Adjustment 

NIST TECHNICAL NOTE 1903 

Methodology to Analyze Wind Pressure 

Data on Components and Cladding of 

Low-Rise Buildings

Dat Duthinh, Joseph A. Main, and Brian M. Phillips

This publication is available free of charge from:

http://dx.doi.org/10.6028/NIST.TN.1903 
NIST TECHNICAL NOTE 1903

Methodology to Analyze Wind Pressure 

Data on Components and Cladding of 

Low-Rise Buildings

Dat Duthinh* 

Joseph A. Main* 

Brian M. Phillips**

*Engineering Laboratory

National Institute of Standards and Technology

Gaithersburg, MD 20899-7311

**Department of Civil and Environmental Engineering

University of Maryland, College Park, MD

This publication is available free of charge from:

http://dx.doi.org/10.6028/NIST.TN.1903

December 2015

U.S. Department of Commerce 

Penny Pritzker, Secretary 

National Institute of Standards and Technology

Willie May, Under Secretary of Commerce for Standards and Technology and Director 
Disclaimers 

(1) The policy of the National Institute of Standards and Technology is to use the

International System of Units in its technical communications. In this document however, works 

of authors outside NIST are cited which describe measurements in certain non-SI units. Thus, it 

is more practical to include the non-SI unit measurements from these references. 

(2) Certain trade names or company products or procedures may be mentioned in the text to

specify adequately the experimental procedure or equipment used. In no case does such 

identification imply recommendation or endorsement by the National Institute of Standards and 

Technology, nor does it imply that the products or procedures are the best available for the 

purpose. 

Cover photo 

University of Western Ontario Boundary Layer Wind Tunnel model perforated with holes for 

pressure measurements. The results of tests of this model and others, commissioned by NIST, are 

analyzed in this report. Photo by T. Ho, D. Surry & D. Morrish, BLWT-SS20-2003, May 2003. 

Acknowledgment 

The authors are grateful to Drs. Emil Simiu and Marc Levitan of NIST for their insightful advice 

and thorough review.

National Institute of Standards and Technology Technical Note 1903 

Natl. Inst. Stand. Technol. Tech. Note 1903, 55 pages (December 2015) 

CODEN: NTNOEF

This publication is available free of charge from:

http://dx.doi.org/10.6028/NIST.TN.1903
ii

Abstract 

This note establishes a method to analyze wind pressure data on cladding and components of 

low-rise buildings using the National Institute of Standards and Technology-University of 

Western Ontario (NIST-UWO) database. The aerodynamic pressures induced on a structure by 

the wind field are random both in time and space. For design purposes, the pressure on any given 

area A is a function of A, and is defined as the aerodynamic force acting on area A divided by A. 

That aerodynamic force is obtained by summing up the product of pressure time series measured 

in wind tunnel tests at adjoining pressure taps by their respective tributary areas. The area A is 

the sum of those tributary areas. These operations are carried out for all sums of tributary areas 

that make up rectangles with aspect ratio not exceeding four. The peak of the resulting areaaveraged time series is extrapolated to a realistic storm duration by the Sadek-Simiu method. The 

envelope of peaks over all wind directions is compared with current specifications from the 

American Society of Civil Engineers, ASCE 7-10. Results for two low-rise buildings for one 

terrain condition indicate serious underestimation by these specifications of the negative 

pressures (suction) on gable roofs, by factors ranging from 1.3 to 2.5, and of both positive and 

negative pressures on walls, by factors ranging from 1.5 to 2.0 and 1.2 to 2.4, respectively. More 

definitive conclusions will require analysis of more data from the NIST-UWO and other 

databases using the proposed or equivalent methodology. Future research includes the analysis of 

additional low-rise building configurations and the estimation of peak pressures by alternative 

methods. 

Keywords: ASCE 7-10; components and cladding; gable roofs; low-rise buildings; NIST-UWO 

database; walls; wind pressure; wind tunnel.

DOI: dx.doi.org/10.6028/NIST.TN.1903 
iii

Contents 

Disclaimers, cover photo, acknowledgment ...................................................... i 

Abstract ................................................................................................ ii

Contents................................................................................................ iii

List of figures ........................................................................................ iv 

List of tables........................................................................................... vi 

Introduction .......................................................................................... 1

Background...... .................................................................................... 1

Methodology........................................................................................ 2

Duration ratio....................................................................................... 6

Results ...................................................................................................7

Aspect ratio............................................................................................ 11

Uncertainty ............................................................................................ 17

Conclusion ............................................................................................. 17

References...............................................................................................18

Appendix A: UWO Bldg 7 roof 3................................................................... 20

Appendix B: UWO Bldg 7 roof 2................................................................... 27

Appendix C: Building 7 Wall 1.......................................................................32

Appendix D: Building 7 Wall 4..................................................................... 35

Appendix E: Bldg 15 Roof 3......................................................................... 38

Appendix F: Bldg 15 Roof 2........................................................................ 44

Appendix G: Bldg 15 Wall 1......................................................................... 50

Appendix H: Bldg 15 Wall 4......................................................................... 53
iv

List of Figures 

Fig. 1 ASCE roof and wall zones for wind loads............................................. 2

Fig. 2a, b Definition of tributary areas or cells for taps on a particular face ..............3

Fig. 3 Cell area combinations ..................................................................4

Fig. 4 Partial cell areas...........................................................................5

Fig. 5a, b Combination of areas with different tap density.. ................................5

Fig. 6a, b, c Bldg 7 roof 3 ASCE zone 1 interior (1 ft2= 0.0929 m2)......................8

Fig. 7a, b, c Bldg 7 roof 3 ASCE zone 2 lower edge (1 ft2= 0.0929 m2)................. 9

Fig. 8a, b Bldg 7 roof 3 ASCE zone 3 lower corner (1 ft2= 0.0929 m2)..................12

Fig. 9a, b Building 7 Wall 1 ASCE zone 5 left edge (1 ft2= 0.0929 m2)..................13

Fig. 10a, b Building 7 Wall 1 ASCE zone 4 interior (1 ft2= 0.0929 m2).................14

Appendix A: UWO Bldg 7 roof 3 

Fig. A1a, b Bldg 7 roof 3 ASCE zone 3 lower corner (1 ft2= 0.0929 m2) .................20

Fig. A2a, b, c Bldg 7 roof 3 ASCE zone 2 side edge (1 ft2= 0.0929 m2) ..................21

Fig. A3a, b, c Bldg 7 roof 3 ASCE zone 2 upper edge (1 ft2= 0.0929 m2) ............... 22

Fig. A4a, b Bldg 7 roof 3 ASCE zone 2 lower edge (1 ft2

= 0.0929 m2) .................. 24

Fig. A5a, b Bldg 7 roof 3 ASCE zone 1 interior (1 ft2= 0.0929 m2)...................... ..25

Appendix B: UWO Bldg 7 roof 2 

Fig. B1a, b UWO Bldg 7 roof 2 ASCE zone 2 side edge (1 ft2= 0.0929 m2)...............27

Fig. B2a, b UWO Bldg 7 roof 2 ASCE zone 2 top edge (1 ft2= 0.0929 m2) ...............28

Fig. B3a, b UWO Bldg 7 roof 2 ASCE zone 2 bottom edge (1 ft2= 0.0929 m

2

) ...........29

Fig. B4a, b UWO Bldg 7 roof 2 ASCE zone 1 interior (1 ft2= 0.0929 m2) .................30

Fig. B5a, b UWO Bldg 7 roof 2 ASCE zone 3 corners (1 ft2

= 0.0929 m2) .................31

Appendix C: Building 7 Wall 1 

Fig. C1a, b Building 7 Wall 1 ASCE interior (1 ft2= 0.0929 m2) ...........................32

Fig. C2a, b Building 7 Wall 1 ASCE right edge (1 ft2= 0.0929 m2)........................33

Fig. C3a, b Building 7 Wall 1 ASCE left edge (1 ft2= 0.0929 m2)..........................34

Appendix D: Building 7 Wall 4 

Fig. D1a, b Building 7 Wall 4 ASCE interior (1 ft2

= 0.0929 m2) ...........................35

Fig. D2a, b Building 7 Wall 4 ASCE left edge (1 ft2= 0.0929 m2) ..........................36

Fig. D3a, b Building 7 Wall 4 ASCE right edge (1 ft2= 0.0929 m2) ........................37

Appendix E: Bldg 15 Roof 3 

Fig. E1a, b Bldg 15 Roof 3 ASCE interior (1 ft2= 0.0929 m2) ..............................38

Fig. E2a, b Bldg 15 Roof 3 ASCE lower edge (1 ft2

= 0.0929 m2) ........................39

Fig. E3a, b Bldg 15 Roof 3 ASCE upper edge (1 ft2= 0.0929 m2) ..........................40

Fig. E4a, b Bldg 15 Roof 3 ASCE right edge (1 ft2= 0.0929 m2) ...........................41

Fig. E5a, b Bldg 15 Roof 3 ASCE lower corner (1 ft2= 0.0929 m2) ........................42

Fig. E6a, b Bldg 15 Roof 3 ASCE upper corner (1 ft2= 0.0929 m2) ........................43
v 

Appendix F: Bldg 15 Roof 2

Fig. F1a, b Bldg 15 Roof 2 ASCE interior (1 ft2

= 0.0929 m2) .................................44

Fig. F2a, b Bldg 15 Roof 2 lower edge (1 ft2= 0.0929 m2) ......................................45

Fig. F3a, b Bldg 15 Roof 2 upper edge (1 ft2

= 0.0929 m2) .....................................46

Fig. F4a, b Bldg 15 Roof 2 side edge (1 ft2= 0.0929 m2) ........................................47

Fig. F5a, b Bldg 15 Roof 2 lower corner (1 ft2= 0.0929 m2) ....................................48

Fig. F6a, b Bldg 15 Roof 2 upper corner (1 ft2= 0.0929 m2) ....................................49

Appendix G: Bldg 15 Wall 1 

Fig. G1a, b Bldg 15 Wall 1 Interior (1 ft2= 0.0929 m

2

) ..........................................50

Fig. G2a, b Bldg 15 Wall 1 left edge (1 ft2= 0.0929 m2)..........................................51

Fig. G3a, b Bldg 15 Wall 1 right edge (1 ft2= 0.0929 m2) .......................................52

Appendix H: Bldg 15 Wall 4 

Fig. H1a, b Bldg 15 Wall 4 Interior (1 ft2= 0.0929 m

2

) ..........................................53

Fig. H2a, b Bldg 15 Wall 4 left edge (1 ft2

= 0.0929 m2)..........................................54

Fig. H3a, b Bldg 15 Wall 4 right edge (1 ft2= 0.0929 m2) ........................................55
vi 

List of Tables 

Table 1 Results for Building 7 ........................................................................15

Table 2 Results for Building 15...................................................................... 16
Introduction 

Current ASCE 7-10 (American Society of Civil Engineers 2010) specifications of wind pressures 

on low-rise buildings are based on data that are thirty to forty years old. Advances in computer 

technology allow simultaneous recording of many more pressure taps (on the order of hundreds) 

than was possible a few decades ago. Furthermore, wind tunnel test measurements have become 

publicly available for considerably more building geometries. The most well-referenced publicly 

available sources of data are the National Institute of Standards and Technology (NIST 2004) 

database, which covers tests conducted at the University of Western Ontario (UWO, Ho et al. 

2003, 2003, 2005), and the Tokyo Polytechnic Institute (TPU, Tamura 2012) database. 

The main purpose of this study is to establish a clear and reproducible methodology for using a 

general wind tunnel test database, namely the NIST-UWO database, to calculate peaks of wind 

pressure over different size areas of building surfaces. The methodology is an essential 

component to updating wind pressure coefficients for the design of components and cladding, 

considering the deficiencies in current wind load specifications. A similar effort has been carried 

out with the TPU database (Gierson et al. 2015) with methodology based on the unique features 

of that database. 

Background 

Current ASCE 7-10 wind load provisions on components and cladding of low-rise buildings are 

largely based on the work of Stathopoulos (1979), supplemented by Meecham (1988) for hip 

roofs, and updated by Stathopoulos et al. (1999). Wind pressure on building enclosures continues 

to be an active area of research. 

Gavanski et al. (2013 a, b) tested 1:50 scale models of houses with gable or hip roofs and 

concluded that roof slope and upstream terrain had the most significant effect on wind loads 

acting on roof sheathing, and that ASCE 7-10 standards substantially underestimated wind 

pressures, more so for gable roofs than hip roofs. Pressure coefficients were averaged over the 

area of sheathing panels 4 ft × 8 ft (1.2 m × 2.4 m) and the Best Linear Unbiased Estimator 

(BLUE, Lieblein 1974) method was used to determine the peak pressure coefficients. Vickery et 

al. (2013) analyzed the same data and found that, for gable roof zone 1 (interior, Fig. 1), ASCE 

7-10 provisions were “woefully inadequate” for effective areas less than 50 ft2(5 m2), but could

be reduced for areas greater than 100 ft2(10 m2); for zone 2 (edges), ASCE 7-10 provisions

underestimated roof pressure for areas less than 100 ft2

(10 m2), but were adequate for larger

areas. For zone 3 (corners), Vickery et al. (2013) suggested that the ASCE 7-10 minimum area of

10 ft2 (1 m2) was too large because of the large pressure gradients at roof corners.

Gavanski and Uematsu (2014) analyzed wind pressure on walls of low-rise buildings and 

concluded that zoning for positive pressure is unnecessary as pressure was approximately 

uniform over the entire wall surface. For roof slopes less than 14°, positive wall pressures 

increased slightly as the roof slope decreased. For negative pressures, larger suctions were 

observed at the wall edges than in the interior, as expected, and the width of these higher suction 

zones increased with roof slope and eave height. ASCE 7-10 provisions underestimated positive 

pressures for almost all effective areas by a factor of 1.2 to 1.5. A similar tendency was found 

1
for negative pressures, though not for all building geometries. In fact, for several geometries, 

ASCE 7-10 provisions overestimated wall pressures on large effective areas. 

Under the sponsorship of the NIST, the University of Western Ontario (UWO) conducted wind 

tunnel tests on thirty seven different buildings of one basic type: rectangular in plan; gable roofs 

with various slopes and no overhang; and open country and suburban terrain conditions (Ho et al. 

2003, 2003, 2005). The roof slope ranged from 1⁄4:12 (1.2°) to 6:12 (26.6°), the building width 

from 30 ft (9.14 m) to 160 ft (48.80 m), the building length from 45 ft (13.70 m) to 200 ft (61.0 

m), and the eave height from 12 ft (3.66 m) to 40 ft (12.20 m). These test results underpinned the 

Database-Assisted Design (DAD) method for Main Wind Force Resisting Systems (Main and 

Fritz 2006, Habte, Chowdhury and Park 2015) and were used in the current study. 

Methodology

Herein, the methodology is developed around the NIST-UWO database, and results for two 

buildings are presented in the appendices, with illustrations excerpted in the main text for 

explanation purposes. 

1. Within NIST-UWO wind tunnel database, select the building, roof or wall zones to study.

Zones currently defined in ASCE 7-10 (Fig. 1) are investigated. For wind loads, ASCE 7-

10 divides a gable roof, with slope not exceeding 7°, into four corner zones (zone 3) of

side a, four edge zones (zone 2) of width a running along the edges, excluding the

corners, and an interior zone (zone 1), which is the rest of the gable. a is defined as 10

% of the least horizontal dimension of the building, or 0.4 h, whichever is smaller, but not

less than either 4 % of the least horizontal dimension or 3 ft (0.9 m). h is the eave height

(or the mean roof height when the roof slope exceeds 10°). For walls, two edge zones

(zone 5) of width a are defined, and the rest of the wall is called zone 4.

Fig. 1 ASCE roof and wall zones for wind loads 

(adapted from ASCE 7-10 Figs. 30.4-1 and 30.4-2A by M. Gierson)

2. The aerodynamic pressures induced on a structure by the wind field are random both in

time and space. The randomness in space means that, at any given time, the pressures

2
differ from point to point, that is, the spatial coherence of the pressures at any two points 

decreases as the distance between those points increases. For design purposes the 

pressure on any given area A is, therefore, a function of A, and is defined as the 

aerodynamic force acting on area A divided by A. That aerodynamic force is obtained by 

summing up the product of pressure time series measured in wind tunnel tests at 

adjoining pressure taps by their respective tributary areas or cells. Cell boundaries are 

straight lines equidistant to adjacent taps, but taps are at the center of cells only in a 

regular grid (Fig. 2). The area A is the sum of those tributary areas. These operations 

were carried out for all sums of tributary areas that make up rectangles. 

Fig. 2 Definition of tributary areas or cells for taps on a particular face: a) simple tap 

array; b) more complicated tap array with varying tap density (from Main and Fritz 2006) 

The summation of tributary areas is simplest when the grid of taps is regular, and that is 

explained in Fig. 3. Special consideration must be given to the study zone edges and 

corners, which generally do not coincide with cell boundaries; and to places where grids 

of different densities merge (indicated by arrows in Fig. 2b). These situations are 

explained in Figs. 4 and 5. 

Figure 3 illustrates a case where the zone of interest only includes six cells. The area 

summation procedure starts with the step denoted by Aa, which consists of the selection 

of one cell on the upper left corner. This is the first rectangle where the number of cells is 

the same in both coordinate directions, denoted by s and y. The next step, denoted by 

Aa2, consists of adding a cell in the y direction downward. With this step the lower 

boundary of the zone is reached; therefore no additional cell can be added in direction y. 

To the cell selected in step Aa is added one cell in direction s, rightward, in step Aa3,1. In 

a next step, denoted by Aa3,2, an additional cell is added, again in direction s, rightward. 

Thus two additional rectangles have been created in step Aa3. With step Aa3,2 the 

rightmost boundary of the zone has been reached, so further expansion in the direction s 

is not possible. Next, step Ab consists of adding to the cell selected in step Aa via 

expansion in both directions y downward and s rightward. Thus a rectangle consisting of 

four cells is created. Expansion in the direction y downward is attempted in step Ab2, but 

is not possible. Step Ab3 consists of expanding in the s direction rightward, which results 

in a six-cell rectangle. All possibilities of expansion from the single cell selected in step 

Aa being exhausted, one proceeds to the next initial cell (step Ba). The procedure is 

repeated until all possible initial cells have been used. Figure 3 shows six rectangles 

formed by one cell, seven rectangles formed by two cells, two rectangles formed by 

3
Fig. 3 Cell area combinations 

three cells, two rectangles formed by four cells, and one rectangle formed by six cells, 

for a total of eighteen rectangles. 

To limit the number of combinations of ai, the aspect ratio of the rectangles formed by 

the aggregation of cells is limited not to exceed 4. This aspect ratio covers many 

practical units of components and cladding, and allows consideration of long, narrow 

zones along the edges of roofs and walls. This choice also covers all “effective wind 

areas used to evaluate (GCp)”, whose width, according to the Commentary of ASCE 7-

10, “need not be taken as less than one-third of the length of the area. This increase in 

effective wind area has the effect of reducing the average wind pressure acting on the 

component.” How the aspect ratio of rectangular areas affect the peak area-averaged 

pressure will be discussed further in the results section. 

Partial cells may be necessary and are accounted for at the edges and the corners of the 

study zone being considered. In Figs. 4 and 5 the black lines represent the cell 

boundaries. In Fig. 4, a corner of the zone being studied is colored and includes one full 

cell and three partial cells. The pressures in the partial cell areas are the same as in the 

three full cells from which the partial cells are formed. The partial areas are considered 

when calculating weighted average pressures. 

If the zone being studied overlaps areas of different tap density, the coarser density is 

used overall, and full and partial cell areas in the high density region are combined as 

needed. Figure 5a shows a portion of a study zone, with two grid densities. To conform 

with the coarser grid, the two rows of three cells each at the bottom of the figure are 

transformed into two rectangles each (Fig. 5b). 

4
Fig. 4 Partial cell areas Fig. 5a, b Combination of areas with different tap density

3. Database-Assisted Design (DAD) software (Main and Fritz 2006) was supplemented by densities

software developed as part of this project to calculate the time series of wind pressure

coefficients Cp3600 on area A = ∑ aifor each specified wind direction. The time series

is the area-weighted average of pressure coefficients Cpi calculated from wind pressures

pi measured by taps with their tributary areas ai that overlap with the zone being

studied. Typically, there are many combinations of aifor the same value of A. As the

peak of the sum is less than the sum of the peaks of several time series, the peak pressure

decreases as the area increases. In physical terms, the spatial correlation of pressure peaks

as measured by the taps decreases as the area increases, resulting in lower peak pressures

over larger areas. pi, Cpi, and Cp3600 are functions of time and wind direction.

Cpi =

pi − p0

1⁄2 ρ V3600

2

; Cp3600 =

∑(ai Cpi)

∑ ai

p0 = static pressure at reference height (roof eave); 

V3600 = mean hourly wind speed at reference height; 

ρ = air density. 

4. For each area combination A = ∑ ai, use Rice’s zero up-crossing method adapted to nonGaussian time series (Sadek and Simiu 2002, Main 2011) to calculate minima and

maxima over time of Cp for a 60-minute (full scale) windstorm. The Sadek-Simiu method

uses the Gamma distribution and a normal distribution to estimate the peaks

corresponding, respectively, to the upper and lower tails of the time series’ histograms.

The peak distribution is represented by the Extreme Value Type I (Gumbel) distribution,

and the values selected correspond to the mean of this distribution applied to the upper

and lower tails. The extension of test results to a longer time than the test duration

converted to full scale is discussed in more detail in the next section.

The selection of peaks (in absolute value) of minima (negative pressure or suction) and 

maxima (positive pressure inward) of Cp for each area combination A = ∑ airesults in

two vectors of minima and maxima versus A for each wind direction. The gust effect 

factor G accounts for the variability of the pressure coefficient due to the randomness of 

the aerodynamic response and is introduced implicitly when the averaging process and 

the peak selection process are applied (Simiu, 2011). The peak pressures are functions of 

wind direction. 

5. Repeat for all wind directions tested. This results in two matrices of minima and maxima

of GCp for various areas and wind directions. From these two matrices, select two

vectors of peaks over all wind directions of minima and maxima of GCp vs. A.

5
6. Renormalize results to 3-s wind gust speed V3 as in ASCE 7-10 using the Durst (1960)

curve.

GCp ≡ GCp3 = GCp3600 (

V3600

V3

)

2

= GCp3600 (

1

1.52)

2

Durst (1960) estimated the uncertainty in his calculations of wind gust speed over 

durations shorter than one hour to be “about one mile per hour” (0.4 m/s). For a mean 

hourly wind speed of 80 mph (36 m/s), Durst (1960) calculated the 5-s wind gust speed to 

be 118 mph (53 m/s). The ratio of the 5-s wind gust speed to the hourly wind speed is 

(118 ± 1) / 80 = 1.475 ± 0.012. The uncertainty for the ratio 1.52 of the 3-s gust speed to 

the hourly wind speed can be considered to be ± 0.01.

7. Repeat for other zones, terrains and buildings.

Note there are two consecutive steps in the selection of the peak wind pressures for 

design purposes: selection of peaks over time (step 4), and selection of peaks over all 

wind directions (step 5). The selection of the peaks over all wind directions is inherent in 

the envelope method, as defined in the ASCE 7 Standard. Finally, the peaks 

corresponding to the most unfavorable combination of cells forming various areas A are 

chosen for the development of design specifications. 

Duration ratio 

The Sadek-Simiu (2002) method uses a duration ratio that is explained by the following 

example. The University of Western Ontario wind tunnel tests a 1/100 model of size Dm = 6.0 in 

(0.152 m), by exposing it to mean wind speed Vm = 30.0 ft/s (9.144 m/s) in open country, for a 

duration Tma = 100 s. The mean wind speed is calculated over the duration of the test, and is 

measured at a reference height (href = 6.8 ft × 100 = 680 ft = 207.26 m full scale), then 

converted to eave height (H = 40 ft = 12.19 m) by the relationship (Ho, Surry and Morrish 

2003. For a discussion of this power law and various values of the exponent proposed over the 

years, see Simiu and Scanlan 1996 p. 46): 

VH

Vref = ( H

href)

1 7. ⁄ 446

These data are used to design a building of size Dp = 50 ft (15.2 m) for a region with 3-s gust 

speed of 140 mi/h (225 km/h) measured at 33 ft (10 m) elevation. The hourly wind speed is 

(140 mi⁄h) 1. ⁄ 52 = 92.11 mi⁄h = 135.09 ft⁄s = 41.17 m/s. The 33 ft (10 m) elevation is 

close enough to the eave height that no correction is required. Scaling laws require (Simiu and 

Scanlan 1996): 

(

D

VT)

m

= ( D

VT)

p

where subscripts m and p stand for model and prototype respectively. Thus: 

6
Tm = Tp

Dm

Dp

Vp

Vm

= 3600

1

100

135.09

30.0 = 162 s

The following duration ratio must be applied in the extreme value procedure to obtain the proper 

estimate for peak wind gusts: 

Tm

Tma

=

162 s

100 s

= 1.62

Results 

Results are shown for two buildings in the UWO-NIST database, Building 7 (data set jp1) and 

Building 15 (data set eh1), tested in open country. Both buildings were modelled at a scale of 

1:100, and data were collected for 100 s at 500 Hz. 

Building 7 (Fig. 6c) is 40 ft (12.19 m) wide, 62.5 ft (19.05 m) long, 40 ft high (12.19 m, eave 

height) and has a roof slope of 1:12 (4.8°). It was tested for wind directions ranging from 0° to 

90° and 270° to 360° every 5°. Due to building symmetry, only half of all possible wind 

directions need to be investigated. In Fig. 6c, 0° and 90° are in the +y and the +x directions 

respectively. Results are summarized in Table 1 and graphed in appendices A to D. Selected 

results covering ASCE zones 1 to 5 are discussed in this section. 

Building 15 (Fig. E1b, Appendix E) is 80 ft (24.38 m) wide, 125 ft (38.10 m) long, 40 ft high 

(12.19 m, eave height) and has a roof slope of 1:12 (4.8°). It was tested for wind directions 

ranging from 180° to 360° every 5°. Results are summarized in Table 2 and graphed in 

appendices E to H. 

Figure 6c (the appendices show complete sets of results, so Fig. 6 is also Fig. A5, Appendix A) 

shows an outline of Building 7, with dimensions in feet. Pressure sensors, or taps, are shown on 

half of the gable roof (called roof 3 here), and the interior zone (defined in ASCE 7-10 as zone 1) 

being investigated is delineated by blue lines. The area combination scheme of rectangles with 

aspect ratio less than or equal to 4 is used, and is also specialized to the case of squares (aspect 

ratio 1) that cover at least 4 taps. This last scheme has been used by other researchers (Morrison 

2015). Each area combination results in a maximum and a minimum pressure coefficient (Figs. 

6a, b). The current ASCE 7 specifications are plotted for comparison (+ means positive maxima, 

- means negative minima).

Figure 6a shows the current ASCE specifications underestimate negative pressures by a factor 

ranging from 1.3 for larger areas close to 1000 ft2

(100 m2) to 2.5 for smaller areas of 10 ft2

(1 m

2

) or less. The square area scheme also captures the same trend, albeit at fewer area

combinations, as expected. Limiting the data areas including at least four taps results in a lower 

limit of 37 ft2(3.4 m2), compared with the area of 10 ft2(1 m

2

) below which ASCE specifies the

pressure coefficients to remain constant. ASCE underestimates positive pressures by a factor of 

2.0 for areas between 5 ft2

(0.5 m2) and 30 ft2(3m2), but the pressures are small, and the ASCE

specifications are acceptable for larger areas. Figure 6b will be discussed later in a separate 

section on aspect ratio. 

7
-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1 10 100 1000

GCp

Area ft^2

Bldg 7 roof 3 ASCE zone 1 interior >= 4 tap squares min

>= 4 tap squares Max

ASCE zone 1-

ASCE zone 1+

min

Max

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

0 0.5 1 1.5 2 2.5 3 3.5 4

GCp

Aspect ratio y/s

Bldg 7 roof 3 ASCE zone 1 interior

Max

min

8
Fig. 6a, b, c Bldg 7 roof 3 ASCE zone 1 interior (1 ft2

= 0.0929 m2)

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1 10 100

GCp

Area ft^2

Bldg 7 roof 3 zone 2 ASCE bottom edge

ASCE zone 2+

ASCE zone 2-

4x4 by 1 Max

4x4 by 1 min

2x2 by 1 Max

2x2 by 1 min

3x3 by 1 Max

3x3 by 1 min

Max

min

9
Fig. 7a, b, c Bldg 7 roof 3 ASCE zone 2 lower edge (1 ft2

= 0.0929 m2)

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

0 1 2 3 4

GCp

Aspect ratio s/y

Bldg 7 roof 3 zone 2 ASCE bottom edge

Max

min

10
One particularly attractive feature of the NIST-UWO database is the high density of pressure 

taps on one part of the roof. This allows high resolution in edge and corner zones, shown in Figs. 

7 and 8 for Building 7, roof 3 (in the DAD software, the roof gables are numbered 2 and 3, and 

the side walls 1 and 4. The DAD software focuses on structural response in the transverse 

direction x and does not use the end wall pressure data). The upper corner of roof 3 (x = 40, 

y = 62.5) does not have a sufficient number of taps for meaningful results. 

Figure 7 (also Fig. A4, Appendix A) shows the results for the roof edge on the windward side in 

the UWO tests. Observations are consistent with those regarding the interior zone just discussed. 

For negative pressures, current ASCE specifications underestimate the measurements by a factor 

ranging from 1.6 for the larger areas (60 ft2or 6 m2) to 2.2 for the smaller areas (2 ft2 or 0.2 m2).

ASCE underestimates positive pressures by a factor of 1.7 for areas smaller than 3 ft2 (0.3 m2),

but the pressures are small, and the ASCE specifications are acceptable for larger areas. The 

notation “2×2 by 1 min” indicates negative pressures (or minima) estimated from square areas 

with a 2×2 arrangement of pressure taps, with the squares being shifted by 1 ft (0.30 m) in 

consecutive steps in both directions of the planar surface to cover all possible areas within the 

study zone. Similar notation holds for the maxima and other size squares. 

Figure 8 (also Fig. A1, Appendix A) shows that ASCE specifications underestimate negative 

pressures over virtually all of the areas within the corner zone, by up to a factor of 2.3. For areas 

that include at least four taps, the underestimation is by 1.5. On the other hand, positive pressure 

specifications are adequate. This corner is on the windward side in the UWO tests. 

Figure 9 (also Fig. C3, Appendix C) shows results for the left edge, part of ASCE zone 5, of 

Wall 1 of Building 7. ASCE underestimates negative pressures and positive pressures by a factor 

of 1.6. Note the tap density is not high in this zone, which is less than two-cell wide. The peaks 

of negative pressure occur for wind directions between 50° and 65°, and the peaks of positive 

pressures occur for wind directions of 10° (0° is +y and 90° is +x). Since the tests were conducted 

only for wind directions between 0° and 90° and 270° and 360°, the corresponding peaks for both 

positive and negative pressure were missed for the right edge of Wall 1, as a comparison of 

Figs. C2 and C3, Appendix C, confirms.

Fig. 10 (also Fig. C1, Appendix C) shows that for the interior, zone 4, of Wall 1 of Building 7, 

ASCE 7-10 specifications underestimate negative pressures by a factor ranging from 1.2 for 

areas of 1100 ft2

(110 m2) to 1.9 for areas 60 ft2 (6 m2); and underestimate positive pressures by

a factor of 1.8 over all areas. The rest of the results are summarized in Table 1 for Building 7, 

and Table 2 for Building 15. 

Aspect ratio 

The choice of aspect ratios of 4 or less makes more effective use of the UWO data than, say 3 or 

less. Results show a slight decreasing trend of GCp as the aspect ratio increases (Figs. 6b, 7b, 

A2b, A3b, A4b and A5b). This is true for edge zones as well as interior zones, and validates the 

ASCE 7-10 Commentary. The envelope of GCp is not affected by extending the aspect ratio from 

3 to 4. (It had been expected that, along the edges of roofs and walls, and for certain wind 

11
Fig. 8a, b Bldg 7 roof 3 ASCE zone 3 lower corner (1 ft2

= 0.0929 m2)

-6.5

-5.5

-4.5

-3.5

-2.5

-1.5

-0.5

0.5

1 10 100

GCp

Area ft^2

Bldg 7 roof 3 ASCE zone 3 lower corner

Max

min

4-tap squares min

4-tap squares Max

ASCE zone 3 -

ASCE zone 3 +

12
Fig. 9a, b Building 7 Wall 1 ASCE zone 5 – left edge (1 ft2

= 0.0929 m2)

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

1 10 100

GCp

Area ft^2

Bldg 7 Wall 1 left edge

Max

min

ASCE Max

ASCE min

13
Fig. 10a, b Building 7 Wall 1 ASCE zone 4 - interior (1 ft2

= 0.0929 m2)

-2

-1.5

-1

-0.5

0

0.5

1

1.5

10 100 1000 10000

GCp

Area ft^2

Bldg 7 Wall 1 ASCE interior

min

Max

ASCE +

ASCE -

14
Table 1 Results for Building 7 

(ASCE underestimates by n means the ratio of the envelope 

of the data to the ASCE specification for that area is n.) 

Fig. part zone - pressure + pressure

A1

8

Roof 

3

Lower 

corner

ASCE underestimates by 1.5 for A > 4 

cells, by 2.3 for smaller areas.

ASCE acceptable.

A2 Roof 

3

Side 

edge

ASCE underestimates by 1.8 for A = 

70 ft2(7 m2) to 2.0 for A = 7 ft2(0.7 m2).

ASCE acceptable. 

A3 Roof 

3

Upper 

edge

ASCE underestimates by 1.1.

This edge is on the leeward side.

ASCE acceptable 

A4

7

Roof 

3

Lower 

edge

ASCE underestimates by 1.6 for larger 

areas (60 ft2or 6 m2) and 2.2 for smaller 

areas (2 ft2or 0.2 m2).

ASCE underestimates by 1.7 for 

A ≤ 3 ft2(0.3 m

2

), acceptable for 

larger areas.

A5

6

Roof 

3

Interior ASCE underestimates by 1.3 for 

A = 1000 ft2(100 m2) to 2.5 for 

A = 10 ft2(1 m2)

ASCE underestimates by 1.7 for 

5 ft2≤ A ≤ 30 ft2 

(0.5 m2≤ A ≤ 3 m2)

B1 Roof 

2

Side 

edge

ASCE underestimates by 1.8 for 

A = 70 ft2(7 m2) to 2.0 for 

A = 7 ft2(0.7 m

2

).

ASCE acceptable

B2 Roof 

2

Upper 

edge

ASCE acceptable.

This edge is on the leeward side.

ASCE acceptable 

B3 Roof 

2

Lower 

edge

ASCE underestimates by 1.5 for 

A = 70 ft2(7 m2) to 2.0 for A = 7 ft2

(0.7 m

2

). 

ASCE acceptable 

B4 Roof 

2 

Interior ASCE underestimates by1.3 for 

A = 1000 ft2(93 m2) to 2.5 for 

A = 8 ft2(0.8 m

2

).

ASCE acceptable 

B5 Roof 

2

Corners ASCE underestimates by 1.6 for 

A = 5 ft2 (0.5 m2), acceptable for 

A ≥ 10 ft2 (1 m2).

ASCE acceptable 

The lower corner, on the windward side, records higher suction than the upper corner.

C1

10

Wall 

1

Interior ASCE underestimates between 1.2 for 

A = 1100 ft2(110 m2) and 1.9 for 

A = 60 ft2(6 m2).

ASCE underestimates by 1.8

C2 Wall 

1

Right 

edge

ASCE underestimates by 1.2. ASCE acceptable 

The most demanding wind directions are not tested for the right edge.

C3

9

Wall 

1

Left 

edge

ASCE underestimates by 1.6.

- peaks for wind between 50° and 65°.

ASCE underestimates by 1.6.

+ peaks for wind directions of 10°.

D1 Wall 

4

Interior ASCE underestimates by 2.1 for A = 

20 ft2 (2 m2), 1.4 for A = 1000 ft2

(90 m

2

). Linear trend of log A in 

between.

ASCE underestimates by 1.8 for A 

= 20 ft2(2 m2), 2.0 for A = 500 ft2

(50 m2).

D2 Wall 

4

Left 

edge

ASCE underestimates by 1.6.

- peaks for wind between 330° and 360°.

ASCE underestimates by 1.6.

+ peaks between 290° and 335°.

D3 Wall 

4

Right 

edge

ASCE underestimates by 1.2. ASCE overestimates by 1.2.

The most demanding wind directions are not tested for the right edge.

15
Table 2 Results for Building 15 

Fig. part zone - pressure + pressure

E1 Roof 

3

Interior ASCE acceptable for A = 3000 ft2(300 m2), 

underestimates by 2.5 for A = 10 ft2(1 m2). 

Linear trend of log A in between.

ASCE acceptable

E2 Roof 

3

Lower 

edge

ASCE underestimates by 1.5 for A = 200 ft2

(20 m2), by 2.2 for A = 8 ft2(0.8 m2). Linear 

trend of log A in between.

ASCE acceptable

E3 Roof 

3

Upper 

edge

ASCE underestimates by 1.4 for A = 200 ft2

(20 m2), by 1.7 for A = 10 ft2(1 m

2

). Linear 

trend of log A in between.

ASCE acceptable

E4 Roof 

3

Side

edge

ASCE underestimates by 1.5 for A = 200 ft2

(20 m2), by 1.7 for A = 10 ft2(1 m2). Linear 

trend of log A in between. 

ASCE acceptable

E5 Roof 

3

Lower 

corner

ASCE underestimates by 1.4 for A = 60 ft2

(6 m

2

), by 1.8 for A = 7 ft2(0.7 m

2

).

ASCE acceptable

E6 Roof 

3

Upper 

corner

ASCE underestimates by 1.7 for A ≥ 20 ft2

(2 m

2

), by 1.2 for A = 8 ft2(0.8 m

2

).

ASCE acceptable

F1 Roof 

2

Interior ASCE overestimates by 2.0 for A = 2000 ft2

(200 m2), underestimates by 2.2 for A = 30 ft2

(3 m2). Linear trend of log A in between.

ASCE acceptable

F2 Roof 

2

Lower 

edge

ASCE underestimates by 1.2 for A = 200 ft2

(20 m2), by 1.5 for A = 15 ft2(1.5 m2).

ASCE acceptable

F3 Roof 

2

Upper

edge

ASCE underestimates by 1.2 for A = 200 ft2

(20 m2), by 1.4 for A = 7 ft2(0.7 m2). 

ASCE acceptable

F4 Roof 

2 

Side

edge

ASCE underestimates by 1.2. ASCE acceptable

F5 Roof 

2

Lower

Corner

ASCE underestimates by 1.3 for A = 70 ft2 

(7 m2) to 1.5 for A = 12 ft2(1.2 m

2

).

ASCE overestimates by 2.5, 

but pressures are small.

For lower corner, -peaks for wind at 360°, +peaks for wind between 180° and 260°.

Symmetrical directions were covered for upper corner.

F6 Roof 

2

Upper

Corner

ASCE overestimates by 1.6 for A < 10 ft2

(1 m

2

).

ASCE overestimates by 2.5, 

but pressures are small.

G1 Wall 

1

Interior ASCE overestimates by 1.3 for A = 4000 ft2

(400 m2), underestimates by 2.0 for A = 60 ft2

(6 m2). Linear trend of log A in between.

Negligible on leeward side.

Wall 1 is on leeward side.

G2 Wall 

1

Left 

edge

ASCE underestimates by 1.4. Negligible on leeward side.

G3 Wall 

1

Right 

edge

ASCE underestimates by 1.3. Negligible on leeward side.

H1 Wall 

4

Interior ASCE overestimates by 1.8 for A = 3000 ft2

(300 m2), underestimates by 2.4 for A = 60 ft2

(6 m2).

ASCE underestimates by 2.0 

for A = 1000 ft2(100 m2), by 

1.6 for A = 60 ft2(6 m2).

H2 Wall 

4

Left 

edge

ASCE underestimates by 1.4 ASCE underestimates by 1.5.

H3 Wall 

4

Right 

edge

ASCE underestimates by 1.4. ASCE underestimates by 1.7.

16
directions, the spatial coherence of wind pressure may extend over longer shapes than those 

mentioned in the Commentary.) 

Uncertainty 

The design of buildings for wind involves many uncertainties in the micrometeorological, wind 

climatological and aerodynamic elements that determine wind loads (see, e.g., Simiu 2011, p. 

229, Duthinh and Simiu 2011). A fundamental difficulty in achieving reproducible wind tunnel 

measurements of wind effects, especially on low-rise buildings, is the simulation of atmospheric 

flows (Simiu, 2009). Ho et al. (2003, 2003, 2005) discussed the methodology used in the NISTUWO tests in modelling the terrain, characterizing the modelled wind, and measuring wind 

pressures by a tubing system. They found it difficult to arrive at an overall uncertainty factor, 

but they compared wind tunnel measurements to full scale measurements of a building at Texas 

Tech University (TTU), and concluded that “mean pressures compared well”, but root mean 

square “rms pressures... showed significant differences.”

In the analysis of the wind pressure data, it was discovered that a few pressure taps 

malfunctioned, and their records have been replaced by the average of neighboring taps. The 

area-averaging method is not unique, but similar methods produced comparable results (Gierson 

et al. 2015, Morrison 2015). 

Finally, statistics is an essential element in the definition of wind effects for design purposes, 

especially for the determination of peak wind pressures induced by a given wind speed. For the 

Sadek-Simiu method used here, the goodness of the peak estimation depends on the goodness of 

fit of the distributions to the peaks of the tails of the time series. A future publication that 

discusses alternative methods, using the Generalized Extreme Value distribution, is planned. 

Conclusion 

This note presents a methodology used to exploit wind tunnel pressure measurements to arrive at 

graphs of peak positive and negative pressure coefficients corresponding to various areas over all 

wind directions. Such plots will eventually lead to specifications required for the design of 

components and cladding by the envelope method. According to the results shown here for two 

buildings and one terrain exposure, the negative wind pressure coefficients (suction) specified by 

ASCE 7-10 for gable roofs of low-rise buildings are too small, by factors ranging from 1.3 to 

2.5, whereas the positive coefficients appear adequate. For walls, both positive and negative 

pressures are underestimated by current ASCE specifications, by factors ranging from 1.5 to 2.0

and 1.2 to 2.4, respectively. Future work will include the checking of these conclusions by using 

alternative methods for the estimation of peaks. 

All buildings in the NIST-UWO database are being investigated, together with those in other 

publicly available databases such as the Tokyo Polytechnic Institute (Gierson et al. 2015). Only 

at the conclusion of the study can more definitive recommendations be made, including possibly 

changes in the number, size, shape and location of the various wind pressure zones, together with 

their associated pressure coefficients. This will be the subject of a future paper. 

17
References 

ASCE 7-10 (2010) “Minimum Design Loads for Buildings and Other Structures,” American 

Society of Civil Engineers, Reston, VA 

Durst, C.S. (1960) “Wind Speeds Over Short Periods of Time,” Meteor. Mag. 89, 181-187

Duthinh, D. and Simiu, E. (2011) “The Use of Wind Tunnel Measurements in Building Design,” 

Wind Tunnels and Experimental Fluid Dynamics Research, Jorge Colman Lerner and Ulfilas 

Boldes (Eds.), Ch. 13, pp. 281-300, InTech - Open Access, DOI: 10.5772/18670

Gavanski, E., Kordi, B., Kopp, G.A. and Vickery, P.J. (2013a) “Wind Loads on Roof Sheathing 

of Houses,” J. Wind Eng. & Ind. Aerodyn., 114, 106-121 

Gavanski, E., Kopp, G.A. and Vickery, P.J. (2013b) “Roof Sheathing Wind Loads on WoodFrame Residential Houses,” 12th Americas Conf. on Wind Eng. (12ACWE), Seattle, WA, June

Gavanski, E. and Uematsu, Y. (2014) “Local Wind Pressures Acting on Walls of Low-Rise 

Buildings and Comparisons to the Japanese and US Wind Loading Provisions,” J. Wind Eng. & 

Ind. Aerodyn., 132, 77-91

Gierson, M.L., Phillips, B.M. and Duthinh, D. (2015) “Evaluation of ASCE 7-10 Wind Velocity 

Pressure Coefficients on the Components and Cladding of Low-rise Buildings Using Recent 

Wind Tunnel Testing Data,” 6th Int. Conf. on Advances in Experimental Structural Engineering, 

and 11th Int. Workshop on Advanced Smart Materials and Smart Structural Technology, 

Urbana, IL 

Habte, F., Chowdhury, A. G. and Park, S. (2015) “The Use of Demand-to-Capacity Indexes for 

the Iterative Design of Rigid Structures for Wind,” NIST Technical Note, National Institute of 

Standards and Technology, Gaithersburg, MD 

Ho, T.C.E., Surry, D., and Morrish, D. (2003) “NIST/TTU Cooperative Agreement – Windstorm 

Mitigation Initiative: Wind Tunnel Experiments on Generic Low Buildings” University of 

Western Ontario, London, ON, Canada 

Ho, T.C.E., Surry, D., and Nywening, M. (2003) “NIST/TTU Cooperative Agreement –

Windstorm Mitigation Initiative: Further Experiments on Generic Low Buildings” University of 

Western Ontario, London, ON, Canada 

Ho, T.C.E., Surry, D., Morrish, D., and Kopp, G.A. (2005) “The UWO Contribution to the NIST 

Aerodynamic Database for Wind Loads on Low Buildings Part 1: Archiving Format and Basic 

Aerodynamic Data” J. Wind Eng. Ind. Aerodyn., 93 (1),1-30 

Lieblein, J. (1974) “Efficient Methods of Extreme Value Methodology,” NBSIR74-602, National 

Bureau of Standards, Washington, DC 

18
Main, J.A. (2011) “Special-Purpose Software: MATLAB Functions for Estimation of Peaks from 

Time Series,” www.itl.nist.gov/div898/winds/homepage.htm, National Institute of Standards and 

Technology, Gaithersburg, MD 

Main, J. and Fritz, W.P. (2006) “Database-Assisted Design for Wind: Concepts, Software, and 

Examples for Rigid and Flexible Buildings,” NIST Building Science Series 180, National 

Institute of Standards and Technology, Gaithersburg, MD 

Meecham, D. (1988) “Wind Action on Low-Rise Buildings,” M.E.Sc. Thesis, The University of 

Western Ontario, London, ON, Canada 

Morrison, M. (2015) “Wind Pressure on Cladding of Low-Rise Buildings,” private 

communication 

NIST (2004) “Extreme Winds and Wind Effects on Structures” (Aerodynamic Database for 

Rigid Buildings) www.itl.nist.gov/div898/winds/homepage.htm, National Institute of Standards 

and Technology, Gaithersburg, MD, created 03/05/2004, last updated 05/22/2015, last accessed 

09/04/2015 

Sadek, F. and Simiu, E. (2002) “Peak Non-Gaussian Wind Effects for Database-Assisted LowRise Building Design,” ASCE J. Eng. Mech. 128 (5), 530-539, May 

Simiu, E. (2011) “Design of Buildings for Wind,” 2nd ed. John Wiley, Hoboken, N.J.

Simiu, E. (2009). "Toward A Standard on the Wind Tunnel Method," NIST Technical Note 

1655, National Institute of Standards and Technology, Gaithersburg, MD 

Simiu, E. and Scanlan, R.H. (1996) “Wind Effects on Structures,” 3rd ed. Wiley, New York, N.Y.

Stathopoulos, T. (1979) “Turbulent Wind Action on Low-Rise Buildings,” Ph.D. Thesis, The 

University of Western Ontario, London, ON, Canada 

Stathopoulos, T., Wang, K. and Wu, H. (1999) “Wind Standard Provisions for Low-Building 

Gable Roof Revisited,” 10th Int. Conf. on Wind Eng., Copenhagen, Denmark, 155-162

Tamura, Y. (2012) “Aerodynamic Database for Low-Rise Buildings,” (Database) Global Center 

of Excellence Program, Tokyo Polytechnic University, Tokyo, Japan 

Vickery, P.J., Kopp, G.A. and Twisdale, L.A. (2013) “Component and Cladding Wind Pressures 

on Hip and Gable Roofs: Comparisons to the US Wind Loading Provisions,” 12th Americas

Conf. on Wind Eng. (12ACWE), Seattle, WA, June 

19
Appendix A Building 7, roof 3

Fig. A1a, b Bldg 7 roof 3 ASCE zone 3 lower corner (1 ft2= 0.0929 m2)

-6.5

-5.5

-4.5

-3.5

-2.5

-1.5

-0.5

0.5

1 10 100

GCp

Area ft^2

Bldg 7 roof 3 ASCE zone 3 lower corner

Max

min

4-tap squares min

4-tap squares Max

ASCE zone 3 -

ASCE zone 3 +

20
-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1 10 100

GCp

Area ft^2

Bldg 7 roof 3 ASCE zone 2 side edge

Max

min

4 x 4 by 1 Max

4 x 4 by 1 min

3 x 3 by 1 Max

3 x 3 by 1 min

2 x 2 by 1 Max

2 x 2 by 1 min

ASCE zone 2 +

ASCE zone 2-

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

0 1 2 3 4 5

GCp

Aspect ratio y/s

Bldg 7 roof 3 ASCE zone 2 side edge

Max

min

21
Fig. A2a, b, c Bldg 7 roof 3 ASCE zone 2 side edge (1 ft2

= 0.0929 m2)

-2

-1.5

-1

-0.5

0

0.5

1 10 100

GCp

Area ft^2

Bldg 7 roof 3 ASCE zone 2 upper edge

Max

min

4-tap squares min

4-tap squares Max

ASCE zone 2 +

ASCE zone 2 -

22
Fig. A3a, b, c Bldg 7 roof 3 ASCE zone 2 upper edge (1 ft2

= 0.0929 m2)

-2

-1.5

-1

-0.5

0

0.5

0 1 2 3 4

GCp

Aspect ratio s/y

Bldg 7 roof 3 ASCE zone 3 upper edge

Max

min

23
-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1 10 100

GCp

Area ft^2

Bldg 7 roof 3 zone 2 ASCE bottom edge

ASCE zone 2+

ASCE zone 2-

4x4 by 1 Max

4x4 by 1 min

2x2 by 1 Max

2x2 by 1 min

3x3 by 1 Max

3x3 by 1 min

Max

min

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

0 1 2 3 4 5

GCp

Aspect ratio s/y

Bldg 7 roof 3 zone 2 ASCE bottom edge

Max

min

24
Fig. A4a, b, c Bldg 7 roof 3 ASCE zone 2 lower edge (1 ft2

= 0.0929 m2)

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1 10 100 1000

GCp

Area ft^2

Bldg 7 roof 3 ASCE zone 1 interior >= 4 tap squares

min

>= 4 tap squares

Max

ASCE zone 1-

ASCE zone 1+

25
Fig. A5a, b, c Bldg 7 roof 3 ASCE zone 1 interior (1 ft2

= 0.0929 m2)

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

0 0.5 1 1.5 2 2.5 3 3.5 4

GCp

Aspect ratio y/s

Bldg 7 roof 3 ASCE zone 1 interior

Max

min

26
Appendix B Building 7, roof 2 

Fig. B1 UWO Bldg 7 roof 2 ASCE zone 2 edge (1 ft2= 0.0929 m2)

-4.5

-3.5

-2.5

-1.5

-0.5

0.5

1 10 100

GCp

Area ft^2

UWO Bldg 7 roof 2 ASCE zone 2 edge

ASCE zone 2

min

ASCE zone 2+

4-tap squares min

4-tap squares Max

Max

27
Fig. B2 UWO Bldg 7 roof 2 ASCE zone 2 top edge (1 ft2

= 0.0929 m2)

-2.5

-2

-1.5

-1

-0.5

0

0.5

1 10 100

GCp

Area ft^2

UWO Bldg 7 roof 2 ASCE zone 2 top edge

ASCE zone 2

ASCE zone 2+

Max upper edge

min upper edge

Max 4-tap squares

min 4-tap squares

28
Fig. B3 UWO Bldg 7 roof 2 ASCE zone 2 bottom edge (1 ft2

= 0.0929 m2)

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1 10 100

GCp

Area ft^2

UWO Bldg 7 roof 2 ASCE zone 2 bottom edge

ASCE zone 2

ASCE zone 2+

min

Max

4-tap squares Max

4-tap squares min

29
Fig. B4 Bldg 7 roof 2 ASCE zone 1 interior (1 ft2

= 0.0929 m2)

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1 10 100 1000

GCp

Area ft^2

Bldg 7 roof 2 ASCE zone 1 interior

>= 4 tap squares min

>= 4 tap squares

Max

ASCE zone 1-

ASCE zone 1+

30
Lower corner Upper corner

Fig. B5a, b Bldg 7 roof 2 ASCE zone 3 corners (1 ft2= 0.0929 m2)

-5

-4

-3

-2

-1

0

1 10 100

GCp

Area ft^2

UWO Bldg 7 roof 2 ASCE corners

ASCE zone 3+

ASCE zone 3

Max lower corner

min lower corner

Max upper corner

min upper corner

31
Appendix C Building 7 Wall 1

Fig. C1a, b Building 7 Wall 1 ASCE interior (1 ft2= 0.0929 m2)

-2

-1.5

-1

-0.5

0

0.5

1

1.5

10 100 1000 10000

GCp

Area ft^2

Bldg 7 Wall 1 ASCE interior

min

Max

ASCE +

ASCE -

32
Fig. C2a, b Building 7 Wall 1 ASCE right edge (1 ft2

= 0.0929 m2)

-2

-1.5

-1

-0.5

0

0.5

1

1.5

10 100

GCp

Area ft^2

Bldg 7 Wall 1 ASCE right edge

Max

min

ASCE Max

ASCE min

33
Fig. C3a, b Building 7 Wall 1 ASCE left edge (1 ft2

= 0.0929 m2)

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

1 10 100

GCp

Area ft^2

Bldg 7 Wall 1 left edge

Max

min

ASCE Max

ASCE min

34
Appendix D Building 7 Wall 4 

Fig. D1 Building 7 Wall 4 ASCE interior (1 ft2= 0.0929 m2)

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

10 100 1000 10000

GCp

Area ft^2

Bldg 7 Wall 4 interior

Max

min

ASCE+

ASCE35
Fig. D2 Building 7 Wall 4 ASCE left edge (1 ft2

= 0.0929 m2)

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

1 10 100

GCp

Area ft^2

Bldg 7 Wall 4 left edge

Max

min

ASCE+

ASCE36
Fig. D3 Building 7 Wall 4 ASCE right edge (1 ft2

= 0.0929 m2)

-2

-1.5

-1

-0.5

0

0.5

1

10 100

GCp

Area ft^2

Bldg 7 Wall 4 right edge

Max

min

ASCE+

ASCE37
Appendix E Building 15, roof 3

Fig. E1a, b Bldg 15 Roof 3 ASCE interior (1 ft2= 0.0929 m2)

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1 10 100 1000 10000

GCp

Area ft^2

Bldg 15 Roof 3 ASCE interior

Max

min

ASCE+

ASCE38
Fig. E2a,b Bldg 15 Roof 3 ASCE lower edge (1 ft2

= 0.0929 m2)

-5

-4

-3

-2

-1

0

1

1 10 100 1000

GCp

Area ft^2

Bldg 15 Roof 3 ASCE Lower edge

Max

min

ASCE+

ASCE39
Fig. E3a, b Bldg 15 Roof 3 ASCE lower edge (1 ft2

= 0.0929 m2)

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1 10 100 1000

GCp

Area ft^2

Bldg 15 Roof 3 upper edge

Max

min

ASCE+

ASCE40
Fig. E4a,b Bldg 15 Roof 3 ASCE right edge (1 ft2

= 0.0929 m2)

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

10 100 1000

GCp

Area ft^2

Bldg 15 Roof 3 right edge

Max

min

ASCE+

ASCE41
Fig. E5a, b Bldg 15 Roof 3 ASCE lower corner (1 ft2

= 0.0929 m2)

-6

-5

-4

-3

-2

-1

0

1

1 10 100

GCp

Area ft^2

Bldg 15 Roof 3 lower corner

Max

min

ASCE+

ASCE42
Fig. E6a, b Bldg 15 Roof 3 ASCE upper corner (1 ft2

= 0.0929 m2)

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1 10 100

GCp

Area ft^2

Building 15 Roof 3 upper corner

Max

min

ASCE+

ASCE43
Appendix F Building 15, roof 2

Fig. F1a,b Bldg 15 Roof 2 ASCE interior (1 ft2= 0.0929 m2)

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1 10 100 1000 10000

GCp

Area ft^2

Bldg 15 Roof 2 interior

Max

min

ASCE+

ASCE44
Fig. F2a, b Bldg 15 Roof 2 lower edge (1 ft2

= 0.0929 m2)

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

10 100 1000

GCp

Area ft^2

Bldg 7 Roof 2 lower edge

Max

min

ASCE+

ASCE45
Fig. F3a,b Bldg 15 Roof 2 upper edge (1 ft2

= 0.0929 m2)

-2.5

-2

-1.5

-1

-0.5

0

0.5

1 10 100 1000

GCp

Area ft^2

Bldg 15, Roof 2 upper edge

Max

min

ASCE+

ASCE46
Fig. F4a, b Bldg 15 Roof 2 side edge (1 ft2

= 0.0929 m2)

-2

-1.5

-1

-0.5

0

0.5

1 10 100 1000

GCp

Area ft^2

Bldg 15 Roof 2 side edge

Max

min

ASCE+

ASCE47
Fig. F5a, b Bldg 15 Roof 2 lower corner (1 ft2

= 0.0929 m2)

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

10 100

GCp

Area ft^2

Bldg 15 Roof 2 lower corner

Max

min

ASCEASCE+

48
Fig. F6a, b Bldg 15 Roof 2 upper corner (1 ft2

= 0.0929 m2)

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1 10 100

GCp

Area ft^2

Bldg 15 Roof 2 upper corner

Max

min

ASCE+

ASCE49
Appendix G Building 15, Wall 1 

Fig. G1a, b Bldg 15 Wall 1 Interior (1 ft2= 0.0929 m2)

-2

-1.5

-1

-0.5

0

0.5

1

1 10 100 1000 10000

GCp

Area ft^2

Bldg 15 Wall 1 interior Max

min

ASCE+

ASCE50
+

Fig. G2a, b Bldg 15 Wall 1 left edge (1 ft2= 0.0929 m2)

-2

-1.5

-1

-0.5

0

0.5

1

1 10 100 1000

GCp

Area ft^2

Bldg 15 Wall 1 left edge

Max

min

ASCE+

ASCE51
Fig. G3a, b Bldg 15 Wall 1 right edge (1 ft2

= 0.0929 m2)

-2

-1.5

-1

-0.5

0

0.5

1

10 100 1000

GCp

Area ft^2

Bldg 15 Wall 1 right edge

Max

min

ASCE+

ASCE52
Appendix H Building 15, Wall 4 

Fig. H1a, b Bldg 15 Wall 4 Interior (1 ft2= 0.0929 m2)

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

1 10 100 1000 10000

GCp

Area ft^2

Bldg 15 Wall 4 interior

Max

min

ASCE+

ASCE53
Fig. H2a, b Bldg 15 Wall 4 left edge (1 ft2

= 0.0929 m2)

-2

-1.5

-1

-0.5

0

0.5

1

1.5

GCp

10 100 Area ft^2 1000

Bldg 15 Wall 4 left edge

Max

min

ASCE+

ASCE54
Fig.H3a, b Bldg 15 Wall 4 right edge (1 ft2

= 0.0929 m2)

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

1 10 100 1000

GCp

Area ft^2

Bldg 15 Wall 4 right edge

Max

min

ASCE+

ASCE55