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
Large earthquakes are global natural disasters,which accompany intense ground shaking that can cause damages to buildings and infrastructure and sometimes lead to secondary disasters such as tsunamis and landslides.Th...Large earthquakes are global natural disasters,which accompany intense ground shaking that can cause damages to buildings and infrastructure and sometimes lead to secondary disasters such as tsunamis and landslides.The severity and spatial distribution of seismic hazards highly depend on the magnitude and rupture process of the earthquake.展开更多
This study describes a developing process of lifeline earthquake engineering from historical aspects.Currently various seismic design methods have been furnished for ground shaking and for permanent ground displacemen...This study describes a developing process of lifeline earthquake engineering from historical aspects.Currently various seismic design methods have been furnished for ground shaking and for permanent ground displacement.The seismic design method for ground shaking introduces different travelling wave models in the US and in Japan.As a result,Japanese approach was developed by actively taking into account the slippage effect in order to solve the inelastic response of the pipeline for a severe earthquake.The seismic design method for permanent ground displacement,on the other hand,prepared various numerical modeling and database in the US,while the simplified design formula for ground displacement was furnished in the seismic design guidelines in Japan.The detail design formula for liquefied ground settlement and fault displacement are expressed in this study.Various approaches of the performance-based seismic design method are compared among EU,the US and Japan.Unfortunately,the design method in Japan does not show the safety target in the guidelines.Then a simple evaluation approach to obtain the safety index is proposed herein.The different performance of two actual pipeline systems is compared,in which one pipeline system demonstrated a good performance for 2011 East Japan Great Earthquake,and the other did not.In state-of-the-art study,the seismic experiments and design method of expansion joints are described,because the ultimate limit performance of the expansion joints has not been explicit,although many seismic damages have occurred at the locations of vulnerable expansion joints.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.
基金supported by the National Natural Science Foundation of China(Grant No.42488301)。
文摘Large earthquakes are global natural disasters,which accompany intense ground shaking that can cause damages to buildings and infrastructure and sometimes lead to secondary disasters such as tsunamis and landslides.The severity and spatial distribution of seismic hazards highly depend on the magnitude and rupture process of the earthquake.
文摘This study describes a developing process of lifeline earthquake engineering from historical aspects.Currently various seismic design methods have been furnished for ground shaking and for permanent ground displacement.The seismic design method for ground shaking introduces different travelling wave models in the US and in Japan.As a result,Japanese approach was developed by actively taking into account the slippage effect in order to solve the inelastic response of the pipeline for a severe earthquake.The seismic design method for permanent ground displacement,on the other hand,prepared various numerical modeling and database in the US,while the simplified design formula for ground displacement was furnished in the seismic design guidelines in Japan.The detail design formula for liquefied ground settlement and fault displacement are expressed in this study.Various approaches of the performance-based seismic design method are compared among EU,the US and Japan.Unfortunately,the design method in Japan does not show the safety target in the guidelines.Then a simple evaluation approach to obtain the safety index is proposed herein.The different performance of two actual pipeline systems is compared,in which one pipeline system demonstrated a good performance for 2011 East Japan Great Earthquake,and the other did not.In state-of-the-art study,the seismic experiments and design method of expansion joints are described,because the ultimate limit performance of the expansion joints has not been explicit,although many seismic damages have occurred at the locations of vulnerable expansion joints.
