scholarly journals Identification of pulse-like ground motions during the 1994 Northridge Earthquake

2021 ◽  
Vol 787 (1) ◽  
pp. 012147
Author(s):  
Lu Han ◽  
Zhengru Tao ◽  
Xinyan Wang
Keyword(s):  
Ground Motions ◽  
Northridge Earthquake ◽  
1994 Northridge Earthquake

scholarly journals Response of seismically isolated buildings with buffers subjected to near-source ground motions and possible alternative isolation systems

2004 ◽  
Vol 37 (3) ◽  
pp. 111-133 ◽  
Author(s):  
J. X. Zhao
Keyword(s):  
Inelastic Deformation ◽  
Ground Motions ◽  
Damping Ratio ◽  
Structural Response ◽  
Deformation Capacity ◽  
Northridge Earthquake ◽  
Period Range ◽  
Isolation System ◽  
Seismically Isolated ◽  
1994 Northridge Earthquake

The response of a seismically isolated building with lead rubber bearings (LRB) to near source ground motions from large earthquakes was investigated. The building was assumed to have a buffer to limit the maximum bearing displacement in a rare event of large magnitude and the buffer gap was assumed to be only 150mm (the level of maximum isolator displacement used in the 1980s). The structure was assumed to be designed for 1.5 times the NS component of the 1940 El Centro record. The 15% damped (an amount of damping which is close to the equivalent damping ratio for an seismically isolated building at its isolator design displacement) displacement spectrum of the design motion is only 40% that of the Sylmar County Hospital Parking Lot record from the 1994 Northridge earthquake (Mw= 6.7) in the period range around the first modal periods of both isolated and un-isolated structure used in the present study. Among the near-source records that are available, the near-source Sylmar record from the 1994 Northridge earthquake was found to have a very large displacement demand in a period range of 2.0 - 3.0s and this record is thought to be a better representation of the expected near-source motions than the 1.5 times the 1940 El Centro record. Structure-buffer impact was found to impose very large inter-storey drifts and produce very large storey accelerations, when the building was subjected to the excitation of the Sylmar record. The structure-buffer impact was found to be detrimental to the structural response if the structure was not designed to provide inelastic deformation capacity, and the structural response did not improve when the gap was increased to 200-250 mm, the expected maximum displacement capacity of the LRBs used in the building. An alternative isolation system of LRBs and hysteretic dampers was investigated and found to be adequate for resisting near-source motions. A large initial damper stiffness and relatively small buffer stiffness (compared with the total initial stiffness of LRBs) were found to be effective in reducing inter-storey drifts and storey accelerations at floors except for the base and roof of the structure. A disadvantage of such a system is the relatively large base and roof accelerations. The system has relatively large inter-storey drifts and storey accelerations compared with an isolated structure using LRBs only when the structure was subjected to either the 1940 El Centro type ground motions or the Joshua Tree type ground motions with backward directivity effect. Such an isolation system would still enable the structure to respond essentially elastically under the excitation of the Sylmar record even though the isolated structure was designed for a much lower level of ground shaking. As the upper structure of a seismically isolated building is usually designed to respond essentially elastically, the detailing used in the design of a reinforced concrete structure to provide inelastic deformation capacity was generally uncommon and was not fully accounted for in the present study.

A Multidimension Source Model for Generating Broadband Ground Motions with Deterministic 3D Numerical Simulations

2021 ◽  
Author(s):  
Xiang-Chao Wang ◽  
Jin-Ting Wang ◽  
Lei Zhang ◽  
Shuai Li ◽  
Chu-Han Zhang
Keyword(s):  
Numerical Simulations ◽  
Ground Motions ◽  
Source Parameters ◽  
Spectral Characteristics ◽  
Source Model ◽  
Rupture Process ◽  
Northridge Earthquake ◽  
Scenario Earthquake ◽  
Source Models ◽  
1994 Northridge Earthquake

ABSTRACT A multidimension source model for generating broadband ground motions with deterministic 3D numerical simulations is proposed in this article. In this model, the source is composed of several superimposed layers, and the total seismic moment is assigned to these layers in different proportions. Each layer exactly fills up the seismic fault and is uniformly divided into subsources with size decreased progressively to reflect different levels of rupture details. Hence, the proposed multidimension source model may consider the realistic rupture process of an earthquake, that is, the spatial and temporal heterogeneity of source parameters, and generate broadband ground motions. To verify this source model, the 1994 Northridge earthquake is simulated with four multidimension source models, based on different source inversion results. The amplitudes, durations, and spectral characteristics of the observed ground motions of the 1994 Northridge earthquake are respectably reproduced in a range of frequencies up to 5 Hz. In addition, a scenario earthquake is also simulated with four multidimension source models, with different synthetic rupture process. The simulated ground motions of the scenario earthquake are generally in good agreement with the Next Generation Attenuation-West 2 ground-motion prediction equations. This demonstrates that it is promising to simulate realistic broadband ground motions of strong earthquakes with a proper source description and realistic Earth models.

Deformation of Embankments Due to Liquefaction During 1994 Northridge Earthquake

1998 ◽  
Vol 1633 (1) ◽  
pp. 9-18
Author(s):  
J.P. Bardet ◽  
C.A. Davis
Keyword(s):  
Ground Motions ◽  
Geotechnical Engineering ◽  
Three Dimensional ◽  
Northridge Earthquake ◽  
Earth Dams ◽  
Case Histories ◽  
Hydraulic Fill ◽  
Engineering Community ◽  
San Fernando ◽  
1994 Northridge Earthquake

The 1994 Northridge and 1971 San Fernando earthquakes subjected the Lower and Upper San Fernando Dams of the Van Norman Complex in the San Fernando Valley, California, to strong near-source ground motions. In 1994, these earth dams, which were out of service and retained only a few meters of water, extensively cracked and settled because of liquefaction of their hydraulic fill. The Lower San Fernando Dam moved more than 15 cm upstream as the hydraulic fill liquefied beneath its upstream slope. The Upper San Fernando Dam moved even more, and it deformed in a complex three-dimensional pattern. The responses of the Lower and Upper San Fernando Dams during the 1994 Northridge earthquake, although less significant than in 1971, provided the geotechnical engineering community with two useful case histories.

Nonlinear ground-motion amplification by sediments during the 1994 Northridge earthquake

Nature ◽  
10.1038/37586 ◽  
1997 ◽  
Vol 390 (6660) ◽  
pp. 599-602 ◽  
Author(s):  
Edward H. Field ◽  
Paul A. Johnson ◽  
Igor A. Beresnev ◽  
Yuehua Zeng
Keyword(s):  
Ground Motion ◽  
Northridge Earthquake ◽  
Ground Motion Amplification ◽  
1994 Northridge Earthquake

The 1994 Northridge Earthquake Disaster Response: The Local Emergency Medical Services Agency Experience

1996 ◽  
Vol 11 (3) ◽  
pp. 172-179 ◽  
Author(s):  
Samuel J. Stratton ◽  
Virginia Price Hastings ◽  
Darlene Isbell ◽  
John Celentano ◽  
Miguel Ascarrunz ◽  
...  
Keyword(s):  
Public Health ◽  
Emergency Medical Services ◽  
Disaster Response ◽  
Communication Systems ◽  
Medical Services ◽  
Northridge Earthquake ◽  
Power Sources ◽  
Incident Command ◽  
Emergency Medical ◽  
1994 Northridge Earthquake

AbstractIntroduction:This paper describes the 1994 Northridge earthquake experience of the local emergency medical services (EMS) agency. Discussed are means that should improve future local agency disaster responses.Methods:Data reported are descriptive and were collected from multiple independent sources, and can be reviewed publicly and confirmed. Validated data collected during the disaster by the Local EMS Agency also are reported.Results:The experience of the Los Angeles County EMS Agency was similar to that of earthquake disasters previously reported. Communication systems, water, food, shelter, sanitation means, power sources, and medical supplies were resources needed early in the disaster. Urban Search and Rescue Teams and Disaster Medical Assistance Teams were important elements in the response to the Northridge earthquake. The acute phase of the disaster ended within 48 to 72 hours and public health then became the predominant health-care issue. Locating community food and water supplies near shelters, providing transportation to medical care, and public-health visits to shelter locations helped prevent the development of long-term park encampments. An incident command system for the field, hospitals, and government responders was necessary for an organized response to the disaster.Conclusion:Disaster preparedness, multiple forms of reliable communication, rapid mobilization of resources, and knowledge of available state and federal resources are necessary for a disaster response by a local EMS agency.

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