U. S. Department of Housing and Urban Development

Executive Summary xi

Introduction 1

Problem Statement 2

Literature Review 3

Historical Basis (Wind Profile) 4

Historical Basis of Wind Engineering 4

Canopy Flow (Wind in the Interfacial Layer) 9

Modern Wind Engineering 12

Summary of Key Findings in the Literature 18

Review of ASCE 7-95 19

Wind Monitoring Approach 23

Results 28

Selected Wind Events 28

Power Law Wind Profile 29

Turbulence Intensity Profile 39

Conclusions 41

Recommendations 42

References 43

POWER LAW EXPONENTS 6

FOR VARIOUS DESCRIPTIONS OF TERRAIN 6

BY DAVENPORT (1960) [3] 6

TABLE 2 7

VARIATION IN GUSTINESS WITH HEIGHT 7

IN A TERRAIN CHARACTERIZED BY A POWER LAW 7

EXPONENT OF 1/4.75 7

TABLE 3 10

SELECT LEAST-SQUARES SOLUTIONS FOR THE 10

ATTENUATION COEFFICIENT [5] 10

TABLE 4 16

ESTIMATES OF DISPLACEMENT HEIGHT (D) 16

AND AERODYNAMIC ROUGHNESS (ZO) 16

FOR VARIOUS SHAPES [12] 16

TABLE 5 22

HISTORY OF THE POWER LAW EXPONENT, a, 22

IN THE ASCE 7 STANDARD [1],[14] 22

TABLE 6 29

SUMMARY DATA FOR ALL WIND EVENTS DURING THE PERIOD OF RECORD 29

Table A-1 - Characteristics of Monitoring Locations 1

Interfacial Layer 3

Figure 2 - Portable near-ground wind station 23

with a anemometer at a 10-ft (3-m) height above ground. 23

Figure 3a - Lower tower anemometer 24

at a 33-ft (10-m) height above ground. 24

Figure 3b - Upper tower anemometer 24

at a 187-ft (57 m) height above ground. 24

Figure 4 - Aerial photograph of 10-ft (3-m) height wind monitoring stations 26

with an approximate scale of 1:8400. The tower station with anemometers at 33-ft (10-m) and 187-ft (57 m) heights is labeled as #2. 26

Figure 5 - Maximum hourly gust trace for ground stations 28

Figure 6 - Plot of estimated  for daily peak gust wind measurements based on 187-ft (57-m) tower anemometer and 33-ft (10-m) tower anemometer. 30

Figure 7 - Plot of estimated  for daily maximum 1-minute mean wind measurements based on 187-ft (57-m) tower anemometer and 33-ft (10-m) tower anemometer. 30

Figure 8 - Plot of estimated  for daily maximum 10-minute mean wind measurements based on 187-ft (57-m) tower anemometer and 33-ft (10-m) tower anemometer. 31

Figure 9 - Plot of estimated  for daily peak gust wind measurements based on 187-ft (57-m) tower anemometer and 10-ft (3-m) tower anemometer. 31

Figure 10 - Plot of estimated  for daily maximum 1-minute mean wind measurements based on 187-ft (57-m) tower anemometer and 10-ft (3-m) tower anemometer. 32

Figure 11 - Plot of estimated  for daily maximum 10-minute mean wind measurements based on 187-ft (57-m) tower anemometer and 10-ft (3-m) tower anemometer. 32

Figure 12 - Plot of COV of  for daily peak gust wind measurements based on the 187-ft (57-m) tower anemometer and the 10-ft (3-m) near-ground anemometers. 33

Figure 13 - Plot of COV of  for daily maximum 1-minute mean wind measurements based on 187-ft (57-m) tower anemometer and the 10-ft (3-m) near-ground anemometers. 34

Figure 14 - Plot of COV of  for daily maximum 10-minute mean wind measurements based on 187-ft (57-m) tower anemometer and the 10-ft (3-m) near-ground anemometers. 34

Figure 15 - Power law profile for peak gust wind speeds based on the 187-ft (57-m) tower data and an assumed gradient height of 1,200 ft (366 m). 36

Figure 16 - Power law profile for maximum 1-minute mean wind speeds based on the 187-ft (57-m) tower data and an assumed gradient height of 1,200 ft (366 m). 37

Figure 17 - Power law profile for maximum 10-minute mean wind speeds based on the 187-ft (57-m) tower data and an assumed gradient height of 1,200 ft (366 m). 38

Figure 18 - Turbulence intensity profile for a 1-minute period 39

at the time of each station’s peak gust record. 39

Figure 19 - Turbulence intensity profile for a 10-minute 40

period at the time of each station’s peak gust record. 40

Figure A-1 - View Looking Northwest 2

(Station 1) 2

Figure A-3 - View Looking East 2

(Station 1) 2

Figure A-2 - View Looking Northeast 2

(Station 1) 2

Figure A-4 - View Looking Southeast 2

(Station 1) 2

Figure A-5 - View Looking South 3

(Station 1) 3

Figure A-7 – View Looking West 3

(Station 1) 3

Figure A-6 - View Looking Southwest 3

(Station 1) 3

Figure A-8 – View Looking Northwest 3

(Station 1) 3

Figure A-9 - View Looking North 4

(Station 3) 4

FigureA-11 - View Looking East 4

(Station 3) 4

Figure A-10 - View Looking Northeast 4

(Station 3) 4

Figure A-12 - View Looking Southeast 4

(Station 3) 4

Figure A-13 - View Looking South 5

(Station 3) 5

FigureA-15 - View Looking West 5

(Station 3) 5

Figure A-14 - View Looking Southwest 5

(Station 3) 5

Figure A-16 - View Looking Northwest 5

(Station 3) 5

Figure A-17 - View Looking North 6

(Station 4) 6

Figure A-19 - View Looking East 6

(Station 4) 6

Figure A-18 - View Looking Northeast 6

(Station 4) 6

Figure A-20 - View Looking Southeast 6

(Station 4) 6

Figure A-21 - View Looking South 7

(Station 4) 7

Figure A-23 - View Looking West 7

(Station 4) 7

Figure A-22 - View Looking Southwest 7

(Station 4) 7

Figure A-24 - View Looking Northwest 7

(Station 4) 7

Figure A-25 - View Looking North 8

(Station 5) 8

Figure A-27 - View Looking East 8

(Station 5) 8

Figure A-26 - View Looking Northeast 8

(Station 5) 8

Figure A-28 - View Looking Southeast 8

(Station 5) 8

Figure A-29 - View Looking South 9

(Station 5) 9

Figure A-31 - View Looking West 9

(Station 5) 9

Figure A-30 - View Looking Southwest 9

(Station 5) 9

Figure A-32 - View Looking Northwest 9

(Station 5) 9

Figure A-33 - View Looking North 10

(Station 6) 10

Figure A-35 - View Looking East 10

(Station 6) 10

Figure A-34 - View Looking Northeast 10

(Station 6) 10

Figure A-36 - View Looking Southeast 10

(Station 6) 10

Figure A-37 - View Looking South 11

(Station 6) 11

Figure A-39 - View Looking West 11

(Station 6) 11

Figure A-38 - View Looking Southwest 11

(Station 6) 11

Figure A-36 - View Looking Northwest 11

(Station 6) 11