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).

Design Guidelines for Steel Moment Frames for New Buildings

2003 ◽  
Vol 19 (2) ◽  
pp. 269-290
Author(s):  
C. Mark Saunders
Keyword(s):  
Lateral Force ◽  
Design Guidelines ◽  
Northridge Earthquake ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Simple Set ◽  
Frame Buildings ◽  
New Buildings

The damage to steel moment frames observed in the Northridge earthquake of 1994 led to requirements in codes for use of tested connections, when these systems were to be employed in new buildings. One of the primary goals of the FEMA/SAC project was to develop guidelines for the design of steel moment frames that would return the design process to a relatively simple set of procedures similar to those used in the design of other lateral force-resisting systems. Recommended Seismic Design Criteria for New Steel Moment-Frame Buildings, FEMA-350, presents design guidelines for use of steel moment frames in new buildings, developed from the FEMA/SAC research. This paper provides a general summary of the criteria, and a description of the prequalified connections and recommendations for their use.

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.

Overview of the U.S. Program for Reduction of Earthquake Hazards in Steel Moment-Frame Structures

2003 ◽  
Vol 19 (2) ◽  
pp. 237-254 ◽  
Author(s):  
Stephen A. Mahin ◽  
James O. Malley ◽  
Ronald O. Hamburger ◽  
Michael Mahoney
Keyword(s):  
Guideline Development ◽  
Cost Effective ◽  
The United States ◽  
Frame Structures ◽  
Earthquake Hazards ◽  
Steel Buildings ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
The U.S ◽  
Design And Construction

Considerable research has been conducted worldwide to assess the unexpected damage to welded steel moment-frame buildings during the 1989 Loma Prieta, 1994 Northridge, and 1995 Hyogo-ken Nanbu earthquakes, as well as to find effective and economical remedies that can be incorporated into analysis, design, and construction practices. A major six-year program has been undertaken with the sponsorship of the U.S. Federal Emergency Management Agency (FEMA) to synthesize and interpret the results of this research, and to conduct additional investigations to develop reliable, practical, and cost-effective guidelines for the design and construction of new steel moment-frame structures, as well as for the inspection, evaluation and repair or upgrading of existing ones. Topics investigated as part of this program include (1) performance of steel buildings in past earthquakes; (2) material properties and fracture issues; (3) joining and inspection; (4) connection performance; (5) system performance; (6) performance prediction and evaluation; and (7) social, economic, and political impacts. The project utilizes a performance-based engineering framework and addresses issues pertaining to various types of steel moment-resisting frames including those utilizing welded, bolted, and partially restrained connections. The guidelines are applicable to regions of low, medium, and high seismicity throughout the United States. This paper reviews the overall organization and management of this program of research, guideline development, training and peer evaluation, the scope of the investigations undertaken, and the general organization and contents of the guidelines developed.

Earthquake Loss Estimation Methods for Welded Steel Moment-Frame Buildings

2003 ◽  
Vol 19 (2) ◽  
pp. 365-384 ◽  
Author(s):  
Charles A. Kircher
Keyword(s):  
Los Angeles ◽  
Joint Venture ◽  
Loss Estimation ◽  
Loss Functions ◽  
Estimation Methods ◽  
Seismic Evaluation ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Welded Steel ◽  
Frame Buildings

This paper describes procedures that may be used by experienced structural engineers to develop earthquake damage and related loss functions for welded steel moment-frame (WSMF) buildings. The damage and loss functions are based on and compatible with the loss estimation methods of HAZUS, a technology developed by Federal Emergency Management Agency (FEMA) for assessing regional impacts of earthquakes. The loss estimation procedures were developed by the SAC Steel Program as described in SAC Joint Venture Topical Report SAC/BD-99/13. These procedures form the basis for Appendix B of FEMA-351, Recommended Seismic Evaluation and Upgrade Criteria for Existing Welded Steel Moment-Frame Buildings. The procedures for developing damage and loss functions for WSMF building response are general in nature and applicable to WSMF buildings designed to different seismic criteria and having different connection details. Default values of damage and loss function parameters are provided for typical 3-story, 9-story, and 20-story WSMF buildings, designed for Los Angeles, Seattle, or Boston seismic criteria and having pre-Northridge, post-Northridge, or damaged pre-Northridge connection conditions.

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.

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.

Interpretation of significant ground-response and structure strong motions recorded during the 1994 Northridge earthquake

1996 ◽  
Vol 86 (1B) ◽  
pp. S231-S246 ◽  
Author(s):  
A. F. Shakal ◽  
M. J. Huang ◽  
R. B. Darragh
Keyword(s):  
Flexible Structures ◽  
Northridge Earthquake ◽  
Moment Frame ◽  
Ground Response ◽  
Short Period ◽  
Frame Buildings ◽  
Story Drift ◽  
San Fernando ◽  
San Fernando Valley ◽  
The Moment

Abstract Some of the largest accelerations and velocities ever recorded at ground-response and structural sites occurred during the Northridge earthquake. These motions are greater than most existing attenuation models would have predicted. Although the motions are large, the correspondence between measured acceleration and damage requires further study, since some sites with high acceleration experienced only moderate damage. Also, some peak vertical accelerations were larger than the horizontal, but in general, they are smaller and fit the pattern observed in previous earthquakes. Strong-motion records processed to date show significant differences in acceleration and velocity waveforms and amplitudes across the San Fernando Valley. Analysis of processed data from several buildings in the San Fernando Valley indicates that short-period buildings such as shear-wall buildings experienced large forces and relatively low inter-story drift during the Northridge earthquake. However, long-period (1 to 5 sec) steel or concrete moment-frame buildings experienced large inter-story drift. For this earthquake, accelerations did not always amplify from base to roof for flexible structures like the moment-frame buildings, but the displacements were always larger at the roof. The drifts at many of the moment-frame buildings were larger than the drift limit for working stress design in the building code. The records from a base-isolated building indicate that high-frequency motion was reduced significantly by the isolators. The isolators deformed about 3.5 cm, which is much less than the design displacement. The records from a parking structure show important features of the seismic response of this class of structure.

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