報告書番号

385045

タイトル（和文）

設計地震動のスペクトル特性の研究（１）岩盤上の加速度波形の特性について

タイトル（英文）

STUDY ON SPECTRAL CHARACTERISTICS OF DESIGN EARTHQUAKE MOTIONS(1)CHARACTERISTIC OF ACCELEROGRAMS OBSERVED ON BEDROCK

概要 （図表や脚注は「報告書全文」に掲載しております）

当所が全国に展開している岩盤上強地震観測点による主要な観測データをとりまとめ，設計地震動の策定に必要な加速度波形の特性について検討した。主な成果は次の通り。（１）最大加速度，最大速度の距離に従った減衰性は概ね既往の経験式と同程度かこれを下回る傾向にある。（２）震源から近距離における最大加速度とＭ（マグニチュード）の間には明瞭な比例関係が成立するが，その定式化は今後さらに検討する必要がある。（３）近距離における最大加速度は応力降下量，断層の半径と震源距離の比に強く支配される。（４）加速度波形の継続時間はＭとともに大きくなり，Ｍに対する匂配は概ね０．２５と考えられる。（５）観測位と現在用いられている

概要 （英文）

CRIEPI HAS BEEN CONSTRUCTING THE EARTHQUAKE OBSERVATION STATIONS ON BEDROCK IN JAPAN FOR THE PURPOSE OF EVALUATION OF DESIGN EARTHQUAKE INPUT MOTIONS FOR NUCLEAR FACILITIES. THIS TIME,THE AUTHORS SUMMARIZE THE OBSERVATIONAL DATA OBTAINED AT THESE STATIONS DURRING SEVERAL EARTHQUAKES OCCURED IN RECENT YEARS,AND INVESTIGATE THE CHARACTERISTICS OF ACCELEROGRAMS WHICH IS IN NEED OF EVALUATING THE MORE REASONABLE DESIGN SPECTRUM. SOME RESULTS OF THIS INVESIGATION ARE AS FOLLOWS. (1)THE ATTENUATION CURVES OF MAXIMUM AMPLITUDES AGAINST M(EARTHQUAKE MAGNITUDE) GENERALLY ARE EQUAL OR LESS TO THE EMPIRICAL FORMULA USED AT PRSENT IN ASEISMIC DESIGN. (2)IT IS EVIDENT THAT THE PROPORTIONAL RELATIONS ARE OBSERVED BETWEEN MAXIMUM ACCELERATION AND M AT SHORT DISTANCE FROM FOCUS,BUT THE FORMULATION OF THESE RELATIONS IS REMAINED TO FURTHER STRICT INVESTIGATION. (3)THE MAXIMUM ACCELERATION AT SHORT DISTANCE TO HYPOCENTER IS STRONGLY EFFECTED BY THE STRESS DROP AND THE RATIO BETWEEN A RADIUS OF FAULT AND HYPOCENTRAL DISTANCE. (4)THE DURATIONTIME OF ACCELEROGRAM BECOMES LONGER IN PROPORTION TO M,AND ABOUT 0.25 IS OBTAINED AS THE PROPORTIONAL CONSTANT NUMBER OF DURATION TIME AGAINST M. (5)IT IS INDICATED THAT THE STANDARD SPECTRUM USED IN ASEISMIC DESIGN OF STRUCTURE IS CONSERVATIVE AND CAN BE IMPROVED TO MORE RATIONAL ONE.

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