WIND ISSUES IN THE DESIGN OF TALL BUILDINGS - PEER

Comparison of Me
at Low and High R
Dubai

ean Pressure Coefficients
Reynolds Number - Burj

Pressure
Taps

High Reynolds
Shanghai Cent

Example of Mean Pressure Coefficie

Pressure tap count

s number tests on
ter

ents

Damping and
beyond the ela

ζ eff = 1 δE1/ 2

2π E

η = ( x2 − x1) / x1

1 1 − k2 η + 1 k2 η2 
k1 2 k1
ζ eff = π
1 + 2η + k2 η 2
k1

dynamic response
astic limit

F2 k2
F1 k1 x1 x2

Effect of stiffness r
deflections on effe

ζ = 1 δE1/ 2
eff
2π E

Example: For 20%
deflection beyond
elastic limit effective
increment in damping
ratio = 0.024.
This would be additive
to the damping ratio
below the elastic limit
which is typically
assumed to be 0.01 to
0.02.

reductions and inelastic
ective viscous damping ratio

k2/k1=0.5
k2/k1=0.75

(x2 − x1) / x1

Damping and
research

Non-linear time domain ana
realistic wind loading will all
more efficient structures can
How feasible is it to load the
limit and how far can one go
Can we learn how to keep th
after going plastic. What can
engineering?
More full scale monitoring n
deflections.

inelastic response

alysis of structures under
low us to evaluate whether
n be developed.
e structure beyond its elastic
o with this?
he structure stable and robust
n be learnt from earthquake

needed at representative

Building motio

Problem is complex due
people
What return period shou
What quantity best enca
acceleration; jerk; some
velocity; noises combine
Designers have to make
What is the actual exper
approaches?

ons and criteria

e to variability amongst

uld be used?
apsulates comfort:
ething in between; angular
ed with motion, etc?
e decisions and move on.
rience using traditional

TTaabblele11: : Building Motion Criter
buildings wind tunnel te
1990s.

Building Building Height
Number (m)

1* 249.4
2 163.4
3 198.1
4 137.2
5 236.2
6 178.0
7 215.0
8 110.9
9 163.0
10 124.4
11* 207.8
12* 145.2
13 94.0
14 141.2
15 143.3
16 259.4
17 175.4
18* 247.8
19* 259.4

* For these buildings, wind tunnel stud
above the 15 –18 milli-g range.

ria. Historical review of 19
ested by RWDI in the 1980s and

First Order Modes Frequencies Assumed
(Hz) Damping Ratio
(% of critical)
fx fy ftor

0.193 0.199 0.295 2.0
0.176 0.224 0.250 2.0
0.189 0.184 0.300 1.5
0.185 0.135 0.323 2.0
0.154 0.169 0.400 2.0
0.244 0.250 0.400 2.0
0.177 0.149 0.331 1.5
0.192 0.164 0.250 2.0
0.195 0.208 0.224 1.5
0.170 0.224 0.204 2.0
0.147 0.171 0.250 1.5
0.411 0.213 0.440 2.0
0.278 0.243 0.139 2.0
0.370 0.216 0.356 2.0
0.135 0.180 0.333 2.0
0.131 0.125 0.263 1.25
0.201 0.157 0.200 1.5
0.131 0.154 0.211 2.0
0.179 0.159 0.236 2.0

dies predicted peak resultant accelerations

Summary of c
of 19 buildings

0.40 100 150
0.35 fx
0.30 Buil di n
0.25
0.20 fy
0.15
0.10
0.05

50

computed frequencies
s

0 200 250 300

ng Hei ght , H ( m )

f = 33/HFitting Curve

Acceleration ( milli - g )Summary of P
Improved Acce

30
25
20
15
10

5
0

0 12 34 5 67

15-18 milli-g range accelerations
Reduced acceleration responses using

Predicted and
eleration Responses

8 9 10 11 12 13 14 15 16 17 18 19 20
Building #
Above 15-18 milli-g range accelerations

g SDS

Buildings with Supplem

Building Name and
Location

BNuuimldbinegr

1 Park Tower, Chicago, I
11 Random House, New

York, NY
12 Wall Centre, Vancouve

BC
18 Bloomberg Tower, New

York, NY

19 Trump World Tower, N
York, NY

mental Damping System

SIDnsStaTllyepde 10-Year Peak Resultant
Acceleration
( milli – g )

Without SDS With SDS

IL TMD 24.0 16.6
w TLCD 25.3 15.4

er, TLCD 28.0 15.2

w TMD 22.5 15.5

New TMD 27.4 17.3

Park Tower, Random
Damping Systems

Chicago

m House and Wall Center with

New York

Vancouver

Trump world Tower a
Damping Systems

New York

and Bloomberg Center with

New York

Chicago Spire – V
Mode Effects

Very Long period – Higher

Higher modes can aff
~ questions re freque

such as ISO comfort

Height, m700 2 nd harmonic
600
500 -1 -0.5 0
400
300 Mode defle
200
100

0
-1.5

fect response
ency dependent motion criteria

criteria.

1st harmonic

0 0.5 1 1.5

ection shape

Chicago spire - motion and deflection con

ntrol through use of damping system.

Assessing build

ISO Criteria f
single frequenc

Moving room
simulations of multiple

frequencies

ding motions.

25

for 20 Peak acceleration, milli-g

cy 15 ResidentialCommercial

10

5

0 1

0.1
Frequency, Hz

Meso-scale Model

lling of June 1988 Event

Thank y

you