Seismic Response of an Instrumented 13-Story Steel Frame Building Damaged in the 1994 Northridge Earthquake

1997 ◽  
Vol 13 (1) ◽  
pp. 131-149 ◽  
Author(s):  
Chia-Ming Uang ◽  
Qi-Song Yu ◽  
Ali Sadre ◽  
David Bonowitz ◽  
Nabih Youssef ◽  
...  
Keyword(s):  
Time History ◽  
Regular Structure ◽  
Primary Objective ◽  
Elastic Model ◽  
Northridge Earthquake ◽  
Steel Moment Frame ◽  
Modeling And Analysis ◽  
Panel Zone ◽  
Inelastic Analysis ◽  
1994 Northridge Earthquake

This paper summarizes a case study of a 13-story welded steel moment frame (WSMF) building affected by the 1994 Northridge earthquake. The building, which was instrumented, sustained extensive damage to its welded connections. Ground motion records from the basement and response records from the sixth and twelfth floors were available. Damage data was collected with post-earthquake inspection and testing of each joint. The primary objective of the study was to compare modeled behavior with recorded response in order to assess the value of present analytical tools and modeling techniques for predicting the distribution and severity of connection failures. Calculated elastic time-history displacements matched well with recorded displacements in the E-W direction, less so in the heavily-damaged N-S direction where the elastic model was unable to simulate fractured moment connections. In the elastic analyses, joint demand was represented by beam demand-capacity ratios (DCRs). The highest beam DCRs were concentrated between the second and seventh floors; these locations correlated strongly with observed damage. Inelastic time-history analyses improved the displacement match in the N-S direction. They also indicated that panel zone yielding would have controlled the intended ductile response. This study suggests that for a regular structure, current modeling and analysis tools for both elastic and inelastic analysis, while unable to simulate premature brittle fractures, can be useful for predicting in a probabilistic way the intensity and distribution of damage expected in moderate seismic events.

Case Study of a Northridge Welded Steel Moment-Frame Building Having Severed Columns

2004 ◽  
Vol 20 (3) ◽  
pp. 951-973 ◽  
Author(s):  
Bruce F. Maison ◽  
Tom H. Hale
Keyword(s):  
Northridge Earthquake ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Seismic Safety ◽  
Welded Steel ◽  
Collapse Prevention ◽  
The North ◽  
Panel Zone ◽  
Frame Building ◽  
Special Studies

The two-story welded steel moment-frame (WSMF) essential services building had columns severed by the 1994 Northridge earthquake. Two of eight columns suffered fracture across both flanges and panel zones in the WSMFs oriented in the north-south direction. Building and connection damage are described; computer models of the building are formulated and used in a damage correlation exercise that aids in damage interpretation; and a calibrated model is used as the basis of special studies. Factors contributing to the severed columns appear to be column-steel low-fracture toughness, panel zone detailing, and panel-zone shear yielding. Using FEMA-351 guidelines, the as-built as well as the Northridge-damaged structure pass the global collapse prevention drift criterion and fail the local collapse prevention drift criterion. The results provide insight regarding the seismic safety of buildings having similar conditions.

scholarly journals Quasi-Resonance Effects Observed in The 1994 Northridge Earthquake, and Others

1998 ◽  
Vol 5 (3) ◽  
pp. 153-158 ◽  
Author(s):  
Edward G. Fischer ◽  
Thomas P. Fischer
Keyword(s):  
Time History ◽  
Shaking Table ◽  
Northridge Earthquake ◽  
Shaking Table Tests ◽  
Circuit Breakers ◽  
Resonance Effects ◽  
Earthquake Records ◽  
San Fernando ◽  
Conservative Simulation ◽  
1994 Northridge Earthquake

Sine-beat phenomena have been found in the 1994 Northridge earthquake records, and they are capable of producing time-history responses and damaging quasi-resonance effects in structures. Linear, single DOF (degree of freedom) oscillators, in lieu of nonlinear, multiple DOF systems, have been found adequate to discuss the failures of tall circuit breakers during the 1971 San Fernando and the 1989 Loma Prieta quakes in California. The use of sine-beat excitation for seismic-shaking-table tests of equipment continues to be a conservative simulation of earthquakes.

A Model of Steel Frame for Simulating Connection Fractures

2010 ◽  
Vol 452-453 ◽  
pp. 469-472
Author(s):  
Hong Bo Liu ◽  
Long Jun Xu ◽  
Shuang Li ◽  
Yong Song Shao
Keyword(s):  
Seismic Damage ◽  
Steel Frame ◽  
Frame Structures ◽  
Steel Beams ◽  
Northridge Earthquake ◽  
Seismic Evaluation ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Welded Steel ◽  
Panel Zone

Following the 1994 Northridge earthquake, widespread damages were discovered in welded steel moment frame buildings. In order to accurately simulate the typical seismic damage of welded steel moment frame structures, a new simplified model is proposed for performing seismic evaluation of welded steel moment frame structures. In this model, the slabs effect is considered, as well as the effects of the slip between slabs and steel beams, deformation of panel zone and connection fractures. Fracture toughness demands were evaluated in terms of the mode I stress intensity factor. The model was employed in simulation of seismic damage of Blue Cross Building which experienced fractured connections in the Northridge earthquake. It indicates that the model can accurately predict the earthquake response of welded steel moment frame structures and estimate the level of damage. The approach proposed in this paper has important meaning to the research on seismic damage of steel frame which may experience fractured connections.

Nonlinear Analyses of an Instrumented Structure Damaged in the 1994 Northridge Earthquake

1998 ◽  
Vol 14 (2) ◽  
pp. 265-283 ◽  
Author(s):  
Y. Roger Li ◽  
James O. Jirsa
Keyword(s):  
Nonlinear Dynamic ◽  
Shear Failure ◽  
Time History ◽  
Lateral Force ◽  
Economic Losses ◽  
Northridge Earthquake ◽  
Dynamic Time ◽  
Nonlinear Dynamic Analyses ◽  
Structural Engineers ◽  
1994 Northridge Earthquake

The extensive damage and economic losses that occurred during the 1994 Northridge and other recent moderate earthquakes have stimulated structural engineers to consider how to protect economic investment besides meeting life safety requirements of buildings. The equivalent lateral force procedure for seismic design is based on implicit consideration of inelastic response of structures in earthquakes. Experience with past earthquakes has indicated that this procedure is inadequate in controlling damage in buildings. The objective of this study is to demonstrate the capability of nonlinear dynamic analyses to predict performance of reinforced concrete structures subjected to earthquake ground motions. An instrumented building damaged during the 1994 Northridge earthquake was analyzed using DRAIN-2D, and the results were compared with recorded response data. Both nonlinear dynamic time history and nonlinear static push-over analyses were performed, and correlations between these two nonlinear analysis methods were studied. A simplified shear failure model was proposed in the study.

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

scholarly journals Seismic Performance of a Green Roof Structure

2021 ◽  
Vol 13 (8) ◽  
pp. 4278
Author(s):  
Svetlana Tam ◽  
Jenna Wong
Keyword(s):  
Green Roof ◽  
Time History ◽  
Green Roofs ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Roof Structure ◽  
Nonlinear Time History Analyses ◽  
Vegetated Roofs ◽  
Nonlinear Time History ◽  
The Impact

Sustainability addresses the need to reduce the structure’s impact on the environment but does not reduce the environment’s impact on the structure. To explore this relationship, this study focuses on quantifying the impact of green roofs or vegetated roofs on seismic responses such as story displacements, interstory drifts, and floor level accelerations. Using an archetype three-story steel moment frame, nonlinear time history analyses are conducted in OpenSees for a shallow and deep green roof using a suite of ground motions from various distances from the fault to identify key trends and sensitivities in response.

Seismic Time-History Analysis of Gravity Dam Based on Nonlinear Finite Element Method

2013 ◽  
Vol 351-352 ◽  
pp. 1047-1051
Author(s):  
He Zhu ◽  
Gang Wang ◽  
Zhen Yue Ma ◽  
Yi Kang Su
Keyword(s):  
Time History ◽  
Nonlinear Finite Element ◽  
Gravity Dam ◽  
Elastic Model ◽  
Nonlinear Finite Element Method ◽  
Initial Stiffness ◽  
Cohesive Model ◽  
Damage Initiation ◽  
History Analysis ◽  
Constitutive Response

A cohesive model (CM) was introduced in this paper. The constitutive response of cohesive behavior depends on a traction-separation description characterized by the initial stiffness, damage initiation threshold, and damage evolution properties.Through the aseismic analysis of a gravity dam, the displacement, stress and anti-sliding safety factor were discussed in the paper, the results were also compared between elastic model (EM) and plastic model (PM). The results shown that the displacement amplitude computed by PM and CM was nearly twice larger than that by EM, and the area of stress concentration became not so obvious. The cohesive model could efficiently simulate the discontinuous structure and the responses of seismic computed by PM and CM were more correspond to actual situation.

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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