研究発表

To improve estimation accuracy of damage of buildings on irregular ground, amplification factors of response spectra is studied using 2-D ground model and compensation factors are proposed for 1-D ground model results. First, the 2-D models of a slope and a hill are constructed which are typical in a peripheral region of a loam plateau. Then, a Ricker wavelet with the central frequency of 2 Hz or 3 Hz and the maximum velocity 100 cm/s2 is input on engineering bedrock and nonlinear time history analysis is carried out. A response spectrum on ground surface is evaluated and compensation factors are calculated.

Effective seismic response control of a building is studied to reduce sway of elevator rope. A building with elevator system controlled by active mass damper (AMD) is modeled, and the evaluation function of the optimum regulator is constructed in which story drift, absolute acceleration response and relative displacement between a building and elevator rope are considered. Result of examination in frequency domain revealed that frequency range exists where elevator rope sway widely though a building does not sway and the sway of the rope is reduced more effective by considering the rope. However, the response in a high frequency range should be carefully considered.

The project of E-Simulator is under way at Hyogo Earthquake Engineering Research Center (E-Defense) that facilitates the world’s largest shaking table. The E-Simulator uses ADVC as a platform. In this study, we report the results of high-precision FE-analysis for simulation of collapse behavior of steel building frames. It is shown that elastoplastic dynamic analysis can be carried out for a high-rise building with more than 70 million DOFs. The results of a total collapse test of a 4-story frame in E-Defense are also simulated.

最上階に巻上機を設置した吊りロープ式エレベーターを含む60階建の超高層建物を想定し，アクティブマスダンパーを用いた建物とエレベーターロープの揺れの同時制御の有効性について検討を行った。最適レギュレータ理論を用いて制御を行い，評価関数には建物応答に関わる項と制御力に関わる項に加えエレベーターロープに関わる項を導入し，それぞれに重み係数を乗じて，適切な係数の組合せを複数の地震動入力をもとに検討した。

敷地地盤と耐震等級の違いによる木造建物の地震被害確率を比較するため，地盤モデルと木造建物モデルの剛性・耐力を変化させ解析を行った。同じ等級の建物でも地盤ごとに建物被害確率が異なることや，地盤によって等級を上げた時の建物被害の低減効果が異なるとことが定量的に明らかにされた。特に粘性土の地盤では，他の土質よりも被害低減効果は大きい傾向があるが，層厚によってその効果のばらつきも大きいことが明らかとなった。

建物の耐震性能を，建物敷地に応じある発生確率をもった地震動の周期特性や継続時間を考慮した模擬地震動を作成して，建物を使用する期間に被害が発生する確率を地震応答解析結果より評価を行った。地表面最大速度を媒介変数としたフラジリティ曲線とハザード曲線を用いた結果と比較し，フラジリティ曲線を用いた手法では，対象地点の地盤特性を考慮できておらず，被害確率の評価が適切に行えないことが明らかとなった。