asep nscp section 207 wind loads part 1.pdf

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WIND LOADS ON BUILDINGSIN ACCORDANCE WITH NSCP 2010

SECTION 207

Lecturer ENGR. ADAM C. ABINALES, M.ENG, F.ASEP

Course STRUCTURAL ENGINEERING

Introduction/Course Description

� Introduction� 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.

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.

� Skills developed� Proficiency on wind load derivation for building

� Proficiency on wind load derivation for tower structure

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.

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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, 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, 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, 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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� 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.



� The significant provisions that may affect the design

process are listed as follows:

� Introduction of the simplified procedure, which is

expanded (Section 207.4)



� Introduction of wind directionality factor (Section 207.5.4.4)



� Introduction of surface roughness length to define

exposure coefficients (Section 207.5.6.2)

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� Exposure A is deleted from the tabulated values

(Section 207.5.6.3)



� Load cases are applied to buildings of all heights for

main wind-force resisting system (MWFRS)

(Figure 207-9)





� New pressure coefficients are provided to determine

wind loads for domed roof buildings (Figure 207-7)

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� Provisions for calculating wind loads for parapets

(MWFRS and C&C) are added (Section 207.5.12.2.4)





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� 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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� Gust effect factors

for other structures

such as poles,

masts, trussed

towers, billboard

structures, free-

standing wall and

solid signs are also

defined.

(Section 207.7)

Table 207-5.

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� Wind loads on all

structures

supporting

antennas, cables

and other

attachments and

appurtenances shall

be referred to TIA-

222-G (2005)

(Section 207.5.15.2)

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


� 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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� Method 2 – Analytical

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


� Method 3 – Wind

Tunnel 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


� Low-Rise Buildings


� Flexible Buildings


� Components & Cladding

elements of Parapets

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� Open Buildings with

Monoslope, Pitched or

Trough Slope


� Solid Free-standing Walls and Solid Signs


� Other Structures

Velocity Pressure

� Velocity Pressure �� 47.3�10��

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Velocity Pressure

� �� 47.3�10��

Velocity Pressure

Velocity Pressure

� �� 47.3�10��

Velocity Pressure

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Velocity Pressure Velocity Pressure

Velocity Pressure

� �� 47.3�10��

Velocity Pressure

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Velocity Pressure

� �� 47.3�10��

Velocity Pressure

Velocity Pressure

� Wind Zone Map of

the Philippines

Velocity Pressure

� Wind Zone for the

Different Provinces

of the Philippines

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Velocity Pressure

� �� 47.3�10��

Exposure Category

� Exposure

Exposure Category Exposure Category

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Exposure Category

� Example Scenario of

Exposure Category B

Exposure Category

Exposure Category Exposure Category


Exposure Category C

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Exposure Category


Exposure Category C

Pressure and Force Coefficient

� Internal Pressure Coefficient ��

Pressure and Force Coefficient Pressure and Force Coefficient

� External Pressure Coefficient ��

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� Refer to Figure 207-6 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

� Given a 60-m x 75-m Gable Roof Warehouse

Building with dimensions and framing as shown

below:

Example Problem 1

� 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

� 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 60-m 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

Example Problem 1

� 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

Problem 1

� 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

� Reference /

Notes

Sections

207.5.6.2 and

207.5.6.3

Section

207.5.6

Table 207-3


Problem 1

� 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.

� Reference /

Notes

Table 207-1 or

Figure 207-24

Section 207.5

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Problem 1

� 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

� Reference /

Notes

Section

207.5.4.4 or

Table 207-2

Section

207.5.10

Equation 207-

15

Table 207-4

Section

207.5.7


Problem 1

� Velocity

Pressure Substituting the values into

Equation 207-15 yields:�� 47.3�10��1��0.85� 200

��1�

�� 1608.2� N/m2

*�� 1608.2� N/m2

� Reference /

Notes

Section

207.5.4.4 or

Table 207-2

� 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.

Height Elev. (m) � �� (N/m2)

4.50 0.85 1367

Eave 6.00 0.90 1447

9.00 0.98 1576

� 11.00 1.02 1640*

12.00 1.04 1673

15.00 1.09 1753

Ridge 16.00 1.10 1769


Problem 1

� Design Wind

Pressure

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

� Reference /

Notes

Section

207.5.4.4 or

Table 207-2

Section

207.5.12.2.1

Equation 207-

17

Figure 207-6

Figure 207-5


Problem 1

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Problem 1


Problem 1

� Design Wind

PressureFor 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.

� Reference /

Notes

Figure 207-6


Problem 1

� 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.

� Reference /

Notes

Figure 207-6


Problem 1

� External

Pressure

Coefficient

�� on Wall

� Reference /

Notes

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Problem 1

� External

Pressure

Coefficient

�� on Wall

For wind parallel to the ridge, '/( =

75/60 = 1.25; the value of ��,

obtained by linear interpolation, = -

0.45.

In summary, the wall pressure coefficients

are:

� Reference /

Notes

Figure 207-6

Surface Wind direction '/( ��

Windward wall All All 0.80

Leeward wall Normal to

ridge0.8 -0.50

Parallel to

ridge1.25 -0.45

Side wall All All -0.70


Problem 1

� External

Pressure

Coefficient

�� on Roof

The roof pressure coefficients for

the MWFRS are determined

and shown below:

*Values obtained by linear interpolation. For

wind normal to ridge, �/' = 11/60 = 0.186.

� Reference /

Notes

Figure 207-6

Surface 15° 18.4° 20°

Windward

roof-0.5 -0.36* -0.3

0.0 0.14* 0.2

Leeward

roof-0.5 -0.57* -0.6


Problem 1

� External

Pressure

Coefficient

�� on Roof

� Reference /

Notes

Figure 207-6


Problem 1

� Internal

Pressure

Coefficient

��

Values for �� for buildings are

addressed in:

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

� Reference /

Notes

Section

207.5.11.1

Figure 207-5

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Problem 1

� 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:

� � 0.9251 * 1.7+,��̅.

1 * 1.7+/��̅where

+, = +/ = 3.4

�̅ � 0.6� = 0.6(11) = 6.6 m or �̅ � �0�1 = 4.5 m

2 = 0.2

ℓ = 150 m

ε5 = 1/5

� Reference /

Notes

Section

207.5.8.1

Table 207-5


Problem 1

� Gust Effect

Factor �

� Reference /

Notes

Table 207-5


Problem 1

� Gust Effect

Factor �Then, compute the other notations

��̅ � 267

�̅

6/�

� 0.267

�.�

6/�

��̅ � 0.214

. �1

1 * 0.63( * �'�̅

7.�8

in which

'�̅ � ℓ�̅

10

9̅

� 1506.6

106/;

'�̅ � 138.04

� Reference /

Notes

Section

207.5.8.1

Equation 207-

5

Equation 207-

6, use ( = 60

m (the smaller

value gives

larger value of

�)

Equation 205-

7


Problem 1

� Gust Effect

Factor � Then,

. �6

6<7.�8=>?@@

@AB.>C

>.=A

. � 0.84

Substituting the computed

values to evaluate �:

� � 0.9251 * 1.7�3.4��0.214��0.84�

1 * 1.7�3.4��0.214�

� � 0.883

� Reference /

Notes

Equation 207-

6

Equation 207-

4

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Problem 1

� Net Wind

Pressures on

MWFRS

Wind pressure on the MWFRS is

determined as

� � �� & �� 0.883�� & �1640��D0.18�

On the windward wall from 0 –

4.5 m, wind normal to ridge:

� � 1367�0.883��0.8� & �1640��D0.18�

� � 670 N/m2 with (+) internal pressure

� � 1261 N/m2 with (-) internal pressure

� Reference /

Notes

Equation 207-

17


Problem 1

� Net Wind

Pressures on

MWFRS

In summary, the net pressures

for the MWFRS (wind normal

to ridge) are shown in table:

� Reference /

Notes

Surface � (m) � (N/m2) � ��Net pressure (N/m2) with

(+��) (-��)

Windward

wall4.50 1367 0.883 0.80 670 1261

6.00 1447 0.883 0.80 727 1317

Leeward

wallAll 1640 0.883 -0.50 -1019 -429

Side walls All 1640 0.883 -0.70 -1309 -719

Windward

roof* - 1640 0.883-0.36 -816 -226

0.14 -92 498

Leeward

roof- 1640 0.883 -0.57 -1120 -530


Problem 1

� 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.

� Reference /

Notes

Refer to

Figures 1-1

through 1-2 in

next slides


Problem 1

� 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

� Reference /

Notes


(+��) (-��)

Windward

wall4.50 1367 0.883 0.8 670 1261

6.00 1447 0.883 0.8 727 1317

Leeward

wallAll 1640 0.883 -0.5 -1019 -429

Side walls All 1640 0.883 -0.7 -1309 -719

Windward

roof*- 1640 0.883

-0.36 -816 -226

0.14 -92 498

Leeward

roof- 1640 0.883 -0.57 -1120 -530

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Problem 1

� 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

� Reference /

Notes


(+��) (-��)

Windward

wall

4.50 1367 0.883 0.8 670 1261

6.00 1447 0.883 0.8 727 1317

Leeward

wallAll 1640 0.883 -0.5 -1019 -429

Side walls All 1640 0.883 -0.7 -1309 -719

Windward

roof*- 1640 0.883

-0.36 -816 -226

0.14 -92 498

Leeward

roof- 1640 0.883 -0.57 -1120 -530


Problem 1

� Net Wind

Pressures on

MWFRS



Positive Windward External Roof Pressure

Coefficient

� Reference /

Notes


(+��) (-��)

Windward

wall

4.50 1367 0.883 0.8 670 1261

6.00 1447 0.883 0.8 727 1317

Leeward

wallAll 1640 0.883 -0.5 -1019 -429

Side walls All 1640 0.883 -0.7 -1309 -719

Windward

roof*- 1640 0.883

-0.36 -816 -226

0.14 -92 498

Leeward

roof- 1640 0.883 -0.57 -1120 -530


Problem 1

� Net Wind

Pressures on

MWFRS



PositiveWindward External Roof Pressure

Coefficient

� Reference /

Notes


(+��) (-��)

Windward

wall

4.50 1367 0.883 0.8 670 1261

6.00 1447 0.883 0.8 727 1317

Leeward

wallAll 1640 0.883 -0.5 -1019 -429

Side walls All 1640 0.883 -0.7 -1309 -719

Windward

roof*- 1640 0.883

-0.36 -816 -226

0.14 -92 498

Leeward

roof- 1640 0.883 -0.57 -1120 -530


Problem 1

� External

Pressure

Coefficient

�� on Roof

(Wind

Parallel to

Ridge)

� Reference /

Notes

Figure 207-6For wind parallel to ridge, �/' = 11/75 = 0.147 and θ < 10°. The values of

�� for wind parallel to ridge are:

*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.

Surface �/'Distance from

windward edge��

Roof ≤ 0.5 0 to � -0.9, -0.18*

� to 2� -0.5, -0.18*

> 2� -0.3, -0.18*

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Problem 1

� External

Pressure

Coefficient

�� on Roof

(Wind

Parallel to

Ridge)

� Reference /

Notes

Figure 207-6


Problem 1

� External

Pressure

Coefficient

�� on Roof

(Wind

Parallel to

Ridge)

� Reference /

Notes

Refer to

Figures 1-5

through 1-6 in

next slide

The net pressures for the MWFRS (wind parallel to ridge) are:

�� = 1640 N/m2; �� = ±0.18;

�� = ±295 N/m2

*Distance from windward edge.


(+��) (-��)

Windward wall 0 - 4.50 1367 0.883 0.80 670 1260

6.00 1447 0.883 0.80 727 1317

9.00 1576 0.883 0.80 818 1408

12.00 1673 0.883 0.80 886 1476

15.00 1753 0.883 0.80 943 1533

16.00 1769 0.883 0.80 954 1544

Leeward wall All 1640 0.883 -0.45 -947 -357

Side walls All 1640 0.883 -0.70 -1309 -719

Roof* 0 to h* 1640 0.883 -0.90 -1598 -1008

h to 2h* 1640 0.883 -0.50 -1019 -429

> 2h* 1640 0.883 -0.30 -729 -139


Problem 1

� External

Pressure

Coefficient

�� on Roof

(Wind

Parallel to

Ridge)

Figure 1-5 –Net Design Wind Pressures for MWFRS when Wind

is Parallel to Ridge with Positive Internal Pressure

� Reference /

Notes


(+��) (-��)

Windward wall 0 - 4.50 1367 0.883 0.80 670 1260

6.00 1447 0.883 0.80 727 1317

9.00 1576 0.883 0.80 818 1408

12.00 1673 0.883 0.80 886 1476

15.00 1753 0.883 0.80 943 1533

16.00 1769 0.883 0.80 954 1544

Leeward wall All 1640 0.883 -0.45 -947 -357

Side walls All 1640 0.883 -0.70 -1309 -719

Roof* 0 to h* 1640 0.883 -0.90 -1598 -1008

h to 2h* 1640 0.883 -0.50 -1019 -429

> 2h* 1640 0.883 -0.30 -729 -139


Problem 1

� External

Pressure

Coefficient

�� on Roof

(Wind

Parallel to

Ridge)

� Reference /

Notes


(+��) (-��)

Windward wall 0 - 4.50 1367 0.883 0.80 670 1260

6.00 1447 0.883 0.80 727 1317

9.00 1576 0.883 0.80 818 1408

12.00 1673 0.883 0.80 886 1476

15.00 1753 0.883 0.80 943 1533

16.00 1769 0.883 0.80 954 1544

Leeward wall All 1640 0.883 -0.45 -947 -357

Side walls All 1640 0.883 -0.70 -1309 -719

Roof* 0 to h* 1640 0.883 -0.90 -1598 -1008

h to 2h* 1640 0.883 -0.50 -1019 -429

> 2h* 1640 0.883 -0.30 -729 -139

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Problem 1

� External

Pressure

Coefficient

�� on Roof

(Wind

Parallel to

Ridge)


is Parallel to Ridge with Negative Internal Pressure

� Reference /

Notes


(+��) (-��)

Windward wall 0 - 4.50 1367 0.883 0.80 670 1260

6.00 1447 0.883 0.80 727 1317

9.00 1576 0.883 0.80 818 1408

12.00 1673 0.883 0.80 886 1476

15.00 1753 0.883 0.80 943 1533

16.00 1769 0.883 0.80 954 1544

Leeward wall All 1640 0.883 -0.45 -947 -357

Side walls All 1640 0.883 -0.70 -1309 -719

Roof* 0 to h* 1640 0.883 -0.90 -1598 -1008

h to 2h* 1640 0.883 -0.50 -1019 -429

> 2h* 1640 0.883 -0.30 -729 -139


Problem 1

� External

Pressure

Coefficient

�� on Roof

(Wind

Parallel to

Ridge)


is Parallel to Ridge with Negative Internal Pressure

� Reference /

Notes


(+��) (-��)

Windward wall 0 - 4.50 1367 0.883 0.80 670 1260

6.00 1447 0.883 0.80 727 1317

9.00 1576 0.883 0.80 818 1408

12.00 1673 0.883 0.80 886 1476

15.00 1753 0.883 0.80 943 1533

16.00 1769 0.883 0.80 954 1544

Leeward wall All 1640 0.883 -0.45 -947 -357

Side walls All 1640 0.883 -0.70 -1309 -719

Roof* 0 to h* 1640 0.883 -0.90 -1598 -1008

h to 2h* 1640 0.883 -0.50 -1019 -429

> 2h* 1640 0.883 -0.30 -729 -139


Problem 1

� Design Wind

Load Cases

� Reference /

Notes

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.


Problem 1

� Design Wind

Load Cases

� Reference /

Notes

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

8/14/2013

38


Problem 1

� Design Wind

Pressures on

Components

& Cladding

(C&C)

� Reference /

Notes

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

asep nscp section 207 wind loads part 1.pdf

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