Study Trip Report on
THE SENDAI GOVERNMENT OFFICE BUILDING #3
By: Muhammad Rusli (E-Course)

The visit to the Sendai Government Office Building #3 was conducted on Tuesday, September 6, 2011.
The Building is addressed at 1-3-15 Gorin, Miyagino-ku, Sendai-shi, located about 470m northeast
from Tsutsujigaoka Station. This building was constructed in 1991 and used as a joint office building
by the governmental institutions in Sendai City, and the structure consisted of 9 floors which weremade from reinforced concrete. In 2008, the building was retrofitted and the base isolator system wasinstalled to enhance its seismic resistant. The 850 base isolators were constructed from the 80% LeadRubber Bearing (LRB) which was to cover the horizontal building displacement up to 50 cm. The
location and the view of the building are represented in Figure 1.

(a)(b)
Figure 1. The Sendai Government Office Building #3, location (a)and the front view (b)In this building, we had a chance to observe some rooms in accordance with earthquake
monitoring system, those are: the basement that had a displacement monitoring plate, the top floor, theJMA office room, and JMA strong motion instrument.
1.

Visit to the basement and the top floor

In the basement floor, the visitors were introduced to the displacement monitoring plate that wasinstalled to record the trace of building movement anytime when an earthquake struck. The instrument
consists of the needle and the plate. The steel needle with vertical spring is anchored to the mainbuilding structure above the base isolator and could move as well as the movement of the building,and the plastic plate with circle scale is anchored to the basement floor below the base isolator tomeasure the maximum trace directly. The displacement monitoring instruments can be seen in Photo 1.
Mr. Kagaya from the Ministry of Land Infrastructure, Transport and Tourism (MLIT)
explained that on March 11, 2011 the plate recorded the building movement due to the mainshock of
the off Pacific coast of Tohoku Earthquake 2011 with maximum displacement 18 cm from the center
point, some needle on the other places were broken during the shaking caused by the power of theshock or the high acceleration of the vertical motion. After recording the mainshock, the plastic plate
was replaced by the new one and then recorded the biggest aftershock on April 7, 2011 with themaximum displacement 11 cm. All of the needles were turn back into the original position after
experiencing strong motions, it means that the structure did not suffer any residual displacement, thebase isolation system were working properly and still in a good condition.

(a)
(b)
(c)
Photo 1. The plastic plate (a), Needle (b), and the trace records of themainshock of Tohoku earthquake March 11, 2011
According to the strong motion data that were recorded on the basement, the second, theforth and the ninth floor, the maximum acceleration of the building was reduced by 50% comparing tothat of the ground (on the basement). Although the structural members were safe, some damages wereobserved on the non-structural elements when the building moved with the maximum velocity up to40 cm/sec under the mainshock of the Tohoku Earthquake March 11, 2011. Some of the non-structuralelements were broken such as the fire resistant material that filled the gap between the top of thebasement wall and the bottom of the building, and some parts of the ceiling were also broken causedby collision with the lid of the utility holes which was placed right below the ceiling. The photo ofsome damages can be seen in Photo 2.

(a)(b)
Photo 2. Damage on the non-structural elements such as gap filler and ceiling
After visiting the basement floors, Mr. Kagaya showed us the top floor which was in agood condition and no damage was observed. There were some instruments placed and belonged to
the Japan Meteorological Agency (JMA) and other institution which were used for acquiring data,
sending or receiving data, or other purpose like power sources. Some of the instruments such as strong
motion sensors, sunlight and weather sensors, GPS, and communication antenna were placed. There
were also the solar cells installed to generate electric power for daily use.
2.

Visit to the JMA office and strong motion instrument

The JMA Office was located on the second floor which had the phenomena observation systems
corresponding with earthquakes and volcanoes matters. Mister Funakoshi kindly explained the daily
activity of the JMA that had planted about 4,000 seismographs throughout Japan. This office also
included the volcanoes monitoring system for the Tohoku area that has 18 active volcanoes.
The earthquakes data which has been collected in this regional office is then sent to theJMA Office centre in Tokyo to be processed and resulted earthquake parameters as very useful
information. The earthquake parameters such as location, magnitude and intensity which are analyzed
by the JMA are then disseminated to the public within 3 minutes after an earthquake is detected byseismographs. The information of earthquake is released to the public through mass communication

systems such as television, radio, website and cell phone. The JMA regional office analyzes more
precise earthquakes everyday and always checks all of the data including the very minor earthquakes.
During the mainshock of the Tohoku Earthquake on March 11, 2011 that generated thehigh tsunami, the JMA recorded the sea levels through the 25 observation points on the Pacific Coastof Tohoku. In the last 3 months, some big earthquakes were recorded in this JMA office, but nodamage occurred on the building because most of the earthquakes were the short period vibration
whereas the building itself had a long natural period, about 1 second under the small earthquake up to
4 seconds under the big earthquake due to the base isolation system.
According to the public survey by the JMA, the aftershock on April 7, 2011 was more
fearful than the mainshock on March 11, it could be explained by the graph of response spectrum that
had a long range of period from 0.2 to 1.2 second. Besides that, the event occurred at night whilepeople at that time were sleeping and big vertical motion was felt larger because people were lying
down. A graph of the aftershock which occurred on the April 9, 2011 was showed by Mr. Funakoshi.
He explained that the aftershock had maximum intensity "6 upper" in Sendai City, while the intensity
scale of the JMA are 0 to 7 with the scale 4, 5, and 6 are divided into the "lower" and the "upper".
After showing the activity of the JMA office, Mr. Funakoshi led the visitors to the strong
motion installation building on the western side of the Sendai Governmental Office Building #3. Itwas a square reinforced concrete building with the seismograph installed on the base floor about 3
meters below the ground surface. The office room and the strong motion installation are shown in
Photo 3.

(a)
(b)
(c)
Photo 3. JMA Sendai Regional Office (a), Strong motion installationbuilding (b), and Strong motion instruments (c)There were many types of the seismograph which were placed on the massive concrete
block with the rectangular shape about 150x350x80 cm3, from the old types to the new one. The oldseismographs were operated from 1960 to 1990 and manually recorded the strong motion to the sheetsof paper and archived on the shelves placed in the same room with those seismographs. All of the dataon papers had been copied in the microfilm files to save the contents of the data records and to bequickly accessed. Now, the newest seismographs record the data to the computer server, and there are
two sensors: one is the main strong motion sensors and the other is used to monitor the noise forcorrecting the data records.
3.

Conclusions

By visiting the Sendai Government Office Building #3, we witnessed the effect of retrofitting andseismic base isolation system on the building that evidently enhanced the building safety under a big
earthquake such as the mainshock of the Tohoku earthquake that occurred on March 11, 2011.
Monitoring on seismic activity as well as volcanoes are very important to carry out, inorder to increase awareness and to provide early warning for society, hence reducing a risk of thedisasters. Data records of seismic and volcanic activities can be used to study its phenomena for more
understanding of natural disaster characteristics to support the effort in reducing the disaster risk.