Seismic Resilience Assessment Research Articles

Assessment of urban seismic resilience of a town in Eastern Turkiye: Turkoglu, Kahramanmaras before and after 6 February 2023 M 7.8 Kahramanmaras earthquake

Assessment of urban seismic resilience of a town in Eastern Turkiye: Turkoglu, Kahramanmaras before and after 6 February 2023 M 7.8 Kahramanmaras earthquake

Mainshock-aftershock building fragility methodology for community resilience modeling

This study introduces a methodology for developing fragility functions that enable the assessment of seismic vulnerability and resilience at the community level for buildings subjected to mainshock-aftershock sequences. To date, this has been assessed at a single structural level or through statistical combinatorial approaches. This paper provides a solution for a suite of archetypes including ductile and non-ductile reinforced concrete frames as well as woodframe buildings. The findings highlight the central role of aftershocks in exacerbating damage states and increasing economic losses, emphasizing the importance of including these events in accurate assessments of community resilience and seismic risk. The suite of archetypes is applied at the community level using the IN-CORE platform to quantify the effect of incorporating aftershocks into community-level seismic vulnerability analyses. The ability to accurately include the effect of aftershocks within community-level risk and resilience analyses will be key to planning for earthquakes.

Energy-based damage assessment method for masonry walls under seismic and fire loads

The evaluation of the out-of-plane (OOP) behavior for infilled walls is a critical aspect of regional seismic and fire resilience assessment. This study presents a detailed finite element (FE) model that comprehensively captures the seismic and fire behaviors of masonry walls. The FE model incorporates key factors governing the thermo-mechanical behavior of masonry walls, including temperature-dependent material properties, nonlinearities in geometry and material, block cracking and crushing, and mortar damage. Then, an energy-based damage criterion is proposed based on the principle of energy conservation, leveraging the combined mixed fracture energy and internal energy of elements. In addition, this study defines the damage levels of masonry walls under OOP loading and fire and determines corresponding damage indices using the proposed energy-based damage criterion. This criterion is further compared with a stiffness-based damage criterion. Finally, the proposed damage assessment method is employed to evaluate the damage evolution of infilled walls under seismic, fire and post-earthquake fire scenarios, and to conduct a fragility analysis. The results demonstrate a high degree of agreement between the predicted and measured damage states of masonry walls under seismic and fire loads. More severe seismic damage does not always result in diminished fire resilience. Evaluating post-earthquake fire damage requires considering the impact of displacement directions caused by earthquakes and fires.

Vulnerability-based seismic resilience and post-earthquake recovery assessment for substation systems

The function of substation systems is significantly influenced by earthquakes. To assess the seismic resistance of substation systems and improve post-earthquake recovery efficiency, this study constructs a multi-module framework for seismic vulnerability assessment of substations. Based on the equipment functional status analysis module, a functional network model was established considering the structural function and electrical load of substation systems. The system functional state matrix was obtained through Monte Carlo simulation, and the seismic vulnerability was assessed from the aspects of electrical transmission reliability and the importance of power users. Subsequently, a substation functional index was established based on seismic vulnerability parameters. Post-earthquake functional recovery strategy analysis frameworks were constructed to quantitatively evaluate the recovery process. A stepped functional time-varying function was proposed through iterative analysis, thereby converting the probability parameters of functional status into seismic resilience deterministic indices. Through seismic resilience analysis of a typical 220 kV step-down substation, seismic vulnerability curves for both electrical transmission and power users were obtained. Furthermore, the seismic sensitive intervals of the substation and key equipment for post-earthquake recovery were clarified. Notably, the seismic resilience level and optimal recovery strategy of the typical 220 kV step-down substation were determined.

Seismic resilience assessment of sheet-pile wharves in liquefiable soils using different liquefaction countermeasures

Seismic resilience assessment is essential for maintaining the functionality of sheet-pile wharves in liquefiable soils, preventing significant damages and minimizing losses during earthquakes. This study delves into the seismic resilience of sheet-pile wharves, focusing specifically on the effectiveness of four different liquefaction countermeasure techniques: anchor lengths, cement deep mixing, stone columns, and soil compaction. As such, an advanced two-dimensional (2D) Finite Element (FE) computational framework is established, motivated by a typical large-scale sheet-pile wharf configuration. Within this framework, a recently developed multi-yield surfaces plasticity model is employed, with the modeling parameters calibrated through undrained stress-controlled cyclic triaxial tests and a centrifuge test. Subsequently, the impacts of these liquefaction countermeasures on the seismic resilience of the sheet-pile wharves are systematically investigated. Additionally, the effectiveness of combining longer anchor lengths with the other three mitigation techniques to enhance the seismic resilience of the sheet-pile wharves are examined. It is demonstrated that the synergistic effects of different liquefaction countermeasures can further reduce the liquefaction potential, thereby improving the seismic resilience. Overall, the FE analysis technique and the resulting insights are highly significant for the seismic resilience assessment of equivalent sheet-pile wharves in liquefiable soils, particularly when implementing such liquefaction mitigation countermeasures.

Comprehensive resilience assessment of bridge networks using ensemble learning method

The assessment of seismic resilience in bridge networks holds significant importance for urban disaster prevention and mitigation efforts. Unlike individual bridges, there has been limited efficiency in assessing bridge networks. A seismic resilience assessment methodology for bridge networks using ensemble learning methods is proposed in this paper. Initially, a comprehensive resilience index is proposed, integrating both structural and functional aspects of bridge networks. Using 3 ensemble learning methods, 9 parameters related to network structure and traffic characteristics are chosen as input variables for predicting the seismic resilience index. Finite element models of 18 bridges are constructed and combined to generate 3500 sets of virtual bridge networks for model training. The predictive accuracy of models trained using the 3 ensemble methods exceeds 89 %, and the expected values of peak ground acceleration (PGA) and functional loss rate are the most influential features. The methodology offers insights into the application of ensemble learning for bridge network seismic resilience assessment.

Seismic Resilience Assessment for Steel-concrete Composite Bridges including Impacts of Near-fault Earthquakes

This paper proposes a seismic resilience assessment method for steel-concrete composite bridges (SCCB) considering near-fault earthquake hazards. Based on conventional probabilistic seismic hazard disaggregation analysis, a correction factor is defined to represent the proportion of the occurrence probability of the near-fault pulse-like, near-fault non-pulse-like and far-field earthquake conditioned on a given intensity level concerning the total occurrence probability of all earthquakes. The parameters of functionality recovery functions are modified using the factor proposed, and then the restoration processes after each type of earthquake are estimated. Correspondingly, vulnerabilities of a typical SCCB under near-fault and far-field earthquakes are developed as a case study. Based on the seismic hazard and fragility results, the seismic risk for each type of earthquake in a 50-year horizon is estimated. After that, the modified functionality recovery function is derived from the expected functionality. For implementation of the method proposed, the expected seismic resilience indices of a typical SCCB involved in the SEQBRI project are estimated, and the seismic resilience assessment is conducted. For comparison analysis, the seismic resilience assessment without considering earthquake type is also conducted using the same bridge. The result shows that the seismic resilience of bridges in near-fault earthquake scenarios can be analyzed by the method proposed, and reducing the structural vulnerability under low-intensity level earthquakes and improving the structural recovery efficiency for slight and moderate damage states are more meaningful to enhance the seismic resilience of bridges.

Life-cycle seismic resilience prediction of sea-crossing bridge piers exposed to chloride-induced corrosion in marine environments

The life-cycle seismic resilience assessment of sea-crossing highway bridges plays a crucial role in guiding decisions for their long-term operation, maintenance, and rehabilitation. Due to the inherently stochastic nature of marine environments, evaluating the resilience of bridges while considering all possible environmental scenarios throughout their service life necessitates substantial computational efforts and presents practical challenges. Thus, this study develops a three-stage framework for predicting the life-cycle seismic resilience of sea-crossing highway bridges. Stochastic models for marine environmental conditions and bridge durability are developed and validated using experimental measurement data. A modified Good Lattice Point-Partially Stratified Sampling (GLP-PSS) method is employed to generate a uniform and limited number of samples. A typical prestressed concrete sea-crossing highway bridge is selected as the benchmark bridge, and parameterized numerical models are established using 460 representative environmental parameter samples on the OpenSees platform. Leveraging the environmental model and material properties, the durability of the bridge is predicted over its service life. Nonlinear time history analyses are carried out for each bridge model using 120 real ground motion records, which allow the identification of variations in seismic demands, capacities, and system fragilities at different time intervals. Subsequently, the life-cycle seismic resilience of the bridge is predicted utilizing surrogate models based on the response surface method (RSM) and artificial neural networks (ANN), respectively. Finally, the time-dependent probabilistic characteristics of seismic resilience are thoroughly discussed. Results indicate that ANN demonstrates a higher degree of generalization capability in predicting the life-cycle seismic resilience. Focusing solely on changes in mean resilience over the service time may lead to an underestimation of bridge resilience, as it may ignore the tails of its distribution, potentially resulting in an overestimation of bridge resilience. Furthermore, global warming may expedite the decline in resilience.

Auto-WoodSDA: A scalable end-to-end automation framework to perform probabilistic seismic risk and recovery assessment of new residential woodframe buildings

The seismic performance of residential woodframe buildings has a widespread and lasting impact on the socioeconomic vitality of a community. To enable efficient seismic risk and resilience assessment, a comprehensive framework that is rooted in performance-based earthquake engineering (PBEE) methodology is proposed. The framework is formulated as a computational workflow which is operationalized as an automation program dubbed “Auto-WoodSDA”. The end-to-end platform is developed to perform four major tasks: (1) generate code-compliant seismic design, (2) create numerical models, (3) perform nonlinear analyses, and (4) assess earthquake-induced financial losses and functional recovery time. Given the user inputs, Auto-WoodSDA sequentially executes the four tasks without intermediate human intervention to produce seismic performance metrics such as the expected annual loss. It is presented as a ready-to-implement platform that is computationally efficient and scalable in performing large-scale seismic risk and resilience assessment. An example building from the existing literature is used to demonstrate the key features of the automation framework and verify the results. The results underscore the ability of the AutoWoodSDA computational workflow to automate the generation of reliable new code-compliant woodframe building designs, perform nonlinear analysis, and assess the earthquake-induced impacts using PBEE principles.

Seismic fragility and resilience assessment of large‐span cable‐stayed bridges under multi‐support ground motions with non‐Gaussian characteristics

Seismic fragility and resilience assessment of large‐span cable‐stayed bridges under multi‐support ground motions with non‐Gaussian characteristics

Seismic behavior and resilience assessment of prefabricated beam–column joint with replaceable graded-yielding energy-dissipating connectors

Conventionally assembled monolithic concrete frame structures achieve structural ductility through beam-end failure, which results in structures that are difficult to repair after an earthquake. To improve the seismic and resilience performance, a prefabricated concrete beam–column joint with replaceable graded-yielding energy-dissipating connectors (RGECs) is introduced. The connectors assembled on the upper and lower sides of the beam end dissipate energy and transfer the beam-end load with the steel hinge device. By adjusting the design bearing-capacity coefficient of RGECs to precast beams, the plasticity and damage of the structure can be centered on the core energy-dissipation bending–shear components (BSCs) and buckling segment (BS) of the RGEC, and the structural function can be quickly recovered by replacing only the damaged RGECs after a seismic disaster. Moreover, compared to the conventional joints, the joint with RGEC can achieve target seismic-performance goals at different seismic-risk levels by designing BSCs and BS with graded yielding. Low-cyclic-loading tests were performed on seven full-scale beam–column joint specimens to investigate the effects of different core energy-dissipating member thicknesses, beam reinforcement ratios and loading protocols on the seismic behavior of the proposed joint. Subsequently, the damaged RGECs were replaced, and the structural-function resilience performance was evaluated in terms of the function-recovery efficiency and quality, indicated by the hysteresis response, strain development, and component energy dissipation. The experimental results proved that the beam–column joint exhibited excellent seismic performance and could realize graded-yielding energy dissipation. The damage to the specimens was concentrated in the RGECs, the key members (beams and columns) were in an elastic state, and the energy dissipation ratio of the RGEC was more than 97 %. This enables the rapid recovery of function after earthquakes. After replacing the RGEC, the hysteresis response, strain development, and component energy dissipation of the specimens were consistent with those of the initial specimens. Compared with the original specimen, the difference in each seismic index of the replaced specimen was less than 10 %. Additionally, the structural function recovered quickly, and the resilient performance was good.

Design of Radial Flux PM Synchronous Motor for EV Applications

Abstract: In recent years, with the accelerated process of urbanization, the continuous growth of urban areas and population sizes has posed higher demands on urban earthquake safety. The theory of resilient cities offers a new approach to effectively address urban earthquake safety risks. However, there is still a lack of reasonable methods for assessing and constructing urban seismic resilience both domestically and internationally. Therefore, this paper elucidates the connotation, essential characteristics, components, and evaluation indicators of a seismic-resilient city, summarizing the components of urban seismic resilience as "one fundamental, two guarantees," which include the engineering system, institutional system, and social and economic system. This paper establishes a dual-parameter urban seismic resilience assessment method based on post-earthquake losses and recovery time, proposing a "set goals, assess, improve, reassess" approach for building resilient cities. The proposed method can provide theoretical guidance and practical basis for assessing and enhancing the seismic resilience of individual infrastructures, engineering systems, urban systems, and resilience to other disasters.

A practical method for functional recovery analysis based on seismic resilience assessment of city building portfolios

Enhancing the seismic resilience of city building portfolios represents a pivotal strategy for mitigating the adverse effects of earthquakes. A practical method for functional recovery analysis is proposed to quantitatively assess the seismic resilience of city building portfolios. The proposed method involves quantifying delay time and developing repair scheduling schemes. The delay time considers the dependencies of normal functioning buildings on infrastructure service availability and road accessibility. It emphasizes the varying demands of buildings for critical versus general infrastructure services. The repair scheduling scheme, conducted in two steps, employs a rational repair priority index that integrates the post-earthquake residual functionality, service capacity, and relative importance of buildings. This scheme prioritizes the repair of life-rescue-related buildings, distinguishes the repair sequence for different occupancy types of buildings, and reflects the principles of local governments in repair decision-making. The effectiveness of this practical method is demonstrated through a case study. Recovery curves are compared under different earthquake scenarios and levels of labor force constraints. The concept of normalized time is introduced to allow for a comparative assessment of seismic resilience across different recovery scenarios in a more practical manner. The results can provide valuable guidance for formulating pre-earthquake risk reduction strategies, developing post-earthquake functional recovery schemes, and constructing more resilient cities.

A demand-based three-stage seismic resilience assessment and multi-objective optimization method of community water distribution networks

This paper proposes a three-stage resilience concept that takes into account reliability, vulnerability and recovery resilience of water distribution networks (WDNs) from three phases, namely, pre-disaster preparation (PDP) phase, disaster response (DR) phase and the post-disaster recovery (PDR) phase. Based on the three-stage resilience concept, the initial performance, robustness and multi-objective optimization recovery method are proposed. In PDP phase, based on the reliability concept and the user demand, the initial performance of WDNs is defined, and the method is proposed based on Monte Carlo simulation method combined with seismic fragility of pipelines. In DR phase, a comprehensive quantitative index is proposed to quantify the robustness of WDNs by integrating the structural attributes, topological attributes and operational characteristics of WDNs. Finally, on the basis of the previous two stages, the disaster recovery process of failed pipelines of WDNs is further analyzed, and a multi-objective recovery optimization model of failed pipelines with consideration of users’ demands under the resources constraints is proposed to achieve the resilience enhancement. Through a case, the three-stage resilience assessment optimization enhancement of WDNs is implemented using the improved NSGA-II. The proposed method can be used as a basis for disaster prevention planning and seismic measures.

Seismic fragility and resilience assessment of steel frame with replaceable T-stub connection components

Based on a rational design, steel beam-column joints with replaceable T-stub connection components (SBCJ-RTCCs) possess superior structural fuse performance and seismic resilience performance. To further evaluate the benefits of steel frames using RTCCs in terms of dynamic response, structural and non-structural components damage as well as seismic resilience, a 12-story steel frame equipped with RTCCs (SF-RTCCs) and a steel moment resisting frame (SMRF) were designed and established. On the basis of validating the simulation results with the experimental findings, the nonlinear dynamic analyses and incremental dynamic analysis (IDA) based seismic fragility analysis was performed. The results confirm that the introducing RTCCs into steel frames can significantly mitigate base shear and floor acceleration as well as produce a more uniform inter-story deformation and a more rational yielding mechanism. Meanwhile, the SF-RTCCs can obtain comparable collapse-resistant performance compared to SMRF, and both frames possess sufficient redundancy to resist structural collapse. Thanks to the lower floor acceleration responses, the SF-RTCCSs performs much better than SMRF in controlling non-structural components damage. After DBE excitations, the probabilities of RTCCs can be replaced by 1st class and 2nd class was 17.2 % and 84.9 %, respectively. After MCE excitations, RTCCs has about 29.3 % and 67.2 % probability that it can be replaced by 2nd class and 3rd class, respectively. Considering the lower economic losses, short repair time and fewer casualties, the rating of seismic resilience of SF-RTCCs was enhanced from one-star of SMRF to two-star.

A Novel Method for the Seismic Resilience Assessment of Railway Stations Based on Quantitative Indices

ABSTRACT A novel method for assessing the seismic resilience of railway stations is introduced. With this method, a railway station is divided into five constituent systems. The structural components, nonstructural components, and especially professional equipment that affect the functions in each system are identified and analyzed. Significantly, a new calculation method for seismic resilience indices, encompassing repair cost, repair time, casualties, and resilience grade, is proposed. Additionally, the complete seismic resilience assessment process is outlined. Furthermore, a case study was conducted on a typical railway station in China to demonstrate the application of this new seismic resilience assessment method.

A probabilistic framework to evaluate seismic resilience of substations based on three-stage uncertainty

Electrical substation systems exhibit vulnerability after an earthquake. It results in significant economic losses because of the uncertainty of the functional state and recovery process. To quantitatively assess the uncertainty of substations, this paper proposes a probability-based seismic resilience assessment framework. This framework considers uncertainty in three stages: functional state, functional recovery, and resource constraints. Based on the functional characteristics of substation systems, a directed acyclic graph was constructed, and the Monte Carlo algorithm was used to obtain the functional state matrix, thereby establishing a probability-based functional state model. Moreover, a dynamic post-earthquake functional recovery analysis framework was built based on recovery efficiency metrics, and functional recovery paths were obtained through iterative simulations. A stepped functional recovery curve was developed based on resource constraints. Three-stage uncertainty parameters were transformed into resilience features for quantitative assessment. By analysing seismic resilience of a typical 220 kV step-down substation, probability distributions of functional recovery curves and confidence intervals for seismic resilience metrics were obtained. Notably, mutual constraint relationships among resource conditions were identified.

On the integration of inspection data with seismic resilience assessment of corroded reinforced concrete structures

This research aims to improve the traditional statistical approach to evaluate the seismic resilience of concrete structures exposed to chloride attack. In the mentioned approach, the uncertain parameters are modeled using certain probability distribution functions (PDFs) selected from some standards such as fib. However, the mentioned PDFs should contain the actual conditions of the desired structure. This paper introduces a Bayesian framework for updating PDFs used in deterioration analysis, which is an important part of the life-cycle seismic resilience assessment process of corroded concrete structures. The proposed methodology was applied to a two-story reinforced concrete school in Iran that suffered from chloride corrosion for twenty years. The seismic resilience of the structure was investigated for a 50-year life cycle. The results showed that the updated model can significantly reduce the uncertainty of the influencing parameters in the seismic resilience evaluation process. Using the updated model resulted in a conservative seismic resilience index compared to the non-updated model. This research shows that the role of inspection data in periodically updating the seismic-resistance calculations of corroded concrete structures is not only necessary but also possible and beneficial.

Seismic time-dependent resilience assessment of aging highway bridges incorporating the effect of retrofitting

Bridges are one of the most critical components of transportation networks, which are highly vulnerable due to exposure to natural hazards. In addition, multiple degradation mechanisms can considerably affect the functionality of highway bridges during their service life. Therefore, accumulated damage could also arise continuously because of seismic loading and structural deterioration, which consequently can change system resilience over its life-cycle. This study presents a probabilistic methodology to systematically evaluate and develop the time-dependent seismic resilience curves for Reinforced Concrete (RC) bridges under chloride attacks. In this regard, different jacketing materials with varying thicknesses are chosen for retrofitting purposes. In each case, the time-dependent seismic fragility curves (four damage states) for calculating the time-dependent seismic resilience curves are established through Probabilistic Seismic Demand Models (PSDMs) by performing Incremental Dynamic Analysis (IDA). Finally, the time-dependent seismic resilience curves are evaluated based on the time-dependent seismic fragility curves using the restoration function for all the retrofitting strategies by considering the effect of structural deterioration over time. The results indicate that aging, earthquake intensities, and retrofitting strategies undeniably affect the time-variant seismic resilience of bridges, which is helpful for the long-term safety and reliability of bridges.

Seismic fragility analysis of structures via an Adaptive Gaussian Mixture Model and its application to resilience assessment

Seismic fragility analysis and seismic resilience assessment are pivotal tasks within the performance-based earthquake engineering framework. The former aims to quantitatively assess the probability of engineering structures sustaining various degrees of damage when subjected to earthquakes of varying intensity levels. In contrast to many traditional seismic fragility methods, this paper introduces a precise and versatile approach grounded in reliability analysis, with the goal of eliminating the restrictive lognormal assumption. Initially, the proposed method involves conducting seismic reliability analysis of structures using the Fractional Exponential Moments-based Maximum Entropy Method (FEM-MEM). This approach efficiently yields failure probabilities. Subsequently, an Adaptive Gaussian Mixture Model (AGMM) is presented for fitting a set of failure probability points, producing comprehensive and continuous seismic fragility curves. Notably, AGMM offers remarkable flexibility in modeling fragility curves, ensuring precise estimations for subsequent resilience assessments. Building upon the results of the fragility analysis, the paper proceeds to assess the seismic resilience of structures. The proposed method’s feasibility and effectiveness are validated through two illustrative numerical examples. The results demonstrate that, in comparison to the conventional lognormal assumption, the proposed method offers superior accuracy and broader applicability for conducting seismic fragility analyses of structures.