報告書番号

383021

タイトル（和文）

軟質地盤上の大型基礎の動的挙動に関する実証研究（その７）３次元Ｆ．Ｅ．Ｍ．複素振動解析法（ＴＢ３Ｄ２）による基礎・地盤系の地震応答解析

タイトル（英文）

A STUDY ON THE DYNAMIC BEHAVIOR OF A LARGE-SCALE FOUNDATION ON THE SOFT GROUND (7) -EARTHQUAKE RESPONSE ANALYSIS BY3-D FEM COMPLEX DYNAMIC ANA1YSIS METHOD AND THE COMPARISON WITH OBSERVED RESULTS-

概要 （図表や脚注は「報告書全文」に掲載しております）

洪積地盤上に建設された大型基礎の地震応答解析を実施し，実測値と対比した。解析には，当所で開発された３次元Ｆ．Ｅ．Ｍ．複素振動解析法（ＴＢ３Ｄ２）を用い，併せて実施された２次元Ｆ．Ｅ．Ｍ．による結果も含め，解析手法の妥当性について考察し次の知見を得た。１）ＴＢＳＤ２による解析結果は，基礎でも地盤でも，最大振幅値分布，時系列波形，伝達特性，応答スペクトルのいずれで見ても，地震時の基礎・地盤系挙動の概略を模擬しえており，本手法の妥当性が示された。２）ＴＢ３Ｄ２による解析では，観測に現れた基礎の制震効果（短周期ほど大となるローパスフィルタ的特性）を大略，模擬しており，従来の鉛直下方よりの平面波入力による解析で基礎の制震効果をほぼ説明しうることを示した。３）擬似３次元付き２次元解析手法は，基礎加振の模擬では減衰のききすぎとなり，不十分であったが，地震応答解析では十分に有効な手法であることが示された

概要 （英文）

EARTHQUAKE RESPONSE ANALYSIS OF A LARGE-SCALE FOUNDATION ON THE SOFT GROUND WAS CARRIED OUT. THE COMPUTER PROGRAM TB3D2 WAS USED IN THE ANALYSIS WHICH WAS DEVELOPED IN CRIEPI. TB3D2 IS THE CODE FOR EARTHQUAKE RESPONSE ANALYSIS OF THE SOIL-STRUCTURE SYSTEM. IN THE CODE TB3D2, 3-D REGION WITH RECTANGULAR CO-ORDINATES IS ABLE TO BE INTRODUCED AMONG THE AXISYMMETRIC REGULAR REGION WITH CYLINDRICAL CO-ORDINATES CALLED TRANSMITTING BOUNDARY. THE CALCULATED RESULTS WERE COMPARED WITH THE OBSERVED ONES. 2-D FEM COMPLEX DYNAMIC ANALYSIS METHOD WITH PSEUDO 3-D DAMPERS WAS ALSO APPLIED TO THIS EACH OTHER AND AS THE RESULT, THE FOLLOWINGS WERE MADE CLEAR.(1)FROM THE POINT OF ANY ONE OF NEXT FOUR, THAT IS, THE MAXIMUM AMPLITUDE DISTRIBUTIONS, TIME SERIES DATA,TRANSFER FUNCTIONS, RESPONSE SPECTRA,THE CALCULATED RESULTS BY TB3D2BOTH ON THE FOUNDATION AND ON&IN THE GROUND WERE GOOD ENOUGH WHEN COMPARED WITH THE OBSERVED ONES. THUS IT IS SHOWN THAT THE PROPOSED METHOD HERE IS VALID AND EFFECTIVE FOR THE EARTHQUAKE RESPONSE ANALYSIS OF THESOIL-STRUCTURE SYSTEM.(2)AS TO THE ASEIMISC EFFECT OF THE FOUNDATION, IT USUALLY BECOMES MORE EFFECTIVE AT HIGH FREQUENCY RANGE.THE OBSERVATORY RESULTS OF THIS FOUNDATION ALSO SHOWED THE SAME TENDENCY AS MENTIONED ABOVE. THE CALCULATED RESULTS BY TB3D2 SHOWED, TOO,THE SAME TENDENCY,INDICATING THAT THE ASEISMIC EFFECT OFTHE FOUNDATION COULD APPROXIMATELY BE SIMULATED BY THE TRADITIONAL METHOD IN WHICH THE PLANE WAVE WAS INPUT TO THE UNDERGROUND PLANE PARALLEL TO THE SURFACE.(3)IT WAS ALSO SHOWN THAT 2-D FEM COMPLEX DYNAMIC ANALYSIS METHOD WITH PSEUDO 3-D DAMPERS WAS AN EFFECTIVE MENTHOD IN THE EARTHQUAKE RESPONSE ANALYSIS, THOUGH IT WAS NOT SO GOOD IN THE SIMULATION OF FOUNDATION EXCITATION BECAUSE OF THE OVER ESTIMATION OF THE DAMPING.

報告者

キーワード