Showing papers in "Earthquake Spectra in 2003"
TL;DR: In this article, the authors present a conceptual framework to define seismic resilience of communities and quantitative measures of resilience that can be useful for a coordinated research effort focusing on enhancing this resilience.
Abstract: This paper presents a conceptual framework to define seismic resilience of communities and quantitative measures of resilience that can be useful for a coordinated research effort focusing on enhancing this resilience. This framework relies on the complementary measures of resilience: ‘‘Reduced failure probabilities,’’ ‘‘Reduced consequences from failures,’’ and ‘‘Reduced time to recovery.’’ The framework also includes quantitative measures of the ‘‘ends’’ of robustness and rapidity, and the ‘‘means’’ of resourcefulness and redundancy, and integrates those measures into the four dimensions of community resilience—technical, organizational, social, and economic—all of which can be used to quantify measures of resilience for various types of physical and organizational systems. Systems diagrams then establish the tasks required to achieve these objectives. This framework can be useful in future research to determine the resiliency of different units of analysis and systems, and to develop resiliency targets and detailed analytical procedures to generate these values. [DOI: 10.1193/1.1623497]
3,399 citations
TL;DR: In this article, a simple analytical model is developed to calculate load factors associated with various collapse mechanisms of wall assemblies, and vulnerability functions are derived to quantify reduction in vulnerability associated with strengthening implementations for different typologies.
Abstract: In historic city centers the mitigation of seismic risk is dependent on the possibility of implementing strengthening programs. Given the cultural and economic value attached to the historic structures, however, interventions should be tailored to suit aesthetic and structural requirements of each building type, and provide sufficient reliability of performance in future earthquakes. A simple analytical model is developed to calculate load factors associated with various collapse mechanisms of wall assemblies, and vulnerability functions are derived. An application shows the capability of the procedure to quantify reduction in vulnerability associated with strengthening implementations for different typologies. [DOI: 10.1193/1.1599896]
344 citations
TL;DR: In this paper, the scissor-jack-damper system was developed as a variant of the toggle-bracedamper, with the added advantage of compactness, and demonstrated through testing of a large scale steel-framed model structure on an earthquake simulator.
Abstract: Installation of damping devices has been limited to diagonal or chevron brace configurations until the recent development of the toggle-brace configurations. These configurations magnify the effect of damping devices, thus facilitating their use in stiff framing systems. This paper introduces the scissor-jack-damper system that was developed as a variant of the togglebrace-damper systems, with the added advantage of compactness. The effectiveness of the scissor-jack configuration is demonstrated through testing of a large-scale steel-framed model structure on an earthquake simulator. Experiments showed that despite the small size of the damping device considered, the scissor-jack system provided a significant amount of damping and substantially reduced the seismic response of the tested structure. Response history and simplified analyses produce results that are consistent with the experimental results. [DOI: 10.1193/1.1540999]
150 citations
TL;DR: In this paper, the authors present a methodology for conducting a site-specific probabilistic analysis of fault displacement hazard, which can be applied to any region and indicate the type of data needed to apply the methodology elsewhere.
Abstract: We present a methodology for conducting a site-specific probabilistic analysis of fault displacement hazard. Two approaches are outlined. The first relates the occurrence of fault displacement at or near the ground surface to the occurrence of earthquakes in the same manner as is done in a standard probabilistic seismic hazard analysis (PSHA) for ground shaking. The methodology for this approach is taken directly from PSHA methodology with the ground-motion attenuation function replaced by a fault displacement attenuation function. In the second approach, the rate of displacement events and the distribution for fault displacement are derived directly from the characteristics of the faults or geologic features at the site of interest. The methodology for probabilistic fault displacement hazard analysis (PFDHA) was developed for a normal faulting environment and the probability distributions we present may have general application in similar tectonic regions. In addition, the general methodology is applicable to any region and we indicate the type of data needed to apply the methodology elsewhere.
110 citations
TL;DR: In this paper, the authors investigate the definition of irregular structures for different vertical irregularities: stiffness, strength, mass, and that due to the presence of nonstructural masonry infills.
Abstract: Seismic building codes such as the Uniform Building Code (UBC) do not allow the equivalent lateral force (ELF) procedure to be used for structures with vertical irregularities. The purpose of this study is to investigate the definition of irregular structures for different vertical irregularities: stiffness, strength, mass, and that due to the presence of nonstructural masonry infills. An ensemble of 78 buildings with various interstory stiffness, strength, and mass ratios is considered for a detailed parametric study. The lateral force-resisting systems (LFRS) considered are special moment-resisting frames (SMRF). These LFRS are designed based on the forces obtained from the ELF procedure. The results from linear and nonlinear dynamic analyses of these engineered buildings exhibit that most structures considered in this study performed well when subjected to the design earthquake. Hence, the restrictions on the applicability of the equivalent lateral force procedure are unnecessarily conservativ...
97 citations
TL;DR: In this article, procedures for calculating the effective damping and effective period and higher mode damping ratios for buildings equipped with yielding, viscoelastic, linear viscous, and nonlinear viscous damping devices are presented.
Abstract: Equivalent lateral force and modal analysis procedures for yielding buildings with damping systems were developed, validated, and incorporated in the 2000 NEHRP Provisions. The technical basis for each procedure is described in the paper together with the simplifications adopted for inclusion in the Provisions. Procedures for calculating the effective damping and effective period and higher mode damping ratios for buildings equipped with yielding, viscoelastic, linear viscous, and nonlinear viscous damping devices are presented.
76 citations
TL;DR: In this article, the authors examined SSI analysis procedures in the pre-2000 and 2000 NEHRP Provisions are examined relative to a database of observed SSI effects previously evaluated using system identification analyses.
Abstract: The NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Other Structures have contained procedures for soil-structure interaction analysis that were originally developed between 1975 and 1977 by the Applied Technology Council Committee on Soil-Structure Interaction (ATC3 Committee 2C). These procedures affect the analysis of seismic demand in structures by modifying the base shear for a fixed-base structure to that for a flexible-base structure with a longer fundamental mode period and a different (usually larger) system damping ratio. In the 2000 NEHRP Provisions and Commentary, several changes were made to these procedures that affect the analysis of foundation stiffness, and in turn affect the SSI adjustment to base shear. In this paper, SSI analysis procedures in the pre-2000 and 2000 NEHRP Provisions are examined relative to a database of observed SSI effects previously evaluated using system identification analyses. Through this calibration exercise and focused numerical analyses, we discuss the motivation and justification for the modifications to the NEHRP SSI analysis procedures.
73 citations
TL;DR: In this article, a procedure is presented to select and scale strong-motion records for site-specific analysis by matching records' smooth response spectra with the site response spectrum by scaling of the acceleration histories.
Abstract: A procedure is presented to select and scale strong-motion records for site-specific analysis. The procedure matches records’ smooth response spectra with the site response spectrum by scaling of the acceleration histories. The parameters defining the smooth spectrum of various records are computed and tabulated to allow easy selection of records. Hazard de-aggregation is used to identify closer and distant seismic events, which are simulated by the scaled ground motion histories. The procedure can also be used to obtain ground motion pairs in orthogonal directions for multidimensional dynamic response analyses.
69 citations
TL;DR: In this paper, a screen analysis is performed to distinguish sites for which only small ground deformations are likely from sites where larger, more damaging landslide movements could occur, whereas relatively detailed analyses are required for sites that fail the screen.
Abstract: Site-specific seismic slope stability analyses are required in California by the 1990 California Seismic Hazards Mapping Act for sites located within mapped hazard zones and scheduled for development with more than four single-family dwellings A screen analysis is performed to distinguish sites for which only small ground deformations are likely from sites for which larger, more damaging landslide movements could occur No additional analyses are required for sites that pass the screen, whereas relatively detailed analyses are required for sites that fail the
55 citations
TL;DR: In this paper, the authors reconciled the results of a recent study by the authors that linked cyclic resistance and relative density of the sand skeleton void ratio of the soil and showed that the trend of decreasing cyclic resistances with increasing silt content does not occur in non-plastic silts.
Abstract: The literature presents several seemingly contradictory reports concerning the effects of non-plastic (i.e., silty) fines content on the liquefaction resistance of sands. These seemingly contradictory trends were reconciled in light of the results of a recent study by the authors that linked cyclic resistance and relative density. It was shown that the trend of decreasing cyclic resistance with increasing silt content reported in the literature could be explained by considering the soil’s relative density. The same argument was made for the trend of decreasing and then increasing cyclic resistance with increasing silt content. The concept that cyclic resistance is controlled by the sand skeleton void ratio of the soil was also reconciled with the results of the authors’ previous study. The trend of increasing cyclic resistance (without a corresponding initial decrease) with increasing silt content that has been reported in the literature does not appear to occur in non-plastic silts.
55 citations
TL;DR: In this paper, the equivalent lateral force and modal analysis procedures for yielding buildings with damping systems were developed, validated, and incorporated in the 2000 NEHRP Provisions.
Abstract: Equivalent lateral force and modal analysis procedures for yielding buildings with damping systems were developed, validated, and incorporated in the 2000 NEHRP Provisions. Key to the implementation of the procedures was the validation process that demonstrated the accuracy of the proposed procedures. The procedures for implementing yielding, viscoelastic, linear viscous, and nonlinear viscous dampers were tested using the results of nonlinear response-history analysis on sample three- and six-story frames and were found to be robust. [DOI: 10.1193/1.1622392]
TL;DR: In this paper, a performance-based design and evaluation procedure for steel moment-frame performance is presented in a familiar demand and resistance factor engineering format to provide engineers with the ability to define a level of confidence associated with the prediction that a building design will be able to meet a desired performance objective.
Abstract: The extensive research on steel moment-frame performance developed by the FEMA/SAC program was implemented in a probabilistic reliability framework to develop performance-based design and evaluation procedures. These procedures, presented in a familiar demand and resistance factor engineering format provide engineers with the ability to define a level of confidence associated with the prediction that a building design will be able to meet a desired performance objective. This approach builds upon and extends the performance-based design procedures developed under the SEAOC Vision 2000 and FEMA 273 projects in two important ways. First, it provides a direct method for structural performance to be evaluated on the basis of global, as opposed to local behaviors. Second, it permits quantification of the likelihood that desired performance will actually be achieved, potentially alleviating liability concerns related to implementation of performance-based design approaches. Perhaps more important, the ...
TL;DR: In this paper, the authors investigated design relationships to estimate the following four seismic demand indices for single-degree-of-freedom (SDOF) systems: (1) the peak displacement ductility demand, μ; (2) the cumulative plastic displacement ductile demand, µp; (3) the residual displacement ductiliary demand, mm; and (4) the number of yield events, ny.
Abstract: This paper investigates design relationships to estimate the following four seismic demand indices for single-degree-of-freedom (SDOF) systems: (1) the peak displacement ductility demand, μ; (2) the cumulative plastic displacement ductility demand, μp; (3) the residual displacement ductility demand, μr; and (4) the number of yield events, ny. The main objectives of the study are (1) to develop relatively simple regression relationships that can be used to estimate mean values of these demand indices; and (2) to investigate the effects of structure yield strength, hysteretic behavior, fundamental period, site soil characteristics, seismic demand level, site seismicity, and epicentral distance on these relationships. It is shown that the correlation between μ and the other demand indices is usually relatively strong. In some cases, the cross-correlations between the demand indices are weak, indicating that these indices carry independent measures of seismic demand.
TL;DR: In this paper, a simple equation was established and calibrated to relate the fatalities in earthquakes having tolls lower than the bounding function to the upper bounding functions, which provided a procedure for estimating fatality counts in future theoretical events with a specific combination of circumstances.
Abstract: Structures present a risk during seismic events from partial or full collapse that can cause death and injury to the occupants. The United States Geological Survey (USGS) has collated data on deaths from and magnitudes of earthquakes. These data have not previously been analyzed to establish any relationships between fatality tolls or fatality rates in different earthquakes. An investigation of the fatality catalogue establishes a bounding function for the twentieth-century fatality data using the USGS assigned earthquake magnitude as the dependent variable. A simple equation was established and calibrated to relate the fatalities in earthquakes having tolls lower than the bounding function to the bounding function. This equation and the calibration data, essentially for unreinforced masonry and timber-framed buildings, provides a procedure for estimating fatality counts in future theoretical events with a specific combination of circumstances. Potential uses of the fatality function with further...
TL;DR: The second edition of Earthquake Protection as discussed by the authors is an up-to-date primer on the full range of earthquake preparedness and planning issues and is a must for government officials, risk managers, planners, emergency managers, and teachers.
Abstract: The second edition of Earthquake Protection is an up-to-date primer on the full range of earthquake preparedness and planning issues. The book is comprehensive in scope, remarkably detailed, and easy to read. The book is a must for government officials, risk managers, planners, emergency managers, and teachers. It is equally valuable for earthquake engineering professionals to use as a reference guide to areas outside their own specialty.
TL;DR: In this article, two bilinear R−μ−T/Tg relationships are recommended for most strong ground motions and structural systems, which are indexed by the characteristic period of the ground motion, Tg.
Abstract: Recent studies have demonstrated the need to consider the ground motion frequency content in the development and use of R−μ−T relationships. Results from two different approaches to determining these relationships are unified in the present paper. Two bilinear R−μ−T/Tg relationships are recommended for most strong ground motions and structural systems. One is more accurate, while the other, more conservative relationship is used in FEMA 273, ATC-32, and the simple version of the N2 method. Both relationships are indexed by the characteristic period of the ground motion, Tg. Simple methods to determine Tg from smoothed design spectra and recorded ground motions are provided. Neither recommended relationships are applicable to the nearly harmonic ground motions that may be generated at sites containing soft lakebed deposits. An example illustrates the application of these relationships to a code design spectrum in both the acceleration-displacement and yield point spectra formats.
TL;DR: In this paper, the spectral-analysis-of-surface-waves (SASW) method was used to measure the shear-wave velocity profiles of the Kocaeli and Duzce earthquakes in Turkey.
Abstract: The 1999 Kocaeli and Duzce earthquakes in Turkey generated a moderate amount of strong ground motion data. This paper describes the shear-wave velocity profiles measured at a number of strong motion stations in Turkey using the spectral-analysis-of-surface-waves (SASW) method. The shear-wave velocity profiles from SASW testing compare well with deeper profiles developed by microtremor surface wave inversion, but SASW provides more shear-wave velocity resolution near the ground surface. The developed shear-wave velocity profiles are used to define site classifications for each station. For the Kocaeli earthquake, event-specific attenuation relationships are developed. These relationships show considerable amplification of peak ground acceleration and spectral acceleration (at a period of 0.3 s) at deep soil sites in the far field, but no amplification in the near-fault region. For spectral accelerations at longer spectral periods (1.0 and 2.0 s), amplification is indicated in both the near field a...
TL;DR: In this paper, a simple procedure to identify site frequencies using earthquake response records from roofs and basements of buildings is presented, and a simple code-formula is used to calculate site frequencies and compare them with the identified site frequencies from records.
Abstract: A simple procedure to identify site frequencies using earthquake response records from roofs and basements of buildings is presented. For this purpose, data from five different buildings are analyzed using only spectral analyses techniques. Additional data such as free-field records in close proximity to the buildings and site characterization data are also used to estimate site frequencies and thereby to provide convincing evidence and confirmation of the site frequencies inferred from the building records. Furthermore, simple code-formula is used to calculate site frequencies and compare them with the identified site frequencies from records. Results show that the simple procedure is effective in identification of site frequencies and provides relatively reliable estimates of site frequencies when compared with other methods. Therefore the simple procedure for estimating site frequencies using earthquake records can be useful in adding to the database of site frequencies. Such databases can be used to better estimate site frequencies of those sites with similar geological structures. [DOI: 10.1193/1.1542618]
TL;DR: In this article, design recommendations to control ductility demands of torsionally unbalanced multistory buildings are given based on the simple static procedure and include two values and an expression for the amplification factor α to compute story eccentricities, three values of the Torsion-shear reduction factor δ, an additional lateral force to be applied at the building top level, and a minimal story eccentricity for the building.
Abstract: Multistory models are studied to assess design recommendations for torsionally unbalanced multistory buildings. Structural systems are assumed as shear beams with nonlinear lateral-resisting elements oriented along two orthogonal directions and subjected to a bidirectional earthquake ground motion. Five-story rigid-diaphragm models with mass or stiffness eccentricity are considered in the study. Accidental eccentricity is not included in the modeling and, therefore, its related recommendations are not assessed. Design recommendations studied here are based on the simple static procedure and include two values and an expression for the amplification factor α to compute story eccentricities, three values of the torsion-shear reduction factor δ, an additional lateral force Ft to be applied at the building top level, and a minimal story eccentricity for the building. Design recommendations to control ductility demands of torsionally unbalanced multistory buildings are given.
TL;DR: In this paper, S-wave velocities (Vs) to about 40m depth at 65 locations in the Memphis-Shelby County, Tennessee, area were determined using high-resolution seismic refraction and reflection methods on the ground surface.
Abstract: We determined S-wave velocities (Vs) to about 40-m depth at 65 locations in the Memphis-Shelby County, Tennessee, area. The Vs measurements were made using high-resolution seismic refraction and reflection methods on the ground surface. We find a clear difference in the Vs profiles between sites located on the Mississippi River flood plain and those located to the east, mostly covered by loess, in the urban areas of Memphis. The average Vs to 30-m depth at 19 sites on the modern Mississippi River floodplain averages 197 m/s (±15 m/s) and places 17 of these sites at the low end of NEHRP soil profile category type D (average Vs 180-360 m/s). The two remaining sites are type E. Vs to 30-m depth at 46 sites in the urban areas east of the modern floodplain are more variable and generally higher than the floodplain sites, averaging about 262 m/s (±45 m/s), still within category D. We often observed the base of the loess as a prominent S-wave reflection and as an increase in Vs to about 500 m/s. Based o...
TL;DR: In this paper, the seismic performance of eleven half-scale and three full-sized reinforced concrete beam-column knee joints was tested under inelastic cyclic loading, and the results showed that all the knee joints approached or exceeded their nominal beam strengths in both directions and only degraded in strength at displacement ductility factors greater than 2, while the 1960 designs failed prematurely in joint shear at about 70% of the beam nominal strengths.
Abstract: The seismic performance of eleven half-scale and three full-sized reinforced concrete beam-column knee joints was tested under inelastic cyclic loading. Twelve joints were designed to the current New Zealand Concrete Standard, NZS 3101 while the remaining two were designed to the 1964 New Zealand Code, which contained few seismic provisions. All the 1995 designs approached or exceeded their nominal beam strengths in both directions and only degraded in strength at displacement ductility factors greater than 2, while the 1960 designs failed prematurely in joint shear at about 70% of the beam nominal strengths. Many of the half-scale joints failed when cover concrete split off in the joint zone, allowing loss of anchorage and slip of the top beam bars. Two full-scale joints were designed to carry the maximum specified code joint shear stress (0.2 fc′), and one subsequently failed due to joint shear when the concrete compressive strength did not reach the specified design value. A third full-size jo...
TL;DR: In this paper, a nonlinear dynamic response of the structure to the seismic action is studied considering, among the uncertainties, the peak acceleration and the frequency content of the ground motion.
Abstract: Performance-based seismic design requires consideration of the uncertainties in corresponding demands and capacities. A response surface methodology is used to evaluate the annual exceedance probability in each specified, damage-related performance level. The nonlinear dynamic response of the structure to the seismic action is studied considering, among the uncertainties, the peak acceleration and the frequency content of the ground motion. Advantages and disadvantages of two types of response surface formulations are discussed, including two ways of considering dispersion produced by different ground motions. The procedure is illustrated with two examples: an elevated water tank and a five-story portal frame. Finally, the method is applied to the calibration of a deterministic, factored design code approach with multiple performance objectives.
TL;DR: In this article, a test protocol was established to measure the seismic strength of pipe bracing components and a series of tests were conducted to gain insight into the cyclic behavior of pipe brace components.
Abstract: The design codes and standards (e.g., UBC, IBC, NFPA-13) estimate the amplitude of the seismic load in sprinkler-pipe braces, but they do not specify the number of cycles for which this load must be resisted by various components of pipe braces. Because the components can fail in low-cycle fatigue, the number of load cycles must be considered in establishing the strength of the brace components. The first part of this study deals with determining the number of cycles for which a component must resist its rated capacity. Strong-motion records from 18 strongly shaken buildings were incorporated into a low-cycle fatigue model to develop a test criterion for measuring the seismic strength of brace components. In the second part of this study, a series of tests were conducted to gain insight into the cyclic behavior of brace components. Finally, a test protocol was established to measure the seismic strength of brace components. With some modifications, the protocol can be applied to many other nonstr...
TL;DR: In this paper, a probabilistic approach was proposed to estimate ground motion from modified Mercalli intensity (MMI) from past earthquakes to make quantitative estimates of ground shaking parameters (i.e., peak ground acceleration, peak ground velocity, 5% damped spectral acceleration values, etc.).
Abstract: We describe a new probabilistic method that uses observations of modified Mercalli intensity (MMI) from past earthquakes to make quantitative estimates of ground shaking parameters (i.e., peak ground acceleration, peak ground velocity, 5% damped spectral acceleration values, etc.). The method uses a Bayesian approach to make quantitative estimates of the probabilities of different levels of ground motions from intensity data given an earthquake of known location and magnitude. The method utilizes probability distributions from an intensity/ground motion data set along with a ground motion attenuation relation to estimate the ground motion from intensity. The ground motions with the highest probabilities are the ones most likely experienced at the site of the MMI observation. We test the method using MMI/ground motion data from California and published ground motion attenuation relations to estimate the ground motions for several earthquakes: 1999 Hector Mine, California (M7.1); 1988 Saguenay, Quebec (M5.9); and 1982 Gaza, New Hampshire (M4.4). In an example where the method is applied to a historic earthquake, we estimate that the peak ground accelerations associated with the 1727 (M;5.2) earthquake at Newbury, Massachusetts, ranged from 0.23 g at Newbury to 0.06 g at Boston. [DOI: 10.1193/1.1596549]
TL;DR: This paper reviewed the roles played by pre-Field Act factors and the politics of the law's enactment, including the central role played by the State Division of Architecture in preparing the legislation and supporting Assemblyman Field's efforts.
Abstract: California’s first major earthquake safety policy initiative was 1933’s Safety of Design and Construction of Public School Buildings Act, popularly known as the Field Act for its author, Assemblyman Don C. Field, who became the Field Act’s legislative champion. The foundation for its enactment a month after the 10 March 1933 Long Beach earthquake was laid earlier by the 29 June 1925 Santa Barbara earthquake, the Dam Act of 1929, the drafting of a proposed Building Code for California, the formation of the Structural Engineers Association of California, and general acceptance of California’s earthquake risk. This paper reviews the roles played by the pre-Field Act factors and the politics of the law’s enactment, including the central role played by the State Division of Architecture in preparing the legislation and supporting Assemblyman Field’s efforts.
TL;DR: In this article, the authors describe procedures that may be used by experienced structural engineers to develop earthquake damage and related loss functions for welded steel moment-frame (WSMF) buildings.
Abstract: 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-s...
TL;DR: On 31 March 2002, an earthquake of magnitude ML=6.8 occurred in northeastern Taiwan that caused five deaths and damage to more than 300 buildings as mentioned in this paper, which left some important lessons.
Abstract: On 31 March 2002, an earthquake of magnitude ML=6.8 occurred in northeastern Taiwan that caused five deaths and damage to more than 300 buildings. The earthquake left some important lessons; these ...
TL;DR: In this article, the present situation of research, codification, design, and applications in the field of steel and composite structures in the European earthquake-prone countries is discussed, and some applications of earthquake-resistant structures recently built in Europe are illustrated.
Abstract: This paper focuses on the present situation of research, codification, design, and applications in the field of steel and composite structures in the European earthquake-prone countries. Emphasis is first given to recent research projects developed in cooperation among European institutions, providing the basis of the research activity and the main conclusions. Then codification rules are focused on, by examining basic principles and new amendments of Eurocode 8, in relation with the current design methodologies adopted in Europe for both steel and steel-concrete composite structures. Finally, some applications of earthquake-resistant structures recently built in Europe are illustrated.
TL;DR: FEMA-351 as discussed by the authors proposes two methods for estimating seismic losses in pre-Northridge WSMFs: detailed and rapid, based on empirical relationships between seismic demand parameters and either damage levels or repair costs.
Abstract: 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.