14 th 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 Site Characteristics (Soil conditions) Building Surface of Ground Sedimentary Layer Seismic Bedrock Propagation Characteristics Source Characteristics (Fault Plane) 8
Framework of the Proposed Method Fourier Amplitude Fourier Phase Source Characteristics Propagation Characteristics Site Characteristics Model Geometrical Damping Multiple Reflection Theory Quantitative Evaluation 9
Fourier Amplitude Source Characteristics: Model M Fourier amplitude log ( T ) 2 0 ( 2 / Tc ) A M (3.1) 2 0 ( 2 / T ) T 1/ c f c log T Propagation Characteristics :Geometrical Damping 1 U ( r0, T ) A ( T ) r (3.2) 0 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 Acc. (m/s 2 ) 3.0 0.0-3.0 0 50 100 150 200 250 300 Time (sec) Distribution of phase differences 0.0 0-0.5-1.0-1.5-2.0 Phase differences (rad) (a) EW component accelerogram and distribution of the phase differences recorded at Hachinohe Harbour during the 1968 Tokachi-oki Earthquake 1.0 0.5 / 0.18 Acc. (m/s 2 ) 10.0 0.0-10.0 0 50 100 150 200 250 300 Time (sec) Distribution of phase differences 1.0 0.5 0.0 0-0.5-1.0-1.5-2.0 Phase differences (rad) (b) NS component accelerogram and distribution of the phase differences recorded at JMA Kobe during the 1995 South Hyogo Prefecture Earthquake / 0.05 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 Standard deviation of phase differences / 0.4 0.3 0.2 0.1 / 0.06 0.0003r 0.0 0 100 200 300 400 500 600 700 Hypocentral distance (km) r 0 0 (2.3) : 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) Standard deviation of phase differences 0.4 0.3 0.2 0.1 0.0 0 100 200 300 400 500 Hypocentral distance (km) (b) Plots of / of the NS and EW components in eastern Hokkaido (In the direction of rupture propagation) Standard deviation of phase differences 0.4 0.3 0.2 0.1 0.0 0 100 200 300 400 500 Hypocentral distance (km) (c) Plots of / of the NS and EW components in western Hokkaido (In the orthogonal direction of 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 / 0.08 0.0003r0 (2.5) Fault length = 100 km r 0 200km / 0.14 Inter-plate Earthquake r 0 100km / 0.11 r 0 0 km / 0. 08 r 0 100 km / 0.10 r 0 100km / 0.09 Hypocenter r0 100km r 200 km r 0 300 km 0 / 0.08 / 0. 11 / 0. 14 / 0.05 0.0003r (2.4) Direction of rupture propagation 0 Figure 3.1 Standard deviation of the phase differences at the observation sites 14
Flow Chart of the Proposed Method Fourier amplitude Source characteristics: model Eqn. 3.1 Propagation characteristics: Eqn. 3.2 Fourier phase Source and propagation characteristics: Crustal earthquake Eqn. 2.3 Inter-plate earthquake In the direction 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) Acc. (m/s 2 ) 3.0 0.0-3.0 0 50 100 150 200 250 Time (sec) (a) Acceleration of observed wave Vel. (m/s) 0.1 0.0-0.1 0 50 100 150 200 250 Time (sec) (c) Velocity of observed wave Acc. (m/s 2 ) 3.0 0.0-3.0 0 50 100 150 200 250 Time (sec) (b) Acceleration of synthesized wave Vel. (m/s) 0.1 0.0-0.1 0 50 100 150 200 250 Time (sec) (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) Acc. (m/s 2 ) 1.0 0.0-1.0 0 50 100 150 200 250 Time (sec) (a) Acceleration of observed wave Acc. (m/s 2 ) 1.0 0.0 Long period component -1.0 0 50 100 150 200 250 Time (sec) (b) Acceleration of synthesized wave Vel. (m/s) Vel. (m/s) 0.2 0.0-0.2 0 50 100 150 200 250 Time (sec) (c) Velocity of observed wave 0.2 0.0-0.2 0 50 100 150 200 250 Time (sec) (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 Tomakomai 2003 city 年 勝沖地震苫 牧 Japanese seismic intensity was 4 15F 30F 45F 60F 24
Differences of the swaying Crustal earthquake 1995 年兵庫県南部地震神 海洋気象台 1995 Hanshin-Awaji earthquake in Kobe city Japanese seismic intensity was 6 15F 30F 45F 60F 25
Tentative spectra for long period ground motion, announced by government 2012 Shinjyuku Tokyo Hamamatsu Shizuoka Kokuji Wave spectrum average + standard deviation 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