Seismic isolation design and resilience improvement of railway station considering the influence of near-fault pulse-like ground motions

To improve the resilience of railway stations,a typical station was selected as the research object,and an isolation design was introduced.Twenty-four groups of near-fault pulse-like ground motions were selected.The seismic resilience of the no-isolation railway stations(NIRS)and the isolation railway stations(IRS)were compared to provide a numerical result of the improvement in resilience.The results show that in the station isolation design,the station's functional requirements and structural characteristics should be considered and the appropriate placement of isolation bearings is under the waiting room.Under the action of a rare earthquake,the repair cost,repair time,rate of harm and death of the IRS were decreased by 8.04 million,18.30 days,6.93×10^(-3)and 1.21×10^(-3),respectively,when compared to the NIRS.The IRS received a seismic resilience grade of three-stars and the NIRS only one-star,indicating that rational isolation design improves the seismic resilience of stations.Thus,for the design of stations close to earthquake faults,it is suggested to utilize appropriate isolation techniques to improve their seismic resilience.

From earthquake resistance structure to earthquake resilience city–urban seismic resilience assessment

Earthquakes pose significant perils to the built environment in urban areas.To avert the calamitous aftermath of earthquakes,it is imperative to construct seismic resilient cities.Due to the intricacy of the concept of urban seismic resilience(USR),its assessment is a large-scale system engineering issue.The assessment of USR should be based on the notion of urban seismic capacity(USC)assessment,which includes casualties,economic loss,and recovery time as criteria.Functionality loss is also included in the assessment of USR in addition to these criteria.The assessment indicator system comprising five dimensions(building and lifeline infrastructure,environment,society,economy,and institution)and 20 indicators has been devised to quantify USR.The analytical hierarchy process(AHP)is utilized to compute the weights of the criteria,dimensions,and indicators in the urban seismic resilience assessment(USRA)indicator system.When the necessary data for a city are obtainable,the seismic resilience of that city can be assessed using this framework.To illustrate the proposed methodology,a moderate-sized city in China was selected as a case study.The assessment results indicate a high level of USR,suggesting that the city possesses strong capabilities to withstand and recover from potential future earthquakes.

Upcrossing-based time-dependent resilience of aging structures

The time-dependent resilience of an in-service aging structure provides quantitative measure of the structural ability to prepare for,adapt to,withstand and recover from disruptive events.Resilience models have been proposed in the literature to evaluate the resilience of aging structures subjected to discrete load processes,which are,however,not applicable to handle resilience problems considering continuous load processes.In this paper,a new method is developed to evaluate the time-dependent resilience of aging structures subjected to a continuous load process.The proposed method serves as the complement of the existing resilience models addressing discrete load processes,and takes into account the aging effects of the structural resistance/capacity and the nonstationarity in loads as a result of climate change.A structure suffers from a damage state upon the occurrence of an upcrossing of the load effect with respect to the resistance/capacity,leading to the reduction of the performance function,followed by a recovery process that restores the performance.The proposed method enables the time-dependent resilience to be evaluated via a closed form solution.It is also revealed that,the proposed resilience model takes an extended form of the existing formula for upcrossing-based time-dependent reliability,thus establishing a unified framework for the two quantities.The applicability of the proposed method is demonstrated through examining the time-dependent resilience of a residential building subjected to wind load.The effects of key factors on resilience,including the nonstationarity and correlation structure of the load process,as well as the resistance/capacity deterioration scenario,are investigated through an example.In particular,the structural resilience would be overestimated if ignoring the potential impacts of climate change,which is a relatively non-conservative evaluation.

Resilience-incorporated seismic risk assessment of precast concrete frames with“dry”connections

A resilience-incorporated risk assessment framework is proposed and demonstrated in this study to manifest the advantageous seismic resilience of precast concrete frame(PCF)structures with“dry”connections in terms of their low damage and rapid recovery.The framework integrates various uncertainties in the seismic hazard,fragility,capacity,demand,loss functions,and post-earthquake recovery.In this study,the PCF structures are distinguished from ordinary reinforced concrete frame(RCF)structures by characterizing multiple limit states for the PCF based on its unique damage mechanisms.Accordingly,probabilistic story-wise pushover analyses are performed to yield story-wise capacities for the predefined limit states.In the seismic resilience analysis,a step-wise recovery model is proposed to idealize the functionality recovery process,with separate considerations of the repair and non-repair events.The recovery model leverages the economic loss and downtime to delineate the stochastic post-earthquake recovery curves for the resilience loss estimation.As such,contingencies in the probabilistic post-earthquake repairs are incorporated and the empirical judgments on the recovery parameters are largely circumvented.The proposed framework is demonstrated through a comparative study between two“dry”connected PCFs and one RCF designed as alternative structural systems for a prototype building.The results from the risk quantification indicate that the PCFs show reduced loss hazards and lower expected losses relative to the RCF.Particularly,the PCF equipped with energy dissipation devices at the“dry”connections largely reduces the expected economic loss,downtime,and resilience loss by 29%,56%,and 60%,respectively,compared to the RCF.

Spatial correlation in building seismic performance for regional resilience assessment

Probabilistic seismic performance assessment method for buildings offers a valuable approach to simulate the broader regional impacts:economic losses,downtime,and casualties.A crucial aspect of this process entails ac-counting for the spatial correlation of building performances,aiming for an accurate estimation of the probability of extreme regional losses,such as the simultaneous collapse of buildings with similar structural characteristics.In this study,a correlation model based on a Gaussian random field is employed,and several key challenges associated with its application are addressed.In addition,efficiency of five different methods of selecting station records from the same earthquake scenario is compared.The minimum number of earthquake records necessary to achieve a stable correlation result is determined.Additionally,spatial correlations derived from different his-tory earthquake events are compared.By addressing these critical issues,this research contributes to refining the reliability of probabilistic methods for regional resilience assessment.

Seismic Resilience Analysis of a Concrete-Framed Hospital Building with Viscous Dampers

To study the seismic resilience of a concrete-framed hospital building with viscous dampers,the elastoplastic time history analysis of a three-story concrete-framed hospital building under moderate and rare earthquakes was carried out by finite element analysis software.The structure’s overall response was studied,meanwhile,the seismic resilience of the building was evaluated from three aspects:repair cost,repair time,and casualties.The results show that viscous dampers can effectively reduce the repair cost,repair time,and casualties under earthquakes.Compared with the structure without dampers,the repair cost and repair time of the structure with dampers have been reduced by 67%and 69%respectively under moderate earthquakes,42%and 39%respectively under rare earthquakes,and the seismic resilience grade has been increased from zero to one star.

Time-dependent reliability and resilience of aging structures exposed to multiple hazards in a changing environment

Engineering structures are often subjected to the influences of performance deterioration and multiple hazards during their service lives,and consequently may suffer from damage/failure as a result of external loads.Structural reliability and resilience assessment is a powerful tool for quantifying the structural ability to withstand these environmental or operational attacks.This paper proposes new formulas for structural time-dependent reliability and resilience analyses in the presence of multiple hazards,which are functions of the duration of the reference period of interest.The joint impacts of nonstationarities in multiple hazards due to a changing environment,as well as the deterioration of structural performance,are explicitly incorporated.The correlation between the structural resistances/capacities associated with different hazard types is modeled by employing a copula function.It is observed that,under the context of multiple hazards and aging effects,the time-dependent resilience takes a generalized form of time-dependent reliability.The proposed formulas can be used to guide the adaptive design of structures,where adaptive strategies are identified across a range of possible future service conditions.An example is presented to demonstrate the applicability of the proposed method for structural reliability and resilience analyses.

Resilience-based retrofitting of existing urban RC-frame buildings using seismic isolation

The improvement of the seismic resilience of existing reinforced-concrete(RC) frame buildings, which is essential for the seismic resilience of a city, has become a critical issue. Although seismic isolation is an effective method for improving the resilient performance of such buildings, target-oriented quantitative improvements of the resilient performance of these buildings have been reported rarely. To address this gap, the seismic resilience of two existing RC frame buildings located in a high seismic intensity region of China were assessed based on the Chinese Standard for Seismic Resilience Assessment of Buildings. The critical engineering demand parameters(EDPs) affecting the seismic resilience of such buildings were identified. Subsequently, the seismic resilience of buildings retrofitted with different isolation schemes(i.e., yield ratios) were evaluated and compared, with emphasis on the relationships among yield ratios, EDPs, and levels of seismic resilience. Accordingly, to achieve the highest level of seismic resilience with respect to the Chinese standard, a yield ratio of 3% was recommended and successfully applied to the target-oriented design for the seismic-resilience improvement of an existing RC frame building. The research outcome can provide an important reference for the resilience-based retrofitting of existing RC frame buildings using seismic isolation in urban cities.

A benchmark city for seismic resilience assessment

The concept of seismic resilience has received significant attention from academia and industry during the last two decades. Different frameworks have been proposed for seismic resilience assessment of engineering systems at different scales(e.g., buildings, bridges, communities, and cities). Testbeds including Centerville virtual community(CVC), Memphis testbed(MTB), and the virtual city of Turin, Italy(VC-TI) have been developed during the last decade. However, the resilience assessment results of Chinese cities still require calibration based on a unified evaluation model. Therefore, a geographic information system(GIS)-based benchmark model of a medium-sized city located in the southeastern coastal region of China was developed. The benchmark city can be used to compare existing assessment frameworks and calibrate the assessment results. The demographics, site conditions, and potential hazard exposure of the benchmark city, as well as land use and building inventory are described in this paper. Data of lifeline systems are provided, including power, transportation, water, drainage, and natural gas distribution networks, as well as the locations of hospitals, emergency shelters, and schools. Data from past earthquakes and the literature were obtained to develop seismic fragility models, consequence models, and recovery models, which can be used as basic data or calibration data in the resilience assessment process. To demonstrate the completeness of the data included in the benchmark city, a case study on the accessibility of emergency rescue after earthquakes was conducted, and the preliminary results were discussed. The ultimate goal of this benchmark city is to provide a platform for calibrating resilience assessment results and to facilitate the development of resilient cities in China.

Seismic resilience assessment of corroded reinforced concrete structures designed to the Chinese codes

The natural landscape in China exposes many existing RC buildings to aggressive environments.Such exposure can lead to deterioration in structural performance with regard to resisting events such as earthquakes.Corrosion of embedded reinforcement is one of the most common mechanisms by which such structural degradation occurs.There has been increasing attention in recent years toward seismic resilience in communities and their constituent construction;however,to date,studies have neglected the effect of natural aging.This study aims to examine the effect of reinforcement corrosion on the seismic resilience of RC frames that are designed according to Chinese seismic design codes.A total of twenty RC frames are used to represent design and construction that is typical of coastal China,with consideration given to various seismic fortification levels and elevation arrangements.Seismic fragility relationships are developed for case frames under varying levels of reinforcement corrosion,i.e.,corrosion rates are increased from 5%to 15%.Subsequently,the seismic resilience levels of uncorroded and corroded RC frames are compared using a normalized loss factor.It was found that the loss of resilience of the corroded frames is greater than that of their uncorroded counterparts.At the Rare Earthquake hazard level,the corrosioninduced increase in loss of resilience can be more than 200%,showing the significant effect of reinforcement corrosion on structural resilience under the influence of earthquakes.

Controlled rocking pile foundation system with replaceable bar fuses for seismic resilience

Bridges designed following a conventional approach minimize the risk of collapse,but often require challenging,costly,and time-consuming restoration after an earthquake occurs.The new seismic design philosophy requires bridges to maintain functionality even after severe earthquakes.In this context,this paper proposes a controlled rocking pile foundation(CRPF)system and numerically evaluates bridges′degree of seismic resilience.The CRPF system allows a pile cap to rock on a pile foundation and dissipate seismic energy through inelastic deformations of replaceable bar fuses that connect a pile cap and piles.Following the conceptual design of the CRPF system,two analytical models were developed for a bridge pier utilizing the CRPF system and a pier designed to develop a plastic hinge in its column.The analytical results indicate that,after experiencing a severe earthquake,a conventionally designed bridge pier sustained substantial damage in its column and exhibited significant residual displacement.In contrast,a pier using the CRPF system showed negligible residual displacement and maintained elastic behavior except,as expected,for bar fuses.The damaged fuses can be rapidly replaced to recover bridge seismic resistance following an earthquake.Therefore,the CRPF system helps to achieve the desired postearthquake performance objectives.

Practical seismic resilience evaluation and crisis management planning through GIS-based vulnerability assessment of buildings

The objective of this paper is to demonstrate how assessment of seismic vulnerability can be effective in protection against earthquakes.Findings are reported from a case study in a densely populated urban area near an active fault,utilizing practical methods and exact engineering data.Vulnerability factors were determined due to technical considerations,and a field campaign was performed to collect the required data.Multi-criteria decision making was carried out by means of an analytical hierarchy process including a fuzzy standardization.Earthquake scenarios were applied through an implicit vulnerability model.GIS was utilized and the results were analyzed by classifying the state of vulnerability in levels as very low,low,moderate,high,and very high.Seismic resilience was evaluated as vulnerabilities below the moderate state,being about 40% in an intensity of 6 Mercalli and less than 10% in 10 Mercalli.It is concluded that seismic resilience in the area studied is not acceptable,the area is vulnerable in the expected scenarios,and due to the high seismicity of the region,proper crisis management planning is required in parallel with attempts toward retrofitting.In this regard,an emergency map was developed with reference to the assessed vulnerabilities.

Seismic resilience of building inventory towards resilient cities

Resilience of a community after an extreme event depends on the resilience of different infrastructure including buildings.There is no well-established approach to characterize and integrate building resilience for community-level applications.This paper investigates how different potential functionality measures can be used to quantify building resilience indexes,and how the results could be aggregated for a set of buildings to provide an indi-cator for the resilience of an entire community.The quantification of building resilience is based on different functionality measures including repair cost,occupancy level,and asset value.An archetype city block with four different buildings is defined.The individual results for each building are combined using a weight-based ap-proach to quantify the resilience index for the city block.The study then considers small-scale communities with different number of buildings to investigate the influence of contractor availability and collapse probability on the resilience indexes for the set of buildings.Both parameters are shown to be important when quantifying the resilience index.It is also demonstrated that the overall resilience of a community is directly influenced by the resilience of individual buildings.The findings presented here are useful both from the perspective of quantifying the resilience of a community on the basis of its building inventory,as well as for possible inclusion into a holistic framework that aims to quantify community resilience.

Resilience of aging structures and infrastructure systems with emphasis on seismic resilience of bridges and road networks:Review

Risk assessment and mitigation programs have been carried out over the last decades in the attempt to reduce transportation infrastructure downtime and post-disaster recovery costs.Recently,the concept of resilience gained increasing importance in design,assessment,maintenance,and rehabilitation structures and infrastructure systems,particularly bridges and transportation networks,exposed to natural and man-made hazards.In the field of disaster mitigation,frameworks have been proposed to provide a basis for development of qualitative and quantitative models quantifying the functionality and resilience at various scales,including components,groups and systems within infrastructure networks and communities.In these frameworks,the effects of aging and environmental aggressiveness must be explicitly considered,affecting the structural performance and functionality of civil infrastructure systems.Significant efforts have been made to incorporate risk and resilience assessment frameworks into informed decision making to decide how to best use resources to minimize the impact of hazards on civil infrastructure systems.This review paper is part of these efforts.It presents an overview of the main principles and concepts,methods and strategies,advances and accomplishments in the field of life-cycle reliability,risk and resilience of structures and infrastructure systems,with emphasis on seismic resilience of bridges and road networks.

Seismic resilience of internet data center building with different disaster mitigation techniques

Internet data center buildings have great importance for maintaining the post-earthquake functionality of telecommunication networks.It is essential to maintain the functionality of internet data center buildings during earthquakes or recover immediately after earthquakes,which is referred to as seismic resilience.In this study,a seismic resilience assessment framework based on the Chinese code GB/T 38591-2020 is introduced first.The seismic damage and post-earthquake repair of both structural components and non-structural components are considered in the resilience assessment framework.A method for post-earthquake functionality loss quantification is proposed based on damage state and functionality loss of component.The subsystem level and system level functionality loss can be obtained by an integration principle.The seismic resilience of a typical internet data center building was evaluated to demonstrate the effectiveness of the proposed method.To enhance the seismic resilience level,different disaster mitigation techniques including the energy dissipation technology using buckling restrained braces and the base-isolation technology using lead-rubber bearings are adopted.The seismic resilience is quantified and the corresponding seismic resilience curves under different earthquake intensities are developed based on evaluation results.

Long-term sustainability and resilience enhancement of building portfolios

The role of community building portfolios in socioeconomic development and the growth of the built environ-ment cannot be overstated.Damage to these structures can have far-reaching consequences on socioeconomic and environmental aspects,requiring a long-term perspective for recovery.As communities aim to enhance their resilience and sustainability,there is a cost burden that needs to be considered.To address this issue,this pa-per proposes a community-level performance enhancement approach that focuses on optimizing the long-term resilience and sustainability of community building portfolios,taking into account recurrent seismic hazards.A Gaussian process surrogate-based multi-objective optimization framework is utilized to optimize the cost objec-tive while considering performance indicators for resilience and sustainability.The proposed framework involves using performance-based assessment methods to evaluate the socioeconomic and environmental consequences under stochastic and recurrent seismic hazard scenarios.These evaluated indicators are then used to efficiently optimize the community resilience and sustainability,taking into account the retrofit costs.Finally,approximate Pareto-optimal solutions are extracted and utilized for decision-making.In summary,this paper presents a novel approach for optimizing the long-term resilience and sustainability of community building portfolios by consid-ering recurrent seismic hazards.The proposed framework incorporates performance-based assessment methods and multi-objective optimization techniques to achieve an optimal balance between cost,resilience,and sustain-ability,with the ultimate goal of enhancing community well-being and decision-making in the face of seismic hazards.

Seismic Site Specific Study for Seismic Microzonation: A Way Forward for Risk Resiliency of Vital Infrastructure in Sikkim, India

Seismic Microzonation comprising study of site specific seismic Microtremor (H/V ratio) is deployed to generate seismological parameters (Peak Frequency, Peak Amplification, Site Vulnerability Index) that may help estimate requisite factors for sound building design codes that can be used to construct risk resilient infrastructures. In this paper the site of Pakyong, Sikkim, India has been investigated by dividing it into three differed zones (Zone 1, Zone II, Zone III). The study area is associated with site amplification factor varying from 1.47 to 11.49 with corresponding frequency variations from 0.5 Hz - 12.5 Hz in which site vulnerability index found varied from 0.2 to 220.6. The anomalous subsurface formation with its high amplification corresponds to the centre of the Pakyong sites having conspicuous trend in NW-SE direction suggesting the existence of geological formations of Chlorite, Phyllite with intercalations of Quartzite beneath the centre of Pakyong site. The risk associated with vulnerability index for different zones maintains its variability as Zone I > Zone II > Zone III, indicating the low vulnerability index values are attributed to compact parts of the sub-surface materials with less amplifications whilst high vulnerability index of the site corresponds to relatively lower strength of the sub-surface materials and soft sediments underlying the Pakyong site which can be used for constructing risk resilient structure by enhancing the stiffness coefficient of the sub-surface by providing plausible engineering solutions for the purpose.

Seismic Microzonation Study of South Asian Cities and Its Implications to Urban Risk Resiliency under Climate Change Scenario

In this study, an attempt has been made to review the existing framework of earthquake risk resiliency for the urban agglomerates of South Asian earthquake-prone countries (Afghanistan;Bangladesh;Bhutan, India, and Pakistan) with aim of suggesting a plausible model for earthquake risk resiliency for urban agglomerates of the region under the influence of uncontrollable climate change scenario. We demonstrated that the existing infrastructures can be retrofitted to mitigate and reduce the nature and extent of damages to structures to the greater extent whilst site response based comprehensive seismic microzonation is very much required for new settlements and for long-term sustainable urban planning by adopting multi-disciplinary investigations using integrated tools consisted of geophysical, geological, and geotechnical methodologies, which in turn help understand how and why underneath sub-surface layers get amplified to cause destruction of buildings and severe damages to critical infrastructures of South Asian Cities. It is inferred that implementation of fourth level comprehensive seismic Micro, Nano, Pico and Femto zonation study for almost all strategic cities of South Asia is a need of an hour in particular, and of the seismically prone regions of the world, in general, which would be helpful for generating a series of new parameters for development of multi-dimensional risk resilient building design codes for the safer and sustainable infrastructures of urban settlement. The methodology has wide-scale applicability to different kinds of structures and typology of the buildings.

面向抗震韧性评价的型钢混凝土柱易损性函数

为满足型钢混凝土(steel reinforced concrete,SRC)结构地震损失评估及抗震韧性评价的需求,建立SRC柱构件的地震易损性函数十分关键。本文首先基于文献调研,结合JGJ 138—2016《组合结构设计规范》,从国内外文献中筛选了227榀拟静力循环加载的SRC柱,建立标准化的SRC柱试验数据库。其次,考虑失效模式的差异性,将构件分为延性SRC柱和偏脆性SRC柱,并给出了不同类别的构件损伤等级划分标准及对应的修复方法。然后,以位移角为工程需求参数,分别提取了各构件对应不同损伤等级的位移角限值,采用FEMA P-58方法,建立了不同类别的SRC柱在各损伤等级下的易损性函数。最后,给出了与GB/T 38591—2020《建筑抗震韧性评价标准》相容的易损性函数参数表,并分析了抗震等级和轴压比对SRC柱易损性函数参数及易损性曲线的影响。最终,通过分析一幢型钢混凝土框架结构办公楼的抗震韧性,说明了所提出的易损性函数在抗震韧性评价中的作用。

带可拆换T型钢连接件的梁柱节点抗震性能和震后功能快速恢复性能研究

为了实现钢框架结构在地震作用下的集中耗能和震后功能快速恢复,提出了一种带可拆换T型钢连接件的梁柱节点。通过控制T型钢连接件与框架梁的承载力比值,即设计承载力系数,即可实现集中耗能的设计目标,震后仅需更换受损的T型钢连接件即可快速恢复结构功能。设计并制作了4个带T型钢连接件的梁柱节点试件,通过试验和有限元相结合的方法研究了其抗震性能。对典型试件拆换受损的T型钢连接件,并采用可拆换残余转角、滞回性能和组件耗能等指标,从功能恢复效率和功能恢复质量两个方面评估了其震后功能快速恢复性能。研究表明:所有试件均呈现出半刚性节点的特性。采用低屈服点T型钢的试件具有较高的刚度、较好的延性和较大的安全储备,建议在工程中优先采用。除了设计承载力系数较大的试件在试验后期钢梁悬臂段根部出现轻微塑性以外,其余试件的梁柱等非耗能构件均处于弹性状态,且T型钢的耗能比例达到90%以上,为震后功能快速恢复提供了可能。T型钢腹板较薄的RT-2试件具有最大的T型钢可拆换残余转角和梁端可拆换残余转角,采用低屈服点T型钢试件的拆换性能优于普通钢试件。拆换试件与原试件相比,虽然延性系数略有降低,但初始刚度和承载能力几乎没有差别,T型钢连接件仍能发挥集中耗能的作用,试件拆换后功能快速恢复性能良好。