14th U.S.-Japan Workshop on the Improvement of Building Structural Design and Construction Practices
“Simulated Earthquake Ground Motion for Structural Design"
Satoru Nagase
Structural Engineering Section, Nikken Sekkei Ltd. Tokyo Japan 1 Contents
1. Introduction Background and development about simulated earthquake ground motion.
2. Method of Simulating Earthquake Ground Motions
3. Dynamic Behavior of High-rise buildings
4．Conclusions For performance-based design・・・
2 1. Introduction Background and development about simulated earthquake ground motion.
3 Comparison of observation records and seismic ground motion figures.
“Aｒｔ Wave” (1988) “Kokuji Wave” (2000) Typical observation records (1960S)
Reliance on observation records alone might result underestimation for period of 3 or more seconds.
⇒ “Art Wave” ,”Kokuji Wave” and ”NS Wave” 4 Examples of ground motions produced by “NS Wave”
Long period range Nagoya Osaka Tokyo
←Art Wave ←Kokuji Wave
0 1 2 3 4 5 6 7 8 9 10 Period (sec) Near Tokyo station projected for South Kanto earthquake (M7.9) Near Osaka station projected for a multi-fault Tokai / Tonankai / Nankai earthquake (M8.7)
Near Nagoya station projected for a multi-fault Tokai / Tonankai / Nankai earthquake (M8.7) Considering earthquake source and transmission characteristics as well as local ground characteristics, ⇒ Expected to produce strong shaking at construction sites 5 2. Method of Simulating Earthquake Ground Motions
6 Basic concepts
Basic concepts of performance-based design (i) examine the performance of each building. (ii) clearly explain the results to the public.
Time histories of the acceleration of seismic waves, which reflect the earthquake environment, soil conditions at the construction site, etc.
Practical method of simulating earthquake ground motions that can be easily applied to a variety of projects.
7 Propagation of Seismic Waves
Building Site Characteristics (Soil conditions) Surface of Ground
Sedimentary Layer Seismic Bedrock
Propagation Characteristics
Source Characteristics (Fault Plane)
8 Framework of the Proposed Method
Fourier Fourier Amplitude Phase
Source Characteristics Model
Propagation Geometrical Quantitative Characteristics Damping Evaluation
Site Multiple Reflection Characteristics Theory
9 Fourier Amplitude ◇Source Characteristics: Model Fourier amplitude (3.1) log A (T ) 2 M 0 (2 / T ) 2 M 0 (2 / Tc )
log T
Tc 1/ f c
◇Propagation Characteristics :Geometrical Damping 1 U(r0 ,T ) A (T ) (3.2) r0 Hypocentral distance
◇Site Characteristics: Multiple Reflection Theory (Ex. SHAKE by U. C. Berkeley) 10 Quantitative Evaluation of the Fourier Phase By Standard Deviation of the Phase Differences σ/π ) 2 3.0 1.0 0.0 0.5 / 0.18
Acc. (m/s Acc. -3.0 0.0 0 50 100 150 200 250 300
Distribution of 0 -0.5 -1.0 -1.5 -2.0 Time (sec) phase differences Phase differences (rad) (a) EW component accelerogram and distribution of the phase differences recorded at Hachinohe Harbour during the 1968 Tokachi-oki Earthquake ) 2 10.0 1.0 0.0 0.5 / 0.05
Acc. (m/s Acc. -10.0 0.0 0 50 100 150 200 250 300 0 -0.5 -1.0 -1.5 -2.0 Distribution of Time (sec) phase differences Phase differences (rad) (b) NS component accelerogram and distribution of the phase differences recorded at JMA Kobe during the 1995 South Hyogo Prefecture Earthquake
Figure 2.1 Examples of accelerograms and distributions of the phase differences
11 Relational Expression of σ/π against the Hypocentral Distance for Crustal Earthquake
/ 0.06 0.0003r0 (2.3) / r0 : hypocentral 0.4 distance (km) 0.3 0.2 0.1 0.0 Standard deviation 0 100 200 300 400 500 600 700
of phase of differences Hypocentral distance (km)
Figure 2.2 Standard deviation of the phase differences against the hypocentral distance for the records at the KiK-net observation sites with respect to the 2000 Western Tottori Prefecture Earthquake
12 Relational Expression of σ/π against the Hypocentral Distance for Inter-plate Earthquake
/ 0.05 0.0003r0 (2.4) / 0.08 0.0003r0 (2.5)
0.4 0.4 0.3 0.3 0.2 0.2 0.1 0.1 0.0 0.0 Standard deviation Standard deviation of phase differences phase of 0 100 200 300 400 500 phase differencesof 0 100 200 300 400 500 Hypocentral distance (km) Hypocentral distance (km) (b) Plots of / of the NS and EW (c) Plots of / of the NS and EW components in eastern Hokkaido components in western Hokkaido (In the direction of rupture (In the orthogonal direction of propagation) rupture propagation) Figure 2.3 Standard deviation of the phase differences at the K-NET observation sites in Hokkaido with respect to the 2003 Tokachi-oki Earthquake
13 Criteria For Selecting Fourier Phase
Inter-plate Earthquake
/ 0.08 0.0003r0 (2.5) Fault length = 100 km r 200km 0 / 0.14
r 100 km r 100km 0 0 / 0.10 / 0.11
r0 100km / 0.09
r0 0 km / 0.08
r 100km r 200 km r0 300 km 0 0 Hypocenter / 0.08 / 0.11 / 0.14
Direction of rupture propagation / 0.05 0.0003r0 (2.4)
Figure 3.1 Standard deviation of the phase differences at the observation sites
14 Flow Chart of the Proposed Method Fourier amplitude Fourier phase Source characteristics: Source and propagation characteristics: model Eqn. 3.1 Crustal earthquake Eqn. 2.3 Inter-plate earthquake Propagation characteristics: ◇In the direction Eqn. 3.2 of rupture propagation Eqn. 2.4 ◇In the orthogonal direction of rupture propagation Eqn. 2.5
(Inverse Fourier transform) Synthesized wave in seismic bedrock Site characteristics: Multiple reflection theory
Synthesized wave at surface of ground
Figure 3.3 Flow chart of the proposed method 15 Verification of the Proposed Method Verification of the Proposed Method
Crustal earthquake（σ/π=0.07） ) 2 3.0 0.1 0.0 0.0 Vel. (m/s) Vel. Acc. (m/s Acc. -3.0 -0.1
0 50 100 150 200 250 0 50 100 150 200 250 Time (sec) Time (sec) (a) Acceleration of observed wave (c) Velocity of observed wave ) 2 3.0 0.1 0.0 0.0 Acc. (m/s Acc. -3.0 (m/s) Vel. -0.1
0 50 100 150 200 250 0 50 100 150 200 250 Time (sec) Time (sec) (b) Acceleration of synthesized wave (d) Velocity of synthesized wave
Figure 4.1 Comparison between observed waves (EW component) recorded at Yubara, Okayama, and synthesized waves with respect to the 2000 Western Tottori Prefecture Earthquake 16 Verification of the Proposed Method
Inter-plate earthquake（σ/π=0.17） ) 2 1.0 0.2 0.0 0.0
-1.0 (m/s) Vel. -0.2 Acc. (m/s Acc.
0 50 100 150 200 250 0 50 100 150 200 250 Time (sec) Time (sec) (a) Acceleration of observed wave (c) Velocity of observed wave Long period component ) 2 1.0 0.2 0.0 0.0
-1.0 (m/s) Vel. -0.2 Acc. (m/s Acc.
0 50 100 150 200 250 0 50 100 150 200 250 Time (sec) Time (sec) (b) Acceleration of synthesized wave (d) Velocity of synthesized wave
Figure 4.2 Comparison between observed waves (NS component) recorded at Sapporo, Hokkaido, and synthesized waves with respect to the 2003 Tokachi-oki Earthquake 17 3. Dynamic Behavior of High-rise Buildings
18 Examples of “NS Wave” figures
Nagoya Osaka Tokyo
←Art Wave ←Kokuji Wave
Period (sec)
Near Tokyo station projected for South Kanto earthquake (M7.9) Near Osaka station projected for a multi-fault Tokai / Tonankai / Nankai earthquake (M8.7)
Near Nagoya station projected for a multi-fault Tokai / Tonankai / Nankai earthquake (M8.7) Expected to produce strong shaking
at construction sites 19 Differences in seismic intensity near plate boundaries inland
Crustal earthquake Inter-plate earthquake
Near Osaka station projected for a multi-fault Tokai / Tonankai / Nankai earthquake (M8.7) Near Osaka station projected for inland earthquake (M7 class) The strength of an earthquake can differ depending on the
earthquake type, even at the same site. 20 How buildings sway? Inter-plate earthquake 200m model building (natural period 5 seconds)
Displacement at top of 200m building model
Long period component
Ground motion Inter-plate earthquake : near Osaka Station projected for a multi-fault Tokai / Tonankai / Nankai earthquakes 21 How buildings sway? Crustal earthquake 200m model building (natural period 5 seconds)
Displacement at top of 200m building model
Ground motion
Crustal earthquake : Osaka Station projected for shallow inland earthquake (magnitude 7) 22 － Movie －
How differences in ground motion characteristics
affect the swaying of the building ?
23 Differences of the swaying Inter-plate earthquake
♯2003 Tokachi-oki Earthquake in Tomakomai2003 city年⼗勝沖地震苫⼩牧 ♯Japanese seismic intensity was 4
24 15F 30F 45F 60F Differences of the swaying Crustal earthquake 1995年兵庫県南部地震神⼾海洋気象台
♯1995 Hanshin-Awaji earthquake in Kobe city ♯Japanese seismic intensity was 6
25 15F 30F 45F 60F Tentative spectra for long period ground motion, announced by government 2012
Shinjyuku Tokyo Hamamatsu Shizuoka Kokuji Wave spectrum averageaverage ++ standardstandard deviationdeviation average wave
Tsushima Aichi Konohana Osaka These are not standard yet.
We’ll have revision of the Building Standards Law.
Next year ?
26 ４. Conclusions
27 Conclusion
1. A method of simulating earthquake ground motions based on a quantitative evaluation of the Fourier phase has been introduced.
Examples of the synthesized waves for inter-plate and crustal earthquakes have shown. 2. The dynamic behavior of high-rise buildings differs widely depending on the property of earthquake ground motions. 3. In performance-based design, it is important to consider the frequency characteristics of seismic waves.
28 And Finally・・・ points of seismic design and suggestions
1. Appropriate choice of seismic safety measures according to required performance and each form of buildings.
2. Adequate damping performance with the well- balanced Installment of devices in a building in addition to the structural strength of buildings.
3. Earthquake resistance of finishing materials and building equipments, not only of structural frame, in terms of “operational” or “fully operational” use of buildings.
4. Correct evaluation of seismic performance for existing skyscrapers.
29 Thank you