報告書番号

U87005

タイトル（和文）

基礎浮き上り振動に関する検討（減衰効果を考慮した解析手法の提案）

タイトル（英文）

INVESTIGATION ON DYNAMIC RESPONSE WITH FOUNDATION UPLIFT (PROPOSAL OF AANALYTICAL METHOD CONSIDERING DAMPING EFFECT)

概要 （図表や脚注は「報告書全文」に掲載しております）

本報告は基礎の浮き上りに伴う減衰効果を解明することを目的として，浮き上り応答の基本的特性，接地率の評価，応答の低減効果について実験的・解析的に検討したものである。浮き上り易い模型を用いた基本的な振動台実験から，基礎の浮き上りに伴い，上下動が誘発されること，水平応答は非線形的な性質を示すことを明らかにした。また，入力の大きさと接地率を詳細に調べることを意図した振動台実験に基づき，現行の接地率評価式の妥当性，適用限界を示すことができた。さらに，接地率の減少に応じて減衰が増加する特性を実験的に確め，この特性を導入したＳ－Ｒ解析モデルを作成した。この解析モデルは浮き上りを伴う水平応答を良好に評価できることが実験値との照合により判明し，解析手法の妥当性がジョイント要素モデルによる解析結果との整合性から裏付けられた。以上の検討により，浮き上り応答評価に関する基本的な知見を得ることができた。

概要 （英文）

WHEN PERFORMING THE NUMERICAL ANALYSIS CONSIDERING THE NON-LINEARITY DUE TO FOUNDATION UPLIFT,IT MUST BE UNDERSTOODTHE MAGNITUDE OF DAMPING CONSTANT DURING UPLIFT QUANTITATIVELY. AND ITIS NECESSARY TO TAKE IT INTO NUMERICAL PROCEDURE. THE PURPOSE OF THIS STUDY IS TO PROPOSE THE ANALYTICAL METHOD WHICH CAN ESTIMATE THE DAMPING EFFECT DUE TO FOUNDATION UPLIFT. SO,THE AUTHORS FRAMED THE NON-LINEARS-R MODEL BASED ON THE DATA DETECTED FROM THE SHAKING TABLE TESTS ON THE SOIL-STRUCTURE INTERACTION MODEL AND CONFIRMED THE VALIDITY OF PROPOSED METHOD COMPARING TO THE EXPERIMENTAL RESULTS. THE PHENOMENA OF THE FOUNDATION UPLIFT WAS ESTIMATED BY THE NON-LINEAR S-R MODEL,OF WHICH THE SWAY SPRING TREATED AS LINEAR,THE ROCKING SPRING AS NON-LINEAR TO EXPRESS UPLIFT. ON THE OTHER HAND,FROM THE RESULTS OF RESONANT EXCITATION TESTS,IT WAS FOUND THAT THE MODE DAMPING CONSTANTS WERE IN PROPORTION TO A RECIPROCAL OF THE CUBE OF CONTACT RATIO. THIS CHARACTERISTICS DEALSTHE DAMPING EFFECT PASSIVELY,SO IT WAS TAKEN INTO THE NUMERICAL PROCEDURE. THE HORIZONTAL RESPONSE FOLLOWING UPLIFT INDUCED BY RANDOM EXCITATION WAS ESTIMATED ANALYTICALLY. AS THE RESULTS,IT WAS CLARIFIED THAT THE ANALYTICAL RESULTS OBTAINED FROM THE PROPOSED MODEL AGREED APPROXIMATELY WITH THE EXPERIMENTAL RESULTS. FURTHERMORE,THE VALIDITY OF THE PROPOSED MODEL WAS ALSO CONFIRMED AS CONTRASTED WITH THE RESULT FROM THE DYNAMIC FEM ANALYSIS HAVING A JOINT ELEMENT WHICH COULD MORE STRICTLY EXPRESS THE SEPARATION OF FOUNDATION AND GROUND SHOWN IN FIG. IT IS CONCLUDED THAT THE PROPOSED MODEL IS MUCH PRACTICAL USE FOR THE EVALUATION OFFOUNDATION UPLIFT CONSIDERING THE DAMPING EFFECT.

報告者

キーワード