Reduced beam section welded steel moment frame connections

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.

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

Earthquake Spectra ◽

10.1193/1.3224159 ◽

2009 ◽

Vol 25 (4) ◽

pp. 927-953 ◽

Cited By ~ 8

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.

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Assembly-Based Vulnerability of Buildings and Its Use in Performance Evaluation

Earthquake Spectra ◽

10.1193/1.1586176 ◽

2001 ◽

Vol 17 (2) ◽

pp. 291-312 ◽

Cited By ~ 144

Author(s):

Keith A. Porter ◽

Anne S. Kiremidjian ◽

Jeremiah S. LeGrue

Keyword(s):

Cost Estimation ◽

Seismic Vulnerability ◽

Structural Model ◽

Structural Response ◽

Time History ◽

Simulation Approach ◽

Moment Frame ◽

Steel Moment Frame ◽

Welded Steel ◽

Specific Level

Assembly-based vulnerability (ABV) is a framework for evaluating the seismic vulnerability and performance of buildings on a building-specific basis. It utilizes the damage to individual building components and accounts for the building's seismic setting, structural and nonstructural design and use. A simulation approach to implementing ABV first applies a ground motion time history to a structural model to determine structural response. The response is applied to assembly fragility functions to simulate damage to each structural and nonstructural element in the building, and to its contents. Probabilistic construction cost estimation and scheduling are used to estimate repair cost and loss-of-use duration as random variables. It also provides a framework for accumulating post-earthquake damage observations in a statistically systematic and consistent manner. The framework and simulation approach are novel in that they are fully probabilistic, address damage at a highly detailed and building-specific level, and do not rely extensively on expert opinion. ABV is illustrated using an example pre-Northridge welded-steel-moment-frame office building.

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Progress with the SAC Joint Venture Program for the Evaluation, Repair, Modification and Design of Welded Steel Moment Frame Structures

Innovation in Engineering for Seismic Regions ◽

10.4203/ccp.47.2.1 ◽

2009 ◽

Cited By ~ 1

Author(s):

R. Shepherd

Keyword(s):

Joint Venture ◽

Frame Structures ◽

Moment Frame ◽

Steel Moment Frame ◽

Welded Steel

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Earthquake Loss Estimation Methods for Welded Steel Moment-Frame Buildings

Earthquake Spectra ◽

10.1193/1.1572171 ◽

2003 ◽

Vol 19 (2) ◽

pp. 365-384 ◽

Cited By ~ 6

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.

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

Earthquake Spectra ◽

10.1193/1.1571843 ◽

2003 ◽

Vol 19 (2) ◽

pp. 317-334 ◽

Cited By ~ 3

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.

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

Earthquake Spectra ◽

10.1193/1.1773593 ◽

2004 ◽

Vol 20 (3) ◽

pp. 951-973 ◽

Cited By ~ 1

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.

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

Earthquake Spectra ◽

10.1193/1.1586090 ◽

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).

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