Download or read book Seismic Risk and Post earthquake Recovery of Older Tall Buildings with Welded Steel Moment Frames written by Francisco Alfonso Galvis López and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Many of the existing tall buildings in the United States use seismically non-conforming welded steel moment frames (WSMFs) of the kind that experienced premature brittle fractures during the 1994 Northridge earthquake. Despite their known vulnerabilities, the vast majority of existing tall WSMF buildings have neither been evaluated nor retrofitted. To support the development of risk management policies for these structures, this study tackles the main impediments to robust quantification of risk and post-earthquake consequences in tall WSMFs by developing (1) a high-fidelity model to improve the nonlinear simulation of fracture-critical connections, (2) a detailed database of a realistic portfolio of tall WSMF buildings to increase the resolution of seismic risk assessments, (3) a screening method for pre-earthquake evaluation of tall WSMF buildings, (4) a damage evaluation method to inform post-earthquake re-occupancy and safety cordon decisions, and (5) a state-of-the-art assessment of earthquake damage, repair cost, and recovery time of tall WSMF buildings. This research presents a new computational model capable of reliably simulating fracture and post-fracture response of welded beam-to-column connections. This model uses a fiber-section element that simulates the welded flanges with single fibers and the shear tab bolted connection with multiple fibers. The flange fibers use a uniaxial stress-strain model that characterizes fracture resistance using a low-cycle fatigue damage rule based on the weld toughness--measured in terms of Charpy-V-notch (CVN) fracture energy--and weld defect size (a0). This stress-strain model also enables a realistic simulation of the connection behavior after flange fracture by capturing crack opening and closure. The stress-strain model is implemented in the OpenSees software as a uniaxial material called, SteelFractureDI. The parameters of SteelFractureDI are calibrated using a comprehensive database of 100 large-scale beam-column connection tests that were digitized and compiled as part of this study. SteelFractureDI is capable of predicting the instant of flange fracture within one half-cycle from the observed instant for 80/100 tests, compared to the 48/100 obtained with state-of-practice rotation limits (ASCE/SEI 2017). Moreover, the proposed connection model provides a more realistic distribution of flange fractures than conventional plastic hinge models due to the proper simulation of post-fracture behavior that avoids fictitious concentrations of drift. The resolution of the proposed connection model is best exploited in structural models that consider the unique features that dominate the seismic behavior of buildings. Thus, we collected a database of the structural characteristic of 89 tall steel moment frame buildings in San Francisco, which are representative of the construction practices in the western U.S. from the 1960's through early 1990's. The information in this database facilitates the creation of high-fidelity nonlinear structural models for several buildings in the database. The seismic response and collapse safety of these building are evaluated using nonlinear response history analyses (NLRHA) under suites of earthquake ground motions at various intensities. This study shows that the collapse safety varies significantly across the portfolio, from collapse risks that are comparable to that expected for current-code buildings to risks that are up to 35 times higher. Furthermore, the estimated performance of WSMFs is especially sensitive to the toughness and quality of the welded connections. These findings motivate broader coordination between structural engineers and public building departments to collect and synthesize data on weld metal toughness. The rigorous collapse metrics from this study enable the development of a rapid screening method to classify the risk of a tall WSMF building as moderate, high, or exceptionally high. This screening method empowers engineers to estimate the relative risk of a tall WSMF building using only basic information on the framing configuration and properties available from structural drawings and linear structural analyses, avoiding time-consuming nonlinear simulations. The screening method is intended to have sufficient specificity to identify the unique building features that influence collapse safety, while being simple enough to expedite the structural evaluation of tall buildings. This screening method can inform preventive decisions, such as whether a building should be prioritized for seismic retrofitting. In high-seismic regions, an earthquake may occur before buildings are retrofitted. Thus, this study also addresses the key post-earthquake issue of determining whether damaged buildings are safe to reoccupy, prior to and during repairs. Using the results of sequential NLRHA on eight WSMF models, we quantify the relationship between an "unsafe" designation using current evaluation guidelines (FEMA 352) and the damaged building's collapse safety. The results show that the FEMA 352 guidelines have two main shortcomings. First, the PGA=0.25g trigger for structural inspection is dangerously misleading for four of the eight frames in this study because more than 30% of the simulations that have a PGA

Download or read book Recommended Seismic Evaluation and Upgrade Criteria for Existing Welded Steel Moment Frame Buildings FEMA 351 written by Federal Emergency Agency and published by FEMA. This book was released on 2013-03-16 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report, FEMA-351 - Recommended Seismic Evaluation and Upgrade Criteria for Existing Welded Steel Moment-Frame Buildings has been developed by the SAC Joint Venture under contract to the Federal Emergency Management Agency (FEMA) to provide structural engineers with recommended criteria for evaluation of the probable performance of existing steel moment-frame buildings in future earthquakes and to provide a basis for updating and revision of evaluation and rehabilitation guidelines and standards. It is one of a series of companion publications addressing the issue of the seismic performance of steel moment-frame buildings. The set of companion publications includes: FEMA-350 - Recommended Seismic Design Criteria for New Steel Moment-Frame Buildings. This publication provides recommended criteria, supplemental to FEMA-302 - 1997 NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Other Structures, for the design and construction of steel moment-frame buildings and provides alternative performance-based design criteria. FEMA-351 - Recommended Seismic Evaluation and Upgrade Criteria for Existing Welded Steel Moment-Frame Buildings. This publication provides recommended methods to evaluate the probable performance of existing steel moment-frame buildings in future earthquakes and to retrofit these buildings for improved performance. FEMA-352 - Recommended Postearthquake Evaluation and Repair Criteria for Welded Steel Moment-Frame Buildings. This publication provides recommendations for performing postearthquake inspections to detect damage in steel moment-frame buildings following an earthquake, evaluating the damaged buildings to determine their safety in the postearthquake environment, and repairing damaged buildings. FEMA-353 - Recommended Specifications and Quality Assurance Guidelines for Steel Moment-Frame Construction for Seismic Applications. This publication provides recommended specifications for the fabrication and erection of steel moment frames for seismic applications. The recommended design criteria contained in the other companion documents are based on the material and workmanship standards contained in this document, which also includes discussion of the basis for the quality control and quality assurance criteria contained in the recommended specifications. The information contained in these recommended evaluation and upgrade criteria, hereinafter referred to as Recommended Criteria, is presented in the form of specific recommendations for design and performance evaluation procedures together with supporting commentary explaining part of the basis for these recommendations.

Download or read book Recommended Postearthquake Evaluation and Repair Criteria for Welded Steel Moment frame Buildings written by SAC Joint Venture. Guidelines Development Committee and published by FEMA. This book was released on 2000 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Recommended Seismic Evaluation and Upgrade Criteria for Existing Welded Steel Moment frame Buildings written by SAC Joint Venture. Guidelines Development Committee and published by . This book was released on 2000 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Recommended Postearthquake Evaluation and Repair Criteria for Welded Steel Moment frame Buildings written by SAC Joint Venture. Guidelines Development Committee and published by . This book was released on 2000 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Policy Guide to Steel Moment Frame Construction written by Federal Emergency Management Agency and published by Createspace Independent Pub. This book was released on 2013-03-16 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Northridge earthquake of January 17, 1994, caused widespread building damage throughout some of the most heavily populated communities of Southern California including the San Fernando Valley, Santa Monica and West Los Angeles, resulting in estimated economic losses exceeding $30 billion. Much of the damage sustained was quite predictable, occurring in types of buildings that engineers had previously identified as having low seismic resistance and significant risk of damage in earthquakes. This included older masonry and concrete buildings, but not steel framed buildings. Surprisingly, however, a number of modern, welded, steel, moment-frame buildings also sustained significant damage. This damage consisted of a brittle fracturing of the steel frames at the welded joints between the beams (horizontal framing members) and columns (vertical framing members). A few of the most severely damaged buildings could readily be observed to be out-of plumb (leaning to one side). However, many of the damaged buildings exhibited no outward signs of these fractures, making damage detection both difficult and costly. Then, exactly one year later, on January 17, 1995, the city of Kobe, Japan also experienced a large earthquake, causing similar unanticipated damage to steel moment-frame buildings. Prior to the 1994 Northridge and 1995 Kobe earthquakes, engineers believed that steel moment-frames would behave in a ductile manner, bending under earthquake loading, but not breaking. As a result, this became one of the most common types of construction used for major buildings in areas subject to severe earthquakes. The discovery of the potential for fracturing in these frames called to question the adequacy of the building code provisions dealing with this type of construction and created a crisis of confidence around the world. Engineers did not have clear guidance on how to detect damage, repair the damage they found, assess the safety of existing buildings, upgrade buildings found to be deficient or design new steel moment-frame structures to perform adequately in earthquakes. The observed damage also raised questions as to whether buildings in cities affected by other past earthquakes had sustained similar undetected damage and were now weakened and potentially hazardous. In response to the many concerns raised by these damage discoveries, the Federal Emergency Management Agency (FEMA) sponsored a program of directed investigation and development to identify the cause of the damage, quantify the risk inherent in steel structures and develop practical and effective engineering criteria for mitigation of this risk. As the project progressed, interim guidance documents were published to provide practicing engineers and the construction industry with important information on the lessons learned, as well as recommendations for investigation, repair, upgrade, and design of steel moment frame buildings. Many of these recommendations have already been incorporated into recent building codes. This project culminated with the publication of four engineering practice guideline documents. These four volumes include state-of-the-art recommendations that should be included in future building codes, as well as guidelines that may be applied voluntarily to assess and reduce the earthquake risk in our communities. This policy guide has been prepared to provide a nontechnical summary of the valuable information contained in the FEMA/SAC publications, an understanding of the risk associated with steel moment-frame buildings, and the practical measures that can be taken to reduce this risk. It is anticipated that this guide will be of interest to building owners and tenants, members of the financial and insurance industries, and to government planners and the building regulation community.

Download or read book Recommended Seismic Design Criteria for New Steel Moment Frame Buildings FEMA 350 written by Federal Emergency Agency and published by FEMA. This book was released on 2013-03-16 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report, FEMA-350 - Recommended Seismic Design Criteria for New Steel Moment-Frame Buildings has been developed by the SAC Joint Venture under contract to the Federal Emergency Management Agency (FEMA) to provide organizations engaged in the development of consensus design standards and building code provisions with recommended criteria for the design and construction of new buildings incorporating moment-resisting steel frame construction to resist the effects of earthquakes. It is one of a series of companion publications addressing the issue of the seismic performance of steel moment-frame buildings. The set of companion publications includes: FEMA-350 - Recommended Seismic Design Criteria for New Steel Moment-Frame Buildings. This publication provides recommended criteria, supplemental to FEMA-302 - 1997 NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Other Structures, for the design and construction of steel moment-frame buildings and provides alternative performance-based design criteria. FEMA-351 - Recommended Seismic Evaluation and Upgrade Criteria for Existing Welded Steel Moment-Frame Buildings. This publication provides recommended methods to evaluate the probable performance of existing steel moment-frame buildings in future earthquakes and to retrofit these buildings for improved performance. FEMA-352 - Recommended Postearthquake Evaluation and Repair Criteria for Welded Steel Moment-Frame Buildings. This publication provides recommendations for performing postearthquake inspections to detect damage in steel moment-frame buildings following an earthquake, evaluating the damaged buildings to determine their safety in the postearthquake environment, and repairing damaged buildings. FEMA-353 - Recommended Specifications and Quality Assurance Guidelines for Steel Moment-Frame Construction for Seismic Applications. This publication provides recommended specifications for the fabrication and erection of steel moment frames for seismic applications. The recommended design criteria contained in the other companion documents are based on the material and workmanship standards contained in this document, which also includes discussion of the basis for the quality control and quality assurance criteria contained in the recommended specifications. The information contained in these recommended design criteria, hereinafter referred to as Recommended Criteria, is presented in the form of specific design and performance evaluation procedures together with supporting commentary explaining part of the basis for these recommendations.

Download or read book The ShakeOut Scenario Supplemental Study High Rise Steel Buildings written by and published by SPA Risk LLC. This book was released on with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Recommended Seismic Design Criteria for New Steel Moment frame Buildings written by SAC Joint Venture. Guidelines Development Committee and published by . This book was released on 2000 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Recommended Postearthquake Evaluation and Repair Criteria for Welded Steel Moment Frame Buidlings FEMA 352 written by Federal Emergency Management Agency and published by Createspace Independent Pub. This book was released on 2013-03-16 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report, FEMA-352 – Recommended Postearthquake Evaluation and Repair Criteria for Welded Steel Moment-Frame Buildings, has been developed by the SAC Joint Venture under contract to the Federal Emergency Management Agency (FEMA) to provide communities and organizations developing programs for the assessment, occupancy status, and repair of welded steel moment-frame buildings that have been subjected to the effects of strong earthquake ground shaking. It is one of a series of companion publications addressing the issue of the seismic performance of steel moment-frame buildings. The set of companion publications includes: FEMA-350 – Recommended Seismic Design Criteria for New Steel Moment-Frame Buildings. This publication provides recommended criteria, supplemental to FEMA 302 – 1997 NEHRP Recommended Provisions for Seismic Regulations for New Buildings and other Structures, for the design and construction of steel moment-frame buildings and provides alternative performance-based design criteria. FEMA-351 – Recommended Seismic Evaluation and Upgrade Criteria for Existing Welded Steel Moment-Frame Buildings. This publication provides recommended methods to evaluate the probable performance of existing steel moment-frame buildings in future earthquakes and to retrofit these buildings for improved performance. FEMA-352 – Recommended Postearthquake Evaluation and Repair Criteria for Welded Steel Moment-Frame Buildings. This publication provides recommendations for performing postearthquake inspections to detect damage in steel moment-frame buildings following an earthquake, evaluating the damaged buildings to determine their safety in the postearthquake environment, and repairing damaged buildings. FEMA-353 – Recommended Specifications and Quality Assurance Guidelines for Steel Moment-Frame Construction for Seismic Applications. This publication provides recommended specifications for the fabrication and erection of steel moment frames for seismic applications. The recommended design criteria contained in the other companion documents are based on the material and workmanship standards contained in this document, which also includes discussion of the basis for the quality control and quality assurance criteria contained in the recommended specifications. The information contained in these recommended postearthquake damage assessment and repair criteria, hereinafter referred to as Recommended Criteria, is presented in the form of specific damage assessment, safety evaluation and repair procedures together with supporting commentary explaining part of the basis for these recommendations.

Download or read book Post Earthquake Rehabilitation and Reconstruction written by F.Y. Cheng and published by Elsevier. This book was released on 1996-10-14 with total page 507 pages. Available in PDF, EPUB and Kindle. Book excerpt: Damage assessment, rehabilitation, decision-making, social consequences, repair and reconstruction; these are all critical factors for considerations following natural disasters such as earthquakes. In order to address these issues, the United States of America and the Peoples Republic of China regularly organize bilateral symposia/workshops to investigate multiple hazard mitigation, particularly with respect to earthquake engineering. This book contains state-of-the-art reports presented by world-renowned researchers at the US/PRC Sympsosium Workshop on Post-Earthquake Rehabilitation and Reconstruction held in Kunming, Yunnan, China, May 1995. The following key areas are addressed: damage assessment of structures after earthquakes; lessons of post-earthquake recovery, rehabilitation and reconstruction, including public policy, land use options, urban planning, and design; issues in and examples of decision-making, and implementation of rehabilitation and reconstruction plans and policies; repair, strengthening, retrofit and control of structures and lifeline systems, post-earthquake socio-economic problems covering issues of relief and recovery; human and organizational behavior during emergency response, and strategies for improvement; real-time monitoring of earthquake response and damage.

Download or read book Rapid Visual Screening of Buildings for Potential Seismic Hazards Supporting Documentation written by and published by Government Printing Office. This book was released on 2015 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Rapid Visual Screening (RVS) handbook can be used by trained personnel to identify, inventory, and screen buildings that are potentially seismically vulnerable. The RVS procedure comprises a method and several forms that help users to quickly identify, inventory, and score buildings according to their risk of collapse if hit by major earthquakes. The RVS handbook describes how to identify the structural type and key weakness characteristics, how to complete the screening forms, and how to manage a successful RVS program.

Download or read book Seismic Demands for Performance Evaluation of Steel Moment Resisting Frame Structures SAC Task 5 4 3 written by Akshay Gupta and published by . This book was released on 1998 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NEHRP Recommended Provisions National Earthquake Hazards Reduction Program for Seismic Regulations for New Buildings and Other Structures Commentary written by United States. Federal Emergency Management Agency and published by . This book was released on 2001 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Stochastic Model for Earthquake Ground Motion Using Wavelet Packets written by Yoshifumi Yamamoto and published by Stanford University. This book was released on 2011 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: For performance-based design, nonlinear dynamic structural analysis for various types of input ground motions is required. Stochastic (simulated) ground motions are sometimes useful as input motions, because unlike recorded motions they are not limited in number and because their properties can be varied systematically to study the impact of ground motion properties on structural response. This dissertation describes an approach by which the wavelet packet transform can be used to characterize complex time-varying earthquake ground motions, and it illustrates the potential benefits of such an approach in a variety of earthquake engineering applications. The proposed model is based on Thr´ainsson and Kiremidjian (2002), which use Fourier amplitudes and phase differences to simulate ground motions and attenuation models to their model parameters. We extend their model using wavelet packet transform since it can control the time and frequency characteristic of time series. The time- and frequency-varying properties of real ground motions can be captured using wavelet packets, so a model is developed that requires only 13 parameters to describe a given ground motion. These 13 parameters are then related to seismological variables such as earthquake magnitude, distance, and site condition, through regression analysis that captures trends in mean values, standard deviations and correlations of these parameters observed in a large database of recorded strong ground motions. The resulting regression equations then form a model that can be used to predict ground motions for a future earthquake scenario; this model is analogous to widely used empirical ground motion prediction models (formerly called "attenuation models") except that this model predicts entire time series rather than only response spectra. The ground motions produced using this predictive model are explored in detail, and are shown to have elastic response spectra, inelastic response spectra, durations, mean periods, etc., that are consistent in both mean and variability to existing published predictive models for those properties. That consistency allows the proposed model to be used in place of existing models for probabilistic seismic hazard analysis (PSHA) calculations. This new way to calculate PSHA is termed "simulation-based probabilistic seismic hazard analysis" and it allows a deeper understanding of ground motion hazard and hazard deaggregation than is possible with traditional PSHA because it produces a suite of potential ground motion time histories rather than simply a distribution of response spectra. The potential benefits of this approach are demonstrated and explored in detail. Taking this analysis even further, this suite of time histories can be used as input for nonlinear dynamic analysis of structures, to perform a risk analysis (i.e., "probabilistic seismic demand analysis") that allows computation of the probability of the structure exceeding some level of response in a future earthquake. These risk calculations are often performed today using small sets of scaled recorded ground motions, but that approach requires a variety of assumptions regarding important properties of ground motions, the impacts of ground motion scaling, etc. The approach proposed here facilitates examination of those assumptions, and provides a variety of other relevant information not obtainable by that traditional approach.

Download or read book Post Earthquake Fire Analysis in Urban Structures written by Behrouz Behnam and published by CRC Press. This book was released on 2017-02-03 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: Post-earthquake fire is one of the most complicated problems resulting from earthquakes and presents a serious risk to urban structures. Most standards and codes ignore the possibility of post-earthquake fire; thus it is not factored in when determining the ability of buildings to withstand load. This book describes the effects of post-earthquake fire on partially damaged buildings located in seismic urban regions. The book quantifies the level of associated post-earthquake fire effects, and discusses methods for mitigating the risk at both the macro scale and micro scale. The macro scale strategies address urban regions while the micro scale strategies address building structures, covering both existing buildings and those that are yet to be designed.

Download or read book Failure Analysis of Welded Steel Moment Frames Damaged in the Northridge Earthquake written by Eric James Kaufmann and published by . This book was released on 1997 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: