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Introduction/Course Description Introduction
WIND LOADS ON BUILDINGS IN ACCORDANCE WITH NSCP 2010 SECTION 207 Lecturer ENGR. ADAM C. ABINALES, M.ENG, F.ASEP Course STRUCTURAL ENGINEERING
Objectives and Results Objectives To provide a guide and information on the use of Section 207 of the NSCP Vol. I Sixth Edition 2010 with some illustrative examples for the civil engineering graduates, practicing civil/structural engineers, private and government stakeholders in construction industry and members of the academe community in the Philippines. To present the major and significant provisions of Section 207 Wind Load of Chapter 2 of the NSCP Vol. I Sixth Edition 2010.
Results Understand and learn the basic wind load calculation as applied to building using Method 1 or Method 2. Understand and learn the basic wind load calculation as applied to tower structure using Method 2.
One of the major and significant revisions of the NSCP Vol. I Sixth Edition 2010 is Chapter 2 which stipulates provisions on the minimum design loads to be applied on buildings, towers and other vertical structures. Section 207 of the NSCP Vol. I Sixth Edition2010 which discusses the wind load provisions of Chapter 2 Minimum Design Requirements is one of the major and significant changes. Wind load provisions of the NSCP Vol. I 2010 are generally referenced from the wind load criteria of the American Society of Civil Engineers (ASCE) publication, SEI/ASCE Standard 7-05, Minimum Design Loads for Buildings and Other Structures.
Vocabulary Basic Wind Speed, denoted by Basic wind speed is a three-second gust speed at 10 m above the ground in Exposure “C” and associated with an annual probability for 2% of being equaled or exceeded (50-year mean recurrence interval).
Design Wind Force, denoted by Design wind force is the equivalent static force to be used in the determination of wind loads for open buildings and other structures.
Skills developed Proficiency on wind load derivation for building Proficiency on wind load derivation for tower structure
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Vocabulary Design Wind Pressure, denoted by Design wind pressure is the equivalent static pressure to be used in the determination of wind loads for buildings and may be denoted as: = pressure that varies with height in accordance with velocity pressure evaluated at height ; or = pressure that is uniform with respect to the height as determined by the velocity pressure evaluated at mean roof height .
Vocabulary Building, Partially Enclosed Building, Partially Enclosed is a building that complies with both of the following conditions: the total area of openings in a wall that receives positive external pressure exceeds the sum of the areas of openings in the balance of the building envelope (walls and roof) by more than 10%; and the total area of openings in a wall that receives positive external pressure exceeds 0.5 m2 or 1% of the area of that wall, whichever is smaller, and the percentage of openings in the balance of the building envelope does not exceed 20%.
Vocabulary Building, Enclosed Building, Enclosed is a building that does not comply with the requirements for open or partially enclosed buildings.
Building, Open Building, Open is a building having each wall at least 80% open.
Vocabulary Building, Low-rise Building, Low-rise is an enclosed or partially enclosed building that comply with the following conditions: mean roof height less than or equal to 18 m; and mean roof height does not exceed least horizontal dimension.
Building, Envelope Building Envelope consists of cladding, roofing, exterior wall, glazing, door assemblies, window assemblies, skylight assemblies and other components enclosing the building.
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Vocabulary Building, Flexible Building, Flexible is a slender building that has a fundamental natural frequency less than 1 Hz.
Building, Rigid Building, Rigid is a building or other structure whose fundamental natural frequency is greater than or equal to 1 Hz.
Vocabulary Components and Cladding (C&C) Components and Cladding (C&C) are elements of the building envelope that do not qualify as part of the main wind-force resisting system. Cladding receives wind loads directly and generally transfers the load to other components or to the MWFRS.
Main Wind-Force Resisting System (MWFRS) Main Wind-Force Resisting System (MWFRS) is defined as the overall structure receiving wind loading from more than one surface.
Vocabulary Wind Engineering Wind Engineering is best defined as the rational treatment of interactions between wind in the atmospheric boundary layer and man and his works on the surface of the Earth. - Dr. Jack Cermak (1975)
Highlights of Significant Provisions in Section 207 – Wind Loads Previous Editions of NSCP Volume I The wind load criteria of NSCP 1992 Fourth Edition were essentially different from that of NSCP 2001 Fifth Edition; the basic wind speed averaging time was changed from the fastest-mile to 3-second gust. This in turn necessitated significant changes in boundary-layer profile parameters, gust effect factor, and some pressure coefficients.
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Highlights of Significant Provisions in Section 207 – Wind Loads NSCP Volume I, Sixth Edition In the latest version NSCP 2010 6th Edition, there are numerous significant provisions that involve expansion of the simplified procedure, load cases for main wind-force resisting systems, and introduction of surface roughness length to define exposure coefficients. The basic approach to assessing and determining wind loading has not been changed (relative to the NSCP 2001 5th Edition), but new parameters, such as roughness surface length, wind directionality factor, are added to provide more flexibility to designers.
Highlights of Significant Provisions in Section 207 – Wind Loads Introduction of wind directionality factor (Section 207.5.4.4)
Highlights of Significant Provisions in Section 207 – Wind Loads The significant provisions that may affect the design process are listed as follows: Introduction of the simplified procedure, which is expanded (Section 207.4)
Highlights of Significant Provisions in Section 207 – Wind Loads Introduction of surface roughness length to define exposure coefficients (Section 207.5.6.2)
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Highlights of Significant Provisions in Section 207 – Wind Loads Exposure A is deleted from the tabulated values (Section 207.5.6.3)
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads Load cases are applied to buildings of all heights for main wind-force resisting system (MWFRS) (Figure 207-9)
Highlights of Significant Provisions in Section 207 – Wind Loads New pressure coefficients are provided to determine wind loads for domed roof buildings (Figure 207-7)
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Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads Provisions for calculating wind loads for parapets (MWFRS and C&C) are added (Section 207.5.12.2.4)
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
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Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
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Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
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Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
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Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
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Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
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Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Reduction factor is allowed for partially enclosed building containing large volume (Section 207.5.11.1.1)
Gust effect factors are more defined for rigid and flexible structures (Section 207.5.8).
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Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads Gust effect factors for other structures such as poles, masts, trussed towers, billboard structures, freestanding wall and solid signs are also defined. (Section 207.7) Table 207-5.
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Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
Highlights of Significant Provisions in Section 207 – Wind Loads
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Highlights of Significant Provisions in Section 207 – Wind Loads Wind loads on all structures supporting antennas, cables and other attachments and appurtenances shall be referred to TIA222-G (2005) (Section 207.5.15.2)
Calculation Procedure
Calculation Procedure Sixth Edition of NSCP Volume I, 2010 Sections 207.4 through 207.6 of the NSCP 2010 prescribe the provisions for the design procedure that may be adopted in the calculation of wind forces on the structure MWFRS and its components and cladding (C&C). Method 1 – Simplified Procedure
Calculation Procedure
Method 1 – Simplified Procedure
as specified in Section 207.4 the simplified procedure may be applied to buildings meeting certain specific requirements which are set for MWFRS and C&C, respectively generally used for evaluating design loads for common regular shaped low-rise buildings
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Calculation Procedure Method 2 – Analytical Procedure
Calculation Procedure Method 3 – Wind Tunnel Procedure
Calculation Procedure Method 2 – Analytical Procedure
as specified in Section 207.5 analytical procedure is applicable to buildings and other structures – buildings of all heights; alternate low-rise buildings with mean roof height less than or equal to 18 m; or open buildings and other structures not susceptible to across wind loading or other special considerations due to location
Calculation Procedure Method 3 – Wind Tunnel Procedure
must meet certain test conditions as specified in Section 207.6 for the proper conduct of such tests particularly useful for obtaining detailed information about pressure distributions on complex shapes and the dynamic response of structures
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Design Wind Pressure / Force Rigid Buildings of All Heights
Design Wind Pressure / Force Flexible Buildings
Design Wind Pressure / Force Low-Rise Buildings
Design Wind Pressure / Force Components & Cladding elements of Parapets
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Design Wind Pressure / Force Open Buildings with Monoslope, Pitched or Trough Slope
Design Wind Pressure / Force Other Structures
Design Wind Pressure / Force Solid Free-standing Walls and Solid Signs
Velocity Pressure Velocity Pressure
47.3 10
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Velocity Pressure
Velocity Pressure
47.3 10
Velocity Pressure
Velocity Pressure
47.3 10
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Velocity Pressure
Velocity Pressure
Velocity Pressure
Velocity Pressure
47.3 10
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Velocity Pressure
Velocity Pressure
47.3 10
Velocity Pressure
Velocity Pressure
Wind Zone Map of the Philippines
Wind Zone for the Different Provinces of the Philippines
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Velocity Pressure 47.3 10
Exposure Category
Exposure Category Exposure
Exposure Category
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Exposure Category
Exposure Category
Example Scenario of Exposure Category B
Exposure Category
Exposure Category Example Scenario of Exposure Category C
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Exposure Category Example Scenario of Exposure Category C
Pressure and Force Coefficient
Pressure and Force Coefficient Internal Pressure Coefficient
Pressure and Force Coefficient External Pressure Coefficient
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Pressure and Force Coefficient
Pressure and Force Coefficient
Refer to Figure 207-6 of NSCP v1 2010
Pressure and Force Coefficient
Pressure and Force Coefficient
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Pressure and Force Coefficient
Pressure and Force Coefficient Refer to Figure 207-7 of NSCP v1 2010
Pressure and Force Coefficient
Pressure and Force Coefficient Refer to Figure 207-8 of NSCP v1 2010
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Pressure and Force Coefficient
Gust Effect Factor Gust Effect Factor
Gust Effect Factor
Gust Effect Factor
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Gust Effect Factor
Gust Effect Factor
Example Problem 1
Example Problem 1
Given a 60-m x 75-m Gable Roof Warehouse Building with dimensions and framing as shown below:
Design parameters: Location: The Fort Global City, Taguig City Topography: Homogeneous Terrain: Flat, open terrain Dimensions: 60-m x 75-m in plan Eave height = 6 m Roof slope 4:12 (18.4°)
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Example Problem 1
Example Problem 1
Framing configuration: Framing: Rigid frames span the 60-m direction Rigid frame bay spacing = 7.5 m Lateral bracing in the 75-m direction is provided by a “wind truss” spanning the 60m to side walls and cable/rod bracing in the plane of the walls Girts and purlins span between rigid frames (7.5 m) Girt spacing = 1.6 m Purlin spacing = 1.2 m
Solution and Discussion to Example Reference / Problem 1 Notes Exposure and Building Classification
The building is located on flat and open terrain. It may not fit Exposure Category B or D; therefore, Exposure Category C is considered. The building function is commercial - industrial. It is not an essential facility or likely to be occupied by 300 persons at one time. Occupancy Category IV is appropriate; therefore, = 1.0
Sections 207.5.6.2 and 207.5.6.3
Section 207.5.6 Table 207-3
Framing configuration: Cladding: Roof panel dimensions = 0.6 m Roof fastener spacing on purlins = 0.3 m on center Wall panel dimensions = 0.6 m x 6 m Wall fastener spacing on girts = 0.3 m on center Openings are uniformly distributed
Solution and Discussion to Example Reference / Problem 1 Notes Basic Wind Speed
Calculation Procedure
The building location is in Metro Manila (NCR) which in Zone II of the Philippine Wind Zone Map. Therefore, the basic wind speed is = 200 kph. Method 2, Analytical Procedure, will be used in this example. In addition, provisions of buildings of all heights, given in Section 207.5.12.2.1 for MWFRS will be used.
Table 207-1 or Figure 207-24
Section 207.5
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Solution and Discussion to Example Reference / Problem 1 Notes Wind Directionality
Velocity Pressure
Wind directionality factor = 0.85 for MWFRS and C&C. The velocity pressures are computed using the following equation: 47.3 10
where =? = 1.0 (no topographic effect) = 0.85 = 1.0 = 200 kph
Section 207.5.4.4 or Table 207-2
Design wind pressures for MWFRS of this building can be obtained using Section 207.5.12.2.1 for buildings of all heights or Section 207.5.12.2.2 for low-rise buildings. In this example, pressures are determined using buildings of all heights criteria: & where for windward wall at height above ground for leeward wall, side walls, and roof at height for enclosed buildings = gust effect factor = external pressure coefficient = internal pressure coefficient
Velocity Pressure
Section 207.5.10 Equation 20715 Table 207-4 Section 207.5.7
Section 207.5.4.4 or Table 207-2
Substituting the values into Equation 207-15 yields: 47.3 10
1 0.85 200
Height
Elev. (m) 4.50 6.00 9.00 11.00 12.00 15.00 16.00
Eave
*
1
N/m2
1608.2
Ridge
Solution and Discussion to Example Reference / Problem 1 Notes Design Wind Pressure
Solution and Discussion to Example Reference / Problem 1 Notes
0.85 0.90 0.98 1.02 1.04 1.09 1.10
1608.2
(N/m2) 1367 1447 1576 1640* 1673 1753 1769
is based on Note 2 of Table 207-4. Values for are the same for Cases 1 and 2 for Exposure C. Mean roof height = 11 m.
N/m2
Solution and Discussion to Example Problem 1
Section 207.5.4.4 or Table 207-2
Section 207.5.12.2.1 Equation 20717
Figure 207-6 Figure 207-5
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Solution and Discussion to Example Problem 1
Solution and Discussion to Example Reference / Problem 1 Notes Design Wind Pressure
Solution and Discussion to Example Reference / Problem 1 Notes External Pressure Coefficient on Wall
The pressure coefficients for the windward wall and for the side walls are 0.8 and -0.7, respectively, for all '/( ratios. The leeward wall pressure coefficient is a function of '/( ratio. For wind normal to the ridge, '/( = 60/75 = 0.8; therefore, the leeward wall pressure coefficient is -0.5.
Figure 207-6
For this example, when the wind is normal to the ridge, the windward roof experiences both positive and negative external pressures. Combining these external pressures with positive and negative external pressures will result in four loading cases when wind is normal to the ridge. When wind is parallel to the ridge, positive and negative internal pressures result in two loading cases. The external pressure coefficients for θ = 0° apply in this case.
Figure 207-6
Solution and Discussion to Example Reference / Problem 1 Notes External Pressure Coefficient on Wall
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Solution and Discussion to Example Reference / Problem 1 Notes External Pressure Coefficient on Wall
For wind parallel to the ridge, '/( = Figure 207-6 75/60 = 1.25; the value of , obtained by linear interpolation, = 0.45. In summary, the wall pressure coefficients are: Surface Windward wall Leeward wall
Side wall
Wind direction All Normal to ridge Parallel to ridge All
'/( All
0.80
0.8
-0.50
1.25
-0.45
All
-0.70
Solution and Discussion to Example Reference / Problem 1 Notes External Pressure Coefficient on Roof
Figure 207-6
Solution and Discussion to Example Reference / Problem 1 Notes External Pressure Coefficient on Roof
The roof pressure coefficients for the MWFRS are determined and shown below: Surface Windward roof Leeward roof
15°
18.4°
20°
-0.5
-0.36*
-0.3
0.0
0.14*
0.2
-0.5
-0.57*
-0.6
Figure 207-6
*Values obtained by linear interpolation. For wind normal to ridge, /' = 11/60 = 0.186.
Solution and Discussion to Example Reference / Problem 1 Notes Internal Pressure Coefficient
Values for for buildings are addressed in:
Section 207.5.11.1 Figure 207-5
The openings are evenly distributed in the walls (enclosed building). The reduction factor of Section 207.5.11.1.1 is not applicable for enclosed buildings; therefore, = ±0.18
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Solution and Discussion to Example Reference / Problem 1 Notes Gust Effect Factor
For rigid structures (where the ratio of to the least width of building = 16/60 = 0.18 < 4), hence, rigid building, can be calculated using Equation 207-4: 1 * 1.7+, ̅ . 0.925 1 * 1.7+/ ̅ where +, = +/ = 3.4 ̅ 0.6 = 0.6(11) = 6.6 m or ̅ 4.5 m 2 = 0.2 ℓ = 150 m ε5 = 1/5
01
=
Section 207.5.8.1
Then, compute the other notations
2 ̅
67 6/ ̅
0.2
67 6/ .
1
. 1 * 0.63
(* '̅
7. 8
in which ' ̅
ℓ
̅ 10 '
Section 207.5.8.1 Equation 2075
0.214 ̅
9̅
6.6 6/; 10 138.04
̅
150
Table 207-5
Gust Effect Factor
Table 207-5
Solution and Discussion to Example Reference / Problem 1 Notes Gust Effect Factor
Solution and Discussion to Example Reference / Problem 1 Notes
Equation 2076, use ( = 60 m (the smaller value gives larger value of ) Equation 2057
Solution and Discussion to Example Reference / Problem 1 Notes Gust Effect Factor
Then, 6
. 6<7. 8
=>?@@ >.=A @AB.>C
Equation 2076
. 0.84 Substituting the computed values to evaluate : 0.925
1 * 1.7 3.4 0.214 0.84 1 * 1.7 3.4 0.214
Equation 2074
0.883
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Solution and Discussion to Example Reference / Problem 1 Notes Net Wind Pressures on MWFRS
Wind pressure on the MWFRS is determined as & 0.883
& 1640 D0.18
Solution and Discussion to Example Reference / Problem 1 Notes Net Wind Pressures on MWFRS
Equation 20717
Surface
On the windward wall from 0 – 4.5 m, wind normal to ridge:
Windward wall Leeward wall Side walls Windward roof*
1367 0.883 0.8 & 1640 D0.18 670 N/m2 with (+) internal pressure 1261 N/m2 with (-) internal pressure
Leeward roof
Solution and Discussion to Example Reference / Problem 1 Notes Net Wind Pressures on MWFRS
From previous calculation, note that = 1640 N/m2; = ±0.18; therefore, the quantity ( ) = ±295 N/m2 *Two loadings on windward roof and two internal pressures yield a total of four loading cases.
In summary, the net pressures for the MWFRS (wind normal to ridge) are shown in table: (m)
Net pressure (N/m2) with
(N/m2)
4.50 6.00
1367 1447
0.883 0.883
0.80 0.80
(+ ) 670 727
() 1261 1317
All
1640
0.883
-0.50
-1019
-429
All
1640
0.883
-0.70
-1309
-719
-0.36
-816
-226
0.14
-92
498
-0.57
-1120
-530
-
1640
0.883
-
1640
0.883
Solution and Discussion to Example Reference / Problem 1 Notes Net Wind Pressures on MWFRS
Figure 1-1 – Net Design Wind Pressures for MWFRS when Wind is Normal to Ridge with Negative Windward External Roof Pressure Coefficient Surface
Refer to Figures 1-1 through 1-2 in next slides
Windward wall Leeward wall Side walls Windward roof* Leeward roof
(m)
Net pressure (N/m2) with
(N/m2)
4.50 6.00
1367 1447
0.883 0.883
0.8 0.8
(+ 670 727
)
() 1261 1317
All
1640
0.883
-0.5
-1019
-429
All
1640
0.883
-
1640
0.883
-0.7 -0.36 0.14
-1309 -816 -92
-719 -226 498
-
1640
0.883
-0.57
-1120
-530
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Solution and Discussion to Example Reference / Problem 1 Notes Net Wind Pressures on MWFRS
Figure 1-2 – Net Design Wind Pressures for MWFRS when Wind is Normal to Ridge with Negative Windward External Roof Pressure Coefficient Surface (m) (N/m ) 2
Windward wall Leeward wall Side walls Windward roof* Leeward roof
Net Wind Pressures on MWFRS Net pressure (N/m2) with
4.50 6.00
1367 1447
0.883 0.883
0.8 0.8
(+ 670 727
)
() 1261 1317
All
1640
0.883
-0.5
-1019
-429
All
1640
0.883
-
1640
0.883
-0.7 -0.36 0.14
-1309 -816 -92
-719 -226 498
-
1640
0.883
-0.57
-1120
-530
Solution and Discussion to Example Reference / Problem 1 Notes Net Wind Pressures on MWFRS
Figure 1-4 – Net Design Wind Pressures for MWFRS when Wind is Normal to Ridge with PositiveWindward External Roof Pressure Coefficient Surface (m) (N/m ) 2
Windward wall Leeward wall Side walls Windward roof* Leeward roof
Solution and Discussion to Example Reference / Problem 1 Notes
Net pressure (N/m2) with
4.50 6.00
1367 1447
0.883 0.883
0.8 0.8
(+ 670 727
)
() 1261 1317
All
1640
0.883
-0.5
-1019
-429
All
1640
0.883
-
1640
0.883
-0.7 -0.36 0.14
-1309 -816 -92
-719 -226 498
-
1640
0.883
-0.57
-1120
-530
Figure 1-3 – Net Design Wind Pressures for MWFRS when Wind is Normal to Ridge with Positive Windward External Roof Pressure Coefficient Surface (m) (N/m ) 2
Windward wall Leeward wall Side walls Windward roof* Leeward roof
Net pressure (N/m2) with
4.50 6.00
1367 1447
0.883 0.883
0.8 0.8
(+ 670 727
)
() 1261 1317
All
1640
0.883
-0.5
-1019
-429
All
1640
0.883
-
1640
0.883
-0.7 -0.36 0.14
-1309 -816 -92
-719 -226 498
-
1640
0.883
-0.57
-1120
-530
Solution and Discussion to Example Reference / Problem 1 Notes External Pressure Coefficient on Roof (Wind Parallel to Ridge)
For wind parallel to ridge, /' = 11/75 = 0.147 and θ < 10°. The values of for wind parallel to ridge are: Surface Roof
/' ≤ 0.5
Distance from windward edge 0 to to 2 >2
Figure 207-6
-0.9, -0.18* -0.5, -0.18* -0.3, -0.18*
*The values of smaller uplift pressures on the roof can become critical with roof live load; load combinations are given in Sections 203.3 and 203.4.
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Solution and Discussion to Example Reference / Problem 1 Notes Figure 207-6
External Pressure Coefficient on Roof (Wind Parallel to Ridge)
Solution and Discussion to Example Reference / Problem 1 Notes The net pressures for the MWFRS (wind parallel to ridge) are:
External Pressure Coefficient on Roof (Wind Parallel to Ridge)
Surface
(m) 0 - 4.50 6.00 9.00 12.00 15.00 16.00 All All 0 to h* h to 2h* > 2h*
Windward wall
Leeward wall Side walls Roof*
(N/m2) 1367 1447 1576 1673 1753 1769 1640 1640 1640 1640 1640
0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883
= 1640 N/m2; = ±0.18; = ±295 N/m2 *Distance from windward edge.
Solution and Discussion to Example Reference / Problem 1 Notes External Pressure Coefficient on Roof (Wind Parallel to Ridge)
Surface Windward wall
Leeward wall Side walls Roof*
Figure 1-5 –Net Design Wind Pressures for MWFRS when Wind is Parallel to Ridge with Positive Internal Pressure
(m) 0 - 4.50 6.00 9.00 12.00 15.00 16.00 All All 0 to h* h to 2h* > 2h*
(N/m2) 1367 1447 1576 1673 1753 1769 1640 1640 1640 1640 1640
0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883
0.80 0.80 0.80 0.80 0.80 0.80 -0.45 -0.70 -0.90 -0.50 -0.30
Net pressure (N/m2) with (+ ) () 670 1260 727 1317 818 1408 886 1476 943 1533 954 1544 -947 -357 -1309 -719 -1598 -1008 -1019 -429 -729 -139
0.80 0.80 0.80 0.80 0.80 0.80 -0.45 -0.70 -0.90 -0.50 -0.30
Net pressure (N/m2) with ) () (+ 670 1260 727 1317 818 1408 886 1476 943 1533 954 1544 -947 -357 -1309 -719 -1598 -1008 -1019 -429 -729 -139
Refer to Figures 1-5 through 1-6 in next slide
Solution and Discussion to Example Reference / Problem 1 Notes External Pressure Coefficient on Roof (Wind Parallel to Ridge)
Surface Windward wall
Leeward wall Side walls Roof*
(m) 0 - 4.50 6.00 9.00 12.00 15.00 16.00 All All 0 to h* h to 2h* > 2h*
(N/m2) 1367 1447 1576 1673 1753 1769 1640 1640 1640 1640 1640
0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883
0.80 0.80 0.80 0.80 0.80 0.80 -0.45 -0.70 -0.90 -0.50 -0.30
Net pressure (N/m2) with (+ ) () 670 1260 727 1317 818 1408 886 1476 943 1533 954 1544 -947 -357 -1309 -719 -1598 -1008 -1019 -429 -729 -139
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Solution and Discussion to Example Reference / Problem 1 Notes External Pressure Coefficient on Roof (Wind Parallel to Ridge)
Surface Windward wall
Leeward wall Side walls Roof*
Figure 1-6 –Net Design Wind Pressures for MWFRS when Wind is Parallel to Ridge with Negative Internal Pressure
(N/m2)
(m) 0 - 4.50 6.00 9.00 12.00 15.00 16.00 All All 0 to h* h to 2h* > 2h*
1367 1447 1576 1673 1753 1769 1640 1640 1640 1640 1640
0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883
0.80 0.80 0.80 0.80 0.80 0.80 -0.45 -0.70 -0.90 -0.50 -0.30
Net pressure (N/m2) with (+ ) () 670 1260 727 1317 818 1408 886 1476 943 1533 954 1544 -947 -357 -1309 -719 -1598 -1008 -1019 -429 -729 -139
Solution and Discussion to Example Reference / Problem 1 Notes Design Wind Load Cases
Section 207.5.12.3 requires that any building whose wind loads have been determined under the provisions of Sections 207.5.12.2.1 and 207.5.12.2.3 shall be designed for wind load cases as defined in Figure 207-9.
Solution and Discussion to Example Reference / Problem 1 Notes External Pressure Coefficient on Roof (Wind Parallel to Ridge)
Surface Windward wall
Leeward wall Side walls Roof*
Figure 1-6 –Net Design Wind Pressures for MWFRS when Wind is Parallel to Ridge with Negative Internal Pressure
(m) 0 - 4.50 6.00 9.00 12.00 15.00 16.00 All All 0 to h* h to 2h* > 2h*
(N/m2) 1367 1447 1576 1673 1753 1769 1640 1640 1640 1640 1640
0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883 0.883
0.80 0.80 0.80 0.80 0.80 0.80 -0.45 -0.70 -0.90 -0.50 -0.30
Net pressure (N/m2) with (+ ) () 670 1260 727 1317 818 1408 886 1476 943 1533 954 1544 -947 -357 -1309 -719 -1598 -1008 -1019 -429 -729 -139
Solution and Discussion to Example Reference / Problem 1 Notes Design Wind Load Cases
Section 207.5.12.3 has exception that if a building is designed with flexible diaphragm, only load cases 1 and 3 need to be considered. Figure 207-9 p.2-47
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Solution and Discussion to Example Reference / Problem 1 Notes Design Wind Pressures on Components & Cladding (C&C)
The following equation is used to obtain the design pressures for components and cladding (C&C): & 1640 & D0.18 where values are obtained from Figure 207-11A
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