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TitleWind Issues in the Design of Buildings
PublisherAmerican Society of Civil Engineers
ISBN 139780784476871
Author
LanguageEnglish
File Size3.5 MB
Total Pages108
Table of Contents
                            Cover
Contents
Preface
Contributors
Chapter 1 Wind Issues in the Design of Buildings
	The Wind and the Built Environment
	Flow and Pressure Fields Around Buildings
	Existing Building Codes
Chapter 2 Extreme Winds (Storms)
	Wind Characteristics
	Hurricanes
	Thunderstorms
	Tornadoes
Chapter 3 Cladding Pressures
	External Pressure
	Internal Pressures
	Windborne Debris
Chapter 4 Structural Loads
	Building Response
	Strategies to Resist Wind
	“Red Flag” Issues
Chapter 5 The Wind Tunnel and Physical Modeling of the Wind
	Structural Load Studies
	Cladding Studies
	Pedestrian Wind Studies
	Topographic Effects
	Snow Deposition Studies
	Frequently Asked Questions
Glossary
References and Recommended Reading
Index
	A
	B
	C
	D
	E
	F
	G
	H
	I
	L
	M
	N
	P
	R
	S
	T
	U
	V
	W
                        
Document Text Contents
Page 2

WIND ISSUES IN THE
DESIGN OF BUILDINGS



PREPARED BY

Structural Wind Engineering Committee
of the Technical Council on Wind Engineering

of the American Society of Civil Engineers

EDITED BY

Leighton Cochran, Ph.D., CPEng











Published by the American Society of Civil Engineers

Page 54

Windborne Debris

A common experience during severe windstorms such as tornadoes, hurricanes, and
severe thunderstorms is the occurrence of flying debris of all types. If these objects
are able to remain airborne long enough, they can impact downwind buildings,
sometimes causing injury or loss of life, as well as increasing the property damage
beyond that produced by direct wind forces (Fig. 3.6). A common occurrence is the
breaching of building envelopes, following which high internal wind velocities and
pressures are created. A well-documented “chain reaction” effect can occur, in which
debris from upwind buildings breach the windward walls of downwind buildings
during a hurricane; high internal pressures occur followed by failure of roof and
sidewall elements, thus generating more debris, and the process continues downwind.

Debris Sources and Flight Speeds

Since the force of gravity always acts and will eventually cause an item of debris to
strike the ground, the most common flying objects are those removed from the upper
parts of buildings, especially roofs of buildings. These include roof cladding such as
shingles or tiles, roofing components such as the classic “2 by 4” (actually about 40
by 90 mm or 1.5 in. by 3.5 in.) wooden members, and gravel from the roofs of high-
rise buildings (this system is not recommended in high wind areas).















Fig. 3.6: Windborne debris can often generate dangerous missiles.

Smaller, lighter objects will start to fly at lower wind speeds and travel faster and
farther than larger, heavy objects. Figure 3.7 shows three types of debris shapes, with
different flying characteristics. The ‘compact’ types (perhaps represented by a piece
of roof gravel), generally do not experience any lifting forces from the wind, and tend
to fall downwards while being projected forward by wind forces. The plate type,
representative of a roof shingle, for example, can experience lifting forces and will
often fly faster and for longer than compact objects. The flight trajectories of plates
are quite dependent on their angle to the wind at the start of their flight. Rod objects,
represented by roofing members, for example, will usually have complicated flights
with rolling and tumbling being present.

WIND ISSUES IN THE DESIGN OF BUILDINGS 45

Page 107

characteristics 17–25, 17f, 18f, 19t,
20f, 22t, 23f, 24f, 25f


façade leakage 42–44, 44f, 77
FEMA 320 57
FEMA 361 57
flat roofs, wind force direction and 47
“flexible” building 69
flutter 51
Foehn winds 19
frequency distribution of wind speeds at

location 12, 25f
Fujita Scale 37–38, 38t

gable roofs 3, 3f, 52
galloping 51, 64–65, 65f
“green buildings” 10
gusts 18, 18f, 23–24, 23f

high-frequency base balance (HFBB) 73–

74, 73f
high-frequency force balance (HFFB) 73
high-rise engineered structures: wind

damage 5–7, 5f, 6f, 7f; wind force
direction 47; wind-tunnel tests 74–76,
75f, 76f

hip roofs 3, 52
horizontally accelerated flows 80, 81f
hot-film anemometer probes 12, 13f, 77
hurricanes 17, 19, 25–31, 26f, 27f, 29t, 30t,

84
HVAC systems: damage to 69, 70f; façade

leakage and 43, 77; natural ventilation
and 10


inertial forces 47
inertial loads 49, 50f
interference effects 66–67, 67f
internal pressures: on cladding 40, 42–44,

42f, 44f; on single family homes 3
International Building Code (IBC) 16;

torsional loads 69; windborne debris
and 46

International Code Council 16, 57

lay-down hazards, to shelters 56
lift. See crosswind loads
lock-in 65

low-rise engineered structures: wind
damage 4, 4f, 44f; wind force direction
47


main wind force resisting system

(MWFRS) loads 6
mean wind speed calculation 22, 22e, 22t
moment-resistant connections 54
motion, governing equation of 72e

National Building Code 16
natural ventilation 10, 12, 13f, 14, 14f
negative suction/negative pressure 7–8
non-resonant loads 49, 50f

peak gusts 23, 23f
pedestrian wind conditions 9, 10f; wind-

tunnel tests 77–80, 78f, 80f, 81f
physical modeling. See wind-tunnel tests
pitched roofs, wind force direction and 47
pressure taps, in cladding 77
public areas. See pedestrian wind

conditions

reattachment, of wind flow 7
refuge floors 52, 53, 53f
residential shelters 57
resonant loads 49, 50f; wind-tunnel models

72, 73, 74
rollover hazards, to shelters 56
roof-edge spoilers 53, 53f
roofs 3, 54; damage to equipment on 69,

70f
roughness elements 20–21, 20f

Saffir-Simpson hurricane scale 29, 29t, 30t
separation, of wind flow 7, 7f, 49, 81–82,

82f
shear layer 58, 59f
shear walls 54
shielding 66, 67f, 68f
single family homes, wind damage and 1,

2f, 3, 3f
snow deposition studies 82, 83f
stack effect, building ventilation and 10–

11
Standard Building Code 16
Standard Effective Temperature (SET) 12

WIND ISSUES IN THE DESIGN OF BUILDINGS98

Page 108

static wind loads 47, 48f, 49
stochastic process, turbulence in ABL and

21
storm shelters 52, 56–57, 57f
storm surge flooding 27–29, 56
storms. See extreme winds (storms)
structural loads: appurtenances and 69–70,

70f; building response aspects 47, 48f,
49–51, 50f; building shape and 58–61,
59f, 60f, 61f; dynamic responses 62–
66, 64f, 65f, 66f; interference effects
66–67, 67f; red flag issues and codes
57–58; torsional response 67–69, 68f;
wind force direction and 47, 47f; wind
resistance strategies 51–57, 53f, 56f,
57f; wind-tunnel tests 72–76, 73f, 75f,
76f

structural strategies, to resist wind 52, 54–
55, 56f

structural damping levels 51
synoptic events 19

thermal comfort 10, 12, 78–79
3-second gusts 23
thunderstorms 19, 31–33, 32f, 33f, 34f
top-floor accelerations, wind-tunnel tests

74–76, 75f, 76f
topographic effects, wind-tunnel tests 81–

82, 82f
tornadoes 19, 27, 32, 34–38, 34f, 35f, 36f,

37f, 38t, 39t, 84
torsional loads 47, 48f, 49, 67–69, 68f

tropical cyclones 27, 29
tropical depressions 29
tube structures 54–55
tuned liquid dampers (TLD) 51, 55
tuned liquid sloshing dampers 55
tuned mass dampers (TMD) 51, 55, 56f
turbulence: in Atmospheric Boundary

Layer 21; structural loads and, 49–50,
64, 64f, 66

typhoons 17, 19, 26

Uniform Building Code 16
urban designs, wind-tunnel tests and 78–79

viscoelastic dampers 55
viscous dampers 51
von Kármán vortices 50f
vortex formation, around buildings 7, 7f, 8
vortex-induced oscillations 49–51, 50f

wake turbulence 50; crosswind loads 63–

64, 64f; structural loads 58–60, 59f
water features, wind flow and 9–10, 11f
wind-tunnel tests 71, 71f; cladding studies

76f, 77; frequently asked questions
83–85; pedestrian wind studies 77–80,
78f, 80f, 81f; snow deposition studies
82, 83f; structural load studies 72–76,
73f, 75f, 76f; testing and consultation
parts of study 85–88; topographic
effects 81–82, 82f

WIND ISSUES IN THE DESIGN OF BUILDINGS 99

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