buena

1. 162162
Section 1608Section 1608 -- Wind LoadsWind Loads
nn Wind SpeedWind Speed
nn ExposureExposure
nn TopographyTopography
nn Return PeriodReturn Period
nn Methods & ProceduresMethods & Procedures
nn ExamplesExamples

2. 163163
Basic Wind SpeedsBasic Wind Speeds
50 Year Return Period50 Year Return Period

3. 164164
33--Second Gust VelocitiesSecond Gust Velocities
50 Year Return Period50 Year Return Period

4. 165165
Wind VelocityWind Velocity
nn Basic Wind Speed (70 mph)Basic Wind Speed (70 mph)
•• Fixed distance/Variable timeFixed distance/Variable time
•• Average Wind SpeedAverage Wind Speed
nn 33--Second Gust Wind Speed (90 mph)Second Gust Wind Speed (90 mph)
•• Variable distance/Fixed timeVariable distance/Fixed time
•• Gust Portion of Wind ProfileGust Portion of Wind Profile
•• National Weather Service MeasurementsNational Weather Service Measurements
•• News Media ReportNews Media Report
•• Includes Hurricane I FactorIncludes Hurricane I Factor

5. 166166
Exposure DefinitionsExposure Definitions
nn Exposure AExposure A--Deleted due to variabilityDeleted due to variability
nn Exposure BExposure B--Urban & Dense SuburbanUrban & Dense Suburban
•• 2630 Ft or 10H Continuous Roughness2630 Ft or 10H Continuous Roughness
•• 60% to 80% of all buildings60% to 80% of all buildings
nn Exposure CExposure C--Open TerrainOpen Terrain
nn Exposure DExposure D--Shorelines, flats, lakesShorelines, flats, lakes
•• Open Water >1 MileOpen Water >1 Mile

6. 167167
Wind Load ExposureWind Load Exposure
Exposure A Exposure B Exposure C & D

7. 168168
ExposureExposure--RoughnessRoughness
Exposure B

8. 169169
Topographic EffectsTopographic Effects
Kzt=(1+K1*K2*K3)2
K1=Feature Shape
K2=Location from Crest
K3=Building Height

9. 170170
Wind LoadWind Load--Return PeriodReturn Period

10. 171171
IBC 2003 MethodsIBC 2003 Methods
nn Section 6 ASCE 7Section 6 ASCE 7
•• Exceptions:Exceptions:
nn Simplified MethodSimplified Method
nn SBCCI (R2 & R3 Buildings)SBCCI (R2 & R3 Buildings)
nn AF & PA (1 & 2 Family Residences)AF & PA (1 & 2 Family Residences)
nn NAAMM (Flagpoles)NAAMM (Flagpoles)
nn TIA/EIA (Antenna)TIA/EIA (Antenna)

11. 172172
MethodsMethods
nn Method 1Method 1--Simplified ProcedureSimplified Procedure
nn Method 2Method 2--AnalyticalAnalytical
•• RigidRigid
nn Less than 60 FeetLess than 60 Feet
nn All buildingsAll buildings
•• FlexibleFlexible
nn Gust FactorGust Factor
nn Method 3Method 3--Wind TunnelWind Tunnel

12. 173173
IBC 2003/ASCE 7IBC 2003/ASCE 7
nn Method 1Method 1--Simplified ProcedureSimplified Procedure
•• ConditionsConditions
•• ProcedureProcedure
•• DeterminationDetermination
nn MWRS TableMWRS Table
nn Components & Cladding TableComponents & Cladding Table

13. 174174
Method 1Method 1--ConditionsConditions
nn Simple DiaphragmSimple Diaphragm
nn Flat RoofFlat Roof
nn <60 ft Height<60 ft Height
nn EnclosedEnclosed BuldingBulding
nn Regular ShapeRegular Shape
nn Rigid (<1 Sec Period)Rigid (<1 Sec Period)
nn No Topographic EffectsNo Topographic Effects
nn Approximately SymmetricalApproximately Symmetrical

14. 175175
Method 1Method 1--ProcedureProcedure
nn GG--Adjustment FactorAdjustment Factor
nn IwIw--Importance FactorImportance Factor
nn PsPs--Wind PressureWind Pressure
P=P=GG**IIww*P*Pss

15. 176176
Method 1Method 1--DeterminationDetermination

16. 177177
ASCE 7ASCE 7--0202
nn Method 2Method 2--Analytical ProcedureAnalytical Procedure
•• ConditionsConditions
•• ProcedureProcedure
•• DeterminationDetermination
nn Rigid FormulaRigid Formula
•• Less than 60 FtLess than 60 Ft
•• All BuildingsAll Buildings
nn Flexible FormulaFlexible Formula

17. 178178
Method 2Method 2--ConditionsConditions
nn Regular ShapeRegular Shape
nn No Dynamic Wind EffectsNo Dynamic Wind Effects

18. 179179
Method 2Method 2--ProceduresProcedures
Step 1Step 1
nn KzKz--Exposure/HeightExposure/Height
nn KztKzt--TopographyTopography
nn KdKd--Building Configuration & Wind DirBuilding Configuration & Wind Dir
nn VelocityVelocity--MapsMaps
nn II--UseUse
q=0.00256Kq=0.00256Kzz**KKztzt**KKdd*V*V22
*I*I

19. 180180
Method 2Method 2--MWRS ProcedureMWRS Procedure
RigidRigid--Buildings Less than 60 FtBuildings Less than 60 Ft
nn GCpfGCpf--External Pressure CoefficientExternal Pressure Coefficient
nn GCpiGCpi--Internal Pressure CoefficientInternal Pressure Coefficient
p=p=qqhh*(*(GCGCpfpf--GCpGCpii))

20. 181181
Method 2Method 2--MWRS DeterminationMWRS Determination
RigidRigid--Buildings Less than 60 FtBuildings Less than 60 Ft

21. 182182
Method 2Method 2--MWRS ProcedureMWRS Procedure
RigidRigid--All Building HeightsAll Building Heights
nn GG--Gust Effect (0.85 Rigid Buildings)Gust Effect (0.85 Rigid Buildings)
nn CpCp--External Pressure CoefficientExternal Pressure Coefficient
nn GCpiGCpi--Internal Pressure CoefficientInternal Pressure Coefficient
p=q*G*Cp=q*G*Cpp--qqii**GCGCpipi

22. 183183
Method 2Method 2--MWRS DeterminationMWRS Determination
RigidRigid--All Building HeightsAll Building Heights

23. 184184
Method 2Method 2--MWRS ProcedureMWRS Procedure
Flexible BuildingsFlexible Buildings
nn GfGf--Gust Effect (Flexible)Gust Effect (Flexible)
nn CpCp--External Pressure CoefficientExternal Pressure Coefficient
nn GCpiGCpi--Internal Pressure CoefficientInternal Pressure Coefficient
p=q*p=q*GGff*C*Cpp--qqii**GCGCpipi

24. 185185
Method 2Method 2--Flexible FormulaFlexible Formula
Gust FactorGust Factor
GfGf=0.925=0.925((1+1.7I1+1.7IzzKK(g(g22
QQQQ22+g+g22
RRRR22))))
1+1.7g1+1.7gvvIIzz
wherewhere ggRR==KK(2ln(3600n(2ln(3600n11))+))+ 0.5770.577
KK(2ln(3600n(2ln(3600n11))))
where R=where R=KK((1/((1/MM)R)RnnRRhhRRBB(0.53+0.47R(0.53+0.47RLL))))
wherewhere RRnn==7.47N7.47N11
(1+10.3N(1+10.3N11)^5/3)^5/3
etcetc…………..

25. 186186
Method 2Method 2--Load CasesLoad Cases
MWRSMWRS
•Case 1-100% Ea Dir
•Case 2-75% Ea Dir
•Case 3-Case 1 w/15%e
•Case 4-Case 2 w/15%e

26. 187187
Method 2Method 2--C & C ProcedureC & C Procedure
nn GCGCpp--External Pressure CoefficientExternal Pressure Coefficient
nn GCGCpipi--Internal Pressure CoefficientInternal Pressure Coefficient
p=p=qqhh*(*(GCGCpp--GCGCpipi) (h<60) (h<60’’))
p=q*p=q*GCGCpp--qqii**GCGCpipi (h>60(h>60’’))

27. 188188
Method 2Method 2--C & C DeterminationC & C Determination
nn LocationLocation
nn Tributary AreaTributary Area
nn Walls/RoofsWalls/Roofs

28. 189189
ASCE 7ASCE 7--0202
nn Method 3Method 3--Wind Tunnel ProcedureWind Tunnel Procedure
•• Irregular ShapeIrregular Shape
•• Flexible (>1 sec)Flexible (>1 sec)
•• WakeWake
•• ChannelingChanneling
•• Dynamic EffectsDynamic Effects

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Dynamic Wind EffectsDynamic Wind Effects
nn Vortex SheddingVortex Shedding

30. 191191
Dynamic Wind EffectsDynamic Wind Effects
nn GallopingGalloping

31. 192192
Dynamic Wind EffectsDynamic Wind Effects
nn FlutterFlutter--Flutter occurs when aFlutter occurs when a
torsionaltorsional disturbance in the structuredisturbance in the structure
increases theincreases the angle of attackangle of attack of theof the
bridge (that is, the angle betweenbridge (that is, the angle between
the wind and the bridge)the wind and the bridge)

32. 193193
Example 1Example 1--Simplified ProcedureSimplified Procedure
nn CriteriaCriteria
•• 130 mph130 mph
•• Exposure CExposure C
•• Flat TerrainFlat Terrain
•• EnclosedEnclosed
•• I=1.0I=1.0

33. 194194
Example 1Example 1-- Simplified ProcedureSimplified Procedure
MWRSMWRS--Figure 6Figure 6--22
•Roof Pressure=-32 psf
•Wall Pressure=27 psf
•G=1.21
Roof=-39 psf
MWRS=33 psf
(Includes Internal Pressure)

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Example 1Example 1--Simplified ProcedureSimplified Procedure
C & C Wall PressuresC & C Wall Pressures--Figure 6Figure 6--33
nn TribTrib Area=15(15/3)=75Area=15(15/3)=75 sfsf
Zone 4 p=27.2*1.21=33Zone 4 p=27.2*1.21=33 psfpsf
Zone 4 p=Zone 4 p=--29.8*1.21=29.8*1.21=--3636
Zone 5 p=27.2*1.21=33Zone 5 p=27.2*1.21=33
Zone 5 p=Zone 5 p=--34.3*1.21=34.3*1.21=--4242

35. 196196
Example 1Example 1--Simplified ProcedureSimplified Procedure
C & C Roof JoistsC & C Roof Joists--Figure 6Figure 6--33
nn TribTrib Area=30*5=150Area=30*5=150 sfsf
or 30*30/3=300or 30*30/3=300 sfsf
Zone 1 p=9.8*1.21=12Zone 1 p=9.8*1.21=12 psfpsf
Zone 1 p=Zone 1 p=--27.8*1.21=27.8*1.21=--3434
Zone 2&3 p=9.8*1.21=12Zone 2&3 p=9.8*1.21=12
Zone 2&3 p=Zone 2&3 p=--33*1.21=33*1.21=--4040

36. 197197
Example 1Example 1--Simplified ProcedureSimplified Procedure
C & C Roof PanelsC & C Roof Panels--Figure 6Figure 6--33
nn TribTrib Area=10Area=10 sfsf
Zone 1 p=12.4*1.21=15Zone 1 p=12.4*1.21=15 psfpsf
Zone 1 p=Zone 1 p=--30.4*1.21=30.4*1.21=--3737
Zone 2 p=12.4*1.21=15Zone 2 p=12.4*1.21=15
Zone 2 p=Zone 2 p=--51*1.21=51*1.21=--6262
Zone 3 p=12.4*1.21=15Zone 3 p=12.4*1.21=15
Zone 3 p=Zone 3 p=--77*1.21=77*1.21=--9393

37. 198198
Example 1Example 1--Simplified ProcedureSimplified Procedure
Tributary Area EffectTributary Area Effect

38. 199199
Example 2Example 2--Analytical MethodAnalytical Method
nn CriteriaCriteria
•• 90 mph90 mph
•• Exposure BExposure B
•• Flat TerrainFlat Terrain
•• EnclosedEnclosed
•• I=1.0I=1.0
•• 33--DD AxisymmetricalAxisymmetrical
HillHill

39. 200200
Example 2Example 2--Analytical MethodAnalytical Method
MWRS, C & CMWRS, C & C
nn qqzz=0.00256*=0.00256*KKzz**KKztzt**KKdd*V*V22
II
•• KKdd=0.85=0.85
•• KKzz=0.57 Case II MWRS=0.57 Case II MWRS
=0.7 Case I C & C=0.7 Case I C & C
MWRSMWRS qqzz=0.00256*0.57*=0.00256*0.57*KKztzt*0.85*90*0.85*9022 1.01.0
=10.04*=10.04*KKztzt
C & CC & C qqzz=0.00256*=0.00256*KKzz**KKztzt**KKdd*V*V22 II
=12.3*=12.3*KKztzt

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Example 2Example 2--Analytical MethodAnalytical Method
MWRS, C & CMWRS, C & C
H/L=0.4H/L=0.4
KK11=0.95*0.4=0.38=0.95*0.4=0.38
KK22=(1=(1--250/(1.5*600))=0.72250/(1.5*600))=0.72
KK33=e=e--4(15)/6004(15)/600
=0.9=0.9
KKztzt=(1+0.38*0.72*0.9)=(1+0.38*0.72*0.9)22
=1.56=1.56
nn q(MWRS)=15.7q(MWRS)=15.7 psfpsf
nn q(C&C)=19.2q(C&C)=19.2 psfpsf

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Wind LoadsWind Loads--SummarySummary
nn Variable ConditionsVariable Conditions
nn Lots of Different ParametersLots of Different Parameters
nn Number of ProceduresNumber of Procedures
nn More complex than you thinkMore complex than you think