Search

The transportation agencies are experiencing numerous challenges in endorsing resilient bridge infrastructure against natural disasters such as earthquakes, floods, and hurricanes. Therefore, assessing bridge infrastructure resiliency against a seismic hazard is critical to improve the bridge's endurance and effective recovery. In this study, assessment of bridge infrastructure resilience against the seismic hazard is performed using Bayesian best–worst method (BWM). Based on a literature review, 15 resilience parameters were identified for bridge infrastructure resiliency against seismic hazard under two primary aspects, namely reliability and recovery. The Bayesian BWM was used to calculate the weight of the seismic resilience variables based on the experts' judgment. Finally, a bridge resiliency index was developed to determine the weights of the parameters. To demonstrate the applicability of the proposed model, the infrastructure resiliency against the seismic hazard of a bridge located in Vancouver Island, British Columbia, Canada is assessed using two sets of data from two different sources. It is mentionable that the resiliency index was close for both of the data sets. The outcome of this study is that the model for determining bridge resiliency index will assist the bridge engineer and policymakers make effective decisions in the face of future seismic danger. [ABSTRACT FROM AUTHOR]

The article presents a study which assessed the seismic performance of plate-shell integrated concrete liquid-storage structures (PSICLSS) using a scale test model for shaking table testing. The dynamic responses of the PSICLSS under unidirectional and bidirectional earthquakes were tested. Among the data collected are the hydrodynamic pressure, liquid sloshing height, and residual displacement of the PSICLSS.

The article discusses the proposed elicitation process that can be utilized to quantify the effectiveness of Bayesian networks in the probabilistic failure analysis of complex structures like bridges and dams. Also cited are a real-life study using the networks to analyze the safety of the Mountain Chute Dam and Generating Station in Ontario, and the possible reasons behind a dam's failure like excessive loads due to unexpected flood events.

Seismic base isolation technique has been successfully used to protect structural as well as nonstructural components from the damaging effects of earthquakes by reducing floor accelerations and inter-story drifts for many decades. The level of floor acceleration is a key issue in the protection of acceleration-sensitive nonstructural components. The intensity of floor acceleration varies depending on the vibration characteristics of the structural system. Furthermore, the viscous damping devices sometimes are used to improve the performance of the superstructure as well as the base isolation system. The characteristics of the ground motions are also influential in the performance of the viscous damping devices. In this paper, the floor acceleration performance of seismically isolated buildings with different lateral load resisting systems such as moment resisting frame, dual system, moment resisting frame plus viscous wall dampers, and dual system plus viscous wall dampers is investigated under near-fault and far-fault earthquake ground motions. Moreover, the effectiveness of supplemental viscous damping devices equipped in parallel with lead-rubber-bearing isolators is studied. It is inferred from the study that the most effective way of reducing floor accelerations is to provide more rigidity to the superstructure. Utilizing supplemental viscous dampers along with lead-rubber-bearing isolators having about 20% of effective damping ratio is meaningless or harmful in relation to floor acceleration and base shear. [ABSTRACT FROM AUTHOR]

The National Research Council of Canada (NRC) has recently developed a Semi-Quantitative Seismic Risk Screening Tool (SQST) to supersede the 1993 NRC Manual for Screening of Buildings for Seismic Investigation. The proposed screening tool incorporates a methodology for estimating global seismic risk of existing buildings associated with failure of their non-structural components. The methodology assesses global seismic risk using a qualitative yet comprehensive scoring system. The scoring system consists of a global non-structural component score and acceptable threshold scores. The global score is based on the most critical components. It combines a basic score with score modifiers for key parameters affecting the seismic response of non-structural components. The acceptable threshold score is based on the building's consequence of failure, the building's importance category, and the component factor. The scoring system is calibrated to be consistent with the seismic risk acceptance criteria previously developed for preliminary seismic risk screening of existing buildings, based on Canadian seismicity, building age, remaining occupancy time, and consequences of failure. [ABSTRACT FROM AUTHOR]

The dynamic properties of Parliament Hill's buildings (Ottawa, Canada) are of particular interest due to their important heritage value and because of the seismic retrofit project currently underway. To measure the dynamic properties directly, ambient vibration data were collected within the Peace Tower of Centre Block and the South-West Tower of East Block and processed together with weak to strong ground motions from six earthquakes. Both datasets found the fundamental mode to be 1.0–1.15 Hz for the Peace Tower and 2 Hz for the South-West Tower. The 2010 magnitude 5 Val-des-Bois earthquake induced peak accelerations of 49% g and 18% g in the top floors of the Peace and South-West towers, respectively, triggering a nonlinear response, causing the frequencies of the dominant modes to be reduced by 10%–15%. The reduction in frequency was temporary and the frequencies returned to baseline values, suggesting that there was no permanent structural damage. [ABSTRACT FROM AUTHOR]

Damage to unreinforced masonry (URM) buildings from earthquake shaking is often caused by out-of-plane failure of walls. This is particularly relevant to the majority of URM buildings in Eastern Canada that were constructed prior to the introduction of seismic design prescriptions. Seismic vulnerability assessment of this type of failure is therefore an essential step towards seismic risk mitigation. This paper presents a simplified procedure for seismic vulnerability assessment of out-of-plane failure of URM wall buildings. The procedure includes the development of an equivalent single degree of freedom model of the wall with a characteristic force-deformation capacity curve. The capacity curve is convolved with displacement response spectrum to predict the displacement demand. The predicted displacement demand is compared to displacement thresholds criteria corresponding to the initiation of each damage state. The procedure is applied to an inventory of URM buildings in Montreal and the corresponding probability of out-of-plane damage is evaluated. [ABSTRACT FROM AUTHOR]

Site amplification effects in southern Ontario are highly variable and strongly influence felt effects and damage potential. Site parameters such as shear-wave velocity in the top 30 metres of soil ( VS30), traditionally used to estimate site amplification, are not well known in this region. Thus, regional maps of shaking potential and seismic hazard are often overgeneralized. In this study, a site amplification model based on peak frequency ( fpeak) is compared to one based on VS30, as given by the 2015 National Building Code of Canada (NBCC). Earthquakes and scenario events are used to estimate ground motions and shaking intensities. It is shown that both models generally predict similar felt intensities but show significant differences in their predicted amplification of ground motions as a function of frequency. The results of this study support the use of fpeak as a site response variable for estimating amplification effects in southern Ontario. [ABSTRACT FROM AUTHOR]

This paper presents a sensitivity analysis of the hierarchical decomposition of networks in the context of seismic vulnerability of power systems. The sensitivity analysis is evaluated by varying the fragility curves and clustering algorithms on the vulnerability measure. For the fragility curves, four different curves are used. For sensitivity to clustering, four representative spectral clustering algorithms are used: SM, KVV, NJW, and Meila-Shi algorithms. The resulting vulnerability rankings are compared for a common case study (IEEE-118 test case) in terms of: correlation, identification of critical nodes, and identification of common clusters. The results show the robustness of the methodology with respect to variation of the fragility curves. On the other hand, the selection of the clustering algorithm is found to be a decisive parameter depending on application. If the application requires identification of critical elements a better performance is found. [ABSTRACT FROM AUTHOR]

The site amplification factors in the 2015 edition of the National Building Code of Canada (NBCC 2015) for South Western British Columbia (SWBC) were developed using only the single site term associated with the ground motion prediction equation (GMPE) for crustal sources. The seismic hazard in SWBC is derived from three source types; crustal, subduction intraplate, and subduction interface sources. Therefore site factors based only on a crustal site term are approximate. This study was conducted to assess the degree of approximation. Alternative site amplification factors for Vancouver and Victoria, British Columbia were calculated using site specific look-up tables incorporating all the GMPEs associated with each seismic source type and their associated site terms. The alternative site factors are significantly greater than those given in NBCC 2015 for periods 0.3 s, 0.5 s, and 1.0 s. These results suggest that the process for calculating site amplification factors should be reassessed by the committee currently reviewing seismic hazard for NBCC 2020. [ABSTRACT FROM AUTHOR]

Fragility curves have proved to be an efficient tool for the seismic vulnerability assessment of buildings made of stone masonry such as those located in historic districts of Eastern Canadian cities. However, most studies do not take into consideration the case of collapse in the out-of-plane direction. This failure mode may be critical for elements such as chimneys, firewalls, and front walls. This study focuses on the assessment of seismic vulnerability of stone masonry buildings sensitive to out-ofplane failure. A model of out-of-plane capacity showing the degree of damage in terms of displacements was developed as well as a calculation method for displacements in the out-of-plane direction taking into account the filter effect of the building in plane direction. Fragility curves derived are used to estimate the probability of damage in different seismic scenarios. [ABSTRACT FROM AUTHOR]

This paper provides a summary of the evolution of the Canadian seismic design provisions for operational and functional components in buildings. The evolution of horizontal seismic force and displacement requirements in the National Building Code of Canada is presented and significant changes and parameters are discussed. Numerical examples illustrate the seismic design force levels as stipulated in recent editions of the NBCC for architectural, mechanical and electrical components attached at different elevations to buildings located in moderate and high seismic zones in Canada. Also, the seismic design force levels, computed according to different editions of the NBCC, are compared for a mechanical component and for an architectural component attached to buildings located in Vancouver. [ABSTRACT FROM AUTHOR]

The last version of the National Building Code of Canada was issued in 2010. The next version will be issued in 2015. In the code cycle between 2010 and 2015 significant changes have taken place in the seismic design provision. The main factor that drives these changes is an improved understanding of the seismic hazard across the country. Changes have also been introduced in the site effect factors. The structural design provisions have been appropriately adjusted to respond to changes in the estimates of hazard and the new site effect factors. There are also new provisions related to design in regions of low hazard, buildings with flexible diaphragms, buildings with inclined columns, passive energy dissipation systems, base isolation, rocking foundations, glazing systems, racks, and elevators. Some of the changes are briefly discussed. The main focus of the paper is, however, on the revisions to the structural design provisions. [ABSTRACT FROM AUTHOR]

Montreal has significant seismic risk due to the combination of moderate seismicity, high population density, and vulnerable infrastructure. An important tool in damage and risk assessment is a scenario shakemap, which shows the expected ground shaking intensity distribution patterns. In this study, we use regional ground motion and site response evaluations to generate scenario shakemaps for Montreal. The impact of event location on expected ground motions and intensities was tested by considering the occurrence of a scenario (a given magnitude event) at various locations, where the scenarios are defined based on an analysis of the most likely future event locations. Variability in near surface geology plays an important role in earthquake ground shaking; we use microzonation information from Montreal to assess the expected site amplification effects. The results of this study may be used as input to seismic risk studies for Montreal. [ABSTRACT FROM AUTHOR]

An existing eight-storey reinforced concrete shear wall building located in Montreal is studied to evaluate the impact of applying a conditional mean spectrum (CMS) in lieu of the conventional uniform hazard spectrum (UHS) to the seismic evaluation of such structures. The construction of the CMS is reviewed and adapted to take account of seismic hazard in Montreal. The developed CMS and their envelopes were used to conduct modal response spectrum analyses of the building and the results are compared to those obtained from the NBCC 2005 UHS. Justifications of similarities or differences between CMS- and UHS-based results are illustrated throughout the paper. [ABSTRACT FROM AUTHOR]

This paper presents the effectiveness of seven ground motion scaling methods and two spectral matching methods to achieve compatibility with the Canadian National Building Code (CNBC) 2005 uniform hazard spectrum for Montreal to perform nonlinear seismic analysis. Databases of 30 historical records and 30 Eastern North America simulated records have been selected to compute the reference mean seismic demand and its dispersion. The characteristics and destructive capacity of ground motions have been studied using a large number of indices computed from ( i) the records themselves, ( ii) a series of single degree of freedom structures, as well as ( iii) a four-story steel frame. Record scaling methods to the target spectrum using ( i) spectral intensity, ( ii) reducing the mean square error, ( iii) and minimizing dispersion as well as time domain spectral matching generated coherent seismic demand and dispersion in agreement with the reference values. Spectral matching to a specified elastic design spectrum does not reduce the dispersion of the nonlinear response. Therefore close spectral matching cannot be used to reduce the number of records to minimize the resources allocated in seismic safety assessment. At least seven records, as recommended in current CNBC and FEMA (2012) guidelines to compute an average response, should be used to characterize the nonlinear behaviour of structural systems. [ABSTRACT FROM AUTHOR]

Ground-motion prediction equations (GMPEs) and their epistemic uncertainty are a key input to seismic hazard assessments, because the GMPEs specify the expected ground-shaking amplitudes as a function of magnitude and distance. We describe a simple and efficient approach to the definition of GMPEs and their epistemic uncertainty for use in seismic hazard mapping in Canada. The approach defines a lower, central, and upper GMPE for each type of event (eastern crustal, western crustal, interface, inslab, offshore) that contributes to the hazard, by considering alternative published GMPEs and data that may be used to constrain these model choices. The proposed model is being applied in trial seismic hazard maps for Canada, for consideration in the 2015 edition of the National Building Code of Canada. [ABSTRACT FROM AUTHOR]

The paper presents observed damage in reinforced concrete buildings during the 27 February 2010 Maule earthquake in Chile. Performance of concrete frame and shear wall buildings are discussed with emphasis on seismic deficiencies in design and construction practices. It is shown that the majority of structural damage in multistorey and high-rise buildings can be attributed to poor performance of slender shear walls, without confined boundary elements, suffering from crushing of concrete and buckling of vertical wall reinforcement. Use of irregular buildings, lack of seismic detailing, and the interference of nonstructural elements were commonly observed seismic deficiencies. A comparison is made between Chilean and Canadian design practices with references made to the applicable code clauses. Lessons are drawn from the observed structural performance. [ABSTRACT FROM AUTHOR]

The seismic performance of a typical 1960s Type 2 construction steel moment-resisting frame hospital structure designed only for lateral wind loads was investigated. The structure was found to have a soft first storey and displayed large P-Δ sensitivities. An experimental program determined that the connections had considerable inherent ductility and were stable up to 2.0% interstorey drift, despite not having been designed for a ductile cyclic response. The structure was numerically modelled using advanced strength degradation considerations. A nonlinear time-history analysis was conducted using Montreal and Vancouver ground motions and the structure's performance was found to be inadequate under the considered design hazard levels. Retrofits were proposed for the two orthogonal frames using a performance-based approach and supplemental damping, rather than local interventions to increase the ductility of these connections, and the performance of the final retrofit designs were investigated numerically to confirm that the desired performance levels were achieved. [ABSTRACT FROM AUTHOR]

Seismic screening software is developed for existing buildings in Canada on the basis of the requirements of 2010 National Building Code of Canada. The software is based on the 'Manual for Screening of Buildings for Seismic Investigation,' published by the National Research Council of Canada in 1992. The new software incorporates updated seismicity and soil classifications used in the National Building Code of Canada (NBCC) since 2005, as well as the new ductility and over-strength factors specified in the 2010 NBCC. The uniform hazard spectrum values of the current Canadian seismicity, defined for each municipality in Canada with a 2500 year earthquake return period, are used as reference hazard values. Seismic risk associated with the use of older seismic hazard values specified in older editions of the NBCC is identified relative to the current reference seismicity. The new site classifications are incorporated, while establishing relative soil amplification values between the new acceleration-based and velocity-based soil amplification factors and the foundation factors used in older codes. The new ductility and over-strength factors used in recent editions of the code are introduced in identifying different structural types with different toughness and energy dissipation capacities. The software can be used to conduct seismic screening of buildings located in different municipalities in Canada relative to the seismic requirements of NBCC-2010. It can also be used to generate tables for different locations in the country for manual screening of buildings. [ABSTRACT FROM AUTHOR]

Effects of the ground motion record orientation on the estimated pseudo-spectral acceleration (PSA) have been investigated and reported in the literature; the statistics of the PSA along the major and minor principal axes differ from that for a random orientation. This is true for California as well as for Mexican records. However, a statistical assessment of the effect of record orientation on the displacement ductility demand is lacking. Such an assessment could be important for gaining confidence in and understanding of using the ductility demand rules for seismic hazard and risk evaluations. The statistical analyses of the effect of orientation on the estimated displacement ductility demand for elastic-perfectly-plastic and bilinear hysteretic (single degree of freedom) systems is carried out in the present study using sets of records from Mexican inslab and interplate earthquakes, and California earthquakes. Based on the obtained statistics, it is suggested that the consideration that the ductility demand is independent of the orientation of the records can be adequate, especially for Tn greater than 0.3 s and elastic-perfectly-plastic hysteretic single degree of freedom systems. [ABSTRACT FROM AUTHOR]

Uncertainty in the ground-motion amplitudes that will be realized from earthquakes at a given magnitude and distance plays a critical role in seismic hazard analysis. Examination of ground-motion variability from an empirical perspective can be used to characterize its epistemic and aleatory components, which are implicitly coupled, in a self-consistent manner that minimizes 'double-counting' of uncertainty. This study empirically evaluates both components of uncertainty for shallow crustal earthquakes in active tectonic regions as deduced from the NGA (Next Generation Attenuation) database. The epistemic component of uncertainty, which I argue should include all inter-event variability, is estimated to be about 0.2 log(10) units near the source, and grows with increasing distance; the growth with distance may be due to regional attenuation variability, but may also be partly due to the relative paucity of near-source observations. The aleatory component (commonly referred to as 'sigma'), which I argue should include only the intra-event variability for a specific magnitude-distance scenario, is about 0.24 log(10) units at low frequencies, decreasing to about 0.19 log(10) units at high frequencies; sigma is approximately independent of magnitude and distance. The joint consideration of the epistemic and aleatory components of uncertainty, in the context of the underlying database, may be useful in reducing unintended conservatism in computed seismic hazard estimates at low probabilities. In particular, by considering inter-event variability as epistemic in nature, reflecting uncertainty in the stress drop and attenuation for an event, we can reduce the aleatory variability component to just that needed to capture the intra-event variability for a given magnitude-distance scenario. [ABSTRACT FROM AUTHOR]

The seismic response of tubular steel wind turbine towers is of significant concern as they are increasingly being installed in seismic areas and design codes do not clearly address this aspect of design. The seismic hazard is hence assessed for the Canadian seismic environment using implicit finite element analysis and incremental dynamic analysis of a 1.65 MW wind turbine tower. Its behaviour under seismic excitation is evaluated, damage states are defined, and a framework is developed for determining the probability of damage of the tower at varying seismic hazard levels. Results of the implementation of this framework in two Canadian locations are presented herein, where the risk was found to be low for the seismic hazard level prescribed for buildings. However, the design of wind turbine towers is subject to change, and the design spectrum is highly uncertain. Thus, a methodology is outlined to thoroughly investigate the probability of reaching predetermined damage states under any seismic loading conditions for future considerations. La réponse sismique des tours d'éoliennes en tubes d'acier est une question importante puisque ces dernières sont de plus en plus installées dans zones sismiques et que les codes de calculs ne traitent pas clairement de cet aspect de la conception. Les aléas sismiques sont ainsi évalués pour l'environnement sismique canadien en utilisant une analyse implicite par éléments finis et une analyse dynamique incrémentielle pour une tour d'éolienne de 1,65 MW. Son comportement sous une excitation sismique est évalué, les dommages sont définis et un cadre est établi pour déterminer la probabilité de dommages à la tour à différents niveaux d'aléas sismiques. Les résultats de l'implantation de ce cadre en deux endroits au Canada sont présentés, où le risque était faible pour le niveau d'aléas sismiques prescrit pour les bâtiments. Toutefois, la conception des tours d'éoliennes est sujette à changement et la plage de conception est très incertaine. Ainsi, une méthode est présentée afin d'examiner en détail la probabilité d'atteindre des niveaux de dommages prédéterminés sous des conditions de charge sismique possibles dans l'avenir. [ABSTRACT FROM AUTHOR]

This paper describes results from a study on the dynamic behaviour of the Confederation Bridge due to seismic loads. For the purpose of the seismic analysis of the bridge, a finite element model was developed using three-dimensional (3D) beam elements. The model was calibrated using measured data of the bridge vibrations during a dynamic load test. Dynamic analyses were conducted by subjecting the model to selected seismic ground motions representative of the expected motions at the bridge location. The bending moments and displacements obtained from the analyses were used for the seismic evaluation of the bridge. It was found that the seismic effects considered in the design are appropriate for the required safety during the service life of the bridge. Cet article décrit les résultats d’une étude sur le comportement dynamique du Pont de la Confédération lors de charges sismiques. Un modèle par éléments finis utilisant des poutres tridimensionnelles a été développé aux fins de l’analyse sismique du pont. Le modèle a été étalonné en utilisant les données mesurées des vibrations du pont durant un test de charge sismique. Des analyses dynamiques ont été réalisées en soumettant le modèle à des mouvements sismiques du sol choisis représentant les mouvements prévus à l’emplacement du pont. Les moments de flexion et les déplacements obtenus des analyses ont été utilisés pout l’évaluation sismique du pont. Il a été conclu que les effets sismiques utilisés dans la conception sont appropriés pour le niveau de sécurité requis durant la vie du pont. [ABSTRACT FROM AUTHOR]

This study provides a preliminary assessment of the impact of new seismological information on the existing seismic hazard model, as implemented in the 2005 National building code of Canada (NBCC); this seismic hazard model was actually developed in the early 1990s, and thus there is significant new information available in the literature since then. A reassessment of seismic hazard is carried out by updating magnitude-recurrence relations based on the earthquake catalog up to the end of 2006, including conversion of all earthquake magnitudes to a homogenous moment magnitude scale. The recent ground-motion prediction equations, which update the knowledge base used in the 2005 NBCC, are also used. Focusing on Vancouver and Victoria, sensitivity analyses are carried out to investigate both individual and combined impacts of these updates on the uniform hazard spectra. The proposed model can be used as a guide to the direction in which future seismic hazard models for western Canada may move. Cette étude fournit une première évaluation de l’impact de nouvelles informations sismologiques dans le modèle existant de risques sismiques tel qu’implanté dans le Code national du bâtiment du Canada (CNBC). Ce modèle de risques sismiques a été développé au début des années 1990; beaucoup de nouvelles informations sont donc disponibles. Le risque sismique est réévalué par une mise à jour des relations magnitude-récurrence en se basant sur le catalogue des séismes jusqu’à la fin de 2006, incluant la conversion de toutes les magnitudes de séismes en une échelle homogène de magnitude de moment. Les équations récentes de prévision du mouvement du sol, qui mettent à jour la base de connaissances utilisée dans le CNBC 2005, sont également utilisées. Des analyses de sensibilité ciblés sur Vancouver et Victoria ont été réalisées afin d’examiner les impacts individuels et combinés de ces mises à jour sur les spectres de risques uniformes. Le modèle proposé peut être utilisé comme guide des directions possibles des futurs modèles de risques sismiques pour l’Ouest canadien. [ABSTRACT FROM AUTHOR]

Throughout history, objects of art have been damaged and sometimes destroyed in earthquakes. Research was undertaken to investigate the seismic vulnerability of art objects exhibited on display cases, and museum floor motions representative of Montreal seismic hazards were simulated for that purpose. Particular attention was paid to the effects on art object seismic vulnerability of support conditions, modified floor surfaces, sliding and rocking responses of unrestrained display cases, floor elevations, art object mass, and the dynamic properties of the display cases. Seismic vulnerability of art objects was evaluated based on the seismic response of the display cases at the level of art object display. Display cases were investigated experimentally using shake table testing. Floor contact conditions and elevation had a crucial effect on the unrestrained display cases, causing them to slide or rock vigorously. As a result of experimental analysis, recommendations and (or) simple mitigation techniques are provided to reduce the seismic vulnerability of art objects exhibited on these display cases. Au cours de l’histoire, plusieurs objets d’art ont été endommagés ou quelque fois détruits lors de séismes. Une recherche a été entreprise pour examiner la vulnérabilité sismique des objets d’art dans les vitrines d’exposition d’après aléa et risque ont un sens technique different sismique pour Montréal; des mouvements représentatifs des planchers de musée ont été simulés à ces fins. Une attention spéciale a été apportée aux conditions des supports, aux effets des conditions de surface de plancher, à la réaction en glissement et en basculement des vitrines d’exposition non fixées, à l’emplacement (niveau de plancher) des vitrines d’exposition, à la masse des objets d’art ainsi qu’aux propriétés dynamiques des vitrines d’exposition. La vulnérabilité aux effets sismiques des objets d’art a été évaluée en se basant sur la réponse sismique des vitrines d’exposition au niveau de las surface d'exposition des objet d'art. Les vitrines d’exposition ont été testées sur une table de vibration. Les conditions de contact avec le plancher ainsi que le niveau de plancher ont un impact majeur sur les vitrines d’exposition non fixées, les faisant glisser ou bercer vigoureusement. En conclusion, des recommandations et-ou des techniques simples d’atténuation sont fournies afin de réduire la vulnérabilité sismique des objets d’art présentés dans ces vitrines d’exposition. [ABSTRACT FROM AUTHOR]

In the context of the seismic vulnerability evaluation of buildings, the score assignment method can be used as the first step of a multiphase procedure aimed at identifying hazardous buildings that must then be analysed in greater detail. Because the existing Canadian rapid visual screening procedure has not been updated since 1992, a new procedure is proposed based on a set of vulnerability indices for different cities in the province of Quebec. A seismicity level (low, moderate, or high) is attributed to each city using the spectral acceleration response values included in the 2005 edition of National building code of Canada (NBCC) and the criteria proposed in FEMA 310 Handbook for the seismic evaluation of buildings - a prestandard. The structural vulnerability indices (SVIs) are calculated using the recently improved nonlinear static analysis procedure in FEMA 440, Improvement of nonlinear static seismic analysis procedures for each seismicity level. The NBCC 2005 reference soil class C is considered in the calculation of the SVIs, and index modifiers for the building height, irregularities, and design and construction year. The application of these indices to the estimation of the probable damage distribution in building inventories is discussed at the end. Dans un contexte d’évaluation de la vulnérabilité sismique des bâtiments, la méthode d’attribution de pointage peut être utilisée comme première étape d'une procédure à phases multiples pour identifier les bâtiments potentiellement dangereux, et nécessitant une analyse plus détaillée. La méthode canadienne d’évaluation rapide n’ayant pas été mise à jour depuis sa parution en 1992, on présente ici une nouvelle procédure proposant une série d’indices de vulnérabilité sismique pour les différentes villes du Québec. Un niveau de sismicité (faible, modéré ou élevé) est attribué à chaque ville selon les nouvelles valeurs d'accélération spectrale de l’édition 2005 du Code national du bâtiment du Canada (CNBC) et les critères proposés dans FEMA 310 « Handbook for the seismic evaluation of buildings - a prestandard. » Pour chaque niveau de sismicité, des indices de la vulnérabilité structurale (IVS) sont calculés à partir de la procédure améliorée du FEMA 440 « Improvement of nonlinear static seismic analysis procedures » pour l’analyse statique non-linéaire. Le sol de référence, catégorie C, de l’édition 2005 du CNBC, est considéré dans le calcul des IVS et des modificateurs. Ceux-ci considèrent la hauteur du bâtiment, ses irrégularités, les conditions du sol et les années de conception et de construction. L'application de ces indices pour l’estimation de la distribution de dommages probables pour un groupe de bâtiments durant une activité sismique est ensuite discutée. [ABSTRACT FROM AUTHOR]

Fire following an earthquake is an important factor causing damage to buildings and life-line structures. Therefore, besides satisfying structural design requirements for normal loads, such as dead and live loads including the seismic hazard, buildings should also be designed to withstand the fire following earthquakes for a certain minimum duration as required for a desired level of performance. This period of time will allow occupants to evacuate the building safely and the emergency crews to cope with the fire. Also, it is essential to reduce the post-earthquake fire (PEF) ignitions and minimize the damage to active fire protection systems as much as possible to prevent the spread of fire. This paper presents a state-of-the-art review on the PEF hazard and discusses the causes, mitigation measures, and performance of building structures under this hazard. Mitigation measures that could be developed based on the experience from the structural engineering field are identified. Both local and global approaches that should be taken to mitigate the PEF hazard, including structural and nonstructural design, various urban planning aspects, and their interactive combinations, are discussed. Based on the review, it is concluded that that there is a strong need for the development of guidelines for structural fire safety design for PEF scenarios. In addition, appropriate analysis and numerical simulation techniques for the evaluation of the structural performance under earthquake-induced fire conditions need to be developed. It is also necessary to conduct experimental studies to validate such numerical models and refine them. Les incendies suivant un séisme sont une importante cause de dommages aux bâtiments et aux structures vitales. Ainsi, en plus d’être conçus pour répondre aux exigences de conception structurale pour les charges normales telles que les charges permanentes et en mouvement, incluant le risque sismique, les bâtiments devraient être conçus pour résister aux incendies suivant les séismes pour une durée minimale requise par le niveau de rendement désiré. La durée permettra aux occupants d’évacuer le bâtiment en toute sécurité et aux équipes d’urgence de combattre l’incendie. De plus, il est essentiel de réduire l’allumage d’incendies suivant les séismes et, dans la mesure du possible, de minimiser les dommages causés aux systèmes actifs de protection contre les incendies afin de prévenir la propagation de l’incendie. Cet article présente une revue de la technologie récente sur les dangers d’incendies suivant les séismes et analyse les causes, les mesures d’atténuation et le comportement des structures de bâtiments lors de tels dangers. Les mesures d’atténuation qui peuvent être établies en se basant sur l’expérience de l’ingénierie des structures sont identifiées. Les approches locales et globales qui devraient être prises pour atténuer le danger d’incendie suivant un séisme, incluant la conception structurale et non structurale, divers aspects de la planification urbaine ainsi que leurs combinaisons interactives sont abordées. Cette revue conclut qu’il est fortement nécessaire de développer des lignes directrices de conception structurale de sécurité incendie pour les cas d’incendies suivant un séisme. De plus, il faut développer une analyse appropriée ainsi que des techniques de simulation numériques pour l’évaluation du comportement structural lors d’incendies causés par un séisme. Il est également nécessaire de réaliser des études expérimentales pour valider et raffiner de tels modèles numériques. [ABSTRACT FROM AUTHOR]

The quantitative seismic hazard maps for the 1970s National Building Code of Canada were evaluated using the Davenport–Milne method. The Cornell–McGuire method is employed to develop recent seismic hazard maps of Canada. These methods incorporate the information on seismicity, magnitude-recurrence relations, and ground motion (or response) attenuation relations. The former preserves and depends completely on details of the historical seismicity; the latter smoothes the irregular spatial occurrence pattern of the historical seismicity into seismic source zones. Further, the Epicentral Cell method, which attempts to incorporate the preserving and smoothing aspect of these methods, has been developed. However, the impact of the adopted assumptions on the estimated quantitative seismic hazard has not been investigated. This study provides a comparative seismic hazard assessment using the above-mentioned methods and simulation-based algorithms. The analysis results show that overall the Davenport–Milne method gives quasi-circular seismic hazard contours near significant historical events, and the Cornell–McGuire method smoothes the transition of contours. The Epicentral Cell method provides estimates approximately within the former and the latter. [ABSTRACT FROM AUTHOR]

Seismic response of concrete-faced rockfill (CFR) dams subjected to asynchronous base excitation is determined by considering dam–reservoir interaction. The equations of motion of the coupled system are obtained using the Lagrangian approach, and the surface sloshing motion is included in the finite element formulation. Torul dam constructed in the city, Gumushane, Turkey, is selected as a numerical example, and its material properties are considered in the analysis. The dam–reservoir interaction system is modelled using the Lagrangian (displacement-based) fluid and solid-quadrilateral-isoparametric finite elements. The east–west component of Erzincan earthquake, which occurred on 13 March 1992, recorded near the region of the dam is used as a ground motion. Propagation velocities of the seismic wave are chosen as 1000 m/s, 3000 m/s, and infinite. Stresses are calculated for empty and full reservoir cases and compared with each other. [ABSTRACT FROM AUTHOR]

This paper presents the results of regional seismic risk assessment studies that were carried out for two cities in southwestern British Columbia, Vancouver and Victoria. Ground shaking intensity in the area was obtained using the seismic source zones delineated by the Geological Survey of Canada for a probability level of 10% chance of exceedance in 50 years. Building inventories were compiled by aggregating data from sidewalk surveys as well as municipal databases. Modified Mercalli intensity-based damage matrices that relate the level of ground shaking to the amount of damage expected in different types of structures were used to estimate damage to structural and non-structural components of buildings. Estimated damage and loss distributions were mapped on a block-by-block basis. The historic sections of the cities were estimated to have damage levels between 10% and 30% of the replacement cost, while in the rest of the cities the estimated damage was generally in the 5% to 10% range. The results show the estimated economic loss distribution is considerably different from the damage distribution. Although the older neighbourhoods of the cities are expected to suffer highest amount of damage, the highest amount of economic loss is estimated to occur in areas with concentration of concrete high-rise buildings. [ABSTRACT FROM AUTHOR]

Concentrically braced timber frames are often used as lateral load resisting systems in wood buildings where large open spaces are required. For application in high-risk earthquake zones, however, the ductility of the system is a concern, since energy absorption is typically limited to the connection region. In this paper, results are presented from a series of shake table tests conducted on single-storey braced frame models with different connections. Diagonal braces with five different connection types were tested, four of which used bolts as fasteners, while one brace had timber riveted connections. Four of the connections had a matching set with an identical configuration that was previously tested quasi-statically. Findings from the tests are presented along with some comments on the seismic behavior of this type of structural system. It was found that the seismic response of the braced frames is highly influenced by the brace connections. Braced frames with small diameter (slender) bolts and timber rivets showed desirable seismic performance, as they were able to dissipate the highest amount of the seismic input energy. A comparison of the quasi-static and shake table tests revealed slight differences in the load–deformation properties of the brace connections. [ABSTRACT FROM AUTHOR]

Presents a study that examined the effect of foundation rocking on the seismic response of shear walls. Background on the provisions of the 1995 National Building Code of Canada regarding foundations; Application of an analysis model to represent a shear-wall structure; Results and implications.

Examines dynamic analysis procedures for the computation of seismic design forces. Categories of dynamic analysis procedures; Information on the seismic provisions of the 1995 National Building Code of Canada; Details of the determination of the structural period to be used in association with the equivalent static force method.

Presents a study that examined the provisions of the 1995 National Building Code of Canada (NBCC) with regard to the elastic response of simple asymmetric building models to earthquake motions. Background on the torsion provisions of the 1995 NBCC; Analysis of the torsional response of the single-story building model; Results and implications.

Examines proposed changes to the 2005 edition of the National Building Code of Canada regarding seismic force modification factors. Background on developments in the base shear equation for seismic design; Analysis of several approaches in determining force modification factors; Results and implications.

Presents a study that investigated seismic design using the equivalent static load method. Background on approaches in determining seismic load forces; Analysis of the effects of higher modes on base shear; Results and implications for the proposed 2005 edition of the National Building Code of Canada.

Provides information on the provisions of the proposed 2005 edition of the National Building Code of Canada regarding earthquake-resistant design. Requirements for complete load paths; Definitions of irregular structures and special design requirements associated with the irregularities; Importance of the effects of displacements.

Presents a study that examined foundation factors in seismic codes to capture the amplification effects of local soil conditions on ground motions. Review of developments in categorizing site conditions for seismic codes; Analysis of approaches to foundation factors; Implications of the results for the proposed 2005 edition of the National Building Code of Canada.

Focuses on the development of a seismic hazard model by the Geological Survey of Canada to update the seismic hazard maps of the country. History of seismic hazard maps; Technological changes in seismic hazard analysis; Information on the provisions of the proposed 2005 edition of the National Building Code of Canada.

Discusses changes in the provisions of the proposed 2005 edition of the National Building Code of Canada regarding seismic loading and design. Seismic hazards in spectral format; Probability of exceedance; Calculation of fundamental periods; Treatment of irregularities; Dynamic analysis requirements.

Comments on the article "Overview of Seismic Provisions of the Proposed 2005 Edition of the National Building Code of Canada," which appeared in the 2003 issue of the "Canadian Journal of Civil Engineering." Increased complexity in the proposed 2005 seismic provisions; Changes in the seismic hazard parameters; Costs of precision.