Pages From Vimp-comparison of Codes-Appendix c

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APPENDIX CCALCULATIONS USING BRFFISH STANDARD

This appendix contains the wind pressure calculations using the British standard. Windpressure calculations for the 160 ft building follow the wind pressure calculations for thelow building . The references cited herein regarding sections, tables, and figures, belong tothe British standard.

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c . l L ow Bu i ld ingThe basic wind speed used in the British standard is a mean houriy wind speed,

measu red at 10 m height in open flat terrain with an annual probability of occurrence of0.02. The equivalent m ean houriy wind speed for the 110 mph (49 m/s) 3-second gustwind speed used in the American standard is 72.7 mph (32.4 m/s). The equivalentsuburban terrain category of exposure B used in the American standard is town categoryin the British standard. The basic wind speed, Vb of 32.4 m/s is modified by followingfour factors to give the site wind speed Vs.Altitude factor Sa: a value of 1.00 is assumed based on the following conditions

(a) the building falls outside the local topographic zone(b) the site altitude A* is not defined (section 5.2.2.2)

Direction factor Sa: l.(X), since the building orientation is ignored (section 5.2.3)

Seasonal factor Ss: 1.00, since the present building is a permanent construction(section 5.2.4.2).

Probability factor Sp: l.(X), since the annual probability is not changed from the standardvalue of 0.02 (section 5.2.5.1).

From the above factors the site wind speed is calculated asVs = (32.4)(1.00)(1.00)(1.00)(1.00) = 32.4 m/s.

The effective wind speed Vc is given by the equation:Ve = Vs(Sb)

from Table 4, for town terrain Sb is 1.352 with effective height He = 4.57 m and 64.4 km(40 miles) away from sea.

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Ve = (32 .4)(1.352) = 43.8 m/sThe velocity or dynamic pressure is given by the equation:

q, = 0.613V, = 0.613(43.8)^ = 1176 pa = 24.6 psfDesign Pressures on the Main W ind-Force Resisting System:

The design pressure on the main wind-force resisting system is given by the equation:P = q-s[(CpeCa)]

External pressure coefficients:windw ard wall: 0.6 for D/H = 60 ft / 15 ft = 4, where D is the dimension of

the building parallel to wind duection and H is the height of thestmcture.

leeward waU: -0.1 for D/H = 60 ft / 15 ft = 4roof: -2.0 for zone A

-1.4 for zone B-0.7 for Z one C0.2 for zone D

Size effect factor for extemal pressures:windward and leeward walls: 0.84 for diagonal dimension of 30.84 m of windward

and leeward wall (Figure 4)roofs: 0.82 for diagonal dimension of 35.56 m (Figure 4).

Intemal pressure coefficients: values of -0.3 or -1-0.2 given in clause 9.1.2 is an appropriatechoice for the present building.

Size effect factor for internal pressure: diagonal dimension 'a' for the intemal pressure is

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a = 10 [y (internal volume of room)]= 137m

from Figu re 4 for a = 137 m, Ca = 0.71Design wind pressure for the windward wall is

p = 24.6 [(0.6)(0.84)] = 12.4 psfdesign wind pressure for the leeward wall is

p = 24.6 [(-0.1)(0.84)] =-2.1 psfdesign wind pressure for the roof

zone A p = 24.6 [(-2.0)(0.82) - (0.2)(0.71)] = -43.8 psfzone B p = 24.6 [(-1.4)(0.82) - (0.2)(0.71)] = -31.9 psfzone C p = 24.6 [(-0.7)(0.82) - (0.2)(0.71)] = -17.6 psfzone D p = 24.6 [(-0.2)(0.82) - (0.2)(0.71)] = -7.5 psf and

p = 24.6 [(0.2)(0.82) -i- (0.3)(0.71)] = 9.3 p sfBase shear and overtuming mom ent for the entire building:Base shear:

= [12.4(15)(100) + 2.1(15)(100)] = 21.75 kipsOvertuming moment:

= [12.4(15)(100)(7.5) + 31.7(3.0)(100)(58.5) + 17.6(12)(100)(51) --7.5(45)(100)(22.5) + 2.1(15)(100)(7.5)] / 1000 = 2555.9 ft-kips

Roof uphft:= 100[31.9(3) + 17.6(12) + 7.5(45)] / 1000 = 64.4 kips

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Design W ind P ressures for Com ponents and Claddings:The design pressure for components and claddings is given by the equation

P = q . s [ (Cpe Ca) - (CpiCa) ]

the internal pressure coefficient is the same as used for the design of the main wind forceresisting system . The extem al pressure coefficients are tabulated in Table C. 1, along withsize effect factor. The uibu tary areas considered in the computations involving Americanstandard are 5 sqft (0.465 m^) and 100 sqft (9.3 m^). The diagonal dimension for the1.525 m X 6.1 m cladding area is 6.3 m, which from Figure 4 gives a size effect factor Caof 0.98. For fasteners, the diagonal dimension for 0.305 m x 1.525 m area is 1.55 m,which gives a size effect factor of 1.00. The calculated values of design pressures aretabulated in Table C.2.Sample calculation for purhns and grits of tributary area 100 sqft:

Positive pressure on wall middle surface:p = 24.6 [(0.6)(0.98) + (0.3)(0.71)] = 19.7 psf

Nega tive pressure on roof eaves:p = 24.6 [(-2.0)(0.98) - (0.2)(0.71)] = -51.7 p sf

Sam ple calculation for fasteners of tributary area 5 sqft:Positive pressure on wall middle surface:

p = 24.6 [(0.6)(1.00) + (0.3)(0.71)] = 20.0 psfNegative pressure on roof corners:

p = 24.6 [(-2.0)(1.00) - (0.2)(0.71)] = -52.7 p sf

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Table C. 1. Extemal pressure coefficients for components and claddingsBuilding Surface

roof middle surfaceroof eaves

roof corners

waU middle surfacewall comers

Tributary Area5 sqft

+ Cpe(Ca)-

-

-

0.6(1.0)0.6(1.0)

-Cpe(Ca)-0.7(1.0)-1.4(1.0)-2.0(1.0)

-0.8(1.0)-1.3(1.0)


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c .2 160 ft BuildingThe basic wind speed Vb, used with the compuUitions involving the low building, and

the factors modifying the basic wind speed to site wind speed V,, are applicable for thefollowing comp utations. The site wind speed Vs is

Vs = (32.4)(1.00)(1.00)(1.00)(1.00) = 32.4 m/s.Section 5.4.2.2 states tha t, the building should be considered as one part if the building

height H is less than or equal to crosswind breadth B. The building should be consideredtwo parts if building height H is greater than B, but less than 2B. The present building isconside red as one part when wind is parahel to the 30.5 m side and is considered twoparts when wind is normal to the 30.5 m side.Wind Parallel to the 30.5 m S ide:

Effective wind speed Ve is given by the equationVe = Vs(Sb)

The terrain and building factor Sb, for town terrain, from Tab le 4, based on He = 48.89m and d istance from sea = 64.4 km (40 miles) is 1.98. Hence, effective wind speed is

Vc = (32.4)(1.98) = 64.15 m /sThe velocity pressure is given by the equation

q^ = 0.613V,' = 0.613(64.15)2 = 2522.6 pa = 52.7 psfDesign Pressures on the Main Wind-Force Resisting System:

The design pressure on the main wind-force resisting system is given by the equationp = q.s[(CpcCa)]

External pressure coefficients, Cpc:134


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Windward wall: 0.8 for D/H = 100 ft/160 ft = 0.62, where D is thedimension of the building parallel to wind direction with height H(from Table 5)

Leeward wall: -0.3 for D/H = 100 ft/160 ft = 0.62, (from Table 5)Size effect factor, Ca:

From Figu re 4, for the windw ard and leeward walls, size effect factor is taken as 0.75for diagonal dimension 78.17 m.

Design windward wall pressure isp = 52.7[(0.8)(0.75)]= 31.6 psf

Design leeward wall pressure isp = 52.7[(-0.3)(0.75)] = -11.9 psf

Base shear:= [200(31.6(160) + 11.9(160))] /1000 = 1392 kips

Overtuming mom ent:= [200(31.6(160)(80) + 11.9 (160)(80) -f- 20(90)(58.5) + 80(40)(35.1))] / 1000= 15.5x10' f t -kips

Roof uphft:= 200 [58.5(20) + 35.1(80)] / 1000 = 795.6 kips

Design pressures on Components and Claddings:Design pressures for the components and claddings are given by the equation

P = q . s [ (Cpe Ca) - (CpiCa) ]

Th e extemal pressure coefficients for windw ard and leeward walls along with the size

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effect factors are shown in Table C.3.Size effect factor:

For wall panels of Uibutary area 1.676 m (5.5 ft) x 1.524 (5 fO, the diagonal dimensionis 2.265 m , which gives a size effect factor of 1.00 from Figure 4. For wall mullions ofU-ibutary area 3.353 m (11 ft) x 1.524 m (5 ft), with a diagonal dimension of 3.683 m sizeeffect factor is 1.00. The diagonal dimensions of areas of components and claddings onthe roof are 3.063 m and 4.31 m, which also gives size effect factor as 1.00.Internal pressure coefficients:

Section 9.1.2 indicates that for the present enclosed building, the intemal pressurecoefficient be taken as -0.3 or 0.2; whichever gives larger net pressure coefficient acrossthe wall.Size effect factor:

For in tema l pressure coefficient the diagonal dimension for obtaining size effect factorIS

a = 10 [y (intemal volume of story)]= 1 0 [ ^ ( 3 0 . 5 X 61 X 3.352) = 184 m

the size effect factor for a diagona l dimension of 184 m is 0.66. The calculated values ofdesign pressures for components and claddings are given in Table C.4 and Table C.5.Wind parallel to 60.0 m Side:

Since the building height H is greater than the crosswind breadth B, the building isdivided into two parts. Effective wind speed Ve is given by the equation

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Table C.3. Extemal pressureBuilding Surface

1 (roof middle surface)

2 (roof edges)

3 (roof corners)

4 (wall middle area)

5 (wall edges)

coefficients for components and claddingsTributary Area, sqft

1010010

10010

10028552855

Pressure Coefficients-i-Cpe(Ca)

-

-

-

-

-

-

0.8(1.0)0.8(1.0)0.8(1.0)0.8(1.0)

-Cpe(Ca)-0.7(1.0)-0.7(1.0)-1.4(1.0)-1.4(1.0)-2.0(1.0)-2.0(1.0)-0.8(1.0)-0.8(1.0)-1.3(1.0)-1.3(1.0)

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Tab le C.4. Design pressures for zone 1 (roof middle surface),zone 2 (roof edges), and zone 3 (roof comers)

Building Surface

1, roof middle surface

2, roof edges

3, roof corners

TribuUiry Area,sqft10

10010

10010

100

Positive DesignPressures, psf

-

-

-

-

-

-

Negative DesignPressures, psf

-43.8-43.8-80.7-80.7

-112.4-112.4

Tab le C.5 . Design Pressures for Zone 4 (wall middle surface) and Zone 5 (wall edges)Height Above

Ground, ft

0 - 15305080120160

Design PressuresZone 4 (wall middle surface)


52.6

52.652.652.652.652.6

-49.1

-49.1-49.1-49.1-49.1-49.1


52.6

52.652.652.652.652.6

-49.1

-49.1-49.1-49.1-49.1-49.1

Design PressuresZone 5 (wall edges)

TributaryArea 28 sqft52.6

52.652.652.652.652.6

-75.5

-75.5-75.5-75.5-75.5-75.5


52.6

52.652.652.652.652.6

-75.5

-75.5-75.5-75.5-75.5-75.5

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Ve = Vs(Sb)For part 1, the terrain and building factor Sb is 1.895 with effective height He = 30.5 m and64.4 km (40 miles) away from the sea. For part 2, Sb is 1.980 for H , = 48.89 m and 64.4km (40 miles) away from the sea.Effective wind speed Ve, is 61.4 m/s for part 1 and is 64.15 m /s for part 2.Design Pressures on the Main Wind-Force R esisting system:

Design pressures for the main wind force resisting system is given by the equationP = q.s[(CpeCa)]

Velocity pressure is given by the equationq,= 0.613V,'

for part 1 qs = 48.3 psf and for part 2 qs = 52.7 psfExtemal pressure coefficients for part 1:

windward waU: 0.733 for D/H = 200 ft/100 ft = 2leeward waU: -0.233 for D/H = 2

Size effect factor:From Figu re 4 for diagonal dimension of 43.13 the size effect factor Ca is 0.80

Design windward wall pressure is p = 48.3[(0.733)(0.80)] = 28.3Design leeward wall pressure is

p = 48.3[(-0.233)(0.80 )] = -9.0 psfExtemal pressure coefficients for Part 2:

windw ard wall: 0.78 for D/H = 200 ft/100 ft = 1.247 from Table 5leeward wall: -0.28 for D/H = 1.247

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Size effect factor:For the loaded area of Part 2 the diagonal dimension is 35.61 m, which gives a size

effect factor of 0.82.Design windward wall pressure is

p = 52.7[(0.78)(0.82)] = 33.7 psfDesign leeward wall pressure is

p = 52.7[(-0.28)(0.82)]=-12.1 psfBase shear and overturning moment for the entire building:Base shear:

= [100(28.3(100) + 33.7(60) -f- 9.0(100) + 12.1(60))] /1000 = 647.8 kipsOvertuming mom ent:

= [100((28 .3 + 9.0)(100)(50) -f- (33.7 + 12.1)(60)(130) + 10(195)(57.9) +40(170)(35.1) + 150(75)(15.1))] / 1000 = 10.7 x lO' ft-kips

Roof uplift:= 100[57.9(10) + 35.1(40) + 15.1(150)] /10 0 0 = 424.8 kips

Design Pressure on Components and Claddings:Design pressures on components and claddings is given by the equation

P = q s [ ( C p c C a ) - ( C p i C a ) ]

The extem al p ressure coefficients, along with the size effect factor, are tabulated inTable C.6. Velocity pressure is equal to 52.7 psf

Th e internal pressure coefficients are -0.3 or 0.2; whichever gives the larger netpressure coefficient across the wall. The size effect factor used with the internal pressure

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Tab le C.6. Extemal pressure coefficients for components and claddingsBuilding Surface

1 (roof middle surface)

2 (roof edges)

3 (roof corners)

4 (wall middle area)

5 (wall edges)

Tributary Area, sqft

1010010

100

1010028552855

Pressure Coefficients-i-Cpe(Ca)

-

-

-

-

-

-

0.78(1.0)0.78(1.0)0.78(1.0)

0.78(1.0)

-Cpe(Ca)-0.7(1.0)-0.7(1.0)-1.4(1.0)-1.4(1.0)-2.0(1.0)-2.0(1.0)

-0.78(1.0)-0.78(1.0)-1.3(1.0)-1.3(1.0)

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coefficient is 0.66. The size effect factor Ca is 1.00 for waU panels of tributary area 2.6m', waU mullions of tribuUiry area 5.12 m^, and for roof tributary areas of 0.93 m' and 9.3m^. The calculated values of design pressures for components and claddings are tabulatedin Table C.7 and Table C.8.

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Table C.7. Design pressures for zone 1 (roof middle surface),zone 2 (roof edges), and zone 3 (roof comers)

Building Surface

1, roof middle surface

2, roof edges

3, roof corners

TribuUiry Area,sqft10

10010

10010

100

Positive DesignPressures, psf

-

-

-

-

-

-

Negative DesignPressures, psf

-43.8-43.8-80.7-80.7

-112.4-112.4

Table C.8. Design pressures for zone 4 (wall middle surface) and zone 5 (wall edges)Height Above

Ground, ft

0 - 1 5305080

120160

Design PressuresZone 4 (wall middle surface)


51.551.551.551.551.551.5

51.551.551.551.551.551.5


51.551.551.551.551.551.5

51.551.551.551.551.551.5

Design PressuresZone 5 (wall edges)

TributaryArea 28 sqft51.551.551.551.551.551.5

-75.5-75.5-75.5-75.5-75.5-75.5


51.551.551.551.551.551.5

-75.5-75.5-75.5-75.5-75.5-75.5

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APPENDIX DCALCULATIONS USING CANADIAN STANDARD

This appendix contains the wind pressure calculations using the Canadian standard.Wind pressure calcu lations for the 160 ft building follow the wind pressure calculations forthe low build ing. The references cited herein regarding sections, tables, and figures,belong to the Canadian standard.

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Pages From Vimp-comparison of Codes-Appendix c