Research Trends and Results

A trend of countermeasures for the long-period earthquake
ground motion to architectural structures
MUKAI Akiyoshi, Director of the Building Department(Keywords) long-period earthquake ground motion, high-rise building, seismic isolated building1.

Actions after submitting the draft proposal for thelong-period
earthquake
groundmotion
countermeasures
In the field of architecture, the long-period earthquake
ground motion (i.e.: ground motion that includes longperiod of pitch and roll and has the characteristics ofgenerating slow and long lasting tremor) is considered togive severe effect on high-rise buildings which have thelong proper period of their own and also to affect seismic
isolated buildings. On December 21, 2010 draft
proposal for the countermeasures was issued from MILT
and invitation of public opinions had been made until
February 2011.
(Ref. (1)) As a result, following
opinions were received:
・ The most agreed with the basic idea that somethingshould be done to accommodate with long-period
ground motion.
・ It should cover Nankai earthquake and interrelated
earthquakes.
・ Not only the input, but the acceptable conditions forthe building should also be shown.
・ Retroaction of the new standard to existing buildings
would be difficult, to which some easing steps
and/or subsidy should be necessary.
On The 2011 off the Pacific coast of Tohoku
Earthquake which occurred just after public opinions
were invited, long-period ground motions were observed.
(Ref. (2))
In the building standard development promotion
project* that started soon after, the following
deliberations were made. (Ref. (3), (4) and (5))*It is the project, when the State lays down and/or revise technicalcriteria in the legislation such as the Building Standard Act, it will
publicly seek for the collection and accumulation of the basic data andtechnical knowledge such as experimental data concerning the agenda
which the State had set and subsidize the cost that had occurred(hereinafter called: “BDP”).

2.

The improvement method of preparation for the
long-period earthquake ground motion (BDPAgenda No. 42)
Earthquake ground motion which was shown in thecountermeasure draft proposal.
Also, collected
information regarding The 2011 off the Pacific coast of
Tohoku Earthquake and prepared long-period earthquake
ground motion wave profile for those earthquakes.
Furthermore, in 2012 fiscal year, deliberations ofimproving flexibility and reliability of earthquake groundmotion preparation method for interrelated earthquakes.
3. Deliberation concerning architectural structure safety
verification method (BDP Agenda No. 27-1, -2, -3)
Since 2010 fiscal year, with regard to reinforced
concrete buildings, steel construction buildings andseismic isolated buildings, implementations of thestructural testing for multiple cycle load, responseevaluation of the buildings and earthquake observation of
the buildings are in progress. Especially, in fiscal 2011,
response analysis and investigation on high-rise buildings
which were observed during The 2011 off the Pacificcoast of Tohoku Earthquake were conducted. Also in
fiscal 2012, shaking table tests for reinforced concretebuilding test structure, multiple cyclic load testing for thesteel frame test structure, and multiple cyclic load testingfor seismically isolated member of actual-size level wereconducted and technical data concerning performanceassessment of structural objects are being gathered.
4. Next step
It is anticipated that countermeasures for thelong-period earthquake ground motion will be made up
by not only focusing on the earthquake ground motion
preparation method shown in above section 2 anddocuments for the performance assessment for structuralobjects shown in above section 3, but also taking in theaccounts of the area of discussions made by the Central
Disaster Prevention Council, Headquarters for
Earthquake Research, the Building Construction StandardCommittee in NILIM and the Working Group for theLong-Period Ground Motion set up in above committee.
【References】(1) Draft proposal for the countermeasures on thelong-period earthquake ground motion on high-risebuildings
http://www.mlit.go.jp/report/press/house05 _hh_000218.html(2) TECHNICAL NOTE of NILIM No.674, Damage
investigation report of the 2011 Tohoku-Pacific Ocean
Earthquake, Mar.2012
http://www.nilim.go.jp/lab/bcg/siryou/tnn/tn_nilim.htm(3) Invite for implementing body: BDP fiscal 2011
http://www.mlit.go.jp/jutakukentiku/house/jutakukentiku_ho
use_fr_000037.html(4) Invite for implementing body: BDP fiscal 2012
http://www.mlit.go.jp/report/press/house05_hh_000307.html(5) Outlines of Results, listed: BDP fiscal 2011
http://www.mlit.go.jp/jutakukentiku/house/jutakukentiku_ho
use_fr_000047.html