This article describes a hybrid simulation method to generate artificial ground motion time histories that are compatible with specified peak seismic acceleration, velocity and displacement as well as the target respo...This article describes a hybrid simulation method to generate artificial ground motion time histories that are compatible with specified peak seismic acceleration, velocity and displacement as well as the target response spectrum of absolute acceleration. First, based on traditional methods that match the target spectrum in the frequency domain, an initial acceleration time history was synthesized to satisfy the specified peak acceleration, target spectral acceleration and intensity envelope. Second, by using the inversion formula of the seismic input to a linear single-degree-of-freedom system and by superimposing a series of narrow-band time histories in the time domain, the initial time history is further modified to allow its peak velocity and displacement to approach the targets and improve its matching precision with the target spectrum. Numerical examples are provided to demonstrate that the proposed method achieves good agreement with the target values.展开更多
A meteorite impacted the ground in Estonia forming the Kaali Crater dated at 1183 - 1162 BC. It set up a Baltic-wide mega-tsunami dated at 1171 absolute varve years BC. It also triggered violent seismotectonic effect ...A meteorite impacted the ground in Estonia forming the Kaali Crater dated at 1183 - 1162 BC. It set up a Baltic-wide mega-tsunami dated at 1171 absolute varve years BC. It also triggered violent seismotectonic effect in Sweden. Ancient legends testify of direct observations of the sky phenomena and personal experiences of the ground shaking and tsunami flooding, which makes the Kaali Crater the oldest impact event documented by humans. The Ragnar<span style="white-space:nowrap;">ö</span>k apocalypse is likely to lead its origin from the violent geodynamic activity along the Swedish east coast.展开更多
基金National Natural Science Foundation of ChinaUnder Grant No.50278090
文摘This article describes a hybrid simulation method to generate artificial ground motion time histories that are compatible with specified peak seismic acceleration, velocity and displacement as well as the target response spectrum of absolute acceleration. First, based on traditional methods that match the target spectrum in the frequency domain, an initial acceleration time history was synthesized to satisfy the specified peak acceleration, target spectral acceleration and intensity envelope. Second, by using the inversion formula of the seismic input to a linear single-degree-of-freedom system and by superimposing a series of narrow-band time histories in the time domain, the initial time history is further modified to allow its peak velocity and displacement to approach the targets and improve its matching precision with the target spectrum. Numerical examples are provided to demonstrate that the proposed method achieves good agreement with the target values.
文摘A meteorite impacted the ground in Estonia forming the Kaali Crater dated at 1183 - 1162 BC. It set up a Baltic-wide mega-tsunami dated at 1171 absolute varve years BC. It also triggered violent seismotectonic effect in Sweden. Ancient legends testify of direct observations of the sky phenomena and personal experiences of the ground shaking and tsunami flooding, which makes the Kaali Crater the oldest impact event documented by humans. The Ragnar<span style="white-space:nowrap;">ö</span>k apocalypse is likely to lead its origin from the violent geodynamic activity along the Swedish east coast.
