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The seismic resilience of structures can be quantified through rigorous seismic assessment. Because no detailed guideline is available for nonlinear modelling parameters and the corresponding acceptance criteria for the seismic evaluation and upgrading of steel structures in Canada, the structural commentary of the National Building Code of Canada suggests using ASCE 41, which has been adopted as a standard for seismic evaluation and retrofit of buildings in the United States (U.S.). However, because the steel design standards in Canada and the U.S. are different, their applicability to steel structures in Canada needs to be investigated. To this end, this paper critically reviews the nonlinear modelling parameters and acceptance criteria, and then recommends whether these values need to be revised or are adopted as is for the seismic evaluation and upgrading of steel structures in Canada. A numerical example of a steel moment- resisting frame is presented to demonstrate the recommended parameters being used for seismic evaluation. Keywords: seismic evaluation and upgrading, structural performance levels, steel structures, nonlinear modelling, acceptance criteria, 1. Introduction The seismic evaluation of existing buildings is paramount in earthquake engineering to improve the seismic resilience of a community. Various standards and guidelines have been developed to help [...]

The National Research Council Canada (NRC) is currently developing seismic evaluation and upgrading guidelines for existing buildings in Canada. The seismic evaluation guidelines consist of three tiers of seismic evaluation procedures, that is, Tier 1 Quick Evaluation, Tier 2 Deficiency-Based Evaluation, and Tier 3 Detailed Evaluation. This paper presents the Tier 1 Quick Evaluation procedure, which aims to update the initial quick evaluation procedure in the existing seismic evaluation guidelines developed by the NRC in early 1990s. The proposed procedure covers seismic assessment of both structural and non-structural elements, and requires the review of construction documents, on-site inspection, and calculations. A set of checklists are contained to uncover potential key seismic deficiencies of the building under evaluation. The checklists are in the form of evaluation statements that relate to potential seismic deficiencies in the structural systems and non-structural components. The proposed procedure is demonstrated by conducting the seismic evaluation of an existing building that is part of a pilot study. Key words: seismic evaluation, quick evaluation, seismic deficiency, life safety objective, existing buildings, 1. Introduction Earthquakes are one of the most disastrous natural phenomena that can cause significant casualties and monetary losses. Past major earthquakes have shown that buildings designed to conform to [...]

An investigation has been done to update key input parameters in the recent seismic-risk-screening tools developed by the National Research Council Canada for the six seismic categories. In this study, the seismic categorization system in the recent seismic-risk-screening tools of the National Research Council Canada is extended to include Canadian buildings abroad by including threshold peak ground acceleration values, a more global set of modified Mercalli intensity, peak ground acceleration, and spectral response acceleration and peak ground acceleration relationships. The relationships among spectral response acceleration, peak ground acceleration, and peak ground velocity values have been derived using least-squares regression analyses to obtain the threshold values of both peak values associated with various modified Mercalli intensity values for each seismic category. Based on the updated relationships, the seismic categorization system is applied to 679 locations in Canada and 226 locations outside Canada. Key words: seismic risk assessment, seismicity, seismic categorization system, existing Canadian buildings, modified Mercalli intensity, Introduction There is a large inventory of existing buildings in Canada and abroad that could potentially suffer severe damage or collapse in the event of strong ground shaking. Assessing and [...]

National Building Code of Canada (NBC) specifies 45 Seismic Force Resisting Systems to ensure the safety of building structures. Conventional construction concrete moment-resisting frame (CC-CMF) is one of these systems whose seismic response has not been systematically studied in Canada. This paper is an attempt to study the seismic performance of this system using the FEMA P695 methodology. In this regard, different archetype configurations were developed and analyzed through nonlinear static and dynamic analyses. Performance assessment results show that the CSA and NBC requirements for CC-CMF system represent the lower bound of values for seismic force modification factors, and conservatively meet life safety objectives presented in the NBC. Furthermore, different scenarios were considered for identifying ductility-related seismic force modification factor from pushover curves. The effect of height and gravity load levels on seismic force modification factors and collapse margin ratios are also presented by comparing archetypes having different configurations. Keywords: conventional construction concrete moment-resisting frames, seismic performance assessment, seismic force modification factors, seismic design requirements, collapse margin ratio Le Code national du batiment du Canada (CNB) precise 45 systemes de resistance sismique pour assurer la securite des charpentes de batiment. Les ossatures resistant au moment de construction classique (<< CC-CMF >>) constituent l'un de ces systemes dont la reponse sismique n'a pas ete systematiquement etudiee au Canada. Dans le cadre de cet article, on tente d'etudier les performances sismiques de ce systeme en utilisant la methodologie FEMA P695. A cet egard, differentes configurations d'archetype ont ete elaborees et examinees au moyen d'analyses statiques et dynamiques non lineaires. Les resultats de l'evaluation de la performance montrent que les exigences de la CSA et du CNB pour le systeme CC-CMF representent la limite inferieure des valeurs pour les facteurs de modification des forces sismiques, et respectent de facon prudente les objectifs de securite des personnes presentes dans le CNB. En outre, differents scenarios ont ete envisages pour determiner le facteur de modification de la force sismique lie a la ductilite a partir des courbes de poussee (<< pushover curves >>). L'effet de la hauteur et des niveaux de charge de gravite sur les facteurs de modification des forces sismiques et les rapports de marge d'affaissement est egalement presente en comparant des archetypes ayant des configurations differentes. [Traduit par la Redaction] Mots-cles : ossatures resistant au moment de construction classique, evaluation de la performance sismique, facteurs de modification de la force sismique, exigences de conception sismique, rapport de marge d'affaissement, 1. Introduction The National Building Code of Canada (NBC 2015a) includes 45 different seismic force resisting systems (SFRSs) applicable to a wide range of seismicity levels and building configurations. Concrete [...]

The National Research Council of Canada (NRC) recently developed a semi-quantitative seismic risk screening tool (SQST) for existing buildings in Canada. The SQST is intended to supersede the Manual for Screening of Buildings for Seismic Investigation developed by the NRC in the early 1990s. The SQST consists of three key components: (i) a structural scoring system that quantitatively assesses the structural seismic risk based on probability of collapse; (ii) a nonstructural component scoring system that qualitatively assesses the seismic risk of nonstructural components based on seismic demand; and (iii) a ranking procedure that prioritizes potentially hazardous buildings for seismic evaluations and possible upgrading. The intent of the SQST is to inexpensively identify and exempt buildings with acceptable life safety risk and optimize the allocation of resources to assess the seismic risks to portfolios of buildings. Seismic screening with the SQST can be completed with either paper-based screening forms or a web-based application. The applicability of the SQST was demonstrated with a pilot study for 33 existing buildings across Canada. Key words: seismic risk management, seismic risk screening, structural scoring system, nonstructural component scoring system, prioritization. Le Conseil national de recherches du Canada (CNRC) a recemment mis au point un outil de selection semi-quantitatif (OSSQ) en fonction des risques sismiques pour les batiments existants au Canada. L'OSSQvise a remplacer le Manuel de selection des batiments en vue de leur evaluation sismique elabore par le CNRC au debut des annees 1990. L'OSSQse compose de trois composantes principales : (i) un systeme de notation structural qui evalue quantitativement le risque sismique structural en fonction de la probabilite d'effondrement; (ii) un systeme de notation non structural qui evalue qualitativement le risque sismique des elements non structuraux en fonction de la demande sismique; et (iii) une procedure de classement qui etablit l'ordre de priorite des batiments potentiellement dangereux en vue d'evaluations sismiques et d'ameliorations possibles. L'OSSQ a pour but d'identifier a peu de frais les batiments presentant un risque acceptable pour la securite des personnes et de les exempter ainsi que d'optimiser l'affectation des ressources pour evaluer le risque sismique des portefeuilles d'immeubles. La selection sismique avec l'OSSQ peut etre completee avec des formulaires de selection papier ou a l'aide d'une application Web. L'applicabilite de l'OSSQest demontree par la realisation d'une etude pilote pour 33 batiments existants au Canada. Mots-cles : gestion des risques sismiques, selection des risques sismiques, systeme de notation structural, systeme de notation des elements non structuraux, priorisation., Introduction There are thousands of buildings in Canada that could suffer severe damage or collapse in strong seismic events. Assessing and mitigating seismic risk in large portfolios of existing buildings [...]

A performance-based unified (PBU) procedure has recently been proposed by the National Research Council Canada to systematically evaluate seismic design requirements available in the National Building Code of Canada (NBC). Conventional construction reinforced concrete moment-resisting frame (CC-CMF) and ductile reinforced concrete moment-resisting frame (D-CMF) systems were used in this paper to first assess the proposed PBU procedure and second determine the adequacy of the basis for seismic design requirements in NBC and see its performance margin against different structural performance levels. Results indicate that the detailed screening in the PBU procedure efficiently reduces the number of incremental dynamic analysis by more than 60% for CC-CMF while providing remarkable accuracy. It was also found that the CC-CMF system designed for the Normal importance category can provide an adequate margin against life safety performance level objectives, while the D-CMF system designed for the same importance category passes the collapse prevention performance level criteria. [ABSTRACT FROM AUTHOR]

The National Research Council Canada recently developed a multi-criteria and multi-level framework for seismic risk management of existing buildings in Canada. One of the key criteria in this framework is benchmark NBC edition, which refers to the applicable edition of National Building Code of Canada (NBC) in which significantly improved seismic requirements were adopted and enforced. Since post-benchmark buildings are expected to demonstrate satisfactory seismic performance, they may be exempt from structural seismic risk assessment. This paper identifies benchmark NBC editions for 17 model building types in Canada. The identification starts by tracking major seismic improvements in the United States benchmark codes and standards. These improvements are then mapped to applicable NBC editions and relevant design standards. Provincial building code editions corresponding to benchmark NBC editions are also identified. The benchmark NBC editions and corresponding provincial building code editions help building owners quickly identify and exempt post- benchmark buildings with acceptable seismic risks and thus allocate resources to the buildings with potentially unacceptable seismic risks. Key words: seismic risk management, seismic risk screening, benchmark NBC edition, National Building Code of Canada, existing buildings. Le Conseil national de recherches du Canada a recemment elabore un cadre a multiples criteres et a multiples niveaux pour la gestion des risques sismiques des batiments existants au Canada. L'un des criteres cles de ce cadre est l'edition de reference du Code national du batiment du Canada (CNB), qui renvoie a l'edition applicable du CNB dans laquelle des exigences sismiques considerablement ameliorees ont ete adoptees et appliquees. Etant donne que l'on s'attend a ce que les batiments construits apres l'etude de reference demontrent un rendement sismique satisfaisant, ils peuvent etre exemptes de l'evaluation des risques sismiques structuraux. Le present document porte sur l'identification des editions de reference du CNB pour dix-sept types de batiments modeles au Canada. L'identification commence par le suivi des ameliorations parasismiques majeures dans les editions de code de reference americaines. Ces ameliorations sont ensuite mises en correspondance avec les editions du CNB applicables et les normes de conception pertinentes. Les codes des provinces correspondant aux codes des editions de reference du CNB sont egalement determines. Les editions de reference du CNB et les editions correspondantes de codes des provinces aident les proprietaires d'immeubles a identifier et a exempter rapidement les batiments post-reference presentant des risques sismiques acceptables et ainsi affecter des ressources aux batiments presentant des risques sismiques potentiellement inacceptables. [Traduit par la Redaction] Mots-cles : gestion des risques sismiques, examen des risques sismiques, edition de reference du Code national du batiment du Canada, Code national du batiment du Canada (CNB), batiments existants., 1. Introduction A large number of existing buildings in Canada could potentially suffer severe damage or collapse due to earthquakes. The assessment and mitigation of seismic risks in building portfolios [...]

This study examines the seismic force modification factors related to overstrength and ductility of wood light-frame shearwalls. Several archetypes were developed to meet different design criteria. Nonlinear static procedure, nonlinear time-history analysis, and nonlinear incremental dynamic analysis were performed. The numerical analyses were based on 2D representations of the designed archetypes. The nonlinear static analysis results revealed an overstrength factor of 2.2, which is greater than the current value of 1.7 for wood light-frame shearwalls. The findings also indicated that existing design requirements for hold-downs and the overcapacity requirement for the first and second stories may not always ensure satisfactory performance. The archetype detailed screening step proved valuable as a preliminary assessment prior to the incremental dynamic analysis in identifying critical archetypes. The results of the performance margin ratios indicated that the archetypes marginally met the life safety performance level. Overall, this study suggests a need for potential adjustments in design standards and considerations for a more comprehensive evaluation of the seismic performance of wood light-frame shearwalls. This study also found that adhering to design requirements related to certain irregularities decreased the probability of collapse in those archetypes. [ABSTRACT FROM AUTHOR]

The mechanical behaviour of wood light-frame shearwalls is difficult to explain unless system-level performance is taken into account. Although the behaviour of wood light-frame shearwalls with wood structural panels is consistent with and represented by the behaviour of the panel to framing nail joints, comprehensive seismic evaluation guidelines for Canadian practice are currently lacking. This study presents a critical review of the available literature on the performance-based seismic evaluation of wood light-frame buildings through nonlinear analysis approach. To verify the applicability of these standards in Canada, the procedure outlined in these documents is compared to available experimental testing. Nonlinear pushover analysis is performed on two representative wood light-frame buildings in Montréal and Vancouver. Results are compared, and further discussion is provided on the adequacy of each document to Canadian practice. [ABSTRACT FROM AUTHOR]

A displacement based method for the seismic design of reinforced concrete shear wall buildings of regular shape is presented. For preliminary design, approximate estimates of the yield and ultimate displacements are obtained, the former from simple empirical relations, and the latter to keep the ductility demand within ductility capacity and to limit the maximum storey drift to that specified by the codes. For a multi-storey building, the structure is converted to an equivalent single-degree-of-freedom system using an assumed deformation shape that is representative of the first mode. The required base shear strength of the system is determined from the inelastic demand spectrum corresponding to the ductility demand. In subsequent iterations a pushover analysis for the force distribution based on the first mode is used to obtain better estimates of yield and ultimate displacements taking into account stability under P-Δ effect. A multi-mode pushover analysis is carried out to find more accurate estimates of the shear demand. Key words: displacement-based seismic design, performance-based seismic design, seismic design of shear walls, modal pushover analysis, capacity demand diagram, higher mode effect. Resume : Une methode basee sur le displacement pour la conception sismique des batiments munis de murs de contreventement en beton arme de forme reguliere est presentee. Des estimations approximatives du rendement et des deplacements limites sont obtenues, la premiere a partir de relations empiriques simples et la derniere, pour conserver la demande en ductilite a l'interieur de la capacite en ductilite et limiter la derive maximale des etages a celle specifiee dans les codes. Pour un batiment a plusieurs etages, la structure est convertie en un systeme equivalent a un seul degre de liberte utilisant une forme de deformation presumee representative du premier mode. La resistance au cisaillement de base requise pour le systeme est determinee a partir du spectre de demande inelastique correspondant a la demande en ductilite. Dans les iterations subsequentes, une analyse statique non lineaire (push over) pour la distribution de force basee sur le premier mode est utilisee pour obtenir de meilleures estimations du rendement et des deplacements limitesen tenant compte de la stabilite sous l'effet P-Δ. Une analyse statique non lineaire (push over) a mode multiple est realisee pour decouvrir des estimations plus precises de la demande en cisaillement. Mots-cles : conception sismique basee sur le deplacement, conception sismique basee sur le rendement, conception sismique des murs de contreventement, analyse statique non lineaire modale, diagramme de la demande en capacite, effet des modes superieurs. [Traduit par la Redaction], Introduction Experience in recent earthquakes has shown that while improvements in design and construction of buildings may have reduced the loss of life, economic loss due to property damage, business [...]

This discussion examines the conclusion reached in the paper that in a single-story asymmetric-plan building the maximum displacement demand in the different resisting elements is reached for the same deformation configuration of the system and that the resultant of the seismic forces producing such demand is located at the center of resistance. It is shown that this conclusion is valid only for the particular model studied and cannot be generalized. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]