報告書番号

N05041

タイトル（和文）

地震ハザード再分解に基づく構造物の損傷確率評価方法の提案

タイトル（英文）

A Method to Evaluate Structural Failure Probability Based on Seismic Hazard Deaggregation

概要 （図表や脚注は「報告書全文」に掲載しております）

構造物の地震リスクを評価する場合、対象地点の地震ハザード曲線と、構造物のフラジリティー曲線に用いて損傷確率をする方法が多く用いられてきた。しかしながら、構造物の動的信頼性評価の精度を高めるためには、PGA等の最大地動だけではなく、地震動の周波数特性や継続時間などの情報を考慮した損傷確率評価方法が必要である。報告者らは、地震ハザード再分解の概念を利用して、地震のマグニチュードや距離を考慮しつつ、地震ハザード曲線を用いず直接的に構造物の年損傷確率を評価する方法を提案した。同時に、従来の地震ハザード再分解の方法との関連を整理した。先ず仮想的な地震ハザードモデルを想定して、質点系モデルと滑動モデルを対象に提案方法の検討を行なった。次に、北日本の一部領域内の複数地点に提案方法を適用し、対象地点における評価結果を基に、地震リスクの地理的分布を概観する図を試作し、適用性および拡張性について考察した。

概要 （英文）

In performing seismic Probabilistic Safety Assessment (PSA) of structures, failure probabilities of the structures are usually evaluated from seismic hazard and structural fragility. However, the question arises that the conventional method is based on only one index of seismic ground motions such as peak ground acceleration, and in this case the evaluation of PSA is not necessarily accurate. Although a large number of studies have been made on seismic hazard and seismic PSA, only few attempts have so far been made to answer this problem. The purpose of this report is to propose a new method which can consider not only single ground motion parameter but also more detailed information on seismic ground motion such as frequency properties and duration time in order to improve the accuracy of reliability evaluation for non-linear structures.We introduce the physics of the earthquake ground motions, and structural dynamics at the maximum, and propose a procedure to calculate directly P_{f/year} from the magnitude and the site-source distance without the seismic hazard curves and the fragility. The proposed method does not require the fragility curves though they can be analytically obtained if need be. The main results of this report are summarized as follows: (i) We have developed a method for evaluating structural failure probabilities per year. Considering information on earthquake parameters such as magnitude and distance corresponding to exceedance probability of seismic intensity, we can generate time histories of earthquake motions consistent to the seismic hazard. By the proposed method, the structural reliability P_{f/year} can be evaluated for any failure criteria. (ii) On the basis of the proposed method, we can obtain failure probabilities per year for stick-mass and sliding-block models through numerical simulations. Through the comparison with the conventional methods to estimate failure probability, we can evaluate the proposed method is possible to improve the accuracy of the evaluation for the structural reliability.

報告者

キーワード