Pub Date : 2024-01-04DOI: 10.1177/87552930231220549
A. Hulsey, Francisco A Galvis, J. Baker, G. Deierlein
This article proposes a framework to support postearthquake building safety and reoccupancy decisions by quantifying the change in building collapse risk following a mainshock earthquake event. This risk may be exacerbated by both an increase in seismic hazard due to aftershock activity and a reduction in building collapse resistance due to structural damage. To address these factors, the framework is based on a hazard that includes (1) both the steady-state and the aftershock occurrence rates, that is, the elevated hazard that accounts for the dependence on the mainshock magnitude and the aftershock rate that decays over time, and (2) revised collapse fragility functions that account for structural damage sustained during the mainshock. The framework is capable of addressing region-specific questions such as (1) What are the mainshock magnitudes for which aftershocks pose a life-safety concern? (2) How long does it take for the elevated risk due to aftershocks to dissipate? and (3) What gaps in current knowledge deserve further attention from the earthquake engineering and seismology communities? The framework addresses these questions for a 20-story building in San Francisco, assuming three different, hypothetical mainshock events of magnitudes 7,7.5, and 8 M W on the San Andreas fault. This is followed by a parametric study that considers a range of buildings and provides a graphical representation of the elevated risk to inform building evaluation (tagging) decisions, based on the intact building’s collapse capacity, the amount of structural damage, and the length of time after the mainshock.
本文提出了一个框架，通过量化主震发生后建筑物倒塌风险的变化，为震后建筑物安全和重新入住决策提供支持。余震活动导致的地震危害增加，以及结构损坏导致的建筑物抗倒塌能力降低，都可能加剧这种风险。为了应对这些因素，该框架基于的危险包括：(1) 稳态和余震发生率，即考虑到主震震级依赖性的升高危险和随时间衰减的余震发生率；(2) 考虑到主震期间遭受的结构破坏的修订倒塌脆性函数。该框架能够解决特定地区的问题，例如：（1）余震对生命安全构成威胁的主震震级是多少？(2) 余震导致的风险升高需要多长时间才能消散？ (3) 地震工程和地震学界需要进一步关注当前知识中的哪些空白？该框架针对旧金山一栋 20 层楼高的建筑，假设在圣安德烈亚斯断层上发生 7、7.5 和 8 M W 级三种不同的假想主震事件，来解决这些问题。随后进行的参数研究考虑了一系列建筑物，并根据完整建筑物的倒塌能力、结构损坏程度以及主震发生后的时间长度，以图表形式展示了升高的风险，为建筑物评估（标记）决策提供依据。
{"title":"Elevated collapse risk based on decaying aftershock hazard and damaged building fragilities","authors":"A. Hulsey, Francisco A Galvis, J. Baker, G. Deierlein","doi":"10.1177/87552930231220549","DOIUrl":"https://doi.org/10.1177/87552930231220549","url":null,"abstract":"This article proposes a framework to support postearthquake building safety and reoccupancy decisions by quantifying the change in building collapse risk following a mainshock earthquake event. This risk may be exacerbated by both an increase in seismic hazard due to aftershock activity and a reduction in building collapse resistance due to structural damage. To address these factors, the framework is based on a hazard that includes (1) both the steady-state and the aftershock occurrence rates, that is, the elevated hazard that accounts for the dependence on the mainshock magnitude and the aftershock rate that decays over time, and (2) revised collapse fragility functions that account for structural damage sustained during the mainshock. The framework is capable of addressing region-specific questions such as (1) What are the mainshock magnitudes for which aftershocks pose a life-safety concern? (2) How long does it take for the elevated risk due to aftershocks to dissipate? and (3) What gaps in current knowledge deserve further attention from the earthquake engineering and seismology communities? The framework addresses these questions for a 20-story building in San Francisco, assuming three different, hypothetical mainshock events of magnitudes 7,7.5, and 8 M W on the San Andreas fault. This is followed by a parametric study that considers a range of buildings and provides a graphical representation of the elevated risk to inform building evaluation (tagging) decisions, based on the intact building’s collapse capacity, the amount of structural damage, and the length of time after the mainshock.","PeriodicalId":505879,"journal":{"name":"Earthquake Spectra","volume":"68 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139385488","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}
Pub Date : 2024-01-03DOI: 10.1177/87552930231222896
Yinghao Duan, Chenyun Li, Jun He
This study proposes a refined method for effectively simulating the evacuation processes of multi-story buildings during earthquakes. The method is developed by combining the exit-option algorithm and multi-velocity field model with the previously developed probabilistic network-based floor-field cellular automaton (PN-FFCA) model. Besides, the formula is also proposed for calculating the time-variant moving velocities of evacuees in the buildings subjected to the earthquake loads. Consequently, the refined method can fully consider the effect of multi-exits and time-variant velocities on the random evacuation processes of multi-story buildings during earthquakes. The recorded evacuation process of a school classroom during the 2022 Luding earthquake in China is reproduced using the refined method, which verifies its validity. In addition, the evacuation processes of an actual three-story office building subjected to random earthquake loads are simulated using the refined method. The simulated results are compared with those obtained from the PN-FFCA to demonstrate the advantages and utility of the refined method.
{"title":"A refined simulation method of building earthquake evacuation processes considering multi-exits and time-variant velocities","authors":"Yinghao Duan, Chenyun Li, Jun He","doi":"10.1177/87552930231222896","DOIUrl":"https://doi.org/10.1177/87552930231222896","url":null,"abstract":"This study proposes a refined method for effectively simulating the evacuation processes of multi-story buildings during earthquakes. The method is developed by combining the exit-option algorithm and multi-velocity field model with the previously developed probabilistic network-based floor-field cellular automaton (PN-FFCA) model. Besides, the formula is also proposed for calculating the time-variant moving velocities of evacuees in the buildings subjected to the earthquake loads. Consequently, the refined method can fully consider the effect of multi-exits and time-variant velocities on the random evacuation processes of multi-story buildings during earthquakes. The recorded evacuation process of a school classroom during the 2022 Luding earthquake in China is reproduced using the refined method, which verifies its validity. In addition, the evacuation processes of an actual three-story office building subjected to random earthquake loads are simulated using the refined method. The simulated results are compared with those obtained from the PN-FFCA to demonstrate the advantages and utility of the refined method.","PeriodicalId":505879,"journal":{"name":"Earthquake Spectra","volume":"121 42","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139387878","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}
Pub Date : 2024-01-03DOI: 10.1177/87552930231222458
Clinton M Wood, Rendon M Rieth, Salman Rahimi, Mohammadyar Rahimi, Alejandro Rosado‐Fuentes, Juan M Mayoral, Daniel de la Rosa, F. Sánchez-Sesma, Hugo Cruz-Jiménez
In this study, a simplified shallow three-dimensional shear wave velocity (Vs) model is presented for the Mexico City Basin. To this end, previous studies were carefully reviewed to assemble a database of Vs and site period measurements for the region. The new site period measurements obtained at the western edge of the Basin were compared to the existing 2004 Complementary Technical Standards of Mexico site period nominal map, the Lermo et al. site period map, and Design Seismic Actions System (SASID) site period predictions. Each site period prediction method was shown to have differences with respect to the new measurements along the western edge of the Basin. However, there was no bias for the prediction methods with the Lermo et al. and SASID predictions, demonstrating less error between the measured values than the NTC predictions. To develop the three-dimensional Vs model, the shallow (top 60 m) subsurface was divided into five generalized soil layers. The site period was used as the only input for the three-dimensional Vs model to simplify and maximize the model’s applicability. The performance of the model was assessed by comparing the measured and predicted Vs profiles. Overall, the three-dimensional Vs model developed in this study is a valuable tool that can be used along with geophysical estimates of deeper structure for ground motion modeling and preliminary site response studies along with other benefits to the seismic resiliency of the region.
本研究提出了墨西哥城盆地的简化浅层三维剪切波速度（Vs）模型。为此，对以前的研究进行了仔细审查，以收集该地区的 Vs 和站点周期测量数据。在盆地西部边缘获得的新场地周期测量结果与现有的 2004 年墨西哥场地周期名义补充技术标准图、Lermo 等人的场地周期图以及设计地震作用系统（SASID）的场地周期预测结果进行了比较。结果表明，每种场地周期预测方法都与盆地西部边缘的新测量结果存在差异。不过，Lermo 等人的预测方法和 SASID 预测方法没有偏差，表明测量值之间的误差小于 NTC 预测值。为了建立三维 Vs 模型，浅层（顶部 60 米）地下被划分为五个通用土层。为了简化和最大限度地提高模型的适用性，现场时期被用作三维 Vs 模型的唯一输入。通过比较测量和预测的 Vs 剖面，对模型的性能进行了评估。总之，本研究开发的三维 Vs 模型是一个宝贵的工具，可与深层结构的地球物理估算一起用于地震动建模和初步场地响应研究，并对该地区的抗震能力有其他益处。
{"title":"Shallow three-dimensional shear wave velocity model for the Mexico City Basin","authors":"Clinton M Wood, Rendon M Rieth, Salman Rahimi, Mohammadyar Rahimi, Alejandro Rosado‐Fuentes, Juan M Mayoral, Daniel de la Rosa, F. Sánchez-Sesma, Hugo Cruz-Jiménez","doi":"10.1177/87552930231222458","DOIUrl":"https://doi.org/10.1177/87552930231222458","url":null,"abstract":"In this study, a simplified shallow three-dimensional shear wave velocity (Vs) model is presented for the Mexico City Basin. To this end, previous studies were carefully reviewed to assemble a database of Vs and site period measurements for the region. The new site period measurements obtained at the western edge of the Basin were compared to the existing 2004 Complementary Technical Standards of Mexico site period nominal map, the Lermo et al. site period map, and Design Seismic Actions System (SASID) site period predictions. Each site period prediction method was shown to have differences with respect to the new measurements along the western edge of the Basin. However, there was no bias for the prediction methods with the Lermo et al. and SASID predictions, demonstrating less error between the measured values than the NTC predictions. To develop the three-dimensional Vs model, the shallow (top 60 m) subsurface was divided into five generalized soil layers. The site period was used as the only input for the three-dimensional Vs model to simplify and maximize the model’s applicability. The performance of the model was assessed by comparing the measured and predicted Vs profiles. Overall, the three-dimensional Vs model developed in this study is a valuable tool that can be used along with geophysical estimates of deeper structure for ground motion modeling and preliminary site response studies along with other benefits to the seismic resiliency of the region.","PeriodicalId":505879,"journal":{"name":"Earthquake Spectra","volume":"47 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139451783","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}
Pub Date : 2024-01-02DOI: 10.1177/87552930231211296
S. Soroushian, Razieh Rezvani, A. Zaghi, M. Maragakis
Suspended ceiling and fire sprinkler piping (CP) systems are two of the most common interacting nonstructural elements inside the buildings. While each of these elements individually is prone to losses during the earthquakes, their interaction can even more intensify their associated damage. This article aims to integrate system-level modeling methodology by using existing subsystem-level models in OpenSees platform to simulate the interacting behavior of CP systems. To do so, the numerical model of the CP systems is developed by using a series of previously developed component-level nonlinear models. Experimental results from a shake table study of CP systems installed in a five-story building (fully scaled) are used for the validation of the proposed methodology. Experimental acceleration and displacement responses of CP systems at different locations as well as the damage-progression pattern in the suspended ceiling system are predicted well through the use of the proposed modeling technique.
{"title":"Experimental-based numerical simulation of interacting suspended ceiling-sprinkler piping systems","authors":"S. Soroushian, Razieh Rezvani, A. Zaghi, M. Maragakis","doi":"10.1177/87552930231211296","DOIUrl":"https://doi.org/10.1177/87552930231211296","url":null,"abstract":"Suspended ceiling and fire sprinkler piping (CP) systems are two of the most common interacting nonstructural elements inside the buildings. While each of these elements individually is prone to losses during the earthquakes, their interaction can even more intensify their associated damage. This article aims to integrate system-level modeling methodology by using existing subsystem-level models in OpenSees platform to simulate the interacting behavior of CP systems. To do so, the numerical model of the CP systems is developed by using a series of previously developed component-level nonlinear models. Experimental results from a shake table study of CP systems installed in a five-story building (fully scaled) are used for the validation of the proposed methodology. Experimental acceleration and displacement responses of CP systems at different locations as well as the damage-progression pattern in the suspended ceiling system are predicted well through the use of the proposed modeling technique.","PeriodicalId":505879,"journal":{"name":"Earthquake Spectra","volume":"102 28","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139391089","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}
Pub Date : 2024-01-02DOI: 10.1177/87552930231217003
Alessandro Valentini, Francisco Beltran
In many countries, seismic characterization of the site selected for a critical structure or industrial facility is required in terms of site-specific seismic ground motion hazard. For this purpose, a probabilistic seismic hazard analysis (PSHA), performed under the Senior Seismic Hazard Analysis Committee (SSHAC) protocol, is an extended practice for nuclear facilities. In the past decade, SSHAC Level 3 studies have been performed for sites in North America, Europe, Japan, Taiwan, and South Africa. When analyzing PSHA results, the mean-to-median spectral acceleration ratios given by the hazard curves can be interpreted as a measure of the degree of epistemic uncertainty associated with the results. In this article, results of 33 SSHAC Level 3 studies have been used to determine mean-to-median spectral acceleration ratios and the statistics of these ratios, as a function of spectral frequency and annual frequency of exceedance (AFE). The purpose was to develop a reference for the range of uncertainty that is typically captured in this kind of studies. It has been found that, for a given AFE, ratios corresponding to different sites are within a relatively small interval, especially for the spectral frequency band between 2.5 and 10 Hz, which is the band normally more relevant for the seismic design of nuclear installations. In this band, for 10−4 yr−1 AFE, a mean/median ratio of 1.40 would envelop practically all investigated sites.
{"title":"Mean-to-median spectral acceleration ratios in Senior Seismic Hazard Analysis Committee Level 3 probabilistic seismic hazard analyses: An analysis of reported results","authors":"Alessandro Valentini, Francisco Beltran","doi":"10.1177/87552930231217003","DOIUrl":"https://doi.org/10.1177/87552930231217003","url":null,"abstract":"In many countries, seismic characterization of the site selected for a critical structure or industrial facility is required in terms of site-specific seismic ground motion hazard. For this purpose, a probabilistic seismic hazard analysis (PSHA), performed under the Senior Seismic Hazard Analysis Committee (SSHAC) protocol, is an extended practice for nuclear facilities. In the past decade, SSHAC Level 3 studies have been performed for sites in North America, Europe, Japan, Taiwan, and South Africa. When analyzing PSHA results, the mean-to-median spectral acceleration ratios given by the hazard curves can be interpreted as a measure of the degree of epistemic uncertainty associated with the results. In this article, results of 33 SSHAC Level 3 studies have been used to determine mean-to-median spectral acceleration ratios and the statistics of these ratios, as a function of spectral frequency and annual frequency of exceedance (AFE). The purpose was to develop a reference for the range of uncertainty that is typically captured in this kind of studies. It has been found that, for a given AFE, ratios corresponding to different sites are within a relatively small interval, especially for the spectral frequency band between 2.5 and 10 Hz, which is the band normally more relevant for the seismic design of nuclear installations. In this band, for 10−4 yr−1 AFE, a mean/median ratio of 1.40 would envelop practically all investigated sites.","PeriodicalId":505879,"journal":{"name":"Earthquake Spectra","volume":"4 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139453201","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}
Pub Date : 2024-01-02DOI: 10.1177/87552930231219220
Raul Rincon, Jamie Ellen Padgett
Although fragility function development for structures is a mature field, it has recently thrived on new algorithms propelled by machine learning (ML) methods along with heightened emphasis on functions tailored for community- to regional-scale application. This article seeks to critically assess the implications of adopting alternative traditional and emerging fragility modeling practices within seismic risk and resilience quantification to guide future analyses that span from the structure to infrastructure network scale. For example, this article probes the similarities and differences in traditional and ML techniques for demand modeling, discusses the shift from one-parameter to multiparameter fragility models, and assesses the variations in fragility outcomes via statistical distance concepts. Moreover, the previously unexplored influence of these practices on a range of performance measures (e.g. conditional probability of damage, risk of losses to individual structures, portfolio risks, and network recovery trajectories) is systematically evaluated via the posed statistical distance metrics. To this end, case studies using bridges and transportation networks are leveraged to systematically test the implications of alternative seismic fragility modeling practices. The results show that, contrary to the classically adopted archetype fragilities, parameterized ML-based models achieve similar results on individual risk metrics compared to structure-specific fragilities, promising to improve portfolio fragility definitions, deliver satisfactory risk and resilience outcomes at different scales, and pinpoint structures whose poor performance extends to the global network resilience estimates. Using flexible fragility models to depict heterogeneous portfolios is expected to support dynamic decisions that may take place at different scales, space, and time, throughout infrastructure systems.
虽然结构的脆性函数开发是一个成熟的领域，但最近在机器学习（ML）方法的推动下，新算法得到了蓬勃发展，同时也更加强调为社区到区域规模的应用量身定制的函数。本文旨在批判性地评估在地震风险和抗震能力量化中采用传统和新兴脆性建模方法的影响，以指导未来从结构到基础设施网络规模的分析。例如，本文探讨了需求建模的传统技术和 ML 技术的异同，讨论了从单参数脆性模型到多参数脆性模型的转变，并通过统计距离概念评估了脆性结果的变化。此外，还通过所提出的统计距离指标，系统地评估了这些做法对一系列性能指标（如损坏的条件概率、单个结构的损失风险、组合风险和网络恢复轨迹）的影响。为此，利用桥梁和交通网络进行了案例研究，系统地检验了其他地震脆性建模方法的影响。结果表明，与经典的原型脆性相反，基于参数化 ML 的模型与特定结构的脆性相比，在单个风险指标上取得了相似的结果，有望改进组合脆性定义，在不同尺度上提供令人满意的风险和恢复力结果，并精确定位那些性能不佳并延伸到全球网络恢复力估算的结构。使用灵活的脆性模型来描述异构组合，有望为整个基础设施系统中可能在不同规模、空间和时间发生的动态决策提供支持。
{"title":"Fragility modeling practices and their implications on risk and resilience analysis: From the structure to the network scale","authors":"Raul Rincon, Jamie Ellen Padgett","doi":"10.1177/87552930231219220","DOIUrl":"https://doi.org/10.1177/87552930231219220","url":null,"abstract":"Although fragility function development for structures is a mature field, it has recently thrived on new algorithms propelled by machine learning (ML) methods along with heightened emphasis on functions tailored for community- to regional-scale application. This article seeks to critically assess the implications of adopting alternative traditional and emerging fragility modeling practices within seismic risk and resilience quantification to guide future analyses that span from the structure to infrastructure network scale. For example, this article probes the similarities and differences in traditional and ML techniques for demand modeling, discusses the shift from one-parameter to multiparameter fragility models, and assesses the variations in fragility outcomes via statistical distance concepts. Moreover, the previously unexplored influence of these practices on a range of performance measures (e.g. conditional probability of damage, risk of losses to individual structures, portfolio risks, and network recovery trajectories) is systematically evaluated via the posed statistical distance metrics. To this end, case studies using bridges and transportation networks are leveraged to systematically test the implications of alternative seismic fragility modeling practices. The results show that, contrary to the classically adopted archetype fragilities, parameterized ML-based models achieve similar results on individual risk metrics compared to structure-specific fragilities, promising to improve portfolio fragility definitions, deliver satisfactory risk and resilience outcomes at different scales, and pinpoint structures whose poor performance extends to the global network resilience estimates. Using flexible fragility models to depict heterogeneous portfolios is expected to support dynamic decisions that may take place at different scales, space, and time, throughout infrastructure systems.","PeriodicalId":505879,"journal":{"name":"Earthquake Spectra","volume":"101 43","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139391101","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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