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Showing papers in "Earthquake Spectra in 2004"


Journal ArticleDOI
TL;DR: Resilience measures that relate expected losses in future disasters to a community's seismic performance objectives are proposed and demonstrated in a case study of the Memphis, Tennessee, water delivery system.
Abstract: This paper demonstrates the concept of disaster resilience through the development and application of quantitative measures. As the idea of building disaster-resilient communities gains acceptance, new methods are needed that go beyond estimating monetary losses and that address the complex, multiple dimensions of resilience. These dimensions include technical, organizational, social, and economic facets. This paper first proposes resilience measures that relate expected losses in future disasters to a community’s seismic performance objectives. It then demonstrates these measures in a case study of the Memphis, Tennessee, water delivery system. An existing earthquake loss estimation model provides a starting point for quantifying resilience. The analysis compares two seismic retrofit strategies and finds that only one improves community resilience over the status quo. However, it does not raise resilience to an adequate degree. The exercise demonstrates that the resilience framework can be valua...

568 citations


Journal ArticleDOI
TL;DR: A practical and detailed example of how to perform incremental dynamic analysis (IDA), interpret the results and apply them to performance-based earthquake engineering is presented.
Abstract: We are presenting a practical and detailed example of how to perform incremental dynamic analysis (IDA), interpret the results and apply them to performance-based earthquake engineering IDA is an emerging analysis method that offers thorough seismic demand and capacity prediction capability by using a series of nonlinear dynamic analyses under a multiply scaled suite of ground motion records Realization of its opportunities requires several steps and the use of innovative techniques at each one of them Using a nine-story steel moment-resisting frame with fracturing connections as a test bed, the reader is guided through each step of IDA: (1) choosing suitable ground motion intensity measures and representative damage measures, (2) using appropriate algorithms to select the record scaling, (3) employing proper interpolation and (4) summarization techniques for multiple records to estimate the probability distribution of the structural demand given the seismic intensity, and (5) defining limit-s

498 citations


Journal ArticleDOI
TL;DR: The modal pushover analysis (MPA) as discussed by the authors, which includes the contributions of all significant modes of vibration, estimates seismic demands much more accurately than current pushover pr...
Abstract: The modal pushover analysis (MPA) procedure, which includes the contributions of all significant modes of vibration, estimates seismic demands much more accurately than current pushover pr...

256 citations


Journal ArticleDOI
TL;DR: In this article, the authors performed a feasibility study on backscattering characteristics of damaged areas in the 1995 Hyogoken-Nanbu (Kobe), Japan, earthquake using the preand post-event ERS images, revealing that the backscatter coefficient and intensity correlation between the two attained values were significantly lowered in hard-hit areas.
Abstract: Synthetic aperture radar (SAR) is remarkable for its capability to record the backscattering coefficient, the physical value of the earth’s surface, regardless of weather condition or sun illumination. Therefore, SAR is a powerful tool that can be utilized to develop a universal method to comprehend damaged areas in disasters such as earthquakes, forest fires, and floods. We performed a feasibility study on backscattering characteristics of damaged areas in the 1995 Hyogoken-Nanbu (Kobe), Japan, earthquake using the preand post-event ERS images, revealing that the backscattering coefficient and intensity correlation between the two attained values were significantly lowered in hard-hit areas. The evaluation, however, was performed without speckle noise reduction. We also investigated the effects of speckle noise reduction and pixel-window size in evaluating building damage using the difference in the backscattering coefficient and correlation coefficient of the pre- and post-event ERS images. From the analysis, an optimum window size for the damage evaluation was obtained. It was also found that the accuracy of damage detection is not significantly improved for speckle-reduction filtering of window size larger than 21321 pixels. We developed an automated method to detect hard-hit areas based on the discriminant analysis, and compared the detected distribution with a damage survey result. [DOI: 10.1193/1.1774182]

254 citations


Journal ArticleDOI
TL;DR: In this article, the frequency content of an earthquake ground motion is analyzed using the mean period, average spectral period, smoothed spectral predominant period (To), and predominant spectral period (Tp).
Abstract: The frequency content of an earthquake ground motion is important because it affects the dynamic response of earth and structural systems. Four scalar parameters that characterize the frequency content of strong ground motions are (1) the mean period (Tm), (2) the average spectral period (Tavg), (3) the smoothed spectral predominant period (To), and (4) the predominant spectral period (Tp). Tm and Tavg distinguish the low frequency content of ground motions, while To is affected most by the high frequency content. Tp does not adequately describe the frequency content of a strong ground motion and is not recommended. Empirical relationships are developed that predict three parameters (Tm, Tavg, and To) as a function of earthquake magnitude, site-to-source distance, site conditions, and rupture directivity. The relationships are developed from a large strong-motion database that includes recorded motions from the recent earthquakes in Turkey and Taiwan. The new relationships update those previously...

198 citations


Journal ArticleDOI
TL;DR: The proposed method is capable of searching a set consisting of thousands of earthquake records and recommending a desired subset of records that match the target design spectrum with minimal tampering and the least mean square of deviation from the target spectrum.
Abstract: This paper presents a new approach to selection of a set of recorded earthquake ground motions that in combination match a given site-specific design spectrum with minimum alteration. The scaling factors applied to selected ground motions are scalar values within the range specified by the user. As a result, the phase and shape of the response spectra of earthquake ground motions are not tampered with. Contrary to the prevailing scaling methods where a preset number of earthquake records (usually between a single component to seven pairs) are selected first and scaled to match the design spectrum next, the proposed method is capable of searching a set consisting of thousands of earthquake records and recommending a desired subset of records that match the target design spectrum. This task is achieved by using a genetic algorithm (GA), which treats the union of 7 records and corresponding scaling factors as a single ‘‘individual.’’ The first generation of individuals may include a population of, for example, 200 records. Then, through processes that mimic mating, natural selection, and mutation, new generations of individuals are produced and the process continues until an optimum individual (seven pairs and scaling factors) is obtained. The procedure is fast and reliable and results in records that match the target spectrum with minimal tampering and the least mean square of deviation from the target spectrum. [DOI: 10.1193/1.1719028]

189 citations


Journal ArticleDOI
TL;DR: In this article, optical satellite images with 1-m ground resolution such as IKONOS were used for rapid post-disaster damage assessment over large areas, which could be of great value.
Abstract: Newly available optical satellite images with 1-m ground resolution such as IKONOS mean that rapid postdisaster damage assessment might be made over large areas. Such surveys could be of great valu...

158 citations


Journal ArticleDOI
TL;DR: In this paper, the authors evaluated the performance of the Modal Pushover Analysis (MPA) procedure against the nonlinear response history analysis (RHA) and investigated the accuracy of seismic demands determined by pushover analysis using FEMA-356 force distributions; the MPA procedure contained several improvements over the original version presented in Chopra and Goel (2002).
Abstract: This paper comprehensively evaluates the Modal Pushover Analysis (MPA) procedure against the ‘‘exact’’ nonlinear response history analysis (RHA) and investigates the accuracy of seismic demands determined by pushover analysis using FEMA-356 force distributions; the MPA procedure in this paper contains several improvements over the original version presented in Chopra and Goel (2002). Seismic demands are computed for six buildings, each analyzed for 20 ground motions. It is demonstrated that with increasing number of ‘‘modes’’ included, the height-wise distribution of story drifts and plastic rotations estimated by MPA becomes generally similar to trends noted from nonlinear RHA. The additional bias and dispersion introduced by neglecting ‘‘modal’’ coupling and P-D effects due to gravity loads in MPA procedure is small unless the building is deformed far into the inelastic range with significant degradation in lateral capacity. A comparison of the seismic demands computed by FEMA-356 NSP and nonlinear RHA showed that FEMA-356 lateral force distributions lead to gross underestimation of story drifts and completely fail to identify plastic rotations in upper stories compared to the values from the nonlinear RHA. The ‘‘Uniform’’ force distribution in FEMA-356 NSP seems unnecessary because it grossly overestimates drifts and plastic rotations in lower stories and grossly underestimates them in upper stories. The MPA procedure resulted in estimates of demand that were much better than from FEMA force distributions over a wide range of responses—from essentially elastic response of Boston buildings to strongly inelastic response of Los Angeles buildings. However, pushover analysis procedures cannot be expected to provide satisfactory estimates of seismic demands for buildings deforming far into the inelastic range with significant degradation of the lateral capacity; for such cases, nonlinear RHA becomes necessary. [DOI: 10.1193/1.1646390]

151 citations


Journal ArticleDOI
TL;DR: In this paper, the authors derived analytical expressions for the displacement waveforms that provide satisfactory fits to the observations and demonstrated that the moment magnitude and distance control the shape of the displacement response spectra consistent with the commonly accepted models of the seismic source.
Abstract: Using selected sets of high-quality digital strong motion data from different regions (Taiwan, Japan, Italy, and Greece), the salient features of displacement response spectra in the long-period range are illustrated (up to 10 s period) as a function of magnitude, source distance, and site conditions. By means of simple analytical models of displacement waveforms, we have derived analytical expressions for the displacement spectra that provide satisfactory fits to the observations. These expressions also demonstrate that the moment magnitude and distance control the shape of the spectra consistent with the commonly accepted models of the seismic source. Furthermore, we derived from simple physical considerations an analytical expression of the variation of peak ground displacement with magnitude and distance that reasonably fits the observations. The findings of this study are believed to be particularly useful in the formulation of design elastic displacement spectra for seismic codes, and in zoning studies of seismic hazard for long-period structures. [DOI: 10.1193/1.1707022]

148 citations


Journal ArticleDOI
TL;DR: In this article, the authors describe a methodology used to assess seismic damage in the churches of Umbria and the Marches, which is based on 18 indicators, each representative of a possible collapse mechanism for a macroelement.
Abstract: This paper describes a new methodology used to assess seismic damage in the churches of Umbria and the Marches, which is based on 18 indicators, each representative of a possible collapse mechanism for a macroelement. The subdivision of the church into macroelements consists of the identification of architectonic elements in which the seismic behavior is almost independent from the rest of the structure (fac¸ade, apse, dome, bell tower, etc.). For each macroelement, by considering its typology and connection to the rest of the church, it is possible to identify the damage modes and the collapse mechanisms. During inspection operations, the surveyors must indicate: (a) the actual macroelements; (b) the damage level; and (c) the vulnerability of the church to that mechanism, related to some specific details of construction. From these data a damage score is defined, which is a number from 0 to 1, obtained as a normalized mean of the damage grades in each mechanism. The analysis of the collected dat...

146 citations


Journal ArticleDOI
TL;DR: A free-field recording of the Denali fault earthquake was obtained by the Alyeska Pipeline Service Company 3 km from the surface rupture of the denali fault as mentioned in this paper, and the recorded ground motion has relatively low peak acceleration (0.36 g) and very high peak velocity (180 cm/s).
Abstract: A free-field recording of the Denali fault earthquake was obtained by the Alyeska Pipeline Service Company 3 km from the surface rupture of the Denali fault. The instrument, part of the monitoring and control system for the trans-Alaska pipeline, was located at Pump Station 10, approximately 85 km east of the epicenter. After correction for the measured instrument response, we recover a seismogram that includes a permanent displacement of 3.0 m. The recorded ground motion has relatively low peak acceleration (0.36 g) and very high peak velocity (180 cm/s). Nonlinear soil response may have reduced the peak acceleration to this 0.36 g value. Accelerations in excess of 0.1 g lasted for 10 s, with the most intense motion occurring during a 1.5-s interval when the rupture passed the site. The low acceleration and high velocity observed near the fault in this earthquake agree with observations from other recent large-magnitude earthquakes. [DOI: 10.1193/1.1778172]

Journal ArticleDOI
TL;DR: In this paper, a benefit-cost analysis methodology is introduced for the comparative evaluation of several seismic retrofitting measures applied to a representative apartment building located in Istanbul, and the analysis is performed probabilistically through the development of fragility curves of the structure in its different retrofitted configurations.
Abstract: In the wake of the 1999 earthquake destruction in Turkey, the urgent need has arisen to evaluate the benefits of loss mitigation measures that could be undertaken to strengthen the existing housing stock. In this study, a benefitcost analysis methodology is introduced for the comparative evaluation of several seismic retrofitting measures applied to a representative apartment building located in Istanbul. The analysis is performed probabilistically through the development of fragility curves of the structure in its different retrofitted configurations. By incorporating the probabilistic seismic hazard for the region, expected direct losses can be estimated for arbitrary time horizons. By establishing realistic cost estimates of the retrofitting schemes and costs of direct losses, one can then estimate the net present value of the various retrofitting measures. The analysis in this work implies that, even when considering only direct losses, all of the retrofitting measures considered are desirable for all but the very shortest time horizons. This conclusion is valid for a wide range of estimates regarding costs of mitigation, discount rates, number of fatalities, and cost of human life. The general methodology developed here for a single building can be extended to an entire region by incorporating additional structural types, soil types, retrofitting measures, more precise space- and time-dependent seismic hazard estimates, etc. It is hoped that this work can serve as a benchmark for more realistic and systematic benefit-cost analyses for earthquake damage mitigation. [DOI: 10.1193/1.1649937]

Journal ArticleDOI
TL;DR: The 2002 M7.9 Denali fault, Alaska, earthquake triggered thousands of landslides, primarily rock falls and rock slides that ranged in volume from rock falls of a few cubic meters to rock avalanches having volumes as great as 15310 6 m 3.
Abstract: The 2002 M7.9 Denali fault, Alaska, earthquake triggered thousands of landslides, primarily rock falls and rock slides, that ranged in volume from rock falls of a few cubic meters to rock avalanches having volumes as great as 15310 6 m 3 . The pattern of landsliding was unusual; the number of slides was less than expected for an earthquake of this magnitude, and the landslides were concentrated in a narrow zone 30-km wide that straddled the fault rupture over its entire 300-km length. The large rock avalanches all clustered along the western third of the rupture zone where acceleration levels and ground-shaking frequencies are thought to have been the highest. Inferences about near-field strong shaking characteristics drawn from the interpretation of the landslide distribution are consistent with results of recent inversion modeling that indicate high-frequency energy generation was greatest in the western part of the fault rupture zone and decreased markedly to the east. [DOI: 10.1193/1.1778173]

Journal ArticleDOI
TL;DR: In this paper, a survey of the specific vulnerability with regard to the different collapse mechanisms that are typical of earthquakes is presented, taking into account, if present, the damage due to historical events as an observed vulnerability.
Abstract: In the context of a seismic prevention strategy, vulnerability analysis has the aim of acquiring knowledge of the buildings in a region, with particular reference to their predisposition to be damaged by an earthquake. The goal may be both at a territorial level, to assess the damage scenario expected after an earthquake of given intensity, and at a detailed level, as a support to the planning of seismic improvement interventions. The latter objective is very important for ancient churches, due to their architectural and historical value. They definitely need a more profound analysis. The survey with the new form proposed in Part I of this paper allows us to highlight the specific vulnerability with regard to the different collapse mechanisms that are typical of earthquakes, taking into account, if present, the damage due to historical events as an observed vulnerability.

Journal ArticleDOI
TL;DR: In this paper, an advanced seismic monitoring system for a 24-story building facilitates recording of accelerations and computing displacements and drift ratios in near-real time to measure the earthquake performance of the building.
Abstract: A recently implemented advanced seismic monitoring system for a 24-story building facilitates recording of accelerations and computing displacements and drift ratios in near-real time to measure the earthquake performance of the building. The drift ratio is related to the damage condition of the specific building. This system meets the owner’s needs for rapid quantitative input to assessments and decisions on post-earthquake occupancy. The system is now successfully working and, in absence of strong shaking to date, is producing low-amplitude data in real time for routine analyses and assessment. Studies of such data to date indicate that the configured monitoring system with its building specific software can be a useful tool in rapid assessment of buildings and other structures following an earthquake. Such systems can be used for health monitoring of a building, for assessing performance-based design and analyses procedures, for long-term assessment of structural characteristics, and for long-...

Journal ArticleDOI
TL;DR: In this article, the authors present guidelines for applying the procedure described in Andrus and Stokoe that was developed using suggestions from two workshops and following the general format of the Seed-Idriss simplified procedure.
Abstract: Small-strain shear-wave velocity measurements provide a promising approach to liquefaction potential evaluation. In some cases, where only seismic measurements are possible, it may be the only alternative to the penetration-based approach. Various investigators have developed relationships between shear wave velocity and liquefaction resistance. Successful application of any liquefaction evaluation method requires that procedures used in their development also be used in their application. This paper presents detailed guidelines for applying the procedure described in Andrus and Stokoe that was developed using suggestions from two workshops and following the general format of the Seed-Idriss simplified procedure. Correction factors to velocity and liquefaction resistance for soil aging are suggested. Based on the work by Juang et. al., factors of safety of 1.0, 1.2, and 1.5 correspond to probabilities of liquefaction of about 0.26, 0.16, and 0.08, respectively. Additional field performance data a...

Journal ArticleDOI
TL;DR: In this article, a data set created from a suite of 112 strong ground motion records from 57 earthquakes that occurred between 1976 and 2003 has been used to develop horizontal attenuation relationships for Turkey.
Abstract: The current spectral shapes in the Turkish Seismic Code (TSC) are based on broadly described geological conditions, ignoring fault distance or magnitude dependencies on spectral ordinates. To address this deficiency, a data set created from a suite of 112 strong ground motion records from 57 earthquakes that occurred between 1976 and 2003 has been used to develop horizontal attenuation relationships for Turkey. This way it is possible to construct hazard-consistent design spectra for any national seismic region. The results are compared with the site-dependent spectral shapes of the Uniform Building Code (UBC) and the current TSC. It is shown that corner periods are consistent with those of UBC. TSC yields wider constant spectral acceleration plateau. Design spectra in both of these documents are conservative if the ground motion library that we used in deriving the spectral shapes is taken as representative. The results of this study enable site-distance‐magnitudespecific design spectra suitable as a tool both for deterministic (scenario earthquakes) and probabilistic seismic hazard assessments. [DOI: 10.1193/1.1812555]

Journal ArticleDOI
TL;DR: In this paper, the inelastic seismic response of bridge and viaduct structures supported on extended cast-in-drilled-hole (CIDH) pile shafts was evaluated.
Abstract: Nonlinear static and dynamic analyses were used to evaluate the inelastic seismic response of bridge and viaduct structures supported on extended cast-in-drilled-hole (CIDH) pile shafts. The nonlinear dynamic analyses used a beam-on-nonlinear-Winkler foundation (BNWF) framework to model the soil-pile interaction, nonlinear fiber beam-column elements to model the reinforced concrete sections, and one-dimensional site response analyses for the free-field soil profile response. The study included consideration of ground motion characteristics, site response, lateral soil resistance, structural parameters, geometric nonlinearity (P-Δ effects), and performance measures. Results described herein focus on how the ground motion characteristics and variations in structural configurations affect the performance measures important for evaluating the inelastic seismic response of these structures. Presented results focus on a representative dense soil profile and thus are not widely applicable to dramaticall...

Journal ArticleDOI
TL;DR: In this article, the authors present results of an extensive survey of damage resulting from recent Italian seismic events (with particular reference to the Molise earthquake), evaluating the effectiveness and applicability of some retrofitting methods in the hope that these findings will be taken into account in technical codes.
Abstract: The 2002 Molise, Italy, earthquake sequence shocked the Italian public because it killed school children, but it also highlighted the fact that seismic vulnerability of historic masonry buildings has increased because of reinforcement work that has been done in the last 50 years. Replacing the original wooden roof structure with new reinforced concrete or steel elements, inserting reinforced concrete tie-beams in the masonry and new reinforced concrete floors, and using reinforced concrete jacketing on the shear walls are all widely used interventions. However, they lead to increased seismic force (because of greater weight) and to deformations incompatible with the masonry walls. The authors present results of an extensive survey of damage resulting from recent Italian seismic events (with particular reference to the Molise earthquake). We evaluate the effectiveness and applicability of some retrofitting methods in the hope that these findings will be taken into account in technical codes.

Journal ArticleDOI
TL;DR: In this paper, a fragility relation for buried segmented pipe subject to either the wave propagation or permanent ground deformation (PGD) hazard is presented, and it is shown that differences in estimated wave propagation repair rates become much smaller when the seismic shaking is characterized by ground strain as opposed to Vmax.
Abstract: A fragility relation for buried segmented pipe subject to either the wave propagation or permanent ground deformation (PGD) hazard is presented. In the past, relations to estimate wave propagation damage to buried segmented pipe frequently use peak particle velocity (Vmax) to characterize the seismic hazard. For example, in 1993, O’Rourke and Ayala developed an empirical relation between damage (quantified by repairs per kilometer of pipe) and Vmax using data from four U.S. and two Mexican events. Existing fragility relations for PGD typically characterize the hazard by the amount of permanent ground movement. It is shown herein that for statistically reliable data, differences in estimated wave propagation repair rates become much smaller when the seismic shaking is characterized by ground strain as opposed to Vmax. Furthermore, damage rates for PGD are shown to be consistent with those for wave propagation when the PGD hazard is similarly characterized by ground strain. The combined wave propag...

Journal ArticleDOI
TL;DR: The Mattinata fault as discussed by the authors is a major active strike-slip feature cutting across the Gargano promontory, with east-west structures known beneath the axial part of the Apennines.
Abstract: Two Mw 5.7 earthquakes struck a sparsely populated region of southern Italy, on October 31 and November 1, triggering a swarm-like sequence that lasted for several days. The earthquakes were caused by pure right-lateral slip between 10 and 24 km depth over a nearly vertical, previously undetected east-west fault. This mechanism is not typical for southern Italy, where normal faulting in the uppermost 12 km of the crust seems to dominate. However, east-west strike-slip faulting is kinematically consistent with the widely documented Apennines extension. The earthquake-causative fault appears to connect the Mattinata fault, a major active strike-slip feature cutting across the Gargano promontory, with east-west structures known beneath the axial part of the Apennines. The 2002 earthquakes thus highlighted a mode of earthquake release that may explain several large yet poorly understood historical earthquakes (e.g., 1361, 1456, 1731, 1930) located between the crest of the Apennines and the Adriatic coastline. [DOI: 10.1193/1.1756136]

Journal ArticleDOI
TL;DR: In this paper, the authors examined seismic risk from the commercial real estate investor's viewpoint and presented a methodology to estimate the uncertain net asset value (NAV) of an investment opportunity considering market risk and seismic risk.
Abstract: We examine seismic risk from the commercial real estate investor's viewpoint. We present a methodology to estimate the uncertain net asset value (NAV) of an investment opportunity considering market risk and seismic risk. For seismic risk, we employ a performance-based earthquake engineering methodology called assembly-based vulnerability (ABV). For market risk, we use evidence of volatility of return on investment in the United States. We find that uncertainty in NAV can be significant compared with investors' risk tolerance, making it appropriate to adopt a decision-analysis approach to the investment decision, in which one optimizes certainty equivalent, CE, as opposed to NAV. Uncertainty in market value appears greatly to exceed uncertainty in earthquake repair costs. Consequently, CE is sensitive to the mean value of earthquake repair costs but not to its variance. Thus, to a real estate investor, seismic risk matters only in the mean, at least for the demonstration buildings examined here.

Journal ArticleDOI
TL;DR: The 2002 Molise, Italy, earthquake struck a relatively limited geographical area where the communities were mainly agrarian as discussed by the authors. While most buildings in the region are masonry, there are significant dif...
Abstract: The 2002 Molise, Italy, earthquake struck a relatively limited geographical area where the communities are mainly agrarian. While most buildings in the region are masonry, there are significant dif...

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a simple evaluation method based on engineering models of the building structures suitable for the evaluation of a larger number of buildings, based on a nonlinear static approach acknowledging the importance of the nonlinear deformation capacity of the buildings subjected to seismic action.
Abstract: In order to assess the seismic risk for Switzerland, and particularly for the city of Basel, the seismic vulnerability of the existing buildings needs to be evaluated. Since no major damaging earthquake has occurred in Switzerland in recent times, vulnerability functions from observed damage patterns are not available. A simple evaluation method based on engineering models of the building structures suitable for the evaluation of a larger number of buildings is therefore proposed. The method is based on a nonlinear static approach acknowledging the importance of the nonlinear deformation capacity of the buildings subjected to seismic action. Eighty-seven residential buildings in a small target area in Basel were evaluated. The results are vulnerability functions that express the expected damage as a function of the spectral displacement. In order to extrapolate the results to other residential areas of the town, building classes were defined for which the vulnerability is presented in a probabili...

Journal ArticleDOI
TL;DR: In this paper, the authors inspected approximately 300 primary and secondary schools in 87 municipalities of Molise and found that about 40% were masonry structures, 40% reinforced concrete (RC) frame structures, and the remaining 20% were a variety of structures Almost all of them were built without seismic criteria and most had no more than three stories.
Abstract: The authors inspected approximately 300 primary and secondary schools in 87 municipalities of Molise About 40% were masonry structures, 40% were reinforced concrete (RC) frame structures, and the remaining 20% were a variety of structures Almost all of them were built without seismic criteria and most had no more than three stories In this paper we compare the distribution of the damage with the vulnerability classes The collapses in San Giuliano di Puglia highlight the comparative vulnerabilities related to structural types, construction phases, and location

Journal ArticleDOI
TL;DR: It is shown that market risk overwhelms uncertainty in seismic risk, allowing one to consider only expected consequences in seismicrisk, and present a simple decision-analysis framework for real-estate investments in seismic regions, accounting for risk aversion.
Abstract: A seismic risk assessment is often performed on behalf of a buyer of commercial buildings in seismically active regions. One outcome of the assessment is that a probable maximum loss (PML) is computed. PML is of limited use to real-estate investors as it has no place in a standard financial analysis and reflects too long a planning period. We introduce an alternative to PML called probable frequent loss (PFL), defined as the mean loss resulting from shaking with 10% exceedance probability in 5 years. PFL is approximately related to expected annualized loss (EAL) through a site economic hazard coefficient (H) introduced here. PFL and EAL offer three advantages over PML: (1) meaningful planning period; (2) applicability in financial analysis (making seismic risk a potential market force); and (3) can be estimated using a single linear structural analysis, via a simplified method called linear assembly-based vulnerability (LABV) that is presented in this work. We also present a simple decision-analysis framework for real-estate investments in seismic regions, accounting for risk aversion. We show that market risk overwhelms uncertainty in seismic risk, allowing one to consider only expected consequences in seismic risk. We illustrate using 15 buildings, including a 7-story nonductile reinforced-concrete moment-frame building in Van Nuys, California, and 14 buildings from the CUREE-Caltech Woodframe Project. [DOI: 10.1193/1.1809129]

Journal ArticleDOI
TL;DR: In this article, a set of empirical attenuation relationships was derived for predicting vertical peak and pseudo-absolute vertical acceleration spectral ordinates in terms of magnitude, source-to-site distance, and local geological conditions.
Abstract: In the aftermath of two destructive urban earthquakes in 1999 in Turkey, empirical models of strong motion attenuation relationships that have been previously developed for North American and European earthquakes have been utilized in a number of national seismic hazard studies. However, comparison of empirical evidence and estimates present significant differences. For that reason, a data set created from a suite of 100 vertical strong ground motion records from 47 national earthquakes that occurred between 1976 and 2002 has been used to develop attenuation relationships for strong ground motion in Turkey. A consistent set of empirical attenuation relationships was derived for predicting vertical peak and pseudo-absolute vertical acceleration spectral ordinates in terms of magnitude, source-to-site distance, and local geological conditions. The study manifests the strong dependence of vertical to horizontal (V/H) acceleration ratio on spectral periods and relatively weaker dependence on site geo...

Journal ArticleDOI
TL;DR: In this paper, six one-third-scale CIDH pile shafts were tested to simulate the subgrade moment pattern in an in situ pile shaft and three levels of transverse reinforcement were tested.
Abstract: Six one-third-scale CIDH pile shafts were tested to simulate the subgrade moment pattern in an in situ pile shaft. The test fixture could also simulate the presence of external confinement provided by soil. Three levels of transverse reinforcement were tested. Three piles were tested with external confinement, and three without. The presence of external confinement played a significant role in enhancing flexural ductility by supporting the confining action of the transverse steel reinforcement. The presence of external confinement also increased the plastic hinge length, significantly reducing local curvature demand by allowing the hinge rotation requirements to be spread over a greater length of the pile shaft. In the absence of external confinement, the transverse reinforcement levels specified under current column design guidelines provided adequate flexural ductility for seismic response. [DOI: 10.1193/1.1647579]

Journal ArticleDOI
TL;DR: The authors in this paper summarized the effects of the 2002 Molise earthquake and highlighted the findings of ongoing studies of the technical and social lessons afforded by the disaster, highlighting the technical sophistication and abundant government resources that have been applied.
Abstract: On October 31 and November 1, 2002, two magnitude Mw 5.7 earthquakes struck the rural Molise region in southeastern Italy killing 30 people, 27 of whom were children trapped in the collapse of an elementary school. This paper summarizes the earthquake’s effects and, as the introductory paper to Spectra’s special issue on the Molise event, highlights the findings of ongoing studies of the technical and social lessons afforded by the disaster. In 1998 the area was declared a medium seismicity zone, but an administrative delay in updating the seismic zonation meant that up until the time of the earthquake, there were no seismic requirements for new construction—construction that included a 2002 second-story addition to the school that collapsed. The emergency response and recovery planning following the earthquake were notable for the technical sophistication and abundant government resources that have been applied, including the building of a prefabricated temporary village.

Journal ArticleDOI
TL;DR: The most frequent type of damage affected the infill masonry walls, but in some cases cracks in concrete columns were observed as discussed by the authors, and heavy damage to both infills and structural elements was restricted to a few cases in the meizoseismal area.
Abstract: About 10% of the almost 20,000 buildings damaged by the 2002 Molise, Italy, seismic sequence were reinforced concrete (RC). The most frequent type of damage affected the infill masonry walls, but in some cases cracks in concrete columns were observed. Heavy damage to both infills and structural elements was restricted to a few cases in the meizoseismal area. Almost all the affected municipalities were only classified as seismic in May 2003, following this earthquake. Consequently, construction generally used verticalload-bearing moment-resisting frames with no explicit design for seismic lateral forces. In particular, the reinforced concrete buildings typically consist of cast-in-place unidirectional RC slabs lightened with hollow clay tiles, supported by RC beams and columns. Usually no shear walls are present, except in some cases for the elevator shaft. This paper covers: a) an overview and statistical analysis of damage to RC buildings, and b) a detailed analysis of two damaged buildings. [DOI: 10.1193/1.1765107] DAMAGE TO RC BUILDINGS The poor performance of the few severely damaged buildings could have resulted from either a higher-than-average vulnerability, or a higher-than-expected level of ground motion for a magnitude and epicentral distance, or a combination of both factors. These buildings are representative of a broad class of RC buildings built without seismic provisions that are common in Italy and other earthquake-prone countries. DAMAGED BUILDINGS IN SAN GIULIANO DI PUGLIA Four RC buildings in San Giuliano suffered heavy damage. (See Table 2 and discussion in following section for number of buildings inspected and damage index.) The first case was a building with five levels: a basement (garage) that acts also as a soil-retaining wall; the unfinished ground floor; the second and third story (dwellings); and the fourth story under an inclined roof (Figures 1 and 2). The building has an irregular plan consisting of three rectangular parts (called B1, B2 and B3 in Figure 3), rotated and connected without joints.