wind-induced response of structures using wind tunnel...
TRANSCRIPT
S. M. Zia Uddin1
Wind-induced Response Of Structures Using Wind Tunnel Model Test
Organized by: In collaboration with: Supported by:
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Failure of Tacoma Narrows Bridge on November 7, 1940 in UnitedStates caused by a 19 m/s wind speed
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Failure of a 50 meter tall billboard structure on 26 June 2002 inBangkok, Thailand
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Failure of 80 meter tall wind turbine on 2nd January 2015 inNorthern Ireland
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47.8 meter tall 5-story Shiten’noji Pagoda collapsed on September21, 1934 in Japan. The maximum wind speed was estimated to bemore than 60m/s.
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The upper-floor occupants of 240 meter tall 60-story John HancockTower suffered from motion sickness when the building swayed inthe wind. Tuned mass dampers and diagonal steel bracing wereinstalled to stabilize the movement.
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Importance of
Wind Load
Building Height
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Wind-induced Response Of Structures
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Wind-induced Overall Response Of Structures
time time
𝑋𝑡𝐹𝑡
time
𝑋𝑡
Overall response = Mean response + Background response + Resonant response
Inertial force
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Wind-induced Overall Response Of Structures
Wind-induced Force
Wind-induced Response Prediction
Building Code Approach Wind Tunnel Model Test
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Building Code Approach
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Building Code Approach: ASCE/SEI 7-10
Design Wind Pressure, P = 𝑞 𝐺𝑓 𝐶𝑝 − 𝑞𝑖 𝐺𝐶𝑝𝑖
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Building Code Approach: ASCE/SEI 7-10
Design Wind Pressure, P = 𝑞 𝐺𝑓 𝐶𝑝 − 𝑞𝑖 𝐺𝐶𝑝𝑖
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Wind-induced Overall Response Of Structures
Wind-induced Force
Wind-induced Response Prediction
Building Code Approach Wind Tunnel Model Test
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ASCE/SEI 7-10 vs Wind Tunnel Model Test
Mx My
Pe
ak
Ba
se M
om
en
t
Comparison of Peak Base Moment
ASCE
Wind Tunnel
Wind Tunnel = 1.35 x ASCE
Wind Tunnel = 1.59 x ASCE
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Limitations Of ASCE/SEI 7-10
Wind
Exposure D
Wind
Exposure C
Wind
Exposure B
• ASCE/SEI 7-10 do not account for interference effects caused by nearby buildings and other obstructions.
Y
X
Z
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Interference Effect
• Reduce mean response
time
𝑋𝑡
• Increase background and resonant response
• Increase overall response
Overall response = Mean response + Background response + Resonant response
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Interference Effect
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Wind Tunnel Model Test
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TU-AIT Boundary Layer Wind Tunnel Laboratory
• 23m X 2.5m X 2.5m
• Open-circuit, Blowing Type
• Test Section: 18.5m X 2.5m X 2.5m
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TU-AIT Boundary Layer Wind Tunnel Laboratory
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TU-AIT Boundary Layer Wind Tunnel Laboratory
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TU-AIT Boundary Layer Wind Tunnel Laboratory
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TU-AIT Boundary Layer Wind Tunnel Laboratory
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Boundary Layer Wind Profile
0
20
40
60
80
100
120
140
160
180
200
0 0.2 0.4 0.6 0.8 1 1.2
Mean Wind Speed Prof i le
Open-terrain
Suburban
Urban
Full Scale Height, m
𝑼𝒊 𝑼𝒊𝒓𝒆𝒇
=𝒊
𝒊𝒓𝒆𝒇
𝝎
Power Law,
0
20
40
60
80
100
120
140
160
180
200
0 0.1 0.2 0.3 0.4 0.5
Turbulence Intensity Prof i le
Open terrain
Suburban
Urban
Full Scale Height, m
𝑰𝒖𝒊 =𝟎. 𝟒 𝜷
𝒍𝒏𝒊𝒊𝟎
Longitudinal Turbulence Intensity,
Normalized Mean Wind Speed, 𝑼𝒊 𝑼𝒈
Longitudinal Turbulence Intensity, 𝑰𝒖𝒊
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Boundary Layer Wind Simulation
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Boundary Layer Wind Simulation
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0
20
40
60
80
100
120
140
160
180
200
0 0.2 0.4 0.6 0.8 1 1.2
Mean Wind Speed Prof i le
Open-terrain
Suburban
Urban
0
20
40
60
80
100
120
140
160
180
200
0 0.2 0.4 0.6 0.8 1 1.2
Mean Wind Speed Prof i le
Open-terrain
Suburban
Urban
Boundary Layer Wind Simulation
Full Scale Height, mLength Scale=1:300
𝑼𝒊 𝑼𝒊𝒓𝒆𝒇
=𝒊
𝒊𝒓𝒆𝒇
𝝎
Power Law,
Normalized Mean Wind Speed, 𝑼𝒊 𝑼𝒈
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0
20
40
60
80
100
120
140
160
180
200
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
Turbulence Intensity Prof i le
Open terrain
Suburban
Urban
Longitudinal Turbulence Intensity,
Turbulence Intensity Prof i le
Open terrain
Suburban
Urban
Boundary Layer Wind Simulation
Full Scale Height, mLength Scale=1:300
𝑰𝒖𝒊 =𝟎. 𝟒 𝜷
𝒍𝒏𝒊𝒊𝟎
Longitudinal Turbulence Intensity,
𝑰𝒖𝒊 =𝝈𝒖𝒊 𝑼𝒊
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Wind-induced Force Measurement
Wind-induced Force Measurement
High Frequency Force Balance (HFFB) Technique
High Frequency Pressure Integration (HFPI) Technique
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High Frequency Pressure Integration (HFPI) Technique
144 m48 cm
1:300 Scale
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High Frequency Pressure Integration (HFPI) Technique
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High Frequency Pressure Integration (HFPI) Technique
AA
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High Frequency Pressure Integration (HFPI) Technique
Basic Parameters
𝐿𝑒𝑛𝑔𝑡ℎ 𝑆𝑐𝑎𝑙𝑒, 𝜆𝐿 = 𝐿𝑚𝐿𝑃= 1/300
𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦 𝑆𝑐𝑎𝑙𝑒, 𝜆𝑉 = 𝑈𝑚 𝑈𝑃= 6.5/49
𝑇𝑖𝑚𝑒 𝑆𝑐𝑎𝑙𝑒, 𝜆𝑇 = 𝜆𝐿𝜆𝑉
𝑇𝑒𝑠𝑡 𝐷𝑢𝑟𝑎𝑡𝑖𝑜𝑛, 𝑇𝑚 = 𝜆𝑇 ∗ 3600Prototype Pressure: 𝑷𝑷𝒊𝒋
𝒕 = 𝑪𝒑𝒊𝒋𝒕 ∗
𝟏
𝟐𝝆 𝑼𝑷
𝟐
Time−Varying Pressure Coefficient: 𝑪𝒑𝒊𝒋𝒕 =
𝑷𝒎𝒊𝒋𝒕
𝟏𝟐𝝆 𝑼𝒎
𝟐
𝒊 = 𝟏𝟎, 𝒋 = 𝟐
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High Frequency Pressure Integration (HFPI) Technique
Modal Drag Force:
𝑄𝑘𝑥𝑡 =
𝑖=1
𝑁
𝐹𝑖𝑥𝑡 𝛷𝑖𝑘𝑥
Drag Force:
𝐹𝑖𝑥𝑡 =
𝑗=1
𝑛𝑖
𝑃𝑃𝑖𝑗𝑡 𝐴𝑃𝑖𝑗𝑥
𝑻𝒊𝒎𝒆
𝑸𝟏𝒙𝒕
0 degree wind direction
𝑸𝟏𝒙
𝑭𝒓𝒆𝒒𝒖𝒆𝒏𝒄𝒚, 𝒇𝒑 = 𝒇𝒎 ∗ 𝝀𝑻
𝒇 𝑺𝒒𝟏𝒙𝒎𝒇
0 degree wind direction
𝑿𝒊𝟏𝒙 = 𝑸𝟏𝒙𝑲𝟏𝒙
𝛷𝑖𝑘𝑥
Mean Displacement Response,
𝒇 𝑺𝒙𝟏𝒙𝒎𝒇
Fluctuating Wind Force
𝝈𝑩𝟏𝒙𝒎𝟐
𝝈𝑹𝟏𝒙𝒎𝟐
Inertial force
Modal Response Spectrum : 𝑺𝒙𝟏𝒙𝒎𝒇
=𝑺𝒒𝟏𝒙𝒎𝒇
𝑲𝟏𝒙𝟐
𝑯𝟏𝒙𝒇 𝟐
𝝈𝑩𝒊𝟏𝒙𝟐 = 𝜱𝒊𝟏𝒙
𝟐 𝝈𝑩𝟏𝒙𝒎𝟐
Background Displacement Response,
𝝈𝑹𝒊𝟏𝒙𝟐 = 𝜱𝒊𝟏𝒙
𝟐 𝝈𝑹𝟏𝒙𝒎𝟐
Resonant Displacement Response,
𝑿𝑫𝒊𝟏𝒙 = 𝑿𝒊𝟏𝒙 + 𝝈𝒙𝒊𝟏𝒙
Total Displacement Response,
𝝈𝒙𝒊𝟏𝒙 = 𝒈𝐵1𝑥𝟐 𝝈𝑩𝒊𝟏𝒙
𝟐 + 𝒈𝟏𝑅𝟐 𝝈𝑹𝒊𝟏𝒙
𝟐
Fluctuating Displacement Response,
Equivalent Static Drag Force,
𝑭𝑫𝒙 =𝑿𝑫𝒊𝟏𝒙 𝑿𝒊𝟏𝒙
𝑭𝑷𝒊𝒙
𝝈𝒒𝟏𝒙𝒎
𝒈𝑩𝟏𝒙𝝈𝒒𝟏𝒙𝒎
𝒈𝑩𝟏𝒙 = 𝑸𝟏𝒙𝒕 − 𝑸𝟏𝒙𝝈𝒒𝟏𝒙𝒎
𝒇 𝑺𝒒𝒊𝒙𝒎𝒇
𝒇 𝑺𝒙𝒊𝒙𝒎𝒇
0
20
40
60
80
100
120
140
160
-0.5 0 0.5 1 1.5H
eig
ht
(m)
Normalized Mode Shape
X direction
Y direction
Rotation
𝑄𝑘𝑥𝑡 =
𝑖=1
𝑁
𝐹𝑖𝑥𝑡 𝛷𝑖𝑘𝑥 +𝐹𝑖𝑦
𝑡 𝛷𝑖𝑘𝑦 + 𝐹𝑖Ɵ𝑡 𝛷𝑖𝑘Ɵ
𝑿𝑪 = 𝑿𝒊𝟏𝒙 + 𝑿𝒊𝟐𝒙 + 𝑿𝒊𝟑𝒙 + 𝒈𝑩𝟏𝑥𝟐 𝝈𝑩𝒊𝟏𝒙
𝟐 + 𝒈𝑩2𝑥𝟐 𝝈𝑩𝒊2𝑥
𝟐 + 𝒈𝑩3𝑥𝟐 𝝈𝑩𝒊𝟑𝒙
𝟐 + 𝒁𝑩𝟏𝒙𝟐𝒙 + 𝒁𝑩1𝑥𝟑𝒙 + 𝒁𝑩2𝑥𝟑𝒙 + 𝒈𝑹𝟏𝑥𝟐 𝝈𝑹𝒊𝟏𝒙
𝟐 + 𝒈𝑹2𝑥𝟐 𝝈𝑹𝒊𝟐𝒙
𝟐 + 𝒈𝑹3𝑥𝟐 𝝈𝑹𝒊𝟑𝒙
𝟐
Coupled Response : Equivalent Static Drag Force,
𝑭𝑫𝒙 =𝑿𝑪 𝑿𝑪 𝑭𝑷𝑪
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Design Wind Load Cases
Equivalent Static Drag Force,
𝑭𝑫𝒙 , 𝑭𝑫𝒚 ,𝑴𝑻Ɵ𝑭𝑫𝒚
𝑭𝑫𝒙𝑴𝑻Ɵ
𝟏𝟎𝟎%
𝟏𝟎𝟎%
𝟏𝟎𝟎% 𝟏𝟎𝟎%
𝟎%
𝟎%
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Design Wind Load Cases: Wind Tunnel Test
𝑭𝑿𝒕
𝑭Ɵ𝒕
( 𝑭𝒙 , 𝑭Ɵ)
( 𝑷𝒙 = 𝑭𝒙 𝑭𝒙= 𝟏)
( 𝑷Ɵ = 𝑭Ɵ 𝑭𝒙= 𝟎. 𝟔𝟐)
( 𝑷𝒙 = 𝑭𝒙 𝑭𝒙= 𝟏)
( 𝑷Ɵ = 𝑭Ɵ 𝑭𝒙= 𝟎. 𝟓𝟗)
Effective Equivalent Static Force (Mean),
𝑭𝒙 = 𝑷𝒙 𝑭𝑫𝒙
𝑭𝒚 = 𝑷𝒚 𝑭𝑫𝒚
𝑴Ɵ = 𝑷Ɵ𝑴𝑻Ɵ
𝑭𝒚
𝑭𝒙
𝑴Ɵ
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Design Wind Load Cases: ASCE/SEI 7-10
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Wind-induced Force Measurement
Wind-induced Force Measurement
High Frequency Force Balance (HFFB) Technique
High Frequency Pressure Integration (HFPI) Technique
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High Frequency Force Balance (HFFB) Technique
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High Frequency Force Balance (HFFB) Technique
𝒇𝐧 =𝟏
𝟐𝛑
𝐊
𝐌
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High Frequency Force Balance (HFFB) Technique
Wind
𝑭𝒙𝒕 (Drag force)
𝑴Ɵ𝒕 (Torsion)
𝑭𝒚𝒕 (Side force)
𝑿𝒊𝟏𝒙 = 𝑸𝟏𝒙𝑲𝟏𝒙
𝛷𝑖𝑘𝑥
Mean Displacement Response,
𝝈𝑩𝒊𝟏𝒙𝟐 = 𝜱𝒊𝟏𝒙
𝟐 𝝈𝑩𝟏𝒙𝒎𝟐
Background Displacement Response,
𝝈𝑹𝒊𝟏𝒙𝟐 = 𝜱𝒊𝟏𝒙
𝟐 𝝈𝑹𝟏𝒙𝒎𝟐
Resonant Displacement Response,
𝑿𝑫𝒊𝟏𝒙 = 𝑿𝒊𝟏𝒙 + 𝝈𝒙𝒊𝟏𝒙
Total Displacement Response,
𝝈𝒙𝒊𝟏𝒙 = 𝒈𝐵1𝑥𝟐 𝝈𝑩𝒊𝟏𝒙
𝟐 + 𝒈𝟏𝑅𝟐 𝝈𝑹𝒊𝟏𝒙
𝟐
Fluctuating Displacement Response,
Equivalent Static Drag Force,
𝑭𝑫𝒙 =𝑿𝑫𝒊𝟏𝒙 𝑿𝒊𝟏𝒙
𝑭𝑷𝒊𝒙
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Advantage Of High Frequency Pressure Integration (HFPI) Technique
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Advantage Of High Frequency Pressure Integration (HFPI) Technique
Wind
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Advantage Of High Frequency Pressure Integration (HFPI) Technique
Wind
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Importance of wind-induced response rises as structures grow taller and slender
Building codes have limited scope and many conditions
Wind tunnel model test provides appropriate wind-induced loading of structures
High Frequency Pressure Integration (HFPI) technique offers effective solution by outweighing disadvantages of High Frequency Force Balance (HFFB) technique
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