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Summarized in this article are the major findings from a detailed damage investigation of an instrumented ductile reinforced concrete moment frame building subjected to a design-level earthquake. The building sustained widespread damage during the 2016 M-7.8 Kaikoura earthquake and was subsequently demolished. Prior to demolition, the structural system was extensively surveyed to document the severity and distribution of the damage sustained in the reinforced concrete frames and the flooring system. Furthermore, the building response during the earthquake was reconstructed from the acceleration records obtained from instruments installed throughout the building. The site seismic demands were also obtained from a local free-field instrument. The data collected from this damage investigation provide a high-quality dataset that is valuable to researchers investigating different parameters related to the seismic performance of reinforced concrete moment frame buildings. The dataset is published and publicly available on DesignSafe-CI (project PRJ-3444); https://www.designsafe-ci.org/data/browser/public/designsafe.storage.published/PRJ-3444v2. The data collection methodology is described, and a roadmap for navigating the dataset is presented to support future use of the archived dataset. [ABSTRACT FROM AUTHOR]

Hollow-core flooring systems were damaged in Wellington buildings during the 2016 Kaikoura earthquake (7.8 Mw) and have been shown to be susceptible to undesirable failure mechanisms (loss of seating, negative moment, and positive moment failure modes) at low drift demands. These undesirable damage mechanisms have also been observed in sub-assembly and super-assembly laboratory testing of hollow-core flooring systems and the test data obtained has enhanced the state-of-the-art knowledge of the probable seismic behaviour of hollow-core floor units. In this study, using currently available sub-assembly test data, fragility functions are defined for hollow-core flooring systems. Furthermore, the proposed fragility functions are combined with fragility information derived from nonlinear dynamic analyses for two eight-storey bare-frame reinforced concrete (RC) buildings designed based on New Zealand standards. This study shows that, in comparison with RC buildings with flooring systems that are not susceptible to gravity load failures, RC buildings with vulnerable hollow-core floors have a significantly higher likelihood of exceeding the collapse prevention limit state, as defined in this study. [ABSTRACT FROM AUTHOR]

Results of a study performed on the out-of-plane instability of reinforced masonry shear walls (RMSW) under seismic loading are presented. The study was conducted to gain understanding of the out-of-plane instability mechanism and the key factors influencing its development through the testing of five reinforced masonry uniaxial specimens under reversed cyclic tension and compression. The specimens represented the end zone of a RMSW. The design parameters considered in the study included longitudinal reinforcement ratio and height-to-thickness ratio for the test specimens. It was found that onset of out-of-plane instability is strongly influenced by the level of tensile strains developed in the specimens, the reinforcement ratio, and the bar size. In this case, out-of-plane instability occurred when out-of-plane displacements exceeded the critical value equal to half the wall thickness. A study on full-scale RMSW specimens subjected to reversed cyclic loading, also undertaken under this research program, is expected to verify the findings of this study and contribute towards development of design criteria for out-of-plane stability of RMSW. Key words: reinforced masonry, shear wall, seismic resistance, out-of-plane instability, in-plane reversed cyclic loading. Les resultats d'une etude de l'instabilite hors-plan de murs de contreventement en maconnerie armee (<< MCMA >>) soumis a des charges sismiques sont presentes. L'etude a ete menee afin de mieux comprendre le mecanisme d'instabilite hors plan et les facteurs cles influant sur son developpement, et ce, au moyen d'essais sur cinq specimens uniaxiaux de maconnerie armee sous traction et compression cycliques inversees. Les specimens representaient la zone de l'extremite d'un MCMA. Les parametres de conception consideres dans l'etude comprenaient le rapport d'armature longitudinal et le rapport de hauteur-aepaisseur pour les specimens d'essai. On a trouve que le degre des allongements en traction developpes dans les specimens ainsi que le rapport d'armature et la taille des barres influent fortement sur le debut de l'instabilite hors plan. Dans ce cas, l'instabilite hors plan est arrivee quand les glissements hors plan ont excede la valeur critique equivalant a la moitie de l'epaisseur du mur. Une etude sur des specimens de MCMA en grandeur nature soumis a des charges cycliques inversees, aussi entrepris conformement a ce programme de recherche, est censee verifier les conclusions de cette etude et contribuer a l'elaboration de criteres de conception en matiere de stabilite hors plan des MCMA. [Traduit par la Redaction] Mots-cles : maconnerie armee, mur de contreventement, resistance sismique, instabilite hors plan, charge cyclique inversee en plan., Introduction Reinforced masonry shear walls (RMSW) constructed using hollow concrete blocks reinforced with vertical and horizontal steel bars are commonly used as a seismic force resisting system (SFRS) in Canada [...]

Architectural features and other irregularities in the gravity system which apply gravity-induced lateral demands to the seismic force resisting system are being incorporated in new buildings. These gravity-induced demands have raised concerns due to the perceived potential for a ratcheting effect to occur during seismic loading. This paper summarizes the results of a study to identify if there are behavioral trends not recognized within the scope of current building codes. To this end, a nonlinear, parametric study was conducted in OpenSees to investigate the inelastic response of concrete shear wall buildings with a range of design characteristics, including gravity-induced lateral demands. The results demonstrated that a seismic ratcheting effect can develop and amplify inelastic displacement demands. The effect is significantly more prevalent in coupled shear walls compared with cantilevered shear walls. An irregularity class to address buildings with gravity-induced lateral demands on the seismic force resisting system is proposed for the 2015 National Building Code of Canada. Key words: irregularities, nonlinear dynamic analysis, shear walls, hysteresis, seismic design, coupled shear walls, inclined columns, national building code. Des caracteristiques architecturales et d'autres irregularites dans le systeme gravitaire, qui appliquent des demandes laterales induites par la gravite au systeme de resistance aux forces sismiques, sont incorporees dans les nouveaux batiments. Ces demandes induites par la gravite ont souleve des inquietudes en raison du potentiel per^u d'un effet d'amplification qui pourrait survenir durant un chargement sismique. Cet article resume les resultats d'une etude pour determiner s'il y a des tendances comportementales non reconnues dans la portee des codes de batiments actuels. A cette fin, une etude parametrique non lineaire a ete realisee avec le logiciel OpenSees afin d'examiner la reponse inelastique de batiments munis de murs de contreventement en beton; le logiciel offre une plage de caracteristiques de conception, dont les demandes laterales induites par la gravite. Les resultats ont demontre que l'effet d'amplification sismique peut se developper et ainsi amplifier les demandes de deplacement inelastique. L'effet est beaucoup plus important dans les murs de contreventement jumeles par rapport a des murs de contreventement en porte-a-faux. Une classe d'irregularites pour aborder les batiments ayant des demandes laterales induites par la gravite sur le systeme de resistance aux forces sismiques est proposee pour le Code national du batiment du Canada 2015. [Traduit par la Redaction] Mots-cles: irregularites, analyse dynamique non lineaire, murs de contreventement, hysterese, conception sismique, murs de contreventement jumeles, colonnes inclinees, Code national du batiment., Introduction Building structural systems are commonly idealized as being composed of a seismic force resisting system, designed to resist all lateral demands during strong ground shaking, and a gravity system. [...]

At 12:51 pm local time on 22 February 2011, a M 6.2 aftershock of the 4 September 2010, Darfield earthquake shook the city of Christchurch, New Zealand. The aftershock occurred on an unmapped fault less than 10 km from the city centre resulting in significant damage, particularly in the Central Business District (CBD). The earthquake resulted in the collapse of two reinforced concrete office buildings, one parking garage, and numerous unreinforced masonry buildings, including many heritage structures, leading to 185 deaths. Liquefaction was wide spread in the CBD and the eastern suburbs, resulting in foundation movement for housing and office buildings alike. Many buildings in the CBD experienced severe damage, some requiring demolition, necessitating careful controlled access to the CBD in the months following the earthquake. This paper summarizes the recorded earthquake shaking and observed damage to concrete buildings in CBD, with a specific focus on identifying future research and possible changes for seismic design practice and codes in Canada to address the Christchurch observations. Key words: earthquakes, collapse, concrete buildings, shear walls, irregularities, precast stairs, deformation compatibility, NBCC. A 12 h 51 heure locale le 22 fevrier 2011, la Ville de Christchurch, Nouvelle-Zelande, a subi une replique sismique d'une magnitude de 6,2 du seisme du 4 septembre 2010 de Darfield. La replique sismique est survenue dans une faille non repertoriee a moins de 10 km du centre-ville, engendrant de graves dommages, particulierement au district des affaires (CBD). Le seisme a cause l'effondrement de deux immeubles a bureaux en beton arme, d'un garage de stationnement et de nombreux immeubles en maconnerie non armee, dont plusieurs batiments patrimoniaux, causant 185 deces. La liquefaction etait etendue dans le CBD et dans les banlieues a l'est, entrainant des mouvements des fondations des maisons et des immeubles a bureaux. Plusieurs immeubles dans le CBD ont subi de graves dommages, certains devant etre demolis, demandant un acces tres controle au CBD pendant les mois suivant le seisme. Le present article resume la secousse sismique enregistree et les dommages observes aux immeubles en beton dans le CBD; il porte une attention speciale a l'identification des recherches futures et aux changements possibles aux pratiques de conception et aux codes sismiques canadiens afin de traiter les observations de Christchurch. Mots-cles : seismes, effondrement, immeubles en beton, murs de refend, irregularites, escaliers prefabrique, compatibilite des deformations, CNBC. [Traduit par la Redaction], Introduction New Zealand lies at the boundary of the Australian and Pacific tectonic plates, experiencing more than 25 earthquakes over magnitude 6 in the past 10 years (GeoNet 2011). Most [...]

In this study, a performance-based model is proposed, capable of simulating seismic behavior of typical confined masonry (CM) walls whose response is governed by shear deformations. This model is developed on the basis of both monotonic and reversed-cyclic experiments assembled in an extensive database, and derived through an iterative linear regression analysis. Owing to the limited data available and inconsistencies in observed behavior in some tests, only specimens with two tie columns, one on either edge of the wall; multiple longitudinal rebar per confining element; no bed joint reinforcement; no openings within the confined panel; and a height-to-length ratio that varies from 0.7 to 1.2, are considered for the purpose of model development. The effect of openings on strength characteristics, the capability of existing models to predict seismic behavior of CM walls, and the limitations of the proposed equations are discussed in detail. The accuracy of the model is also verified for CM walls with different characteristics. The proposed model simulates reasonably well the seismic behavior of CM walls whose properties conform to the assumptions of the model and that correspond to typical CM walls. DOI: 10.1061/(ASCE)ST.1943-541X.0000012 CE Database subject headings: Masonry; Seismic design; Walls; Deformation.

Analytical and experimental studies were undertaken to assess and improve modeling techniques for capturing the nonlinear behavior of flat-plate systems using results from shake table tests of two, approximately one-third scale, two-story reinforced concrete and posttensioned concrete slab--column frames. The modeling approach selected accounts for slab flexural yielding, slab flexural yielding due to unbalanced moment transfer, and loss of slab-to-column moment transfer capacity due to punching shear failure. For punching shear failure, a limit state model based on gravity shear ratio and lateral interstory drift was implemented into a computational platform (OpenSees). Comparisons of measured and predicted responses indicate that the proposed model was capable of reproducing the experimental results well for an isolated connection test, as well as the two shake table test specimens. DOI: 10.1061/(ASCE)0733-9445(2009)135:2(147) CE Database subject headings: Shake table tests; Concrete slabs; Connections; Punching; Limit states; Post tensioning; Plates.

A large number of reinforced concrete buildings constructed prior to the mid-1970s in western North America rely on lightly reinforced, perforated, perimeter shear walls to resist earthquake-induced lateral forces. Although a substantial number of piers may exist, deformation demands can significantly exceed acceptable levels for plastic deformations published in common acceptance criteria such as FEMA 356. A shear-friction model is used to establish the ability of wall piers to support vertical loads after substantial loss of pier lateral-load capacity. The model results indicate that typical wall piers are capable of sustaining relatively large lateral drift ratios prior to loss of vertical load-carrying capacity, which is consistent with postearthquake observations. However, preliminary test results indicate that the drift capacity may be substantially less for poorly detailed walls, where axial failure occurred at a lateral drift ratio of approximately one percent. DOI: 10.1061/(ASCE)0733-9445(2008)134:9(1548) CE Database subject headings: Axial loads; Piers; Walls; Reinforcement; Concrete structures; Drift.

Reinforced concrete columns with light transverse reinforcement may be susceptible to shear and subsequent axial-load failures during strong earthquake ground shaking. An experimental program examined the behavior of two half-scale, one-story frames with axial loads representative of those expected for the lower story of a multistory building. The frames were subjected to unidirectional simulated earthquake motion applied at the base. Shear failures of an interior column led to axial-load failure and redistribution of internal forces to adjacent framing components. Recorded data illustrated the details of the shear and axial failures and the redistribution to adjacent components. This paper discusses the global response of the frames and the shear and axial-load response of the shear-critical interior column. CE Database subject headings: Collapse; Concrete columns; Seismic effects; Shake table tests; Shear failure; Axial loads.

Uncertainty about when post‐earthquake repairs are needed delays decision making, and can lead either to unnecessary demolition or repair, or to inadequate repair actions. This study proposes a framework for assessing the effect of earthquake damage on the future seismic performance of a building. In this framework, we first assess drift demands during a maximum considered earthquake (MCER) level ground motion in an undamaged building, and then compare the drift demands in the same building during the same motion when it has been damaged by a prior shaking. We assess each building for a range of prior shaking events and 15 MCER‐level motions. From these analyses, we determine the relationship between damage in the first motion—quantified as peak story drift demand—and the MCER‐level motion drift demands—quantified as the ratio of peak drift demands in the damaged building to those in the undamaged building. This trend is used to indicate the level of damage at which performance is impaired, and repair is needed due to structural safety concerns. We apply this framework to a set of single‐degree‐of‐freedom structures and reinforced concrete moment frame buildings representative of construction in the United States. The results show that code‐conforming structures do not see significant drift amplifications in the damaged building when story drifts in the damaging motion do not exceed 2%, indicating they would not require major repairs for structural safety. Structures with less deformation capacity saw larger amplifications, and were affected when story drift demands in the damaging motion were lower. We also found that stiffer structures tend to see larger amplifications of drift demands. [ABSTRACT FROM AUTHOR]

Past research has indicated that precast concrete hollow-core floors in buildings are susceptible to non-ductile failure modes when subjected to earthquake deformations. While this research has led to the development of more robust connection details suitable for hollow-core floors in new buildings, the existing building stock with hollow-core floors in New Zealand is still at risk and needs to be assessed. Damage to buildings containing hollow-core floors in Wellington, New Zealand, during the 2016 Kaikoura Earthquake prompted the need to better understand the behavior of hollow-core floors and enable those with limited drift capacity to be retrofitted or replaced. Based on tests described in a companion paper, models are developed for three potential failure modes: loss of seating (LoS), positive moment failure (PMF), and negative moment failure (NMF). Implementation of these models in the New Zealand Seismic Assessment Guidelines is discussed. Applying the Guidelines to a database of 112 existing buildings with hollow-core floor units in Wellington indicates that the most likely mode of failure is loss of seating. [ABSTRACT FROM AUTHOR]

The use of post-earthquake cordons as a tool to support emergency managers after an event has been documented around the world. However, there is limited research that attempts to understand the inherent complexities of cordoning once applied, particularly the longer-term impacts and consequences. This research aims to fill the gap by providing a detailed understanding of cordons, their management, and the implications of cordoning in a post-earthquake environment. We use a qualitative method to understand cordons through case studies of two cities where cordons were used at different temporal and spatial scales: Christchurch (M6.3, February 2011) and Wellington (M7.8 in Kaikōura, November 2016), New Zealand. Data was collected through 21 key informant interviews obtained through purposive and snowball sampling of participants who were directly or indirectly involved in a decision-making role and/or had influence in relation to the cordoning process. The participants were from varying backgrounds and roles i.e. emergency managers, council members, business representatives, insurance representatives, police, and communication managers. We find that cordons are used primarily as a tool to control access for the purpose of life safety and security, but cordons can also be adapted to support recovery. Broadly, our analysis suggests two key aspects, 'decision-making' and 'operations and management', which overlap and interact as part of a complex system. The underlying complexity arises in large part due to the multitude of sectors affected by cordons: economics, law, politics, governance, evacuation, civil liberties, available resources etc. The complexity further increases as the duration of cordoning is extended. [ABSTRACT FROM AUTHOR]

Despite the awareness of the adverse effects of biaxial seismic loading on the response of reinforced concrete (RC) components, the current knowledge of seismic performance of RC columns under biaxial loading is limited in comparison to that of columns under uniaxial lateral loading. Several questions on the effect of biaxial lateral displacement history still remain unanswered. Without proper progress on this topic, the codification of seismic assessment of RC columns under the influence of biaxial lateral loading will remain elusive. This study appraised test results from various experimental programs and identified the characteristics and effects of biaxial lateral displacement paths on seismic response of RC columns. Using the available dataset, recommendations are provided on how the influence of biaxial lateral load on lateral strength, deformation capacity, and stiffness degradation can be accounted. [ABSTRACT FROM AUTHOR]