wind load on pv system

WIND LOAD CALCULATION BASE ON EN1991-4PV SYSTEM REV.ACalculated by:V.N.Reviewed by: V.N.

WIND LOAD ON SURFACES (WALLS) EC-1-4

Assumptions:

Assume that structural factor cscd is equal to 1 (EN1991-1-4,cl.6.0).1.Assume that lack of correlation of wind pressure between the windward and leeward side is2.taken equal to 1 (EN1991-1-4,cl.7.2.2(3)).

Building data

Type of structure: PHOTOVOLTAIC SYSTEM

Total length of strucutre: d 5800mm:=

Width of structure: b 2690mm:=

Height of structure: h 3400mm:=

Spacing frame to frame: ss 2900mm:=

No of frames: No_frames 3:=

Basic values

110


Fundamental basic wind velocity(CYS NA EN1991-1-4,fig.1): vb.o 30m s 1-

:=

Season factor(EN1991-1-4, NA 2.4/cl.4.2(2)): cseason 1.0:=

Directional factor(EN1991-1-4, NA 2.4/cl.4.2(2)): cdir 1.0:=

Basic wind velocity(EN1991-1-4,cl.4.2(2)): vb cdir cseason vb.o 30 m s 1-

=:=

ρ 1.25kg m 3-:=Density of air:

Reference mean velocity pressure(EN1991-1-4,cl.4.5(1)): qb ρ

vb2

2 562.5 N m 2-

=:=

Orography

Orography factor(EN1991-1-4,cl.4.3.3(2): co 1.0:=

Obstruction height(EN1991-1-4,Annex A.5): have 15m:=

Distance to the nearest adjacement building(EN1991-1-4,Annex A.5):

x 500m:=

Displacement height(EN1991-1-4,Annex A.5):

hdis min 0.8 have 0.6h, ( ) x 2 haveif

min 1.2 have 0.2 x- 0.6 h, ( ) 2 have x< 6 have<if

0 x 6 haveif

0 m=:=

210


Terrain category(EN1991-1-4,table 4.1):

Terrain_category "I":=

Roughness length,z0(EN1991-1-4,table 4.1):

zo 0.003m Terrain_category "0"=if

0.01m Terrain_category "I"=if

0.05m Terrain_category "II"=if

0.3m Terrain_category "III"=if

1.0m Terrain_category "IV"=if

10 mm=:=

Roughness length,zmin(EN1991-1-4,table 4.1): zmin 1m Terrain_category "0"=if

1m Terrain_category "I"=if

2m Terrain_category "II"=if

5m Terrain_category "III"=if

10m Terrain_category "IV"=if

1 103 mm=:=

Peak wind velocity pressure

Reference height(EN1991-4,figure 7.4)

ze h 3.4 m=:=

Maximum height(EN1991-1-4,cl.4.3.2(1)): zmax 200m:=

Factor, z0,II(EN1991-4,table 4.1)

z0.II 50mm:=

310


Terrain factor(EN1991-1-4,cl.4.3.2(1)): kr 0.19

zoz0.II

0.07

0.17=:=

Roughness factor(EN1991-1-4,cl.4.3.2(1)): cr kr ln

zminzo

0.782=:=

Mean wind velocity(EN1991-1-4,cl.4.3.1(1)): vm cr co vb 23.453 m s 1-

=:=

Turbulence factorEN1991-1-4,cl.4.4(1)): kI 1.0:=

Turbulence intensityEN1991-1-4,cl.4.4(1)):

IvkI

co lnzmin

zo

0.217=:=

Peak velocity pressureEN1991-1-4,cl.4.5(1)):: qp 1 7 Iv+( ) 0.5 ρ vm

2 0.866 kN m 2-

=:=

Structural factor c s c d

Assume structural factor is 1(for buildings with a height less than 15m)(EN1991-1-4,cl.6.2(1)):

cs.d 1:=

Wind pressure coefficients for canopy roof structure (EN1991-1-4,cl.7.3)

There is no blockage beneath the canopy, however the values of cp.net and cf have been takenusing the ϕ=0 for minimum values and ϕ=all for maximum values.

The overall force coefficient represent the resulting force. The net pressure coefficient representsthe maximum local pressure for all wind directions and have been used in the design of roofingelements and fixing.

410


Table 1: cf values for monopitch canopies (EN1991-1-4,Table 7.6)

Wind pressures for modules 30deg

Wind suction φ=0 (max.) - Upward acting wind action

External pressure coefficient for zone A(EN1991-1-4,Table 7.6): cp.net.A.up.30 3.0-:=

Wind pressure for zone A(EN1991-1-4,Eq.5.1)

we.A.up.30 qp cp.net.A.up.30 2.599- kN m 2-=:=

510


External pressure coefficient for zone B(EN1991-1-4,Table 7.6): cp.net.B.up.30 3.8-:=

Wind pressure for zone B(EN1991-1-4,Eq.5.1) we.B.up.30 qp cp.net.B.up.30 3.292- kN m 2-

=:=

Wind suction φ=0 (max.) - Downward acting wind action

External pressure coefficient for zone A(EN1991-1-4,Table 7.6): cp.net.A.do.30 2.2:=

Wind pressure for zone A(EN1991-1-4,Eq.5.1)

we.A.do.30 qp cp.net.A.do.30 1.906 kN m 2-=:=

External pressure coefficient for zone B(EN1991-1-4,Table 7.6): cp.net.B.do.30 3.2:=

Wind pressure for zone B(EN1991-1-4,Eq.5.1)

we.B.do.30 qp cp.net.B.do.30 2.772 kN m 2-=:=

Figure 2: Location of the centre of force for monopitch canopies (EN1991-1-4,Figure 7.16)

Effective area between two supports Aref.mid b ss 7.801 m2

=:=

Effective area of edges supports Aref.edg

Aref.mid2

3.9 m2=:=

610


Wind loads for modules 30deg

Overall factor coefficient for upward acting wind action(EN1991-1-4,Table 7.6):

cf.up.30 1.8-:=

Overall factor coefficient for upward acting wind action(EN1991-1-4,Table 7.6):

cf.do.30 1.2:=

Downward acting wind forceat edge frame(EN1991-1-4,Eq.5.3)

Fw.ed.do.30 cs.d cf.do.30 qp Aref.edg 4.055 kN=:=

Downward acting wind forceat middle frame(EN1991-1-4,Eq.5.3)

Fw.mid.do.30 cs.d cf.do.30 qp Aref.mid 8.11 kN=:=

Upward acting wind forceat edge frame(EN1991-1-4,Eq.5.3)

Fw.ed.up.30 cs.d cf.up.30 qp Aref.edg 6.082- kN=:=

Upward acting wind forceat middle frame(EN1991-1-4,Eq.5.3)

Fw.mid.up.30 cs.d cf.up.30 qp Aref.mid 12.164- kN=:=

No. 4 Load cases for wind force on structure for inclination of 30deg (edge members)

b4

0.672 m=Fw.ed.do.30 4.055 kN= Fw.ed.do.30 4.055 kN= b

40.672 m=

Fw.ed.up.30 6.082- kN= Fw.ed.up.30 6.082- kN=

b4

0.672 m=b4

0.672 m=

710


No. 4 Load cases for wind force on structure for inclination of 30deg (middle members)

b4

0.672 m=Fw.mid.do.30 8.11 kN= Fw.mid.do.30 8.11 kN= b

40.672 m=

Fw.mid.up.30 12.164- kN= Fw.mid.up.30 12.164- kN=

b4

0.672 m=b4

0.672 m=

Frictional force on structure (EN1991-1-4,cl.7.5)

Frictional force should be considered to the roof canopy structures - see EN1991-1-4,cl.7.3.(7)

Surface type(EN1991-1-4,Table 7.10): Surface_type "Very rough":=

Frictional coefficient(EN1991-1-4,Table 7.10): cfr 0.01 Surface_type "Smooth"=if

0.02 Surface_type "Rough"=if

0.04 Surface_type "Very rough"=if

0.04=:=

Reference area: Afr 2 ss b 15.602 m2=:=

Frictional force per frame(EN1991-1-4,Eq.5.7): Ffr cfr qp

Afrss

0.186 kN m 1-=:=

810


910


1010

wind load on pv system

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