Wataru Goto. NTT FACILITIES, INC. in Japan. 15th World Conference on Earthquake Engineering 24 to 28 September 2012 LISBON PORTUGAL

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1 15th World Conference on Earthquake Engineering 24 to 28 September 212 LISBON PORTUGAL Seismic Performance of Response Controlled High Rise Building in Sendai (Special Session : Significant Building Responses Recorded During the 211 Great East Japan Earthquake) Wataru Goto NTT FACILITIES, INC. in Japan

2 Introduction Damage in the Great East Japan Earthquake Tsunami damage Enormous 1/15 Earthquake damage Relatively little Structural damage Non structural member and equipment damage A little Many The damages of structural control and base isolated buildings Very little They provided sufficient performance. We focus on a high rise building in Sendai as an example that the damper functions effectively. We will show you Analysis of observation records Vibration characteristics of the building Seismic response analysis

3 Overview of the intended building Accelerometer Accelerometer Z-2 X3 X4 X5 X6 X7 X8 X9 X1X11 17,4 42,2 RDT LED Steel tower RDT : The rotary damping tube LED : The lead extrusion damper Y(N344 E) N Y6 Y5 Y4 8, 15,85 X3 Under G.L. 6,4 6,4 6,46,4 6,46,4 6,4 6,4 X4 X5 X6 Above G.L X7 TOWER 51,2 X8 X9 X1 X11 X(N74 E) LED 23,85 RDT 53,5 2/15 Fig. 2.1 Overview of the building A 76,7

4 Observed seismic waves 3 Max, X dir. 3/15 Acc. (cm/s/s) Max, NTT Kobe 1995 NS Y dir. Max, 331 Max, 153 NTT Kobe 1995 EW 21 Time (s) 3 Fig. 4 5 The observation records (Comparison with Southern Hyogo pref. earthquake in 1995) The distinction of these seismic waves are indicated the following The Maximum acceleration in the X direction is gal, and that in the Y direction is gal. This seismic wave last for more than 1 minutes,, and contains two peaks. > It seems that seismic shift have occurred in several areas, from off the southern Iwate prefecture to off Ibaraki prefecture.

5 The designed natural periods 4/15 Sv(5%) [cm/s] Y dir. 3rd.68s Y dir. 2nd 1.11s X dir. 1st 2.97s X dir. 3rd X dir. 2nd 1.1s Y dir. 1st 3.26s s Period [s] Fig. 8 The relations of the response spectrum and the designed natural periods The X dir. contains many components with around a period of 3 sec.. > Aslightly severe seismic force works on the X dir.. The Y dir. contains many components with a period of 2 seconds and a under. > The seismic wave is excited in higher order modes.

6 Analysis model 5/15 Using the records of the 211 Tohoku Earthquake, the earthquake response was analyzed with the space frame elast plastic model. Profile of analysis model Analysis Model Layer Number Column & Beem Member Model Damper Viscous damping factor of frame Space frame inelasic analysis model 36 layered (Above G.L. = 34, Under G.L. = 2) Beam element with rigid plastic edge Lead extrusion damper > Elastic plastic spring model Rotarydamping tube > Maxwell model h = 1. % (Proportion to instantaneous stiffness) The natural periods of the model was adjusted by the superimposed load or the member stiffness.

7 Maximum response distribution 6/ Max. Acc. (cm/s2) Max. Acc. (cm/s2) Max. Disp. (cm) Max. Disp. (cm) In the X direction, the acceleration and the displacement generally agree with both responses. In the Y direction, the responses of the analysis result become smaller than the observation record.

8 Acc. (gal) Acc. (gal) Acc. (gal) Acc. (gal) The time history of acceleration The roof floor Ana.Max, 36.2 Obs.Max, Observation Analysis 7/ Time (s) Observation Analysis Ana.Max, 28.6 Obs.Max, Time (s) The tower top Obs.Max, 54.8 Ana.Max, Observation Analysis Obs.Max, Time (s) Observation Analysis Ana.Max, Time (s)

9 Disp. (cm) Disp. (cm) Disp. (cm) Disp. (cm) The time history of displacement The roof floor Observation Analysis 8/ Time (s) Observation Analysis Time (s) The tower top Observation Analysis Time (s) Observation Analysis Time (s) The analysis model could reproduce the actual phenomena.

10 Damping force (kn) Damping force (kn) The damping performance RDT 75 % The designed damping force Velocity (mm/s) The relation between the velocity and the damping force of RDT LED Displacement (mm) The relation between the displacement and the damping force of LED Absorption energy (kn*m Vibration RDT LED Viscous damping of frame 73 % 25 % 9/ Time(s) The time history of absorption energy RDT provided the sufficient damping performance up to 75 percent of the designed damping force. LED provided the sufficient damping performance by becoming plastic. The absorption energy of dampers consists about 73 percent in the total.

11 With damper.vs. Without damper (Acceleration) 1/ X 54.8 With Damper Without Damper Max. Acc. (cm/s 2 ) Y Max. Acc (cm/s 2 ) It shows little characteristic difference between both case

12 With damper.vs. Without damper (Displacement) 11/ With Damper X X Max. Disp. (cm) Without Damper Y X Max. Disp. (cm) In the Y direction, the maximum amplitude increase about 1.7 times,, compared to with damper.

13 With damper.vs. Without damper (Story drift) With Damper X Max. Story Drift (rad) Design criteria = 1/125 1/15 Without Damper Y 1/ Max. Story Drift (rad) In case that the building was uncontrolled by damper, the main flame would have been damaged. 12/15

14 With damper.vs. Without damper (Shear force) 13/ X Max. Shear Force (kn) Y Max. Shear Force (kn) The building is safeguarded against the earthquake by high damping performance.

15 Changing of the natural period Changing of the natural period before and after a large earthquake Seismic record Microtremor (Ambient noise) The largest aftershock The main earthquake (The 211 off the Pacific coast of Tohoku Earthquake) 3 14/15 Period (s) The average of before 2.5 The average of after Chronological order Fig The comparison of transfer function from each earthquake The natural periods have become larger in the main earthquake (M9.) and the largest aftershock (M7.2), and returned to the original values both both in the X and Y. The natural periods in a large earthquake approach the design natural period. The average of after the main earthquake are slightly larger than n that of before the main earthquake. > This tendency is similar to microtremor records.

16 Conclusion 15/15 The seismic motion is slightly smaller than the design basis spectrum in Japan, but it exceeds in some periodic bands, and this is characterized by the long earthquake duration. The natural periods estimated from the main earthquake are larger than ever observed,, and these periods are close to the design value. As a result of using the parameters based on observation records, the building response during the Tohoku earthquake was simulated. The analysis result verified that the dampers provided the sufficient damping performance,, and the building is safeguarded against the earthquake.

17 END Are there any question?