| ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ KAWASAKI STEEL TECHNICAL REPORT No.3 ( September 1981 ) ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ |
| Earthquake Response Analysis of No.6 Blast Furnace of Chiba Works
Masahiro Ishida, Michihiko Hara, Satoru Nishiyama, Ikuo Jo |
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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 "longdistance" 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-shearing coefficients 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 (June 12, 1978), or twice that in the biggest "long-distance" type (Sept. 24, 1980), the story shear coefficient at the top story will exceed the design value. |
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