Torsionally flexible buildings (that have torsional mode as fundamental mode) twist during earthquake shaking, and may collapse partially or completely depending upon the direction and level of shaking. The problem is aggravated when the building is torsionally unsymmetrical. Some design codes (like Eurocode, Indian Code) explicitly prohibit the design of such buildings. This paper presents a simple approximate method to identify torsionally flexible RC Moment Frame and RC Structural Wall buildings at the initial proportioning stage itself without carrying out a detailed structural analysis. It is possible to identify whether or not the first mode is torsional mode of a building (i.e., torsionally flexible building) if Natural Period Ratio τ>1 by modelling the building with rigid diaphragm and distribution of mass & stiffness along the height of building, and estimating: (1) radius of gyration of rotational mass rm of each floor plan geometry by lumping the masses of slabs, beams and all vertical elements at each nodes, (2) radius of gyration of twisting stiffness rKθ of all vertical elements using their translational and torsional stiffnesses (considering flexibility of adjoining beams and vertical elements accounting for both flexural and shear deformations), and (iv) τ (=rm/rKθ). The method is validated with 3D Modal Analysis (using τ =Tθ/T, where Tθ is Uncoupled Torsional Natural Period and T Uncoupled Translational Natural Period) of hypothetical buildings using a commercial structural analysis software. Also, parameters are identified that lead to τ>1, and solutions suggested to avoid torsional flexibility in buildings. Further, the method helps identify vertical stiffness irregularity in buildings. Draft provisions are suggested for inclusion in seismic codes. Also, poor performance of multi-storey building (with τ>1) is demonstrated using nonlinear static and nonlinear time history analyses.
{"title":"Method to identify if torsional mode of a building is its first mode","authors":"T. G, C.V.R.Mury","doi":"10.5459/bnzsee.1645","DOIUrl":"https://doi.org/10.5459/bnzsee.1645","url":null,"abstract":"Torsionally flexible buildings (that have torsional mode as fundamental mode) twist during earthquake shaking, and may collapse partially or completely depending upon the direction and level of shaking. The problem is aggravated when the building is torsionally unsymmetrical. Some design codes (like Eurocode, Indian Code) explicitly prohibit the design of such buildings. This paper presents a simple approximate method to identify torsionally flexible RC Moment Frame and RC Structural Wall buildings at the initial proportioning stage itself without carrying out a detailed structural analysis. It is possible to identify whether or not the first mode is torsional mode of a building (i.e., torsionally flexible building) if Natural Period Ratio τ>1 by modelling the building with rigid diaphragm and distribution of mass & stiffness along the height of building, and estimating: (1) radius of gyration of rotational mass rm of each floor plan geometry by lumping the masses of slabs, beams and all vertical elements at each nodes, (2) radius of gyration of twisting stiffness rKθ of all vertical elements using their translational and torsional stiffnesses (considering flexibility of adjoining beams and vertical elements accounting for both flexural and shear deformations), and (iv) τ (=rm/rKθ). The method is validated with 3D Modal Analysis (using τ =Tθ/T, where Tθ is Uncoupled Torsional Natural Period and T Uncoupled Translational Natural Period) of hypothetical buildings using a commercial structural analysis software. Also, parameters are identified that lead to τ>1, and solutions suggested to avoid torsional flexibility in buildings. Further, the method helps identify vertical stiffness irregularity in buildings. Draft provisions are suggested for inclusion in seismic codes. Also, poor performance of multi-storey building (with τ>1) is demonstrated using nonlinear static and nonlinear time history analyses.","PeriodicalId":46396,"journal":{"name":"Bulletin of the New Zealand Society for Earthquake Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141388931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Mowll, Julia Becker, L. Wotherspoon, C. Stewart, D. Johnston, Daniel Neely
‘Planning Emergency Levels of Service’ (PELOS) are goals for the delivery of infrastructure services following a major hazard event, such as an earthquake or flood. This paper presents an operationalised PELOS framework for the Wellington region based on interviews with emergency and critical infrastructure managers and discusses important changes from the preliminary to the operationalised framework. A shared understanding of these PELOS will help Wellington region infrastructure providers, emergency management professionals and the potentially impacted communities plan for major events. PELOS for the energy, telecommunications, transport, and water sectors have been developed, and high-level interdependencies considered. The PELOS framework can be updated for other regions, by the critical infrastructure entities and emergency managers, using locally relevant hazard scenarios. In turn, this approach can inform the end-users (communities) of the goals of the critical infrastructure providers following a major hazard event.
规划应急服务水平"（PELOS）是在发生地震或洪水等重大灾害事件后提供基础设施服务的目标。本文基于对应急和关键基础设施管理人员的访谈，介绍了惠灵顿地区可操作的 PELOS 框架，并讨论了从初步框架到可操作框架的重要变化。对这些 PELOS 的共同理解将有助于惠灵顿地区的基础设施提供商、应急管理专业人员和可能受影响的社区为重大事件制定计划。能源、电信、交通和水利部门的 PELOS 已经制定，并考虑了高层次的相互依存关系。关键基础设施实体和应急管理人员可利用与当地相关的灾害情景，为其他地区更新 PELOS 框架。反过来，这种方法可以让最终用户（社区）了解重大灾害事件发生后关键基础设施提供者的目标。
{"title":"Infrastructure planning emergency levels of service for the Wellington region, Aotearoa New Zealand – An operationalised framework","authors":"R. Mowll, Julia Becker, L. Wotherspoon, C. Stewart, D. Johnston, Daniel Neely","doi":"10.5459/bnzsee.1628","DOIUrl":"https://doi.org/10.5459/bnzsee.1628","url":null,"abstract":"‘Planning Emergency Levels of Service’ (PELOS) are goals for the delivery of infrastructure services following a major hazard event, such as an earthquake or flood. This paper presents an operationalised PELOS framework for the Wellington region based on interviews with emergency and critical infrastructure managers and discusses important changes from the preliminary to the operationalised framework. A shared understanding of these PELOS will help Wellington region infrastructure providers, emergency management professionals and the potentially impacted communities plan for major events. PELOS for the energy, telecommunications, transport, and water sectors have been developed, and high-level interdependencies considered. The PELOS framework can be updated for other regions, by the critical infrastructure entities and emergency managers, using locally relevant hazard scenarios. In turn, this approach can inform the end-users (communities) of the goals of the critical infrastructure providers following a major hazard event.","PeriodicalId":46396,"journal":{"name":"Bulletin of the New Zealand Society for Earthquake Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138983229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Free-standing retaining walls are usually designed for earthquake loads assuming cohesionless backfill soil and using the Mononobe-Okabe method. This simple design approach has led to satisfactory performance and is supported by laboratory testing and analytical studies. For major wall structures there are a number of refinements to the method that should be considered. In the paper methods of assessing the influence on the earthquake loads of the flexibility of the wall, soil cohesion and ground water in the backfill are presented. Equations for predicting failure plane angles to allow a better assessment of the soil properties within the failure wedge are included. Procedures for estimating the outward displacement and the influence of passive resistance and wall geometry on the sliding resistance are discussed. Design charts are presented which allow the magnitude of these refinements to be rapidly assessed.
{"title":"Earthquake design loads for retaining walls","authors":"John Wood","doi":"10.5459/bnzsee.1618","DOIUrl":"https://doi.org/10.5459/bnzsee.1618","url":null,"abstract":"Free-standing retaining walls are usually designed for earthquake loads assuming cohesionless backfill soil and using the Mononobe-Okabe method. This simple design approach has led to satisfactory performance and is supported by laboratory testing and analytical studies. For major wall structures there are a number of refinements to the method that should be considered. In the paper methods of assessing the influence on the earthquake loads of the flexibility of the wall, soil cohesion and ground water in the backfill are presented. Equations for predicting failure plane angles to allow a better assessment of the soil properties within the failure wedge are included. Procedures for estimating the outward displacement and the influence of passive resistance and wall geometry on the sliding resistance are discussed. Design charts are presented which allow the magnitude of these refinements to be rapidly assessed.","PeriodicalId":46396,"journal":{"name":"Bulletin of the New Zealand Society for Earthquake Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138585755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The inter-frequency correlation of ground-motion residuals is related to the width of peaks and troughs in the ground-motion spectra (either response spectra or Fourier amplitude spectra; FAS) and is therefore an essential component of ground-motion simulations for representing the variability of structural response. As such, this component of the simulations requires evaluation and validation when the intended application is seismic fragility and seismic risk. This article evaluates the CyberShake NZ [1] crustal earthquake ground-motion simulations for their inter-frequency correlation, including comparisons with an empirical model developed from a global catalogue of shallow crustal earthquakes in active tectonic regions, and with results from similar simulations (SCEC CyberShake; [2]). Compared with the empirical model, the CyberShake NZ simulations have a satisfactory level of total inter-frequency correlation between the frequencies 0.1 – 0.25 Hz. At frequencies above 0.25 Hz, the simulations have lower (statistically significant at 95% confidence level) total inter-frequency correlation than the empirical model and therefore require calibration. To calibrate the total correlation, it is useful to focus on the correlation of the residual components. The between-event residual correlations, physically related to source effects (e.g., stress drop) which drive ground motions over a broad frequency range, are low at frequencies greater than about 0.25 Hz. Modifications to the cross-correlation between source parameters in the kinematic rupture generator can improve the inter-frequency correlations in this range [3]. The between-site residual correlations, which represents the correlation between frequencies of the systematic site amplification deviations, are larger (statistically significant at 95% confidence level) than the empirical model for frequencies less than about 0.5 Hz. We postulate that this relates to the relative simplicity of site amplification methods in the simulations, which feature less variability than the amplification observed in the data. Additional insight would be gained from future evaluations accounting for repeatable path and basin effects, using simulations with refined or alternative seismic velocity models, and using simulations with a higher crossover frequency to deterministic methods (e.g., 1 Hz or higher).
{"title":"Evaluation of the Inter-frequency Correlation of New Zealand CyberShake Crustal Earthquake Simulations","authors":"J. Bayless, Scott Condon","doi":"10.5459/bnzsee.1623","DOIUrl":"https://doi.org/10.5459/bnzsee.1623","url":null,"abstract":"The inter-frequency correlation of ground-motion residuals is related to the width of peaks and troughs in the ground-motion spectra (either response spectra or Fourier amplitude spectra; FAS) and is therefore an essential component of ground-motion simulations for representing the variability of structural response. As such, this component of the simulations requires evaluation and validation when the intended application is seismic fragility and seismic risk. This article evaluates the CyberShake NZ [1] crustal earthquake ground-motion simulations for their inter-frequency correlation, including comparisons with an empirical model developed from a global catalogue of shallow crustal earthquakes in active tectonic regions, and with results from similar simulations (SCEC CyberShake; [2]). Compared with the empirical model, the CyberShake NZ simulations have a satisfactory level of total inter-frequency correlation between the frequencies 0.1 – 0.25 Hz. At frequencies above 0.25 Hz, the simulations have lower (statistically significant at 95% confidence level) total inter-frequency correlation than the empirical model and therefore require calibration. To calibrate the total correlation, it is useful to focus on the correlation of the residual components. The between-event residual correlations, physically related to source effects (e.g., stress drop) which drive ground motions over a broad frequency range, are low at frequencies greater than about 0.25 Hz. Modifications to the cross-correlation between source parameters in the kinematic rupture generator can improve the inter-frequency correlations in this range [3]. The between-site residual correlations, which represents the correlation between frequencies of the systematic site amplification deviations, are larger (statistically significant at 95% confidence level) than the empirical model for frequencies less than about 0.5 Hz. We postulate that this relates to the relative simplicity of site amplification methods in the simulations, which feature less variability than the amplification observed in the data. Additional insight would be gained from future evaluations accounting for repeatable path and basin effects, using simulations with refined or alternative seismic velocity models, and using simulations with a higher crossover frequency to deterministic methods (e.g., 1 Hz or higher).","PeriodicalId":46396,"journal":{"name":"Bulletin of the New Zealand Society for Earthquake Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139010781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tom Francis, Eyitayo A. Opabola, Timothy Sullivan, Kenneth Elwood, Cameron Belliss
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.
{"title":"Seismic fragility of reinforced concrete buildings with hollow-core flooring systems","authors":"Tom Francis, Eyitayo A. Opabola, Timothy Sullivan, Kenneth Elwood, Cameron Belliss","doi":"10.5459/bnzsee.1634","DOIUrl":"https://doi.org/10.5459/bnzsee.1634","url":null,"abstract":"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.","PeriodicalId":46396,"journal":{"name":"Bulletin of the New Zealand Society for Earthquake Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138983240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The current state of practice in soil-structure interaction (SSI) modelling in New Zealand was investigated through an industry-wide questionnaire. This used a mixed methods, sequential explanatory research design involving the collection of quantitative and qualitative questionnaire data, as well as follow-up focus groups. Several statistically significant relationships were observed for SSI modelling approaches between different engineering fields, company sizes, and years of experience. The key findings from this study suggest that there is no consensus on the best SSI analysis methods, modelling strategies, or guidelines to be used. Overall, fixed base analysis remains the most popular method across all company sizes and number of years of industry experience. Engineers from large companies reported higher consideration for SSI modelling and use of performance-based design for design projects, which perhaps reflects the scale and complexity of projects carried out in those companies. However when SSI is considered, analyses are typically limited to nonlinear vertical springs under the foundation as part of a dynamic analysis. Use of SSI for buildings is typically limited to seismic assessments and complex or otherwise high importance structures. However, bridge engineers routinely used pushover analyses with linear and nonlinear springs and dynamic analyses with nonlinear springs, in contrast with the rest of the industry. There is further room to improve on the quality of communication and interaction between structural and geotechnical engineers. A lack of specific guidance on when SSI should be considered was reported, alongside broader training issues to ensure that structural and geotechnical engineers fundamentally understand the requirements and input/output needs of each role.
{"title":"The state of practice in soil-structure interaction modelling in New Zealand","authors":"T. Hnat, Christopher McGann, L. Wotherspoon","doi":"10.5459/bnzsee.1609","DOIUrl":"https://doi.org/10.5459/bnzsee.1609","url":null,"abstract":"The current state of practice in soil-structure interaction (SSI) modelling in New Zealand was investigated through an industry-wide questionnaire. This used a mixed methods, sequential explanatory research design involving the collection of quantitative and qualitative questionnaire data, as well as follow-up focus groups. Several statistically significant relationships were observed for SSI modelling approaches between different engineering fields, company sizes, and years of experience.\u0000The key findings from this study suggest that there is no consensus on the best SSI analysis methods, modelling strategies, or guidelines to be used. Overall, fixed base analysis remains the most popular method across all company sizes and number of years of industry experience. Engineers from large companies reported higher consideration for SSI modelling and use of performance-based design for design projects, which perhaps reflects the scale and complexity of projects carried out in those companies. However when SSI is considered, analyses are typically limited to nonlinear vertical springs under the foundation as part of a dynamic analysis. Use of SSI for buildings is typically limited to seismic assessments and complex or otherwise high importance structures. However, bridge engineers routinely used pushover analyses with linear and nonlinear springs and dynamic analyses with nonlinear springs, in contrast with the rest of the industry.\u0000There is further room to improve on the quality of communication and interaction between structural and geotechnical engineers. A lack of specific guidance on when SSI should be considered was reported, alongside broader training issues to ensure that structural and geotechnical engineers fundamentally understand the requirements and input/output needs of each role.","PeriodicalId":46396,"journal":{"name":"Bulletin of the New Zealand Society for Earthquake Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49427012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In an effort to provide practicing engineers with simple means of limiting earthquake-induced losses to buildings, this paper extends a simplified damage-state loss vs. intensity approach for estimation of expected annual losses in two ways. Firstly, modifications to allow consideration of a threshold replacement limit state are provided. Secondly, an equation for simplified loss assessment of buildings characterised with a three-damage state loss-intensity model is presented. Furthermore, recommendations are provided for the simplified models associated parameters’ values. The proposed approach is trialled for three New Zealand code compliant eccentrically braced frame buildings, and the results compared against those obtained through the PEER framework. It is found that the expected annual loss can be predicted to within 10% of the values obtained via rigorous approaches and opportunities for further research are discussed.
{"title":"Simplified seismic loss assessment using limit state loss-intensity models","authors":"A. Orumiyehei, Timothy J. Sullivan","doi":"10.5459/bnzsee.1579","DOIUrl":"https://doi.org/10.5459/bnzsee.1579","url":null,"abstract":"In an effort to provide practicing engineers with simple means of limiting earthquake-induced losses to buildings, this paper extends a simplified damage-state loss vs. intensity approach for estimation of expected annual losses in two ways. Firstly, modifications to allow consideration of a threshold replacement limit state are provided. Secondly, an equation for simplified loss assessment of buildings characterised with a three-damage state loss-intensity model is presented. Furthermore, recommendations are provided for the simplified models associated parameters’ values. The proposed approach is trialled for three New Zealand code compliant eccentrically braced frame buildings, and the results compared against those obtained through the PEER framework. It is found that the expected annual loss can be predicted to within 10% of the values obtained via rigorous approaches and opportunities for further research are discussed.","PeriodicalId":46396,"journal":{"name":"Bulletin of the New Zealand Society for Earthquake Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43557270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Claire Dong, Giovanni De Francesco, Timothy Sullivan, Rajesh Dhakal, Terri Elder, Emily Fryer, Neeha Velagapudi
Artefacts in museums, galleries, and private collections have great cultural value. In regions with high seismicity, earthquake shaking can pose significant risk of irreversible damage to such pieces. Various seismic protection methods have been proposed in the past for different types of artefacts. This study investigates one of the commonly used methods in New Zealand which consists in applying adhesives to anchor relatively small artefacts. Guidance is provided to determine the size and number of adhesives required for an artefact to survive design-level earthquake shaking. In addition, for large objects where adhesives alone are insufficient, a simple cost-effective base-isolation platform is proposed to reduce the seismic vulnerability of the artefacts. This platform is designed such that it can be assembled and positioned by museum conservators or private collectors. The adhesive material properties are determined through direct tension and shear experimental tests. The friction properties of the base-isolated substrate are determined through unidirectional quasi-static and cyclic load tests. Performance of the proposed methodology is gauged by subjecting the artefacts to shake table testing using a recorded earthquake motion. Results suggest that the recommended seismic protection solution performs as expected.
{"title":"Seismic protection of artefacts with adhesives and base-isolation","authors":"Claire Dong, Giovanni De Francesco, Timothy Sullivan, Rajesh Dhakal, Terri Elder, Emily Fryer, Neeha Velagapudi","doi":"10.5459/bnzsee.1613","DOIUrl":"https://doi.org/10.5459/bnzsee.1613","url":null,"abstract":"Artefacts in museums, galleries, and private collections have great cultural value. In regions with high seismicity, earthquake shaking can pose significant risk of irreversible damage to such pieces. Various seismic protection methods have been proposed in the past for different types of artefacts. This study investigates one of the commonly used methods in New Zealand which consists in applying adhesives to anchor relatively small artefacts. Guidance is provided to determine the size and number of adhesives required for an artefact to survive design-level earthquake shaking. In addition, for large objects where adhesives alone are insufficient, a simple cost-effective base-isolation platform is proposed to reduce the seismic vulnerability of the artefacts. This platform is designed such that it can be assembled and positioned by museum conservators or private collectors. The adhesive material properties are determined through direct tension and shear experimental tests. The friction properties of the base-isolated substrate are determined through unidirectional quasi-static and cyclic load tests. Performance of the proposed methodology is gauged by subjecting the artefacts to shake table testing using a recorded earthquake motion. Results suggest that the recommended seismic protection solution performs as expected.","PeriodicalId":46396,"journal":{"name":"Bulletin of the New Zealand Society for Earthquake Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42575300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, rotational spring and multi-spring models are implemented in SAP2000® software, and numerical solutions are presented for monotonic and cyclic behaviour of a dissipative controlled rocking (DCR) bridge column supported on a monopile foundation that is embedded in sand. The pile-soil system is modelled with elastic frame elements connected to vertically-spaced bi-linear soil springs. Three soil conditions (i.e. loose, medium-dense and dense sand) are considered to account for soil-structure interaction effects. The results from an experimental programme, carried out by the authors at the University of Canterbury, are used to validate the numerical solutions. The numerical simulation results for the three sand conditions are in good agreement with the experimental ones. From a computational standpoint, the relatively simple mathematical formulation and easy implementation would make the rotational spring model more desirable than the complex multi-spring model. On the other hand, the multi-spring model is more versatile and capable of describing the cyclic response of the DCR pier, such as the post-tensioning force, axial stress in the steel dissipaters and gap-opening interface rocking characteristics.
{"title":"Numerical modelling approaches for predicting the seismic response of monopole-supported dissipative controlled rocking bridge piers","authors":"S. Piras, Alessandro Palermo, G. Chiaro","doi":"10.5459/bnzsee.1591","DOIUrl":"https://doi.org/10.5459/bnzsee.1591","url":null,"abstract":"In this paper, rotational spring and multi-spring models are implemented in SAP2000® software, and numerical solutions are presented for monotonic and cyclic behaviour of a dissipative controlled rocking (DCR) bridge column supported on a monopile foundation that is embedded in sand. The pile-soil system is modelled with elastic frame elements connected to vertically-spaced bi-linear soil springs. Three soil conditions (i.e. loose, medium-dense and dense sand) are considered to account for soil-structure interaction effects. The results from an experimental programme, carried out by the authors at the University of Canterbury, are used to validate the numerical solutions. The numerical simulation results for the three sand conditions are in good agreement with the experimental ones. From a computational standpoint, the relatively simple mathematical formulation and easy implementation would make the rotational spring model more desirable than the complex multi-spring model. On the other hand, the multi-spring model is more versatile and capable of describing the cyclic response of the DCR pier, such as the post-tensioning force, axial stress in the steel dissipaters and gap-opening interface rocking characteristics.","PeriodicalId":46396,"journal":{"name":"Bulletin of the New Zealand Society for Earthquake Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48995683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ana Isabel Sarkis Fernandez, T. Sullivan, E. Brunesi, R. Nascimbene
There are many applications in buildings in which precast pre-stressed hollow-core (HC) slabs are subjected to shear, torsion, or combined shear and torsion. Nonetheless, extruded HC units contain no transverse reinforcement, being inherently vulnerable to brittle failure modes due to shear and torsional actions. In previous work by the authors, a finite element (FE) modelling approach for HC units failing in shear was developed and validated against experimental test data. This paper aims to extend the applicability of the proposed FE approach to help improve the understanding of the torsional behavior of HC units. For this purpose, the developed model is further validated against experimental data available in the literature and then used to predict the torsional capacity of New Zealand-specific 200 mm deep HC units. Results suggest that the FE model is capable of predicting the capacity of HC slabs with and without eccentricity of the applied vertical load. Finally, the numerical results are used to evaluate the performance of available simplified analysis approaches for assessing the torsional capacity of HC units, which are found to be non-conservative if used with expected material properties.
{"title":"Assessment of the torsional behaviour of hollow core slabs","authors":"Ana Isabel Sarkis Fernandez, T. Sullivan, E. Brunesi, R. Nascimbene","doi":"10.5459/bnzsee.1572","DOIUrl":"https://doi.org/10.5459/bnzsee.1572","url":null,"abstract":"There are many applications in buildings in which precast pre-stressed hollow-core (HC) slabs are subjected to shear, torsion, or combined shear and torsion. Nonetheless, extruded HC units contain no transverse reinforcement, being inherently vulnerable to brittle failure modes due to shear and torsional actions. In previous work by the authors, a finite element (FE) modelling approach for HC units failing in shear was developed and validated against experimental test data. This paper aims to extend the applicability of the proposed FE approach to help improve the understanding of the torsional behavior of HC units. For this purpose, the developed model is further validated against experimental data available in the literature and then used to predict the torsional capacity of New Zealand-specific 200 mm deep HC units. Results suggest that the FE model is capable of predicting the capacity of HC slabs with and without eccentricity of the applied vertical load. Finally, the numerical results are used to evaluate the performance of available simplified analysis approaches for assessing the torsional capacity of HC units, which are found to be non-conservative if used with expected material properties.","PeriodicalId":46396,"journal":{"name":"Bulletin of the New Zealand Society for Earthquake Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47392361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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