(Ω=1). Note: Omega factor should be limited to the following for all diagonal members Note 6: Vertical deflection limits STEEL MEMBERS (CYS NA EN1993-1-1,table NA.1) Vertical deflection Limits wmax Cantilevers L/180 Beams carrying plaster or other brittle finish L/360 Other beams (except purlin and sheeting rails) L/250 Purlins and sheeting rails To suit cladding General use L/300 ETABS deflection limits DL limit, L/ 360 Super DL+LL Limit, L/ 360 Live load Limit, L/ 360 Total Limit, L/ 360 Total Camper Limit, L/ 360 Check_16 if Ωmax 1.25Ωmin≤ "OK", "NOT OK",( ):=
  64. 64. Page 64 8.0 Analysis and design requirements for Concentrically braced frames according to EN1998-1-1,cl.6.7.2 Analysis requirements according to EN1998-1-1,cl.6.7.2 Beams & Columns 1. Under gravity load conditions, only beams and columns shall be considered to resist such loads, without taking into account the bracing members (EN1998-1- 1,cl6.7.2(1)P). Diagonal members 2. The diagonals shall be taken into account as follows in an elastic analysis of the structure for the seismic action: a) in frames with diagonal bracings, only the tension diagonals shall be taken into account, b) in frames with V bracings, both the tension and compression diagonals shall be taken into account (EN1998-1-1,cl6.7.2(2). 3. Taking into account of both tension and compression diagonals in the analysis of any type of concentric bracing is allowed provided that all of the following conditions are satisfied: a) a non-linear static (pushover) global analysis or non-linear time history analysis is used, b) both pre-buckling and post-buckling situations are taken into account in the modeling of the behavior of diagonals and, c) background information justifying the model used to represent the behavior of diagonals is provided (EN1998-1-1,cl6.7.2(3).
  65. 65. Page 65 8.1 Steps of the design detail of Concentric steel frames Table 8.1: Detail steel frame design Design step number Description Step 1 Design of slab under gravity loads (without CBF bracings) considering columns as fixed supports Step 2 Design columns under gravity loads (without CBF bracings) Step 3 Design beams under gravity loads (without CBF bracings) Step 4 Check concentric bracings under gravity loads combination Step 5 Accidental torsional effects Step 6 Second order effects (P-Δ) (P loads are those taken in the definition of the seismic mass “m”) Step 7 Check of beams and of concentric bracings under gravity loads combination Step 8 Design of concentric bracing under seismic combination of loads with the accidental torsional effects and P-Δ effects taken into account Step 9 Check of beams and columns under seismic combination of loads with bracings overstrength factors Ω and with second order effects taken into account Step 10 Re-run the analysis with the modified overstrength factors Ω
  66. 66. Page 66 8.2 Classification of steel sections Table 8.2: Section classification (EN1993-1-1,cl.5.5) Classes Analysis type Description Class 1 Plastic analysis Section can form a plastic hinge with the rotation capacity required from plastic analysis, without reduction of the resistance Class 2 Plastic/ Elastic analysis Section can develop its plastic moment capacity, but has limited rotation capacity. Class 3 Elastic analysis Section in which the stress in the extreme compression fiber of the section, assuming an elastic distribution of stresses, can reach the yield strength, but local buckling is likely to prevent the development of the plastic moment capacity. Description of detail requirements Equations References Reduction of yield and ultimate strength of sections EN10025-2 ε - Factor EN1993-1-1,Table 5.2 Depth of a part of section for internal compression (I-sections) EN1993-1-1,Table 5.2 Section classification for web element EN1993-1-1,Table 5.2 fy. fy t 16mm<if fy 10N mm 2− ⋅− 16mm t< 40mm<if fy 20N mm 2− ⋅− 40mm t< 80mm<if := fu. fu t 16mm≤if fu 10N mm 2− ⋅− 16mm t< 40mm≤if fu 20N mm 2− ⋅− 40mm t< 80mm≤if := ε 235 fy := cw h 2 tf⋅− 2 r⋅−:= Class_type web "CLASS 1" cw tw 72 ε⋅≤if "CLASS 2" 84 ε⋅ cw tw < 83 ε⋅≤if "CLASS 3" 105 ε⋅ cw tw < 124 ε⋅≤if :=
  67. 67. Page 67 Depth of a part of section for oustand flange (I-sections) EN1993-1-1,Table 5.2 Section classification for flange element EN1993-1-1,Table 5.2 cf b tw− 2.r−( ) 2 := Class_type flange "CLASS 1" cf tf 9 ε⋅≤if "CLASS 2" 9 ε⋅ cf tf < 10 ε⋅≤if "CLASS 3" 10 ε⋅ cf tf < 14 ε⋅≤if :=
  68. 68. Page 68 8.3 Design of composite slab under gravity loads Table 8.3: Detail design of composite slab (with steel sheeting) Partial factor Value References Partial factor of longitudinal shear in composite slabs γvs = 1.25 CYS EN1994-1- 1cl.2.4.1.2(6)P Partial factor for shear connector γv = 1.25 CYS EN1994-1- 1cl.2.4.1.2(5)P Partial factor for steel reinforcement γs = 1.15 CYS EN1992-1-1,table 2.1 Partial factor of concrete γc = 1.5 CYS EN1992-1-1,table 2.1 Partial factor of structural steel γM0 = 1.0 CYS EN1993-1-1,cl 6.1(1) Description of detail requirements Equations References Minimum nominal thickness of profile steel sheets t ≥ 0.70mm CYS EN1994-1-1,cl.3.5(2) Minimum depth of slab h ≥ 90mm EN1994-1-1,cl.9.2.1(2) Depth of concrete slab above steel sheeting hc ≥ 50mm EN1994-1-1,cl.9.2.1(2) Minimum steel reinforcement in both direction As.prov ≥80mm2 /m EN1994-1-1,cl.9.2.1(4) Spacing of the reinforcement bars s = min{2h,350mm} EN1994-1-1,cl.9.2.1(5) Maximum height of steel decking hp ≤ 85mm EN1994-1-1,cl.6.6.4.2(3) Minimum width per ribs b0 ≥ hp EN1994-1-1,cl.6.6.4.2(3) Diameter of stud that welded in the sheeting d ≤ 20mm EN1994-1-1,cl.6.6.4.2(3)
  69. 69. Page 69 For holes provided in the sheeting, the diameter of the stud d ≤ 22mm EN1994-1-1,cl.6.6.4.2(3) Maximum overall height of stud hsc ≤ hp +75mm EN1994-1-1,cl.6.6.4.1(2) Design stage Description of checks Equations References Resistance verifications of metal decking at the construction stage Construction Stage Moment resistance of steel sheeting From manufacture data - Concrete compressive strength fcd = fck / γc EN1994-1-1,cl.2.4.1.2(2)P Design yield strength fyo,d = fyp / γM0 - Bending resistance of metal decking MEd / MRd <1.0 EN1993-1-3,cl.6.1.1 Shear resistance of metal decking 𝑉!,!" = !! !"#$ 𝑡  𝑓!" 𝛾!! EN1993-1-3,cl.6.1.5(1) Deflection of metal decking 𝛿!"# = !"! !"#!"    (W in kN/m2 ) - δmax ≤ min {L/ 180,20mm) EN1994-1-1,cl.9.6(2) Resistance verifications of composite slab at the composite stage Composite Stage Area of concrete Ac = b hc (b=1m) - Compression design force of concrete Nc = 0.85 fcd Ac EN1994-1-1,cl.6.2.1.2 Tensile resistance of profiles steel sheeting Np = fyp,d Ap EN1994-1-1,cl.6.2.1.2
  70. 70. Page 70 Location of neutral axis Neutral axis=if{Np < Nc “Lie above steel sheeting”, “Lie below steel sheeting”} EN1994-1-1,9.7.2(5) & (6) Depth of concrete in compression xpl = Ape fyp,d / 0.85 b fcd EN1994-1-1,fig.9.6 Moment resistance (full shear connection) Mpl, Rd = Ap fyd (dp – 0.5 xpl) - Bending resistance of slab MEd / Mpl,Rd <1.0 - The design values of m and k Should be obtain from the manufacture - Shear span (for UDL load) Ls = L / 4 EN1994-1-1,cl.9.7.3(5) Shear span (for UDL & point load) Ls = 3L/8 EN1994-1-1,cl.9.7.3(5) Shear resistance (in longitudinal direction) Vl,Rd = bdp /γvs [(mAp / bLs ) + k] EN1994-1-1,Eq. 9.7 Longitudinal shear resistance of slab VEd / Vl,Rd - Coefficient factor k k = 1+(200 / dp)1/2 EN1992-1-1,cl.6.2.2(1) Value of vmin vmin = 0.035k3/2 fck 1/2 CYS EN1992-1-1,Eq.6.3 Design vertical shear resistance Vv,Rd = vmin bs dp 1 EN1992-1-1,Eq.6.2b Vertical shear resistance check VEd / Vv,Rd < 1.0 - Serviceability limit state (SLS) - Deflection Calculation of deflection (simply supported slab) 𝛿!"# = !"! !"#!"    (W in kN/m2 ) - Deflection limits (imposed load) L / 350 (not greater than 20mm) Deflection limits (total load) L / 250 (not greater than 30mm) EN1992-1-1,cl.7.4.1(4) Serviceability limit state (SLS) - Cracking Minimum amount of steel ratio (un-propped) As = 0.2% Ac EN1994-1-1,cl.9.8.1(2) Minimum amount of steel ratio (propped) As = 0.4% Ac EN1994-1-1,cl.9.8.1(2)
  71. 71. Page 71 Serviceability limit state (SLS) – Floor vibration Floor vibration limits f = 18 / √δa SCI-P-076 : Design guide on the vibration of floors Note 1: Although in reality the slab is continuous, it is normally convenient to design it as simply supported. As a consequence of this, the beneficial effect of compression from the hogging moment at the support is neglected, such that σcp = 0.
  72. 72. Page 72 8.4 Design of composite beam (with steel sheeting) under gravity loads Table 8.4: Detail design of composite beam Minimum height of stud EN1994-1-1,cl.6.6.1.2(1) Nominal diameter of stud EN1994-1-1,cl.6.6.1.2(1) Ultimate strength of shear connector EN1994-1-1,cl.6.6.4.2(1) Check the minimum spacing of studs EN1994-1-1,cl.6.6.5.5(3) Preliminary depth of beams EN1994-1-1,cl.6.4.3(1) Ultimate limit state Bending Resistance of the steel section (EN1993-1-1,cl.6.2.5) Moment resistance of steel section Y-Y axis Mc,Rd,y =Mpl,Rd,y = Wpl,y fy / γM0 EN1993-1-1,cl.6.2.5(2) Vertical Shear resistance of the steel section (cl.6.2.2) & (EN1993-1-1,cl.6.2.6) Factor for shear area η = 1.0 (conservative value) EN1993-1-1,cl.6.2.6(3g) Shear area 1 Av = A -2 b tf + (tw + 2r) tf ≥ η hw tw EN1993-1-1,cl.6.2.6(3a) Shear resistance of steel Vpl,Rd y = Av (fy / √3) / γM0 EN1993-1-1,cl.6.2.6(2) hmin if hsc 4d≥ "OK", "NOT OK",( ):= dlim if 16mm d< 25mm< "OK", "NOT OK",( ):= fus 450N mm 2− ⋅:= slim if sprov 5 d⋅≥ sprov 6 h⋅<∧ "OK", "NOT OK",( ):= hmax 600mm fy 235N mm 2− ⋅≤if 550mm 235N mm 2− ⋅ fy< 275N mm 2− ⋅≤if 400mm 275 N⋅ mm 2− ⋅ fy< 355N mm 2− ⋅≤if 270mm 355 N⋅ mm 2− ⋅ fy< 460N mm 2− ⋅≤if :=
  73. 73. Page 73 Construction Stage section Y-Y axis Check if the verification of shear buckling resistance required or not (EN1993-1-1,cl.6.2.6(6)) Bending and shear interaction check (cl.6.2.2.4) Area of web Aw = hw tw EN1993-1-1,cl.6.2.8(5) Coefficient of interaction vy=VEd / Vpl.Rd,y EN1993-1-1,cl.6.2.8(5) Reduced yield strength ρ = [(2VEd / Vpl.Rd,y) – 1] 2 EN1993-1-1,cl.6.2.8(3) Reduced design plastic resistance moment Y-Y axis EN1993-1-1,cl.6.2.8(5) Lateral torsional buckling of the steel beam It is assumed that the steel beam is laterally restrained by the steel sheeting during construction. In order to provide restraint, the sheeting is fixed to the beam either by the action of through-deck welding or by short-fired pins Effective width of composite beam (cl.5.4.1.2(5)) Effective width of composite beam (EN1994-1-1cl. 5.4.1.2(5)) Plastic resistance moment of composite section with full shear connection (cl.6.2) hw tw 72 ε η ⋅< Ma.pl.Rd. Wpl.y ρ Aw 2 ⋅ 4tw − ⎛ ⎜ ⎜ ⎝ ⎞ ⎟ ⎟ ⎠ fy⋅ γ M0 vy 0.5>if Ma.pl.Rd vy 0.5<if := beff bo 2 min L1 2 L2 2 + Le 8 , ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ +:=
  74. 74. Page 74 Composite Stage Tensile resistance of steel section (EN1993-1-1,cl.6.2.3(2)) Compression resistance of concrete slab (EN1994-1-1,cl.6.2.1.2(1d) Tensile resistance in web of steel section - Location of neutral axis (EN1994-1-1,cl.6.2.1.2(1)) Bending resistance with full shear connection (EN1994-1-1,cl.6.1.2) Bending resistance check checks (EN1993-1-1,cl.6.2.5(1)) Vertical Shear resistance of the composite steel section (cl.6.2.2) & (EN1993-1-1,cl.6.2.6) Design of shear resistance check (EN1993-1-1,cl.6.2.6(1)P) Check if the verification of shear buckling resistance (EN1993-1-1,cl.6.2.6(6)) Npl.a fy A⋅ γ M0 := Nc.f 0.85 fcd⋅ beff⋅ hc⋅:= Npl.w fy tw⋅ ha 2 tf⋅−( )⋅:= Location_neutral axis "Lies in the concrete slab" Nc.f Npl.a>if "Lies in the top flange of the beam" Nc.f Npl.a≤if "Lies in the web of the beam" Nc.f Npl.w<if := Mpl.Rd Npl.a ha 2 h+ Npl.a Nc.f hc 2 ⋅− ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ ⋅ Location_neutral axis "Lies in the concrete slab"if Npl.a ha 2 ⋅ Nc.f hc 2 hp+ ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ ⋅+ Location_neutral axis "Lies in the top flange of the beam"if Ma.pl.Rd Nc.f hc ha+ 2hp+ 2 ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ ⋅+ Nc.f 2 Npl.w ha 4 ⋅− Location_neutral axis "Lies in the top flange of the beam"if := Check_7 if MEd Mpl.Rd≤ "OK", "NOT OK",( ):= Check_8 if VEd Vpl.Rd≤ "OK", "NOT OK",( ):= Check_9 if hw tw 72 ε η ⋅< "Not required shear buckling resistance", "Required shearbuckling resistance", ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ :=
  75. 75. Page 75 Composite Stage required or not Design resistance of shear stud connector (cl.6.6.3.1(1)) Upper limit of reduction factor kt (EN1994-1-1,Table:6.2) Reduction factor kt Ribs transverse to the supporting beams (EN1994-1-1,cl.6.6.4.2) Limitation of kt (EN1994-1-1,cl.6.6.4.2(2)) Reduction factor kt Ribs parallel to the supporting beams (EN1994-1-1,cl.6.6.4.1) Minimum height of shear stud (EN1994-1-1,cl.6.6.1.2(1)) Limitation of stud diameter (EN1994-1-1,cl.6.6.1.2(1)) Factor α (EN1994-1-1,cl.6.6.3.1(1)) kt.max 0.85 nr 1 1mm ts≥∧ d 20mm<∧if 1.0 nr 1 1mm ts<∧ d 20mm<∧if 0.75 nr 1 1mm ts≥∧ 19mm d≤ 22mm<∧if 0.75 nr 1 1mm ts<∧ 19mm d≤ 22mm<∧if 0.70 nr 2 1mm ts≥∧ d 20mm<∧if 0.80 nr 2 1mm ts<∧ d 20mm<∧if 0.60 nr 2 1mm ts≥∧ 19mm d≤ 22mm<∧if 0.60 nr 2 1mm ts<∧ 19mm d≤ 22mm<∧if := kt 0.7 nr bo hp ⋅ hsc hp 1− ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ ⋅:= Check_10 if kt kt.max< "OK", "NOT OK",( ):= kt 0.6 bo hp ⋅ hsc hp 1− ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ ⋅ 1.0≤:= hmin if hsc 4d≥ "Ductile", "Not Ductile",( ):= dlim if 16mm d< 25mm< "Ductile", "Not ductile",( ):= α 0.2 hsc d 1+ ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ ⋅ 3 hsc d ≤ 4≤if 1 hsc d 4>if 1=:=
  76. 76. Page 76 Composite Stage Design shear resistance of a headed stud (EN1994-1-1,cl.6.6.3.1(1)) Degree of shear connection (cl.6.6.1.2(1)) Ratio of the degree shear connection (EN1994-1-1,cl.6.2.1.3(3)) Minimum degree of shear connection for equal flange (EN1994-1-1,cl.6.6.1.2(1)) Check the degree of shear interaction within the limits (EN1994-1-1,cl.6.6.1.2(1)) Number of shear connector required - Stud spacing - Check the minimum spacing of studs (EN1994-1-1,cl.6.6.5.7(4)) Adequacy of the shear connection (EN1994-1-1,cl.6.6.1.3(3)) Design of transverse reinforcement (cl.6.6.6.2) & (EN1992-1-1,cl.6.2.4) Length under consideration - PRd kt min 0.8 fus⋅ π⋅ d 2 4 ⋅ γ v 0.29 α⋅ d 2 ⋅ fck Ecm⋅⋅ γ v , ⎛ ⎜ ⎜ ⎜ ⎝ ⎞ ⎟ ⎟ ⎟ ⎠ ⋅:= η Nc.f Npl.a := ηmin 1 355 fy N mm 2− ⋅ ⎛⎜ ⎜ ⎜ ⎝ ⎞⎟ ⎟ ⎟ ⎠ 0.75 0.03 Le m ⋅− ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ ⋅− Le 25m<if 1.0 Le 25m>if := Check_11 if η ηmin> η 0.4≥∧ "OK", "NOT OK",( ):= n 2 Npl.a⋅ PRd := sprov Le Nstud := slim if sprov 5 d⋅≥ sprov 6 h⋅<∧ "OK", "NOT OK",( ):= Check_12 if Mpl.Rd 2.5 Ma.pl.Rd⋅< "Uniform spacing", "Not uniform spacing",( ):= Δ x Le 2 :=
  77. 77. Page 77 Longitudinal shear stress (EN1992-1-1,cl.6.2.4(3)) Strength reduction factor (EN1992-1-1,Eq.6.6N) Area of transverse reinforcement required (EN1992-1-1,cl.6.2.4(4)) Check the crushing compression in the flange (EN1992-1-1cl.6.2.4(4)) Serviceability limit state Vertical deflection Construction Stage Maximum deflection at construction stage - Vertical deflection limit (CYS NA EN1993-1-1,table NA.1) Composite Stage Short term elastic modular ration (EN1994-1-1,cl.7.2.1) Second moment of area of the composite section - Deflection with full shear connection - Vibration of floor (Simplified analysis) (EN1990 A1.4.4) vEd Npl.a 2 hc⋅ Δ x⋅ := v 0.6 1 fck 250 N⋅ mm 2− ⋅ − ⎛⎜ ⎜ ⎝ ⎞⎟ ⎟ ⎠ ⋅:= As.req vEd hc⋅ sf⋅ fyd sin θf( ) cos θf( ) ⋅ := Check_14 if vEd v fcd⋅ sin θf( )⋅ cos cos θf( )( )⋅≤ "OK", "NOT OK",( ):= δc 5 Gk.c Qk.c+( )⋅ Le 4 ⋅ 384 Es⋅ Iyy⋅ := Check_15 if δc Le 250 < "OK", "NOT OK", ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ := no Es Ecm := r A beff hc⋅ := Ic A h 2 hp⋅+ hc+( )2 ⋅ 4 1 no r⋅+( )⋅ beff hc 3 ⋅ 12 no⋅ + Iyy+:= δcom 5 Gk Qk+( )⋅ Le( )4 ⋅ 384 Es⋅ Ic⋅ :=
  78. 78. Page 78 Total load on beam is EN1990,A1.4.4 Increase the inertia, Ic by 10% to allow for the increased dynamic stiffness of the composite beam - Instantaneous deflection caused by re-application of the self weigth of the floor and the beam to the composite beam - Natural frequency SCI P354 Check natural frequency limitation - Fv Gk ψ1 Qk⋅+:= Icl Iy Iy 0.1⋅( )+:= δα 5 Fv Le⋅( )⋅ Le 3 ⋅ 384 Es⋅ Icl⋅ := f 18 Hz⋅ δα mm := Check_17 if f 4Hz< "OK", "NOT OK",( ):=
  79. 79. Page 79 8.5 Detail design of steel columns under gravity loads Table 8.5: Detail design of composite beam Partial factor Value References Partial factor of cross-sections whatever the class is γM0 = 1.0 CYS EN1993-1-1,cl 6.1(1) Partial factor of member to instability assessed by member checks γM1 = 1.0 CYS EN1993-1-1,cl 6.1(1) Description of detail requirements Equations References Design plastic resistance of the gross cross-section Npl,Rd = A fy / γM0 EN1993-1-1,cl.6.2.3(2) Compression resistance of steel section Nc,Rd =A fy / γM0 EN1993-1-1,cl.6.2.4(1) Bending interaction check Moment resistance of steel section Y-Y axis Mc,Rd,y =Mpl,Rd,y = Wpl,y fy / γM0 EN1993-1-1,cl.6.2.5(2) Moment resistance of steel section Z-Z axis Mc,Rd,z= Mpl,Rd,z = Wpl,z fy / γM0 EN1993-1-1,cl.6.2.5(2) Shear interaction check Factor for shear area η = 1.0 (conservative value) EN1993-1-1,cl.6.2.6(3g) Shear area 1 Av = A -2 b tf + (tw + 2r) tf ≥ η hw tw EN1993-1-1,cl.6.2.6(3a) Shear resistance of steel section Y-Y axis Vpl,Rd y = Av (fy / √3) / γM0 EN1993-1-1,cl.6.2.6(2) Shear resistance of steel section Z-Z axis Vpl,Rd,z = 2b tf (fy / √3) / γM0 EN1993-1-1,cl.6.2.6(2) Bending and shear interaction check Area of web Aw = hw tw EN1993-1-1,cl.6.2.8(5)
  80. 80. Page 80 Coefficient of interaction vy=VEd / Vpl.Rd,y EN1993-1-1,cl.6.2.8(5) Reduced yield strength ρ = [(2VEd / Vpl.Rd,y) – 1] 2 EN1993-1-1,cl.6.2.8(3) Reduced design plastic resistance moment Y-Y axis EN1993-1-1,cl.6.2.8(5) Coefficient of interaction vz=VEd / VRd,y EN1993-1-1,cl.6.2.8(5) Reduced yield strength ρ = [(2VEd / Vpl.Rd,z) – 1] 2 EN1993-1-1,cl.6.2.8(3) Reduced design plastic resistance moment Z-Z axis EN1993-1-1,cl.6.2.8(5) Check combination of axial and bending EN1993-1-1,cl.6.2.1(7) Bending and axial interaction check Criteria 1 – Y-Y axis c1=NEd ≤ Npl,Rd EN1993-1-1,cl.6.2.9.1(4) Criteria 2 – Y-Y axis c2=NEd ≤ (0.5 hw tw fy )/ γM0 EN1993-1-1,cl.6.2.9.1(4) Check criteria c= max(cy1, cy2) Factor a a = min {(A-2 b tf) / A) ,0.5} EN1993-1-1,cl.6.2.9.1(5) Factor n n = NEd / Npl,Rd EN1993-1-1,cl.6.2.9.1(5) Factor β EN1993-1-1,cl.6.2.9.1(6) Reduced design value of the resistance to bending MN,y,Rd = Mpl,y,Rd (1-n)/(1-0,5a) if c>1.0 and EN1993-1-1,cl.6.2.9.1(5) Mc.Rd.y Wpl.y ρ Aw 2 ⋅ 4tw − ⎛ ⎜ ⎜ ⎝ ⎞ ⎟ ⎟ ⎠ fy⋅ γ M0 vy 0.5>if Mc.Rd.y vy 0.5<if := Mc.Rd.z Wpl.z ρ Aw 2 ⋅ 4tw − ⎛ ⎜ ⎜ ⎝ ⎞ ⎟ ⎟ ⎠ fy⋅ γ M0 vz 0.5>if Mc.Rd.z vz 0.5<if := Check_1 if NEd Npl.Rd MEd.y Mc.Rd.y + MEd.z Mc.Rd.z + 1.0≤ "OK", "NOT OK", ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ := β 5n 5n 1≥if 1 otherwise 1=:=
  81. 81. Page 81 moments making allowance for the presence of axial forces (Y-Y axis) MN,y,Rd = Mpl,y,Rd if 0 ≤ c ≤ 1.0 Reduced design value of the resistance to bending moments making allowance for the presence of axial forces (Z-Z axis) MN,z,Rd = Mpl,z,Rd for n<a and MN,z,Rd = Mpl,z,Rd [1-(n-a/1-a)2 ] for n>a EN1993-1-1,cl.6.2.9.1(5) Check combination of bi-axial bending EN1993-1-1,cl.6.2.9.1(6) Buckling interaction check Buckling length See: Figure 1: Effective length columns Design Guidance of EC3) Elastic critical force for the relevant buckling mode based on the gross cross sectional properties 𝑁!".! = 𝐸! 𝐼! 𝜋! 𝐿!".! ! - Non dimensional slenderness λ! = 𝐴𝑓! 𝑁!".! EN1993-1-1,cl.6.3.1.2(1) Buckling curve EN1993-1-1,table 6.2 Imperfection factor a EN1993-1-1,table 6.1 Check_1 if MEd.y MN.y.Rd ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ a MEd.z MN.z.Rd ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ β + ⎡ ⎢ ⎢ ⎣ ⎤ ⎥ ⎥ ⎦ 1.0≤ "OK", "NOT OK", ⎡ ⎢ ⎢ ⎣ ⎤ ⎥ ⎥ ⎦ := Buckling_class_Y "a" tf 40mm<if "b" 40mm tf< 100mm<if h b 1.2>if "b" tf 100mm≤if "d" tf 100mm>if h b 1.2≤if :=
  82. 82. Page 82 Value to determine the reduction factor χ Φ = 0.5 [1 + α (λ – 0.2) + λ2 EN1993-1-1,cl.6.3.1.2(1) Reduction factor χ χ = 1 Φ + Φ! − λ! ≤ 1,0 EN1993-1-1,cl.6.3.1.2(1) Design buckling resistance of a compression member 𝑁!,!" = 𝜒𝐴𝑓! 𝛾!!) EN1993-1-1,cl.6.3.1.1(3) Buckling length See: Figure 1: Effective length columns Design Guidance of EC3) Elastic critical force for the relevant buckling mode based on the gross cross sectional properties 𝑁!".! = 𝐸! 𝐼! 𝜋! 𝐿!".! ! - Non dimensional slenderness λ! = 𝐴𝑓! 𝑁!".! EN1993-1-1,cl.6.3.1.2(1) Buckling curve EN1993-1-1,table 6.2 Imperfection factor a EN1993-1-1,table 6.1 αy 0.1 Buckling_class_Y "ao"if 0.21 Buckling_class_Y "a"if 0.34 Buckling_class_Y "b"if 0.49 Buckling_class_Y "c"if 0.76 Buckling_class_Y "d"if := Buckling_class_Y "a" tf 40mm<if "b" 40mm tf< 100mm<if h b 1.2>if "b" tf 100mm≤if "d" tf 100mm>if h b 1.2≤if :=
  83. 83. Page 83 Value to determine the reduction factor χ Φ = 0.5 [1 + α (λ – 0.2) + λ2 EN1993-1-1,cl.6.3.1.2(1) Reduction factor χ χ = 1 Φ + Φ! − λ! ≤ 𝜒 ≤ 1,0 EN1993-1-1,cl.6.3.1.2(1) Design buckling resistance of a compression member 𝑁!,!",! = 𝜒𝐴𝑓! 𝛾!!) EN1993-1-1,cl.6.3.1.1(3) Non dimensional slenderness EN1993-1-1,cl.6.3.1.2(1) Check the bukling effects if can be ignored and only cross section check is adequate EN1993-1-1,cl.6.3.1.2(4) Lateral torsional buckling interaction check Elastic critical moment for lateral torsional buckling NCCI: SN003a-EN-EU Effective length factor (Pinned End) k = 1.0 NCCI: SN003a Factor for end warping kw = 1.0 NCCI: SN003a Coefficient factor C1 (Load condition: UDL) NCCI: SN003a Coefficient factor C2 C2 = 1.554 NCCI: SN003a Distance between the point of load application and the shear centre (load applied on centre) zg = 0m NCCI: SN003a αz 0.1 Buckling_class_Z "ao"if 0.21 Buckling_class_Z "a"if 0.34 Buckling_class_Z "b"if 0.49 Buckling_class_Z "c"if 0.76 Buckling_class_Z "d"if := λ max λy λz,( ):= Check if λ 0.2< "Ignored buckling effects", "Consider bucklingeffects",( ):= Mcr C1 π 2 Es⋅ Izz⋅ k Lcr⋅( )2 ⋅ k kw ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ 2 Iw Izz ⋅ k Lcr⋅( )2 G It⋅ π 2 Es Izz⋅ + C2 zg⋅( )2 +⋅ C2 zg⋅−:= C1 1.88 1.40ψ− 0.52ψ 2 +:= Check_5 if C1 2.7≤ "OK", "NOT OK",( ):=
  84. 84. Page 84 Lateral torsional buckling curves EN1993-1-1,table 6.4 Imperfection factors for lateral torsional buckling curves EN1993-1-1,table 6.3 Non dimensional slenderness for lateral torsional buckling EN1993-1-1,cl.6.3.2.2(1) Value to determine the reduction factor χLT EN1993-1-1,cl.6.3.2.2(1) Reduction factor for lateral-torsional buckling EN1993-1-1,cl.6.3.2.2(1) Check if the lateral torsional buckling can be ignored EN1993-1-1,cl.6.3.2.2(4) Moments due to the shift of the centroidal axis for class sections 1,2 & 3 EN1993-1- 1,cl.6.3.3(4)/table 6.7 Characteristic resistance to normal force of the critical cross-section EN1993-1- 1,cl.6.3.3(4)/table 6.7 Characteristic moment resistance of the critical cross-section E1993-1-1,cl.6.3.3(4)/table 6.7) Buckling_curve_Z "a" h b 2≤if "b" h b 2>if := αLT 0.21 Buckling_curve_Z "a"if 0.34 Buckling_curve_Z "b"if 0.49 Buckling_curve_Z "c"if 0.76 Buckling_curve_Z "d"if := λLT Wpl.y fy⋅ Mcr := φ LT 0.5 1 αLT λLT 0.2−( )⋅+ λLT 2 +⎡ ⎣ ⎤ ⎦⋅:= χLT 1 φ LT φ LT 2 λLT 2 −+ := Check_6 if λLT λLTO< "Ignored torsional buckling effects", "Consider torsional buckling effects",( ):= Check_7 if MEd.y Mcr λLTO 2 < "Ignored torsional buckling effects", "Consider torsional buckling effects", ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ := ΔM Ed.z 0:= ΔM Ed.y 0:= NRk fy A⋅:= My.Rk fy Wpl.y⋅:= Mz.Rk fy Wpl.z⋅:=
  85. 85. Page 85 Ratio of end moments EN193-1-1,Table B2) Equivalent uniform moment factor EN1993-1-1,table B.1&B.2 Interaction factors EN1993-1-1,table B.1&B.2 Combined bending and axial compression EN1993-1-1,Eq.6.61 ψy MEd.y1 MEd.y2 1− MEd.y1 MEd.y2 ≤ 1≤if MEd.y2 MEd.y1 1− MEd.y2 MEd.y1 ≤ 1≤if := ψz MEd.z1 MEd.z2 1− MEd.z1 MEd.z2 ≤ 1≤if MEd.z2 MEd.z1 1− MEd.z2 MEd.z1 ≤ 1≤if := Cmy 0.6 0.4 ψy⋅+:= Cmz 0.6 0.4 ψz⋅+:= kyy min Cmy 1 λy 0.2−( ) NEd χy NRk γ M1 ⋅ ⋅+ ⎡ ⎢ ⎢ ⎢ ⎣ ⎤ ⎥ ⎥ ⎥ ⎦ ⋅ ⎡ ⎢ ⎢ ⎢ ⎣ ⎤ ⎥ ⎥ ⎥ ⎦ Cmy 1 0.8 NEd χy NRk γ M1 ⋅ ⋅+ ⎛ ⎜ ⎜ ⎜ ⎝ ⎞ ⎟ ⎟ ⎟ ⎠ ⋅, ⎡ ⎢ ⎢ ⎢ ⎣ ⎤ ⎥ ⎥ ⎥ ⎦ := kzz min Cmz 1 2λz 0.6−( ) NEd χz NRk γ M1 ⋅ ⋅+ ⎡ ⎢ ⎢ ⎢ ⎣ ⎤ ⎥ ⎥ ⎥ ⎦ ⋅ ⎡ ⎢ ⎢ ⎢ ⎣ ⎤ ⎥ ⎥ ⎥ ⎦ Cmz 1 1.4 NEd χz NRk γ M1 ⋅ ⋅+ ⎛ ⎜ ⎜ ⎜ ⎝ ⎞ ⎟ ⎟ ⎟ ⎠ ⋅, ⎡ ⎢ ⎢ ⎢ ⎣ ⎤ ⎥ ⎥ ⎥ ⎦ := kyz 0.6kzz:= kzy 0.6kyy:= NEd xy NRk⋅ γ M1 kyy MEd.y ΔM Ed.y+ χLT My.Rk γ M1 ⋅ ⋅+ kyz Mz.Ed ΔM Ed.z+ Mz.Rk γ M1 ⋅+
  86. 86. Page 86 Combined bending and axial compression EN1993-1-1,Eq.6.62 Note: This equations is applicable only for I and H sections with section class 1 and 2 Note 1: The shear area is for rolled I and H sections, load parallel to web NEd χz NRk⋅ γ M1 kzy MEd.y ΔM Ed.y+ χLT My.Rk γ M1 ⋅ ⋅+ kzz MEd.z ΔM Ed.z+ Mz.Rk γ M1 ⋅+
  87. 87. Page 87 8.6 Detail design rules of steel Concentric Braced Frames (CBF) according to Eurocode 8 8.6.1 Detail design rules of steel bracing according to Eurocode 8 Description Value References Overstrength factor used in design γov = 1.25 CYS EN1998-1-1cl.6.2(3)P Non-dimensional slenderness (X bracing) EN1998-1-1,cl.6.7.3(1) Non-dimensional slenderness (one diagonal) λ ≤ 2.0 EN1998-1-1,cl.6.7.3(2) Non-dimensional slenderness (V bracing) λ ≤ 2.0 EN1998-1-1,cl.6.7.3(3) Non-dimensional slenderness (V,X & one bracing) EN1998-1-1,cl.6.7.3(4) Yield resistance check EN1998-1-1,cl.6.7.3(5) Check Ω factor EN1998-1-1,cl.6.7.3(8) Check Ω factor EN1998-1-1,cl.6.7.3(8) Ductility class require for seismic design EN1998-1-1,cl.6.5.3(2) Check_6 if 1.3 λy< 2< "OK", "NOT OK",( ):= Check_5 if Ns 3≥ "Consider limitation (AsEC8)", "Ignorelimitation (As EC3)",( ):= Check_15 if NEd Npl.Rd≤ "OK", "NOT OK",( ):= Ω. Npl.Rd NEd := Check_16 if Ωmax 1.25Ωmin≤ "OK", "NOT OK",( ):= Class_type_req "CLASS 1 , 2 or 3" 1.5 q< 2≤ Ductility_class "DCM"∧if "CLASS 1 or 2" 2 q< 4≤ Ductility_class "DCM"∧if "CLASS 1" q 4> Ductility_class "DCH"∧if :=
  88. 88. Page 88 8.7 Detail design rules of steel columns and beams according to Eurocode 8 Description Value References Overstrength factor used in design γov = 1.25 CYS EN1998-1-1cl.6.2(3)P Yield resistance check EN1998-1-1,cl.6.7.3(5) Check Ω factor EN1998-1-1,cl.6.7.3(8) Minimum resistance requirement, NEd EN1998-1-1,cl.6.7.4(1) Ductility class require for seismic design EN1998-1-1,cl.6.5.3(2) Check_15 if NEd Npl.Rd≤ "OK", "NOT OK",( ):= Ω. Npl.Rd NEd := NEd. NEd.G 1.1 γ ov⋅ Ω⋅ NEd.E⋅+:= Class_type_req "CLASS 1 , 2 or 3" 1.5 q< 2≤ Ductility_class "DCM"∧if "CLASS 1 or 2" 2 q< 4≤ Ductility_class "DCM"∧if "CLASS 1" q 4> Ductility_class "DCH"∧if :=
  89. 89. Page 89 8.8 Detail design rules of steel composite members according to Eurocode 8 Description Value References Minimum concrete strength C20/25 – C40/50 CYS EN1998-1-1cl.7.2.1(1) Steel reinforcement class B or C EN1998-1-1,cl.7.2.2(2) Minimum degree of connection η ≤ 0.8 EN1998-1-1,cl.7.6.2(3) Reduction factor kt = 0.75 EN1998-1-1,cl.7.6.2(4) Profiled steel sheeting with ribs transverse to the supporting beams is used, the reduction factor kt = kt * kr EN1998-1-1,cl.7.6.2(6) Yield strength of steel EN1998-1-1,cl.7.6.2(8) Ductility class require for seismic design EN1998-1-1,cl.6.5.3(2) fy "fy=355" 1.5 q< 4≤ Ductility_class "DCM"∧ x d 0.27≤∧if "fy=235" 1.5 q< 4≤ Ductility_class "DCM"∧ 0.27 x d < 0.36≤∧if "fy=355" q 4> Ductility_class "DCH"∧ x d 0.20≤∧if "fy=235" q 4> Ductility_class "DCH"∧ 0.20 x d < 0.27≤∧if := xx Class_type_req "CLASS 1 , 2 or 3" 1.5 q< 2≤ Ductility_class "DCM"∧if "CLASS 1 or 2" 2 q< 4≤ Ductility_class "DCM"∧if "CLASS 1" q 4> Ductility_class "DCH"∧if :=
  90. 90. Page 90 8.9 Detail design rules of steel moment resistance frames (MRF) according to Eurocode 8 8.9.1 Detail design rules for MRF - Design criteria Description Value References Below design criteria apply to (Bottom – Top) Single/Multi-story buildings EN1998-1-1cl.6.6.1(1) Moment capacity (where fixed support is provided) ∑MRc ≥ 1.3MRb EN1998-1-1,cl.4.4.2.3(4) 8.9.2 Detail design rules of steel beam for MRF Description Value References Moment capacity verification 𝑀!" 𝑀!".!"   ≤ 1.0 EN1998-1-1,cl.6.6.2.(2) Design shear force VEd = VEd.G + VEd.M Where VEd.M = (Mpl.Rd.A + Mpl.Rd.B)/L EN1998-1-1,cl.6.6.2.(2) Shear capacity verification 𝑉!" 𝑉!".!"   ≤ 0.5 EN1998-1-1,cl.6.6.2.(2) Axial capacity verification 𝑁!" 𝑁!".!"   ≤ 0.15 EN1998-1-1,cl.6.6.2.(2)
  91. 91. Page 91 8.9.3 Detail design rules of steel column for MRF Description Value References Overstrength factor used in design γov = 1.25 CYS EN1998-1-1cl.6.2(3)P Check Ω factor (derivate from all beam with moment connection) Ω!"# = !!".!" !!".!   MEd.E : Lateral force EN1998-1-1cl.6.6.3(1P) Design axial compression force NEd = NEd.G +1.1γvoΩ NEd.E NEd.E : Lateral force EN1998-1-1cl.6.6.3(1P) Design bending moment MEd = MEd.G +1.1γvoΩ MEd.E MEd.E : Lateral force EN1998-1-1cl.6.6.3(1P) Design shear force VEd = VEd.G +1.1γvoΩ VEd. VEd.E : Lateral force EN1998-1-1cl.6.6.3(1P) Design shear force verification 𝑉!" 𝑉!".!"   ≤ 0.5 EN1998-1-1cl.6.6.3(4)
  92. 92. Page 92 9.0 Design of steel frames 9.1 Design of steel member overwrites data Figure 9.1: Steel design result of the member Overwrites
  93. 93. Page 93 Figure 9.2: Steel frame design overwrites for Eurocode 3 3 2 1 4 7 8 9 10 11 12 5 6
  94. 94. Page 94 Table 9.1: Steel frame design overwrites for Eurocode 3 Explanation of Steel frame design overwrites for Eurocode 3 Note No. Parameter Values 1 Effective length factor 2 Moment coefficient kyy kzz
  95. 95. Page 95 3 Bending Coefficient (C1) 4 Moment coefficient 5 Overstrength factor used in design1 6 Omega gamma factor γov = 1.25 7 Compressive/Tensile capacity 8 Major bending capacity, Mc3Rd 9 Minor bending capacity, Mc2Rd 10 Buckling resistance moment Ω. Npl.Rd NEd :=
  96. 96. Page 96 11 Major shear capacity, Vc3Rd 12 Minor shear capacity, Vc2Rd Notes: 1 Ω is not calculated automatically by the program. Rather, its value can be overwritten by the user through design Preference and Overwrites.
  97. 97. Page 97 9.2 Design of columns / beams using ETABS – Gravity load analysis only STEP 1: Analyze > Run Analysis STEP 2: Design > Steel frame design > Select design combo… Note: Under gravity load conditions, only beams and columns shall be considered to resist such loads, without taking into account the bracing members (EN1998-1-1,cl6.7.2(1)P). Design combination at ULS STATIC 1. 1.35DL + 1.5LL STATIC 10. 1.00DL + 0.3LL Figure 9.3: Gravity load combination at ULS Design combination at SLS DSTLD 1. DL + LL DSTLD 2. DL
  98. 98. Page 98 Figure 9.4: Gravity load combination at SLS Figure 9.5: Steel design under gravity load ONLY Write click on each member in order to check it individually Column name: C2 Storey level: Storey 1
  99. 99. Page 99 Figure 9.6: Steel design result of the member Figure 9.7: Ultimate moment results under worst case combination ETABS: Display > Show tables Worst case combination
  100. 100. Page 100 Take the ultimate moment and shear force from the above table and place them into the Excel spreadsheet or Mathcad file in order to verify the steel design results of ETABS. Table 9.2: Summarize of design values required to carry out the design of steel member Design value Symbol Results (kN) Design axial force for gravity load combination (G+0.3Q) NEd.GV 344.75 Design moment at y-y at end 1 (seismic load combination) MEd.GV.y1 -1.293 Design moment at y-y at end 2 (seismic load combination) MEd.GV.y2 3.195 Design moment at z-z at end 1 (seismic load combination) MEd.GV.z1 -0.173 Design moment at z-z at end 2 (seismic load combination) MEd.GV.z2 -0.142 Shear forces at y-y at end (seismic load combination) VEd.GV.y -0.01 Shear force at z-z at end 1 (seismic load combination) VEd.GV.z -1.63 Press the button summary
  101. 101. Page 101 Design results of ETABS ETABS/HAND Description of comparison Results ETABS Equation 6.62 in EC3 0.160 HAND (see section 9.3) 0.135
  102. 102. Page 102 ETABS/HAND N.c.Rd N.t.Rd N.pl.Rd ETABS 2675.75 2675.75 2675.75 HAND (see section 9.3) 2675.75 2675.75 2675.75 ETABS/HAND Curve Alpha LambarBar Phi Chi Nb.Rd y-y z-z y-y z-z y-y z-z y-y z-z y-y z-z y-y z-z ETABS “b” “c” 0.340 0.490 0.268 0.454 0.548 0.66 0.976 0.868 2610 2322 HAND (see section 9.3) “b” “b” 0.340 0.340 0.248 0.42 0.539 0.625 0.983 0.918 2630 2534
  103. 103. Page 103 ETABS/HAND M.c.Rd M.v.Rd M.b.rd y-y z-z y-y z-z ETABS 305.8 142.45 305.8 142.45 302.05 HAND (see section 9.3) 305.8 142.45 305.8 142.45 305.80 ETABS/HAND Curve AlphaLT LambdaBarLT PhiLT ChiLT C1 Mcr ETABS a 0.21 0.255 0.538 0.988 2.532 4694 HAND (see section 9.3) b 0.34 0.24 0.535 0.986 2.532 4679 ETABS/HAND kyy kyz kzy kzz ETABS 0.442 0.582 0.964 0.970 HAND (see section 9.3) 0.441 0.576 0.265 0.96
  104. 104. Page 104 ETABS/HAND V.c.Rd V.pl.Rd η y-y z-z ETABS 504 1234 504 1.2 HAND (see section 9.3) 504 1156 504 1.0
  105. 105. Page 105 9.3 Design of steel column (Gravity design situation) – Hand calculations 1. Rolled I - section 2. Limit to class 1 and 2 section 3. Column not susceptible to torsional deformations Length of column Total axial load on column, NEd Shear force y-y axis Shear force z-z axis Design moment y-y axis Design moment y-y axis Maximum moment Design moment z-z axis Design moment z-z axis Maximum moment Section properties: Depth of section,h: Width of section,b: Thickness of web, tw: Thickness of flange, tf : Thickness of element Second moment of area z-z: Second moment of area y-y: Cross section area, A: Radius of section: Heigth of web, hw hc 3m:= NEd 344.798kN:= VEd.y 0.011kN:= VEd.z 1.626kN:= MEd.y1 3.195kN m⋅:= MEd.y2 1.293− kN m⋅:= MEd.y max MEd.y1 MEd.y2,( ) 3.195kN m⋅⋅=:= MEd.z1 0.142− kN m⋅:= MEd.z2 0.173− kN m⋅:= MEd.z max MEd.z1 MEd.z2,( ) 0.142− kN m⋅⋅=:= h 270mm:= b 280mm:= tw 8mm:= tf 13mm:= t max tw tf,( ) 13 mm⋅=:= Izz 47630000mm 4 := Iyy 1.367 10 8 ⋅ mm 4 := A 9730mm 2 := r 24mm:= hw h 2tf− 2r− 196 mm⋅=:=
  106. 106. Page 106 Area of the web Warping Constant, Iw: Torsional Constant, IT: Plastic Modulus, Wply Plastic Modulus, Wplz Elastic modulus, E: Yield strength of steel , fy: Ultimate strength, fu: Shear modulus Reduction of yield and ultimate strength of sections EN10025-2 Partial safety factor Resistance of cross-sections whatever the class (CYS EN1993-1-1,cl 6.1(1)) Resistance of members to instability (CYS EN1993-1-1,cl 6.1(1)) Resistance of cross-section in tension (CYS EN1993-1-1,cl.6.1(1)) Section classification For section classification the coefficient ε is: For a flange element: Aw hw tw⋅ 1.568 10 3 × mm 2 ⋅=:= Iw 753.7 10 9 ⋅ mm 6 ⋅:= It 635000mm 4 := Wpl.y 1112000mm 3 := Wpl.z 518000mm 3 := Es 210kN mm 2− ⋅:= fy 275N mm 2− ⋅:= fu 430N mm 2− ⋅:= G 81kN mm 2− ⋅:= fy fy t 16mm≤if fy 10N mm 2− ⋅− 16mm t< 40mm≤if fy 20N mm 2− ⋅− 40mm t< 80mm≤if := fy 275 N mm 2− ⋅⋅= fu fu t 16mm≤if fu 10N mm 2− ⋅− 16mm t< 40mm≤if fu 20N mm 2− ⋅− 40mm t< 80mm≤if := fu 430 N mm 2− ⋅⋅= γ M0 1:= γ M1 1:= γ M2 1.25:= ε 235 fy N mm 2− ⋅ 0.924=:=
  107. 107. Page 107 For a web element: Tension resistance (cl.6.2.3) Design plastic resistance of the cross section (EN1993-1-1,cl.6.2.3(2) Design ultimate resistance (EN1993-1-1,cl.6.2.3(2b)) Design tension resistance (EN1993-1-1,cl.6.2.3(2)) Check tension capacity cf b tw− 2.r−( ) 2 112 mm⋅=:= Class_type flange "CLASS 1" cf tf 9 ε⋅≤if "CLASS 2" 9 ε⋅ cf tf < 10 ε⋅≤if "CLASS 3" 10 ε⋅ cf tf < 14 ε⋅≤if := Class_type flange "CLASS 2"= cw h 2 tf⋅− 2 r⋅− 196 mm⋅=:= Class_type web "CLASS 1" cw tw 72 ε⋅≤if "CLASS 2" 84 ε⋅ cw tw < 83 ε⋅≤if "CLASS 3" 105 ε⋅ cw tw < 124 ε⋅≤if := Class_typeweb "CLASS 1"= Class_type if Class_typeflange Class_typeweb Class_typeflange, "ADD MANUALY",( ):= Class_type "ADD MANUALY"= Npl.Rd A fy⋅ γ M0 2.676 10 3 × kN⋅=:= Nu.Rd 0.9A fy⋅ γ M2 1.927 10 3 × kN⋅=:= Nt.Rd min Nu.Rd Npl.Rd,( ) 1.927 10 3 × kN⋅=:= Check1 if NEd Nt.Rd 1.0≤ "OK", "NOT OK", ⎛ ⎜ ⎝ ⎞ ⎟ ⎠ := Check1 "OK"=

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