Engineering Properties of Long-Period Earthquake Motion

发现1983年日本海中部地震和1985年墨西哥地震的加速度反应谱大于高层建筑和大跨度桥梁的设计反应谱。本研究的目的是提出适合于大跨度桥梁的设计谱，考虑以下问题。1)根据JMA强震记录、SMAC加速度记录和大型储罐晃动记录估算日本海中部地震和其它大地震的长周期地震动和反应谱。2)振动试验中SMAC或SAMTAC加速度记录长周期地震记录的误差估计3)用半经验方法估算明石海峡大桥的长周期地震动和大地震的反应谱，研究结果如下：1）在明石海峡大桥（本州四国大桥）桥台附近设置地震仪，观测长周期地震动。到目前为止，共记录到3次地震，并成功地观测到了1989年2月11日岩手县大地震的长周期速度记录。2)我们的一位研究者提出了半经验方法来估计大地震地面运动。将该方法应用于明石附近的大地震反应谱计算，并与明石海峡大桥的设计反应谱进行比较。用该方法对日本海中部地震的地面运动进行了模拟。3)研究了新泻大型储罐的晃动，以估算日本海中部地震的长周期反应谱。4)为了计算更精确的反应谱，研究了长周期域数字加速度记录和饱和JMA记录的修正问题。

The acceleration response spectra of 1983 Nihon-kai Chubu earth-quake and those of 1985 Mexico earthquake were found larger than the design spectra of high-rise buildings and of long span bridges. The object of this research is to suggest the suitable design spectra for the long span bridges considering the following problems. 1) Estimation of the long period ground motion and the response spectra of Nihon-kai Chubu earthquake and other large earthquakes from the JMA strong motion records, SMAC accelerogram and the sloshing records of the huge tanks. 2) Error estimation of the seismic records of SMAC or SAMTAC accelerogram in long period from the vibration testings. 3) Estimation of the long period ground motion at Akashi using semi-empirical method and of the response spectra of that huge earthquake.The results of this research are summarized as follows: 1) The seismograph was set near the abutment of Akashi Kaikyo Ohashi (Honshu Shikoku Bridge) to observe the long-period ground motions. 3 earthquakes were recorded until now and the long-period velocity record of 11/2/1989 Iwate-ken Oki earthquake was successfully observed. 2) One of our investigators proposed the semi-empirical method to estimate the large earthquake ground motion. This method was applied to estimate the huge ground motion near Akashi, and the response spectra were calculated to compare with the design spectra of Akashi Kaikyo Ohashi. The ground motion of Nihon-kai Chubu earthquake was also simulated using this method. 3) The sloshing of the large tanks at Niigata was studied to estimate the long-period response spectra of Nihon-kai Chubu earthquake. 4) The correction of the digital accelerograms in long-period domain and the saturated JMA records were investigated to calculate more accurate response spectra.