Research Trends and Results

Arrangement and assessment towards earthquake
observation and earthquake motion of architecturalstructure
AZUHATA Tatsuya (Dr. (Science)), HeadARAI Hiroshi (Dr. (Engineering)), Senior Researcher
Building Department

Structural Standards Division

INOUE Namihiko, Senior Researcher
IWATA Yoshihiro(Dr. (Engineering)), Senior Researcher
Standards and Accreditation System Division(Keywords) Earthquake observation, Earthquake motion assessment, dynamic interaction, seismic design
１.Introduction(main shock), and Figure 3 a comparison of maximum

To ensure safety of architectural structure for a great

acceleration observed at first floor and 5th floor during main

ocean trench earthquake, it is important to assess earthquake

shock and aftershock. The following will be understood bymotion that impinges on architectural structure. Therefore,

Figure 1 and 2.

earthquake observation has been done for earthquake
motion assessment regarding various architectural structurefrom low rise to super high rise. Arrangement of record /analysis result of 5-story box frame type reinforced concrete
construction is indicated here as an example.

Fourier Spectrum ratio

as part of MILIT general technology development,

10.1

2.An example of arrangement of record and analysis result

theseismographisinstalledoutsideofarchitectural structure to demonstrate the relationshipbetween 『earthquake motion』 of the ground level and『earthquake load』that impinges on architectural structure.
Construction location: Mihama-ku, Chiba
Number of stories: 5 stories

5F

Height: 14.03 m

Seismograph
地震計
Flat surface dimension: 8.06m×65.7m

GL

1F

Ground classification: Second classSuperstructure:
Boxframe
type
reinforced concrete construction
Fundamental structure: Pile foundation(PC pile)

Figure 1 Outline of target architectural

Figure 2 is a Fourier spectrum ratio from earthquake recordof The 2011 off the Pacific coast of Tohoku Earthquake

1Frequency (Hz)10Figure 2 fourier spectrum ration (The 2011 off the Pacific
5F maximum acceleration (cm/s/s)

research,Longside
長辺方向
0.1

5F最大加速度(cm/s/s)

Figure 1 is an outline of installation of seismograph. in this

5F/GL
5F/1F
1F/GL

10Short side direction
Long side direction
The 2011 off the Pacificcoast of Tohoku
2011東北地方
Earthquake
太平洋沖地震

1F最大加速度(cm/s/s)
1F maximumacceleration (cm/s/s)
Figure 3 Maximum acceleration at the 1st floor and 5th floor(main shock and aftershock)Superstructure
上部構造はあま isnotlikely to amplify
り増幅されない
Distributionof versatile
汎用的な設計用地

stSway
地盤の動き(sway)
1F of the 1 floor
isが卓越
remarkableplanningsite ability
震力(現行基準)の分布 standard)(current1F
Figure 4 Assumed behavior during earthquake from therecord and Earthquake assessment

Research Trends and Results(1)Fourier spectrum ratio 5F/GL (red) and 1F/GL (green)
are almost conformable with neighborhood of predominantfrequency (approx. 2Hz) (Figure 2).

(2) Maximum acceleration of the 1st floor and 5th floor isalso almost conformable (Figure 3).

(3) From (1) and (2), this architectural structure is assumed
that it presented the behavior as it's indicated in Figure 4,
and earthquake load in superstructure, it is thought that it isless likely to amplify than assessing on the assumption that
it is foundation fixing.

3. Conclusion
Today, earthquake record of architectural structure has
been arranged and assessed by type of ground, story andstructure. It helps streamlining of earthquake resistantdesign of structure by being able to accurately assess therelationship between earthquake motion on the ground andearthquake load that impinges on architectural structure.