Post on 14-Apr-2018
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Laster enligt Eurocode
Byggnadskonstruktion AE2, ht 2009
Appendix A: Combination of loads
Appendix B: Imposed loadsAppendix C: Snow loads
Appendix D: Wind loads
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Appendix A: Combination of loads
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September 2009
Appendix A: Combination of loads
Fundamental combination, ULS
Characteristic combination, SLS
Quasi-permanent combination, SLS
Partial safety factors ffor permanentand variable loads (ULS and SLS)
--1.01.0Accidental
01.0
1.01.0
01.5
1.01.35
Fundamental
favourableunfavourable
Variable
action q
Permanent
action g
Variable
action q
Permanent
action g
SLSULSDesign
situation
ACTION 0 1 2
Imposed load
Categ. A, B
Categ. C, DCateg. E
0.7
0.71.0
0.5
0.70.9
0.3
0.60.8
Wind load 0.3 0.2 0
Snow loadsk 3 kN/m
2
2.0 sk < 3.0 kN/m2
1.0 sk < 2.0 kN/m2
0.80.70.6
0.60.40.3
0.20.20.1
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Appendix B: Imposed loads
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Appendix B: Imposed loads
=
Imposed loads (ULS)
A = 0.5 + 10/A[m2] 1for categories A D
(0
= 0.7)
Imposed loads qkmay be reduced
(for categories A-E) by
applying a reduction
factor A
Imposed loads qkfrom more than two
storeys may be reduced
(for categories A-E) by
applying a reduction
factor n
The reduction factors A and n must not be combined. For the design of floors and roofsA can be used. For structural members that carry imposed loads from several stories ncan be taken.
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Appendix C: Snow loads EN 1991-1-3:2003 (BFS 2008:19)
Characteristic snow values sk forsome Swedish town (urban) districts
Alingss 2.0
Arvika 2.5
Bors 2.0-2.5
Borlnge 3.0
Falun 2.5-3.0
Gllivare 3.0-4.5
Gteborg 1.5
Halmstad 1.5-2.5
Haparanda 3.0
Hofors 2.5
Hrnsand 3.5
Jokkmokk 3.0-4.5
Jnkping 2.5-3.0Karlstad 2.5
Kiruna 2.5-4.5
Kunglv/Kungsbaka
1.5
Landskrona 1.0
Lule 3.0
Lund 1.5
Malm 1.0
Stockholm 2.0
rebro 2.5
stersund 2.0-3.5
The upper values of the intervals apply to terrain in high places.
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Appendix C: Characteristic value of snow load:
S = i Ce Ct sk s =i sk
sk characteristic value of snow on the ground,
Ce exposure coefficient, should be taken as 1,0 unless otherwise specified for different
topographies
Ct thermal coefficient, high thermal transmittance (> 1 W/m2K), in particular for someglass covered roofs, because of melting caused by heat loss. For all other cases: Ct= 1,0
i shape coefficients
Monopitch roofs Pitched roofs
Multi-span roofs
0 15 30 45 60
0.4
0
0.8
1.6
1.2
i
()
0 15 30 45 60
0.4
0
0.8
1.6
1.2
i
)
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Appendix C
Roofs abutting to taller construction works
1 = 0,8 (assuming the lower roof is flat)
2 = S+W
Shape coefficients
2 = S+ W
S
due to sliding of snow from the upper roof
W due to wind
For 15 S = 0
> 15 S = 0.5 () b/ls
w = (b1 + b2)/2h h/sk
where: is the weight density of snow, which may be taken as 2 kN/m3. 0.8 w 4
The drift length: lS = 2h. The recommended restriction is 5 lS 15 m.
(In Sweden 5 lS 10 m)
b
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Appendix C
Drift against a wall
Shape coefficients
Drifting at projections and obstructions
1 = 0,8 2 = h/sk
With the restriction: 0,8 2 2,0The drift length: lS = 2h
With the restriction is 5 lS 10 m
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Appendix D1:Wind loads prEN 1991-1-4
Wind forces
The wind forces for the whole structure or a structural component should be determined: by calculating forces using force coefficients or by calculating forces from surface pressuresThe wind force Fw acting on a structure or a structural component may be determineddirectly by using:
Fw= cs cdcfqp(ze)Aref
where cs cdassume to be 1 and cf is the force coefficient for the structure or structuralelement.
Wind pressure on surfaces
Wind pressure combination of external (we) and internal (wi) pressures wnet = we wi
External pressure: pecezpqew = Internal pressure: pii cizpqw =
where: cpe and cpi are the pressure coefficients for the external and internal pressurerespectively
The net pressure on a wall, roof or element is the difference between the pressures on theopposite surfaces taking due account of their signs. Pressure, directed towards the surfaceis taken as positive, and suction, directed away from the surface as negative. Examplesare given in Figure 5.1.
Pressure on surfaces
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Appendix D2
ULS: ( )b
qzeczpq = )( 2
21
bv
bq =
The recommended value for is 1.25 kg/m3. Reference wind speed vb in Sweden, see Appendix
D2Terrain categories and terrain parameter
Illustration of the exposure factor ce(z) for c0=1.0, kr=1.0
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Appendix D3.
Reference wind speed vb in [m/s] for Sweden
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Appendix D4
Internal pressure coefficients
For a building with a dominant face the internal pressure should be taken as a fractionof the external pressure at the openings of the dominant face. The values given by Eq (7.2)and (7.3) should be used.When the area of the openings at the dominant face is twice the area of the openings inthe remaining faces,
cpi = 0,75 cpe (7.2)When the area of the openings at the dominant face is at least 3 times the area of theopenings in the remaining faces,
cpi = 0,9 cpe (7.3)where cpe is the value for the external pressure coefficient at the openings in the dominantface.
For buildings without a dominant face, the internal pressure coefficient cpi should be
determined from Figure 7.13, and is a function of the ratio of the height and the depth ofthe building, h/d, and the opening ratio for each wind direction , which should bedetermined from Eq (7.4).
Figure 7.13 Internal pressure coefficients for uniformly distributed openings
=
openingsallofarea
0,0-ornegativeiscwhereopeningsofarea pe
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Appendix D5
Reference height, ze, depending on h and b, and corresponding velocity pressure profile
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Appendix D6Pressure coefficients on the external walls
The values ofcpe,10and cpe,1 may be given in the NA. The recommended values are givenin Table below, depending on the ratio h/d. For intermediate values ofh/d, linear
interpolation may be applied. The values of Table also apply to walls of buildings withinclined roofs, such as duopitch and monopitch roofs.
For intermediate values ofh/d, linear interpolation may be applied.
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Appendix D7Flat roofs
Flat roofs are defined as having a slope () of 5< < 5
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Appendix D8Flat roofs
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Appendix D9 Monopitch roofs
The roof, including protruding parts, should be divided into zones as shown in Figurebelow. The reference height ze should be taken equal to h.
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Appendix D10
Monopitch roofs
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Appendix D11
Duopitch roofs
The roof, including protruding parts, should be divided into zones as shown in Figurebelow. The reference height ze should be taken equal to h.
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Appendix D12
Duopitch roofs
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Appendix D13 Canopy roof
A canopy roof is defined as the roof of a structure that does not have permanentwalls, such as petrol stations, dutch barns, etc.
The degree of blockage under a canopy roof is shown in Figure 7.15. It depends onthe blockage , which is the ratio of the area of feasible, actual obstructions under thecanopy divided by the cross sectional area under the canopy, both areas being normal tothe wind direction. = 0 represents an empty canopy, and= 1 represents the canopy
fully blocked with contents to the down wind eaves only (this is not a closed building).The overall force coefficients, cf, and net pressure coefficients cp,net, given in Tables
7.6 to 7.8 for= 0 and= 1 take account of the combined effect of wind acting on boththe upper and lower surfaces of the canopies for all wind directions. Intermediate valuesmay be found by linear interpolation.
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Appendix D14 Duopitch canopy
Duopitch canopy (Table 7.7) the centre of pressure should be taken at the centre of eachslope (Figure 7.17). In addition, a duopitch canopy should be able to support one pitch withthe maximum or minimum load, the other pitch being unloaded.
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Appendix D15
+ values indicate a net downward acting wind action; - values represent a net upward
acting wind action