1995年兵庫県南部地震における被災建物の動特性とシミュレーション解析
本論文では、1995年兵庫県南部地震で被災した建物の動特性の把握を目的として、SRC造5棟、RC造3棟、S造5棟の被害建物の微動計測を行い、水平方向と上下方向の基本周期と減衰定数について調べた。
その結果、被害による基本周期の伸びは、鉄骨造建物に比べてコンクリート系構造物で顕著で、補修によって耐力は回復しても基本周期は完全には回復しないこと、また、建物被害の顕著であったNS方向は地震動の最大主軸方向と一致していることが、微動計測結果からも確認できた。
また、被災度の異なるSRC造建物3棟のシミュレーション解析を行った。その結果、被災度が大破と中破の建物については、既往の建物のモデル化によってほぼ被災度と整合性のある結果が得られたが、構造的に無被害であった建物の被災度を説明するためには、基礎の浮上りや地下側壁と地盤との剥離を含む地盤と建物の非線形相互作用効果を考慮する必要があった。
Identification and Simulation Analyses of Damaged Buildings in 1995 Hyogo-ken Nambu Earthquake
We investigated the change in the fundamental frequencies and its damping factors in the horizontal and vertical direction of damaged buildings during the 1995 Hyogo-Ken Nambu Earthquake.
We measured the micro-tremors of five steel reinforced concrete buildings, three reinforced concrete buildings and five steel buildings. Decreases in the fundamental frequency were evident in the direction of the building damage and also in buildings made by concrete compared with steel buildings.
The fundamental frequency of damaged concrete buildings did not recover by repair even if the strength of the buildings recovered. We carried out response analyses on three buildings, whose damage was heavy, moderate, and slight. We could simulate the heavily and moderately damaged buildings by means of a conventional response analysis procedure which is used in the structural design. In order to simulate the slightly damaged building, however, we had to consider the nonlinear soil-structure interaction effects such as the base uplift, separation between the side-wall and the soil, and material nonlinearity of the soil.