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BASIS OF STRUCTURAL DESIGN
(EN1990:2002)
Ultimate limit state verification
(EN1990,cl.6.4.1(1)P)
The following ultimate limit states shall be verified as relevant:
EQU: Loss of equilibrium of the structure, (considering for sliding, overturning or uplift)
STR: Internal failure or excessive deformation of the structure of structural member (Design of structural for
strength of members and frames),
GEO: Failure due to excessive deformation of the ground (Design of structural members such as footing,
piles, basement walls, etc.),
FAT: Fatigue failure of the structure or structural member.
Design working life
(CYS NA EN1990,Table 2.1)
Design working lifecategory
Indicative designworking life (years)
Examples
1 10 Temporary structures(1)
2 1025 Replaceable structural parts, e.g. gantry girders,
bearings
3 1530 Agricultural and similar structures
4 50 Building structures and other common structures
5 100 Monumental building structures, bridges, and other
civil engineering structures
(1) Structures or parts of structures that can be dismantled with a view to being re-used should
not be considered as temporary.In the case of replaceable structural parts the design life for the structural determination of loads should be
the design life of the structure.
Design Working life
Ultimate Limit State (ULS)
Ultimate Limit State Concern
(EN1990,cl.3.3(1)P)
Safety of people, Safety of the structure
Design situations
(EN1990,cl.3.2(2)P)
Persistent design situation: Normal use condition
Transient design situation: Temporary condition, e.g. during execution or repair
Accidental design situation: Exceptional condition, e.g. fire, explosion, impact.
Seismic design situation: Structure subject to seismic events.
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Ultimate Limit State (ULS)
COMBINATION OF ACTIONS FOR PERSISTENT/TRANSIENT DESIGN SITUATION
(EN1990,cl.6.4.3.2)
Persistent and transient design situationEQU Equation 6.10 (Set A)
6.10 Ed=G Gk+Q Qk1 + Q 0,2 Qk2
ActionFavourable
Unfavourable
Permanent (dead,
earth), G0.9 1.1
Variable (imposed,
wind), Q0 1.5
Note: Single source is not applicable for EQU design situation. Different factors can be used in favourable and unfavourable
areas.
Persistent and transient design situationSTR/GEO Equation 6.10, 6.10a & 6.10b (Set B)
6.10
6.10a
6.10b
Ed=G Gk+Q Qk1 + Q 0,2 Qk2
Ed=G Gk+Q0,1 Qk1 + Q 0,2 Qk2
Ed=G Gk+Q Qk1 + Q 0,2 Qk2
ActionFavourable
Unfavourable
Permanent (dead,
earth), G1.0 1.35
Variable (imposed,wind), Q
0 1.5
Note: Single source is applicable for STR/GEO design situation.
Persistent and transient design situationGEO Equation 6.10 (Set C)
6.10 Ed=G Gk+Q Qk1 + Q 0,2 Qk2
ActionFavourable
Unfavourable
Permanent (dead,
earth), G1.0 1.0
Variable (imposed,
wind), Q0 1.3
Note: Single source is applicable for STR/GEO design situation.
Important notes
(EN1990,cl.3.2(2)P)
Approach 2 (CYS NA EN1990,Table.A1.2(B)) should be used for thedesign of the structural members of substructure (i.e. footings, piles,
basement walls, etc.) (CYS NA EN1990,cl. 2.2.3.4).
Actions that cannot exist simultaneously due to physical of functionalreasons should not be considered together in combination.
The use of expression 6.10a and 6.10b lead to a more economicdesign in most circumstances.
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Summary table of partial, combination and reduction factors for the STR and GEO ultimate limit states forbuildings
Expression
Unfavourable Permanent action Unfavourable Variable actions
Self-weight Imposed floor loads Wind loads Snow loads
6.10
G=1.35 Q,1 =1.5 Q,i0,i =1.5x05=0.75 Q,i0,i =1.5x05=0.75
G=1.35 Q,i0,i =1.5x07=1.05 Q,1 =1.5 Q,i0,i =1.5x05=0.75
G=1.35 Q,i0,i =1.5x07=1.05 Q,i0,i =1.5x05=0.75 Q,i =1.5
Less favourable equations 6.10a & 6.10b
6.10a
G=1.35 Q,i0,i =1.5x07=1.05 Q,i0,i =1.5x05=0.75 Q,i0,i =1.5x05=0.75
G=1.35 Q,i0,i =1.5x07=1.05 Q,i0,i =1.5x05=0.75 Q,i0,i =1.5x05=0.75
G=1.35 Q,i0,i =1.5x07=1.05 Q,i0,i =1.5x05=0.75 Q,i0,i =1.5x05=0.75
6.10b
G=0.85*1.35 Q,1 =1.5 Q,i0,i =1.5x05=0.75 Q,i0,i =1.5x05=0.75
G=0.85*1.35 Q,i0,i =1.5x07=1.05 Q,1 =1.5 Q,i0,i =1.5x05=0.75
G=0.85*1.35 Q,i0,i =1.5x07=1.05 Q,i0,i =1.5x05=0.75 Q,i =1.5
Note: Shaded boxes indicate the leading variable action,
Combination (sensitivity) factor,
(CYS NA EN1990:2002, Table A1.1)
Category Specific Use 1 2
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 0.6E 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
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Serviceability Limit State (SLS)
COMBINATION OF ACTIONS FOR SERVICEABILITY LIMIT STATE
(EN1990,cl.6.5.3)
Characteristic combination
Equation 6.14bEd=Gk+Qk,1 + 0 Qk,2
Frequent combination
Equation 6.15bE
d=G
k+
1Q
k,1+
2Q
k,2
Quasi-permanent combination
Equation 6.16bEd=Gk+ 2Qk,1
Characteristic value of variable actions
For each variable action there are four representative values:
1.The characteristic value Qk(determine by insufficient data).
2.The combination value 0Qk(of an action is intended to take account of the
reduced probability of the simultaneous of two or more variable actions).
3. Frequent value 1Qk (exceeded only for a short period of time and is used
primary for the SLS and also the accidental ULS).
4. Quasi-permanent value 2Qk(exceeded for a considerable period of time or
considered as an average loading over time and used for the long-term affects
at the SLS and also accidental and seismic ULS).
INDICATIVE LIMITING VALUES FOR VERTICAL DEFLECTIONS
(Manual of EC0 &EC1, Table D.1)
Serviceability Limit States
Vertical deflections
Serviceability Requirement Characteristic Combination (Expression 6.14bin EC0) wmax
Function and damage to non-
structural elements (e.g.
partition walls claddings etc)
Brittle
-Non-brittleFunction and damage to
structural elements
L/500 to L/360
L/300 to L/200
L/300 to L/200
Serviceability Limit State (SLS)Vertical and Horizontal deformations
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INDICATIVE LIMITING VALUES FOR HORIZONTAL DEFLECTIONS
(Manual of EC0 &EC1, Table D.2)
Serviceability Limit States
Vertical deflections
Serviceability Requirement Characteristic Combination (Expression 6.14bin EC0) wmax
Function and damage to non-
structural elements
Single storey buildings top
of column
-Each storey in a multi-storey
building
-The structure as a whole for
a multi-storey building
uH/300
uH/500 to H/300
uH/500
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Category of use
(EN1991-1-1:2002,Table 6.1)
Category Specific Use Example
A Area for domestic and
residential activities
Rooms in residential buildings and houses bedrooms and wards in
hospitals, bedrooms in hotels and hostels kitchens and toilets
B Office areas
C Areas where people may
congregate (with the
exception of areas
defined under category
A, B, and D1))
C1: Areas with tables, etc. e.g. areas in schools, cafs, restaurants,
dining
halls, reading rooms, receptions.
C2: Areas with fixed seats, e.g. areas in churches, theatres or
cinemas, conference rooms, lecture halls, assembly halls, waiting
rooms, railway waiting rooms.
C3: Areas without obstacles for moving
people, e.g. areas in museums, exhibition rooms, etc. and access
areas in public and administration buildings, hotels, hospitals,railway station forecourts.
C4: Areas with possible physical activities, e.g. dance halls,
gymnastic rooms, stages.C5: Areas susceptible to large crowds, e.g. in buildings for public
events like concert halls, sports halls including stands, terraces and
access areas and railway platforms.
D Shopping areas D1: Areas in general retail shops
D2:Areas in departments stores
Imposed loads
(EN 1991-1-1:2002, Table 6.2)
Category Of loaded areas qk
(kN/m2)
Qk
(kN)
Category A
-Floors
-Stairs
-Balconies
Category B
Category C
-C1
-C2
-C3
-C4
-C5
Category D
-D1
-D2
1.5-2.0
2.0-4.0
2.5-4.0
2.0-3.0
2.0-3.0
3.0-4.03.0-5.0
4.5-5.0
5.0-7.5
4.0-5.0
4.0-5.0
2.0-3.0
2.0-4.0
2.0-3.0
1.5-4.5
3.0-4.0
2.5-7.04.0-7.0
3.5-7.0
3.5-4.5
3.5-7.0
3.5-7.0Imposed load on Roof
(CYS NA EN1991-1-1, Table 6.10)
Sub-category Actions
Imposed load,
qk
(kN/m2) Q (kN)
HRoof (inaccessible except for
normal maintenance and repair) 0.4 1.0
STRUCTURAL LOADS
(EN1991:2002)
Imposed Loads
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Permanent load
(EN 1991-1-1:2002, Table A.1-A.12)
Materials Density,
(kN/m3)
Modulus of
Elasticity, E
kN/mm2
Reinforced Concrete
Steel
Glass
Water
Plastic PTFE
Softwood timber
Hardwood timber
Concrete blockwork
Asphalt
Roof tiles
Soil (Sand)
Soil (Clay)
Insulation boardAluminium
Copper
Cement mortar
ylon
Epoxy resin
Polystyrene
Carbon fibre
Fibre glass
Granite
25
78
25
10
21-22
57
18
22
20
16-18
20-22
327
87-89
19-23
11.516-20
10-13
20
15
26
17-31
210
74
-
0.3-0.6
1012
-
-
5-30
-
-
-69
96
20-31
2-3.520
3-3.3
415
10
40-70
Permanent Loads
Typical unit floor Typical loadings Typical unit floor Typical loadings
Steel floor kN/m2
Self weight of beam 0.25
Self weight of decking 0.10
Self weight of meshing 0.05
Ceiling and services 0.15
Total 0.55
Internal ConcreteFloor kN/m2
Partition (minimum) 1.00
Screed (5-70cm) 1.20-1.80
Raised floor 0.40
Concrete floor (15cm) 3.75
Celling and services 0.15
Total 6.50-7.10
External Concrete Floor kN/m
2
Slabs / paving 0.95
Screed (50cm) 1.20
Asphalt waterproofing 0.45
Concrete floor (15cm) 3.75
Celling and services 0.15
Total 6.50
Metal deck roofing kN/m
2
Live loading: snow/
wind uplift 0.6-1.0
Outer covering, insulation and
metal deck liner 0.30
Purlins-150 deep at 1.5m c/c 0.10
Services 0.10
Total 1.1-1.5
Timber Floor kN/m2
Partition 1.00
Timber boards/plywood 0.15
Timber joist 0.20
Celling and services 0.15
Total 1.50
Timber Flat Roof kN/m2
Asphalt waterproofing 0.45
Timber joist and insulation 0.20
Celling and services 0.15
Total 0.80
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SNOW LOAD(EN1991-1-3)
Snow load on roof for transient design situations
s=iCeCtsk
(EN 1991-1-3Equ.5.1)
Snow load shape coefficients,
(EN1991-1-3, Table 5.2)
Angle of pitch of
roof, a
030 30
60
60
1 0.8 0.8(60-)/30 0
2 0.8+0.8 /30 1.6 -
For monopitch roof use only 1
For pitched roof use 1and2
THERMAL COEFFICIENTS C
(1991-1-32003, cl. 5.2(8))
Ct=1.0
Thermal transmission on the roof
60
60
3 should be less than32 0 0.2+10 h/b
Monopitch roof Pitch roof Cylinder roof
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WIND LOAD(EN1991-1-4)
Fundamental Basic wind velocity, vb,0
(CYS NA EN1991-1-4,Fig.1)
Directional factor
(CYSEN1991-1-4,NA 2.4)
cdir=1.0(Conservative value for all direction)
Season factor
(CYS EN1991-1-4,NA 2.4)
cseason=1.0
Basic wind velocity
(EN1991-1-4, Eq. 4.1)
vb=cdir.cseasonvb,0
BASIC WIND VELOCITY
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STRUCTURAL FACTOR(EN1991-1-4, cl.6.0)
cscd =1.0
Builiding with less than
h15m
Natural frequency
f5Hz
Walls100m high Chimney with circular
cross-sectional area and,
h60m
h6.5diameter
Determination of cscd
Determine of structural factor cscd
Size factor
(EN1991-1-4,Eq.6.2)
It is on the safe side to use
B2=1 kp=3
Calculation of R2
can be found in Annex B of
EN1991-1-4:2005
Dynamic factor
(EN1991-1-4,Eq.6.3)
It is on the safe side to use
B2=1 kp=3
Calculation of R2
can be found in Annex B of
EN1991-1-4:2005
Consider Ignore
Upwind Slope3o
NOYES
TERRAIN OROGRAPHY,
(EN1991-1-4, cl.4.3.3)
Detail calculation of terrain orography
factor can be found in Annex A of
EN1991-1-4:2005
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PEAK VELOCITY PRESSURE
Roughness factor, cr(z)
(EN1991-1-4,Eq.4.3-4.5)
cr(z)=kr . ln(z/z0) for zminzzmax
cr(z)=cr . (zmin) for zzmin
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)=v/vm(z)=kl/co(z)ln(z/z0) for
zminzzmax
Iv(z)=Iv(zmin) for zzmin
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)]0.5 vm2
Terrain category and terrain parameters (EN1991-1-4, Tab.:4.1)
Terrain
category
Description z0 (m) zmin(m)
0Sea, costal area exposed to the open
sea. SEA 0.003 1
ILakes or area with negligiblevegetation 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
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Values of external pressure coefficient for vertical walls of rectangular plan buildings
(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 forcpe,1are 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.
Reference height ze, depending on hand b, and corresponding velocity pressure profile
(EN1991-1-4, Fig. 7.4)
Key for vertical wallsFlat Roof
(EN1991-1-4, Fig.7.5)
Key for vertical wallsMono&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=cscdweAref
EXTERNAL WIND PRESSURE/FORCE ON WALLS
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EXTERNAL WIND PRESSURE/FORCE ON FLAT ROOF
Recommended values of external pressure coefficients for flat roofs
(EN1991-1-4,Tab. 7.2)
Roof type
Zone
F G H I
cpe,10 cpe,1 cpe,10 cpe,1 cpe,10 cpe,1 cpe,10 cpe,1
Sharp eaves -1.8 -2.5 -1.2 -2.0 -.07 -1.2 +0.2
With
Parapets
hp/h=0.025 -1.6 -2.2 -1.1 -1.8 -0.7 -1.2 -0.2
hp/h=0.05 -1.4 -2.0 -0.9 -1.6 -0.7 -1.2 +0.2hp/h=0.10 -1.2 -1.8 -0.8 -1.4 -0.7 -1.2 -0.2
Curved
Eaves
r/h=0.05 -1.0 -1.5 -1.2 -1.8 -0.4 +0.2
r/h=0.10 -0.7 -1.2 -0.8 -1.4 -0.3 -0.2
r/h=0.20 -0.5 -0.8 -0.5 -0.8 -0.3 +0.2
Mansard
Eaves
a=30o
-1.0 -1.5 -1.0 -1.5 -0.3 -0.2
a=45o
-1.2 -1.8 -1.3 -1.9 -0.4 +0.2
a=60o
-1.3 -1.9 -1.3 -1.9 -0.5 -0.2
Note: Values forcpe,1are 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.
Pressure on surface &Wind force (EN1991-1-4, Eq. 5.1&5.5)
we=qp(ze).(cpe +cpi) & Fw=cscdweAref
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Recommended values of external pressure coefficients for monopitch roofs
(EN1991-1-4,Tab. 7.3a)
Pitch
Angle
a
Zone for wind direction =0o
Zone for wind direction =180o
F G H F G H
cpe,10 cpe,1 cpe,10 cpe,10 cpe,1 cpe,10 cpe,10 cpe,1 cpe,10 cpe,1 cpe,10 cpe,1
5o -1.7 -2.5 -1.2 -2.0 -0.6 -1.2 -2.3
-2.5 -1.3 -2.0 -0.8 -1.2+0.0 +0.0 +0.0
15o -0.9 -2.0 -0.8 -1.5 -0.3
-2.5 -2.8 -1.3 -2.0 -0/9 -1.2+0.2 +0.2 +0.2
30o -0.5 -1.5 -0.5 -1.5 -0.2-1.1 -2.3 -0.8 -1.5 -0.8
+0.7 +0.7 +0.4
45o -0.0 -0.0 -0.0
-0.6 -1.3 -0.5 -0.7+0.7 +0.7 +0.6
60o
+0.7 +0.7 +0.7 -0.5 -1.0 -0.5 -0.5
75o
+0.8 +0.8 +0.8 -0.5 -1.0 -0.5 -0.5
Recommended values of external pressure coefficients for monopitch roofs
(EN1991-1-4,Tab. 7.3b)
Pitch
Anglea
Zone for wind direction =90o
Fup Flow G H Icpe,10 cpe,1 cpe,10 cpe,10 cpe,1 cpe,10 cpe,10 cpe,1 cpe,10 cpe,1
5o
-2.1 -2.6 -2.1 -2.4 -1.8 -2.0 -0.6 -1.2 -0.5
15o
-2.4 -2.9 -1.6 -2.4 -1.9 -2.5 -0.8 -1.2 -0.7 -1.2
30o
-2.1 -2.9 -1.3 -2.0 -1.5 -2.0 -1.0 -1.3 -0.8 -1.2
45o
-1.5 -2.4 -1.3 -2.0 -1.4 -2.0 -1.0 -1.3 -0.9 -1.2
60o
-1.2 -2.0 -1.2 -2.0 -1.2 -2.0 -1.0 -1.3 -0.7 -1.2
75o
-1.2 -2.0 -1.2 -2.0 -1.2 -2.0 -1.0 -1.3 -0.5
Note: Values forcpe,1are intended for the design of small elements and fixings with an element of 1m2
or less such
as cladding elements and roofing elements. Values forcpe,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.
EXTERNAL WIND PRESSURE/FORCE ON MONOPITCH ROOF
Pressure on surface &Wind force (EN1991-1-4, Eq. 5.1&5.5)
we=qp(ze).(cpe +cpi) & Fw=cscdweAref
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Recommended values of external pressure coefficients for duopitch roofs(EN1991-1-4,Tab. 7.4a)
Pitch
Anglea
Zone for wind direction =0o
F G H I J
cpe,10 cpe,1 cpe,10 cpe,10 cpe,1 cpe,10 cpe,10 cpe,1 cpe,10 cpe,1
-45o
-0.6 -0.6 -0.8 -0.7 -1.0 -1.5
-30o
-1.1 -2.0 -0.8 -1.5 -0.8 -0.6 -0.8 -1.4
-15o
-2.5 -2.8 -1.3 -2.0 -0.8 -1.2 -0.5 -0.7 -1.2
-5o
-2.3 -2.5 -1.2 -2.0 -0.8 -1.2+0.2 +0.2
-0.6 -0.6
5o
-1.7 -2.5 -1.2 -2.0 -0.6 -1.2-0.6
+0.2
+0.0 +0.0 +0.0 -0.6
15o
-0.9 -2.0 -0.8 -1.5 -0.3 -0.4 -1.0 -1.5
+0.2 +0.2 +0.2 +0.0 +0.0 +0.0
30o
-0.5 -1.5 -0.5 -1.5 -0.2 -0.4 -0.5
+0.7 +0.7 +0.4 +0.0 +0.0
45o
-0.0 -0.0 -0.0 -0.2 -0.3
+0.7 +0.7 +0.6 +0.0 +0.0
60o
+0.7 +0.7 +0.7 -0.2 -0.3
75o
+0.8 +0.8 +0.8 -0.2 -0.3
Recommended values of external pressure coefficients for duopitch roofs
(EN1991-1-4,Tab. 7.4b)
Pitch
Angle a
Zone for wind direction =90o
F G H Icpe,10 cpe,1 cpe,10 cpe,10 cpe,1 cpe,10 cpe,10 cpe,1
-45o
-1.4 -2.0 -1.2 -2.0 -1.0 -1.3 -0.9 -1.2
-30o
-1.5 -2.1 -1.2 -2.0 -1.0 -1.3 -0.9 -1.2
-15o
-1.9 -2.5 -1.2 -2.0 -0.8 -1.2 -0.8 -1.2
-5o
-1.8 -2.5 -1.2 -2.0 -0.7 -1.2 -0.6 -1.2
5o
-1.6 -2.2 -1.2 -2.0 -0.7 -1.2 -0.6
15o
-1.3 -2.0 -1.2 -2.0 -0.6 -1.2 -0.5
30o
-1.1 -1.5 -1.4 -2.0 -0.8 -1.2 -0.5
45o
-1.1 -1.5 -1.4 -2.0 -0.9 -1.2 -0.5
60o
-1.1 -1.5 -1.4 -2.0 -0.8 -1.2 -0.5
75o -1.1 -1.5 -1.4 -2.0 -0.8 -1.2 -0.5
EXTERNAL WIND PRESSURE/FORCE ON DUOPITCH ROOF
Pressure on surface &Wind force (EN1991-1-4, Eq. 5.1&5.5)
we=qp(ze).(cpe +cpi) & Fw=cscdweAref