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.

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.

ASCE-41 and FEMA-351 Evaluation of E-Defense Collapse Test

2009 ◽  
Vol 25 (4) ◽  
pp. 927-953 ◽  
Author(s):  
Bruce F. Maison ◽  
Kazuhiko Kasai ◽  
Gregory Deierlein
Keyword(s):  
Seismic Evaluation ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Welded Steel ◽  
Seismic Rehabilitation ◽  
Frame Building ◽  
Weak Beam ◽  
Beam Design ◽  
Safe Side ◽  
Computer Analyses

A welded steel moment-frame building is used to assess performance-based engineering guidelines. The full-scale four-story building was shaken to collapse on the E-Defense shake table in Japan. The collapse mode was a side-sway mechanism in the first story, which occurred in spite of a strong-column and weak-beam design. Computer analyses were conducted to simulate the building response during the experiment. The building was then evaluated using the Seismic Rehabilitation of Existing Buildings (ASCE-41) and Seismic Evaluation and Upgrade Criteria for Existing Welded Steel Moment-Frame Buildings (FEMA-351) for the collapse prevention performance level via linear and nonlinear procedures. The guidelines had mixed results regarding the characterization of collapse, and no single approach was superior. They mostly erred on the safe side by predicting collapse at shaking intensities less than that in the experiment. Recommendations are made for guideline improvements.

Evaluating and Upgrading Welded Steel Moment-Frame Buildings Using FEMA-351

2003 ◽  
Vol 19 (2) ◽  
pp. 317-334 ◽  
Author(s):  
John D. Hooper
Keyword(s):  
Earthquake Engineering ◽  
Joint Venture ◽  
Northridge Earthquake ◽  
Seismic Evaluation ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Welded Steel ◽  
Frame Design ◽  
Frame Buildings ◽  
Simplified Procedures

In July 2000, the SAC Joint Venture (a joint venture of the Structural Engineers Association of California, the Applied Technology Council, and California Universities for Research in Earthquake Engineering) prepared a series of recommendations regarding welded steel moment-frame design, evaluation, and upgrade procedures. FEMA-351, Recommended Seismic Evaluation and Upgrade Criteria for Existing Welded Steel Moment-Frame Buildings, was developed to evaluate the probable performance of existing steel moment-frame buildings in future earthquakes and to provide guidance or upgrading these buildings. The procedures introduced in FEMA-351 allow the determination of the level of confidence a structure will be able to achieve based on a specified performance objective, using simplified analytical methods. Simplified procedures for estimating the probable post-earthquake repair costs and nonstructural damage, based on the losses incurred in the 1994 Northridge earthquake, are presented as well. This paper provides a brief chapter-by-chapter overview of the information contained in FEMA-351 and emphasizes the performance evaluation procedures by stepping through the process using an example building.

Seismic Design Guidelines and Provisions for Steel-Framed Buildings: FEMA 267/267A and 1997 AISC Seismic Provisions

2000 ◽  
Vol 16 (1) ◽  
pp. 179-203
Author(s):  
James O. Malley ◽  
Charles J. Carter ◽  
C. Mark Saunders
Keyword(s):  
Wide Spectrum ◽  
Steel Structures ◽  
Design Guidelines ◽  
Northridge Earthquake ◽  
Earthquake Hazards ◽  
Steel Buildings ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Welded Steel ◽  
Frame Buildings

One of the important surprises of the Northridge earthquake of January 17, 1994, was the widespread and unanticipated brittle fracture of welded steel beam-to-column connections. Although no casualties or collapses occurred during the Northridge earthquake as a result of these connection failures, and many WSMF buildings were not damaged at all, a wide spectrum of brittle connection damage did occur, ranging from minor cracking to completely severed columns. This paper summarizes two of the most important documents that have been developed in response to the damage suffered to steel moment frame buildings in the Northridge earthquake. The first, FEMA 267, Interim Guidelines: Evaluation, Repair, Modification and Design of Welded Steel Moment Frame Structures, was generated from studies undertaken as part of a project initiated by the U.S. Federal Emergency Management Agency (FEMA) to reduce the earthquake hazards posed by steel moment-resisting frame buildings. The second document addressed in this paper is the 1997 edition of the American Institute of Steel Construction (AISC) Seismic Provisions for Structural Steel Buildings (commonly referred to as the AISC Seismic Provisions) that incorporates the new information generated by the FEMA-sponsored project and other investigations on the seismic performance of steel structures, and has been adopted by reference into the 2000 International Building Code (IBC).

Northridge Welded Steel Moment-Frame Damage Data and Its Use for Rapid Loss Estimation

2003 ◽  
Vol 19 (2) ◽  
pp. 335-364 ◽  
Author(s):  
David Bonowitz ◽  
Bruce F. Maison
Keyword(s):  
Rapid Method ◽  
Loss Estimation ◽  
Loss Functions ◽  
Northridge Earthquake ◽  
Seismic Evaluation ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Welded Steel ◽  
Repair Costs ◽  
Damage Data

FEMA-351, Recommended Seismic Evaluation and Upgrade Criteria for Existing Welded Steel Moment-Frame Buildings, offers two methods for estimating seismic losses in pre-Northridge WSMFs: detailed and rapid. The rapid method uses empirical relationships between seismic demand parameters and either damage levels or repair costs. The relationships are based on actual damage data collected after the 1994 Northridge earthquake. This paper summarizes the Northridge data, explains the FEMA-351 rapid method loss functions, and comments on the nature of the damage data and its application to loss estimation. Use of the loss functions can be enhanced by understanding their inherent assumptions and uncertainties and by considering how the underlying data was collected and interpreted in the years following the 1994 earthquake.

Post-earthquake Evaluation and Repair of Welded Steel Moment-Frame Buildings

2003 ◽  
Vol 19 (2) ◽  
pp. 399-414
Author(s):  
Maryann T. Phipps
Keyword(s):  
Structural Damage ◽  
Evaluation Procedure ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Welded Steel ◽  
Frame Building ◽  
Future Performance ◽  
Frame Buildings ◽  
Building Occupancy ◽  
Repair Techniques

In the wake of a potentially damaging earthquake, every affected welded steel moment-frame building should be assessed to determine whether it poses a safety risk. A straightforward, multi-step process has been developed to streamline this formidable task. This paper provides an overview of this procedure and repair techniques as published in FEMA-352, Recommended Post-earthquake Evaluation and Repair Criteria for Welded Steel Moment-Frame Buildings. The evaluation procedure, developed as part of the SAC Steel Project, begins with screening to rapidly identify those buildings unlikely to have been damaged. Subsequent steps help identify buildings that have sustained sufficient structural damage to compromise future performance and to determine appropriate actions regarding building occupancy and repair.

Relative Performance of Kobe and Northridge WSMF Buildings

2006 ◽  
Vol 22 (4) ◽  
pp. 1081-1101 ◽  
Author(s):  
Bruce F. Maison ◽  
Kazuhiko Kasai ◽  
Yoji Ooki
Keyword(s):  
Los Angeles ◽  
The United States ◽  
Office Building ◽  
Superior Performance ◽  
Moment Frame ◽  
Moment Connections ◽  
Steel Moment Frame ◽  
Welded Steel ◽  
The Difference ◽  
Seismic Behaviors

Seismic behaviors of a five-story welded steel moment-frame (WSMF) office building in Kobe, Japan, and a six-story WSMF office building in Northridge, California, are compared. Both experienced earthquake damage (1995 Kobe and 1994 Northridge earthquakes, respectively). Computer models of the buildings are formulated, having the ability to simulate damage in terms of fractured moment connections. Analyses are conducted to assess building response during the earthquakes. The calibrated models are then analyzed using a suite of earthquake records to compare building performance under consistent demands. The Kobe building is found to be more rugged than the Northridge building. Analysis suggests it would experience much less damage than the Northridge building from shaking equivalent to 2,500-year earthquake for a generic Los Angeles site. Superior performance of the Kobe building is attributed to its relatively greater stiffness and strength. The results provide insight into the difference in seismic fragility expected for this class of mid-rise WSMF buildings in Japan and the United States.

Project Specifications for New Steel Moment-Frame Building Construction

2003 ◽  
Vol 19 (2) ◽  
pp. 309-315
Author(s):  
Robert E. Shaw
Keyword(s):  
Quality Assurance ◽  
Building Construction ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Writing Project ◽  
Frame Building ◽  
Industry Standards ◽  
Frame Buildings ◽  
Frame Construction ◽  
New Industry

FEMA-353, Recommended Specifications and Quality Assurance Guidelines for Steel Moment-Frame Construction for Seismic Applications, contains numerous provisions related to the materials, details, quality, and inspection of steel moment-frame buildings in seismic regions. These provisions continue to evolve as industry standards and practices are reviewed, modified, and adopted to meet the need for good seismic performance. Those writing project specifications must remain current with new industry developments and standards.

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