Development of a Passive Damper Device with High Damping Rubber for Wooden Houses

Transcription

1 Development of a Passive Damper Device with High Damping Rubber for Wooden Houses Tomoki Furuta Daiichi Institute of Technology, Japan Masato Nakao Yokohama National University, Japan Nobuyoshi Yamaguchi Building Research Institute, Japan 1

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3 Introduction Numbers of earthquakes had hit every part of Japan. In recent 1 years, JMA(Japan Meteorological Agency) Seismic Intensity 6 (Modified Mercalli intensity scale:mmi=9) or more was observed 17 times. Year.Month Location Magnitude Seismic Intensity 23.5 Miyagi-ken Oki lower 23.7 Miyagi-ken Hokubu upper 23.9 Tokachi Oki 8. 6 lower 24.1 Niigata-ken Cyuuetsu Fukuoka-ken Seihou Oki 7. 6 lower 25.8 Miyagi-ken Oki lower 27.3 Noto Hantou Oki upper 27.7 Niigata-ken Cyuuetsu Oki upper 28.6 Iwate Miyagi Nairiku upper 28.7 Iwate-ken Engan Hokubu lower 29.8 Suruga-wan lower Sanriku Oki Nagano-ken Hokubu upper Shizuoka-ken Toubu upper Miyagi-ken Oki upper Fukushima-ken Hamadouri 7. 6 lower Fukushima-ken Nakadouri lower 3

4 Amount of the annual sensed earthquake ( 検索期間 211/1/1 212/1/1 : - 211/12/31 212/12/3 24:) 震度 弱 5 強 6 弱 6 強 7 不明合計 年 1 1 月 年 2 2 月 年 3 3 月 年 4 4 月 年 5 5 月 年 6 6 月 年 7 7 月 年 8 8 月 年 9 9 月 年 1 1 月 年 月 年 月 年合計 総合計 平均 (/ (/ 月 ) )

5 After the earthquake March 11th, 5 earthquakes recorded Seismic Intensity 6 (MMI=9). (The earthquakes more than seismic intensity 6 are not generated this year.) It is important for buildings to resist repeated large earthquakes. Moreover, It is necessary to keep using buildings even after large earthquakes. New passive damper device for wooden houses has been developed. It includes high damping rubber which had been developed for laminated rubbers for base isolation. The new passive damper device realized High reliability Stable structural characteristic Simple and Low cost 5

6 New Developed Passive Damper Device Outer cylinder Extension pipe Steel rod Steel cylinder Steel cylinder ( =48.6mm, L=45mm, t =2.3mm) Steel rod ( =34mm) Cross section High damping rubber (L=17mm, t =5mm,G=.8N/mm 2 ) 6

7 Axial force (kn) Structural Characteristic of the New Damper 3 Damper Disp.(mm) -3 The hysteresis showed stable characteristic without a decline of stiffness under repeated cyclic force. Axial force at 5mm(g=1%) is approximately 2kN. 7

8 2793mm Static Shear Loading Test Beam(18mmX15mm) Column (15mmX15mm) Sill (15mmX15mm) 91mm 8

9 Shear force (kn) Static Shear Loading Test (Damper) Damper Drift(%) Shear force at 1% of drift was 5.5kN. fastener Slippage between the end of the damper and the fastener was occurred around 3kN. The hysteresis loop was relatively small due to low stiffness of the connection between fastener and wood member. 9

10 Shear force (kn) Static Shear Loading Test (Nailed Plywood) Plywood Drift(%) Shear force at 1% of drift was 5.9kN. A decline of stiffness under repeated cyclic loads was notable compared to the damper. 1

11 Shear force (kn) Static Shear Loading Test (Wood Brace) Brace Drift(%) Shear force at 1% of drift was 4.3kN. Buckling of the wood brace was occurred when the shear force was 4.9kN at 2.5% of drift. 11

12 Shaking Table Test Weight(2kN) Random wave, impulse wave and JMA Kobe wave (1%, 2% and 4%) (328gal) 12

13 Shear force (kn) Shear force (kn) Shear force (kn) Shaking Table Test Though a decline of stiffness was occurred on plywood and wood brace, the hysteresis of damper showed stable characteristics Plywood Drift(%) T=.37sec -8 Drift(%) Heq=2.3% 6 Damper T=.51sec Drift(%) -4 Heq=17.6% Brace 8 4 Drift(%) Drift(%) T=.37sec Drift(%) Heq=13.4%

14 Shaking Table Test Nailed plywood (JMA Kobe 4%) Double wood brace (JMA Kobe 4%) Nailed plywood +Damper (JMA Kobe 4%) Double wood braces +Damper (JMA Kobe 4%) Plywood + Damper Wood brace + Damper Maximum shear force (kn) Maximum drift (%) Maximum shear force (kn) Maximum drift (%) % 44% Rate of decline of the maximum drift

15 Shear force (kn) Shear force (kn) Shear force (kn) Analysis model for Earthquake Response Analysis Bi-linear model was adopted for damper model, while Bilinear + Slip model was for plywood and wood brace Plywood Drift(%) Bi-linear +Slip h=6.% 6 Damper 4 2 Drift(%) Bi-linear h=6.6% Brace Drift(%) Bi-linear +Slip 15 h=3.%

16 Earthquake Response Analysis Mass:2kN Plywood or Wood brace Damper Parallel model Ratio Initial stiffness (kn/mm) Plywood or Damper Total Wood 1: : : : : : : : : : :

17 1: 9:1 8:2 7:3 6:4 5:5 4:6 3:7 2:8 1:9 :1 1: 9:1 8:2 7:3 6:4 5:5 4:6 3:7 2:8 1:9 :1 Drift (%) Shear force (kn) Result of Earthquake Response Analysis (Plywood + Damper) Ratio of initial stiffness (Plywood : Damper) Ratio of initial stiffness (Plywood : Damper) Response drifts at the ratio of 7:3 and 6:4 are the smallest. They are 79% of the largest drift. Replacing 3% or 4% of plywood by the damper decreases 17 drift by 21%.

18 1: 9:1 8:2 7:3 6:4 5:5 4:6 3:7 2:8 1:9 :1 1: 9:1 8:2 7:3 6:4 5:5 4:6 3:7 2:8 1:9 :1 Drift (%) Shear force (kn) Result of Earthquake Response Analysis (Wood brace + Damper) Ratio of initial stiffness (Wood brace : Damper) Ratio of initial stiffness (Wood brace : Damper) The smallest response drift is 72% of the largest one at the ratio of 6:4. Replacing 4% of wood brace by the damper is the most efficient. 18

19 Conclusions To investigate the structural performance of the new passive damper device, static shear loading test, shaking table test and earthquake response analysis were conducted. Shear force of wood frame with the damper device is 5.5kN which is approximately equivalent to the one with plywood. Addition of the damper device to plywood or wood brace reduces response drift by approximately 5%. No remarkable increase of shear force was detected. Replacing 3% or 4% of plywood in wooden houses reduces response drift by 21%. For wood brace, replacing 4% of wood brace reduces drift by 28%. Because the effect of the damper was not clear, after this paper, I analyzed more. 19

20 Axial force (kn) Analysis model Damper (non-linear) Joint Displacement (mm) Wood frame (linear) Wood frame Damper Joint Joint.29kN/mm (8kN/rad) Joint (linear) 3kN/mm Joint 2

21 Response acc. (gal) Response disp. (mm) Shaking table test Analysis Time (sec) Time (sec) Responses of the frames by the dynamic analysis are in accordance with those of shaking table tests. 21

22 Shear force (kn) Shear force (kn) Shear force (kn) Shear force (kn) Nailed plywood Wood brace Story disp. (mm) Experiment Story disp. (mm) Model Story disp. (mm) -1 Experiment Story disp. (mm) To evaluate responses of the frames with both dampers and conventional shear walls, analysis models of the conventional shear walls were developed. -1 Model 22

23 Acceleration (gal) Acceleration (gal) Acceleration (gal) Acceleration (gal) Acceleration (gal) Acceleration (gal) Analysis result Story disp. (mm) P:D=1: 2 P:D=5:5 2 P:D=: Story disp. (mm) Story disp. (mm) Story disp. (mm) Story disp. (mm) Story disp. (mm) B:D=1: B:D=5:5 B:D=:1 As the wall length ratio of dampers increases, the stiffness of the frame increases and response displacements of the frame 23 decreases

24 Response displacement (mm) 2 15 Damper+Nailed plywood,kobe Damper+Nailed plywood,bcj Damper+Wood brace,kobe Damper+Wood brace,bcj Wall length ratio of damper (%) As the wall length ratio of dampers increases, while the peak response displacements of the frame decrease successively, the peak response accelerations of the frame are almost constant. 24

25 Response acceleration (gal) Damper+Nailed plywood,kobe Damper+Nailed plywood,bcj Damper+Wood brace,kobe Damper+Wood brace,bcj Wall length ratio of damper (%) This damper is displacement-dependent as wood, and less velocity-dependent than typical oil dampers. These features of this damper may lead the results of these combination analyses. 25

26 This damper development project is now going on, following improvements are considered. Manufacturing process of the damper Minimize stiffness reduction due to temperature Reducing the displacement between the fastener and wood member Investigating structural characteristics of the damper under large deformation Earthquake response analysis for more several cases 26

27 非常谢谢了 27

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29 Dependence.(Rate of change) Temperature dependence. Speed dependence. (Most of the speed dependence does not change.) A change by the aging. 29

30 JMA Seismic Intensity The Japan Meteorological Agency seismic intensity scale is a seismic scale used in Japan and Taiwan to measure the strength of earthquakes. Unlike the moment magnitude scale, the JMA scale describes the degree of shaking at a point on the Earth's surface. The JMA Scale runs from to 7, with 7 being the strongest. Real-time earthquake reports are calculated automatically from measurements of ground acceleration. The JMA operates a network of 18 seismographs and 627 seismic intensity meters. by Wikipedia 3

31 Response acc.(gal) Acc.(gal) Acceleration Time(sec) h=5% h=1% h=2% Natural period (sec) 31

32 Drift (%) A Cyclic history Test apparatus The specimen was fastened to the test apparatus at the sill. Static shear force was applied to the beam of the specimen. 32

33 2793mm Beam(18mmX15mm) Column (15mmX15mm) Sill (15mmX15mm) 91mm 33

34 tenon (9x3x45) mortise Japanese hemlock (a few knots) 34

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37 Summary of Static Shear Loading Test Shear force at.5% of drift (kn) Secant stiffness at.5% of drift (kn/mm) Shear force at 1% of drift (kn) Damper Nailed plywood Wood brace Shear force of the damper was 79% of the one with plywood at.5% of drift, however, both were almost the same level at 1.% of drift. 37

38 + = Bi-linear Slip Bi-linear+Slip 38

39 Drift(%) Drift(%) Drift(%) Dam per Test Model Plywood Tim e(sec) Test Model Tim e(sec) Brace Test Model Tim e(sec)