2006 Method for estimation of characteristics of wooden houses using vibration test data. 2007 1 1095524
Method for estimation of characteristics of wooden houses using vibration test data. 2 1 6.4Hz2 9.4Hz 6.4Hz 9.4Hz 1 18 i
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Abstract Method for estimation of characteristics of wooden houses using vibration test data. Chika Hosokawa 1. Preface The vibration tests on wooden houses, which aim at contribution to the improvement of the seismic resistant diagnostics, are described in this study. In recent years, seismic resistant diagnostics on wooden houses were carried out, but it is unreliable because diagnosis is based on the visual observation. Evaluation of stiffness is effective for the improvement of the reliability of the earthquake resistant diagnostics, because it is considered that the effectiveness of bracings appear in the stiffness. In this study, a lot of models without partial bracing were used in the analysis, and the best model, which can represent the dynamic characteristics of the tested house, was searched. From this model, the presence of bracing of the house is judged. If the judgment is possible, the improvement of the reliability of the diagnosis can be expected, reflecting the result on the manual of earthquake resistant diagnostics. 2. Vibration test Vibration test of wooden house was conducted using the vibration exciters. The exciters were allocated to the second floor to excite the main column of the house. The larger responsive acceleration was observed than the former test, because the exciters were improved. Thus, the improvement of the exciter is considered to be effective. The exciters are equipped with the displacement meter and control circuit. These are used to control the shaft of the motor. From the Fourier spectrum of the acceleration, the first natural frequency of the house is 6.4Hz, and second is 9.4Hz. From the mode shapes, the vibration at the frequency of 6.4Hz is dominated by the sway motion, and the vibration at 9.4Hz is dominated by the torsion motion. 3. Dynamic analysis The structural model of the tested house was made and analyzed. The section of column and bracing is obtained from the drawing. The Young's modulus of the Japanese cedar is used. To check the movement of the floor in detail, the additional vibration test was conducted, using the accelerometers allocated in line. As a result, there is the slight deformation of the floor but the floor can be assumed rigid in the modeling of the wooden houses. The mass was accumulated to about 18 tons, which include the roof, wall and floor. The weight of column and bracing is not considered. At first, the wall was not modeled. But, in the case of the vibration with small amplitude, the wall has a significant influence on the stiffness. Thus, the wall was modeled hereafter. The damping of the higher mode is not close to the general damping of wooden houses. However, concerning the lower modes, the shape of the spectrum obtained from the dynamic analysis agrees with the experimental one well. Therefore the accuracy of the model can be considered to be sufficient. iii
4. Estimation of the effectiveness of the bracing It is possible to evaluate the presence of the bracing from the result of the Eigen value analysis in the case of the model without wall. However, when the wall was modeled, it became difficult to sense the change in the mode shape due to the presence of bracing, because the stiffness of the wall is too large. Therefore the model which loses a lot of bracing is examined. Though the change in the mode shape is small and is difficult to sense, the influence of the presence of the bracing appears in the sum of the mode difference of all nodal points. Based on this numerical information, the mode shapes were checked in detail and it is found that the influence of the presence of the bracing appears in some particular mode. It is understood that the difference in mode shape is appears by the presence of bracing. 5. Conclusion It can be said that the model has high accuracy because it is able to represent the experimental result. The judgment of the presence of bracing is possible when the stiffness of the wall of the house is small, but, in the cases of the houses built in recent years, it is difficultly to check the presence of bracing because the walls have large stiffness. However, if the results are checked in detail, the difference appears on the mode shape by the presence of bracing and it is not impossible to check the effectiveness of the bracing from the vibration test result. This analytical result cannot be applied in general, at once. It is necessary to test and analyze individual houses more carefully. By this restriction, the merit of easy to estimate the stiffness using vibration test is lost and it limits the applicability of this method. It is necessary to accumulate the more data of change in the mode of each typical house for the practical use of this method. iv
1 2 2 3 3 4 5 5 6 6 8 8 9 10 10 10 10 10 11 12 13 14 15 15 16 17 19 19
2-1 ( ) 2 2-2 ( ) 2 2-1 (1 ) 2 2-2 (2 ) 2 2-3 ( ) 3 2-4 ( ) 3 2-5 4 2-3 4 2-6 4 2-4 4 2-5 5 2-7 6 2-6 6 2-8 7 2-7 7 2-8 7 2-9 8 2-9 8 2-10 8 2-11 9 2-12 9 2-13 6.4Hz( ) 9 2-14 9.4Hz( ) 9 3-1 10 3-2 ( ) 10 3-3 6.4Hz 11 3-4 9.4Hz 11 3-5 12 3-6 13 3-7 14
4-1 Mode1(3.71Hz) 15 4-2 Mode2(3.92Hz) 15 4-3 Mode1(3.6Hz) 15 4-4 Mode2(3.82Hz) 15 4-5 Mode1(6.31Hz) 16 4-6 Mode2(6.74Hz) 16 4-7 Mode1(6.29Hz) 16 4-8 Mode2(6.60Hz) 16 4-9 17 4-10 18 3-1 ( kg/) 11 3-2 12 3-3 13 4-1 17
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59 594 59 5 2 57.31 49.14 24.57 73.71 2-1 2-2 2-1 2-1 ( ) 2-2 ( ) N 2-1 (1 ) 2-2 (2 ) 2
2-3 4 15mm 180g 1,100g 10kg (70N/) 3 1 2 3 3 2 1 15mm 180g 20kg 2-3 2-4 2-3 ( ) 2-4 ( ) 3
LED LED 2 2-3 2-5 2-3 LED 2-5 2-3 () 2-6 2-4 PC + PA VCM DM 2-6 2-4 4
2 2-5 AB B CD 2 2-5 A C B D 2-5 D/A 2 2-7 150cm 2-7 5
2-7 500N A/D 10 20Hz 100 / 4096 / 40.96 2-6 D/A PC D/A Amp Amp 2-6 6 PC
FFT 10 520Hz 520Hz 2-8 2-8 2-7 2.0 1.5 (N) B A 1.0 0.5 0 5 10 15 20 25 2-8 7
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2-11 1 6.4Hz2 9.4Hz 0.14gal 2 2 2-12 B 1 2 2-11 2-12 2-11 2 1 2 6.4Hz 9.4Hz 0.25 6.4H 1.00 9.4H 9.4H 6.4H 0 5 10 15 20 25 0 5 10 15 20 25 2-11 2-12 2 2-13 2-14 2-13 6.4Hz 2-14 9.4Hz 6.4Hz 9.4Hz (2) 0 180 2-11 2-14 6.4Hz 9.4Hz 2-13 6.4Hz( ) 2-14 9.4Hz( ) 9
MIDAS Civil 3-1 3-1 9 2 7.2 10 N m 115115mm 10040mm 0 7 1 3-2 0 1 2 3 4 5 6 7 3-2 ( ) 10
6.4Hz 3-39.4Hz 3-4 6.4Hz 0 9.4Hz 7.2 10 9 N m 2 100mm 3-3 6.4Hz 3-4 9.4Hz (3) 18 3-1 3-1 ( kg/) 0.95 0.75 0.60 1 11
AK 11 3-5 A 1.0 B B B B C C A A A A D A A A I I I A A H A A A A A D E E J J J J A A A A A G G G A F F A A K K A K K 3-5 A 3-2 () () A 2.584 1.00 G 1.003 0.38 B 2.301 0.89 H 2.096 0.81 C 2.094 0.81 I 1.913 0.74 D 1.073 0.41 J 1.829 0.70 E 1.745 0.67 K 1.374 0.53 F 0.851 0.32 12
2 MIDAS Civil 3-3 3-6 3-3 Mode1 Mode2 Mode3 Mode4 Mode5 Mode6 0.13 0.015 0.015 0.015 0.03 0.015 0.015 0.015 6.47 6.74 10.26 13.3 15.20 18.43 Mode6 Mode4 Mode3 Mode5 Mode1,2 0.25 Mode3 Mode6 Mode4 Mode1,2 Mode5 0 5 10 15 20 25 0 5 10 15 20 25 3-6 0.010.03 Mode3 0.010.03 0.13 Mode3 0.03 Mode3 Mode6 13
3-7 6.4Hz 2 9.4Hz 6.4Hz 6.4Hz 2 3-7 6.4Hz 2 0.16 0.14 0.12 0.08 0.06 0.04 0.02 0 5 10 15 20 25 3-7 ( )3 9.4Hz 9.4Hz 14
2 2 4-1 Mode1(3.71Hz) 4-2 Mode2(3.92Hz) 4-3 Mode1(3.6Hz) 4-4 Mode2(3.82Hz) Mode1 Mode2 Mode1 Mode2 6.4Hz 9.4Hz 2 3.71Hz3.92Hz 15
4-5 Mode1(6.31Hz) 4-6 Mode2(6.74Hz) 4-7 Mode1(6.29Hz) 4-8 Mode2(6.60Hz) 4-5 4-8 4-5 4-8 Mode1 6.3Hz Mode2 6.7Hz Mode1 6.4Hz Mode2 9.4Hz Mode1 Mode2 16
1 12 4-10 4-9 2 5 5 4-10 X Y 4-1 4-1 (mm) 2 X Y X Y X Y X Y X Y mode1 0.5696 0.7183 1.2745 0.8023 0.0448 0.0425 0.0403 0.1262 0.9751 0.6973 mode2 1.0592 1.3976 1.1145 0.6796 0.0097 0.0127 0.1342 0.0246 0.0858 0.9679 mode3 0.0203 0.0896 0.0347 0.1254 0.0673 0.0232 35 0.0137 0.5569 0.6805 mode4 0.0615 0.0980 98 0.0957 0.0367 0.0148 0.0234 0.0078 0.0243 0.9713 mode5 0.0242 0.0412 0.0140 0.0482 0.1177 05 0.0602 0.0645 0.9001 0.1897 mode6 0.0400 0.1310 0.0271 0.1267 86 0.0298 0.0881 0.0164 0.5338 0.6676 X X Y Y 2 17
0.5 Mode3 Mode6 Mode3 Mode6 Mode1 Mode2 Mode1 Mode2 Mode4 5 Mode Mode2 1 2 1 2 4-11 Mode Mode2 4-1 Mode1 Mode2 Mode2 Mode1 4-10 18
Mode Mode2 (1) 2004 (2) 2004 (3) 2004 19
( - ) CH0 CH1 0 5 10 15 20 25 0 5 10 15 20 25 0.25 CH2 CH3 0 5 10 15 20 25 0 5 10 15 20 25 0.25 CH4 CH5 0 5 10 15 20 25 0 5 10 15 20 25 0.25 CH6 CH7 0 5 10 15 20 25 0 5 10 15 20 25-1 1
( - ) CH0 CH1 0 5 10 15 20 25 0 5 10 15 20 25 CH2 CH3 0 5 10 15 20 25 0 5 10 15 20 25 CH4 CH5 0 5 10 15 20 25 0 5 10 15 20 25 CH6 CH7 0 5 10 15 20 25 0 5 10 15 20 25-2 2
( - ) CH0 0.25 CH1 0 5 10 15 20 25 0 5 10 15 20 25 CH2 CH3 0 5 10 15 20 25 0 5 10 15 20 25 CH4 0 5 10 15 20 25 0 5 10 15 20 25 CH6 0.30 0.25 CH7 CH5 0 5 10 15 20 25 0 5 10 15 20 25-3 3