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■■■■■■■■■■■■■■■■■■■ 川崎製鉄技報 KAWASAKI STEEL GIHO Vol.13 (1981) No.2 ■■■■■■■■■■■■■■■■■■■ |
| 千葉第6高炉の地震応答解析 Earthquake Response Analysis of No.6 Blast Furnace of Chiba Works 石田 昌弘(Masahiro Ishida) 原 道彦(Michihiko Hara) 西山 領(Satoru Nishiyama) 城 郁夫(Ikuo Jo) |
| 要旨 : 昭和55年9月24日早朝に続き，25日未明にも首都圏を直下型のマグニチュードM6級の地震が見舞った。本報告は千葉製鉄所第6高炉およびその周辺の軟弱地盤で実施中の地震観測からえられた地震応答記録から，とくに高炉基礎という重量基礎構造物の耐震工学上の特質を明確化し，耐震設計上の資料たらしめようとしたものである。得られた成果はつぎのとおりです。（１）本構造物の固有周期を考慮すれば，直下型地震よりも遠距離型地震に対して共振しやすいと言えるが，直下型地震の鉛直成分が構造物の応答に大きく影響するのでこの方面の研究が急がれる。（２）応答が速度から換算した層せん弾力係数は，基礎構造については設計層せん断力係数と同程度であるが，上部工については危険側の値を示す。（３）地震観測以来最大規模の遠距離型地震の11倍弱，直下型地震の2倍弱の基盤加速度が発生すれば最大層設計せん断力係数を超えることになる。 |
| Synopsis : Earthquake measurements have been taken since 1977 in order to investigate the dynamic behavior of No.6 blast furnace and its surrounding soft ground at Chiba Works. Two severe earthquakes of the so-called "directly under" type, hit the Kanto districts on September 24 and 25, 1980, registering Richter magnitudes of 6.0 and 6.1, respectively Their epicenters were located near Chiba Works, and maximum response acceleration at the super-and sub-structures of No.6 blast furnace and its surrounding soft ground is the largest of all the earthquakes ever observed. In this report, the results of earthquake observations are discussed in comparison with those of theoretical approaches, namely, analytical simulations using lumped mass idealization. The following conclusions may be drawn from the observation and analysis of actual earthquakes. (1) Judging from the response spectrum, the structure is more liable to resonate with the so-called "long-distance" type earthquake than with the "directly under" type, and yet in the latter type earthquake, the structure is strongly affected by the vertical motion of the earthquake. Further study in this aspect is required to be expedited. (2) Story shear coefficient at the sub-structure calculated from response acceleration of actual earthquakes approximate to the design values, but those at the super-structure exceed them. (3) It is predicted that if earthquakes occur that have substratum acceleration a little less than eleven times that in the biggest "directly under" type earthquake (June12,1978), or twice that in the biggest "long-distance" type (Sept.24,1980), the story shear coefficient at the tip story will exceed the design value. |
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