Seismic Risk Research Articles

Seismic Risk Evaluation of Existing Reinforced Concrete Buildings: A Case Study for Çanakkale-Türkiye

Türkiye is in an important earthquake zone, and most of the population is under seismic hazard. The high loss of lives in the past earthquakes indicates that our existing building stock is vulnerable. In this study, a field survey was carried out to determine the existing earthquake risks of reinforced concrete buildings in İsmetpaşa, Barbaros, Cevatpaşa, Kemalpaşa, Namıkkemal, Esenler, and Fevzipaşa Neighborhoods of Çanakkale city center. This study was conducted to specify the regional distribution of risky buildings to be examined by the street survey method called "Simplified methods that can be used to determine the regional risk distribution of buildings" in the implementation regulation of Law No. 6306. For this purpose, 585 reinforced concrete buildings were examined with this method, and the earthquake performance scores of these buildings were determined. The performance scores calculated as a result of reflecting the number of stories, earthquake hazard zone, type of structural system, and structural irregularities of the buildings were evaluated based on different parameters. It was seen that soft stories with values ranging from 50% to 100% and heavy overhangs with values ranging from 37% to 63% were the most common irregularities in existing buildings in Çanakkale.

Time-Dependent Aftershock Probabilistic Forecasting and Ensemble Model Implementation: Insights from the 2021 Ms 7.4 Maduo Earthquake

Abstract On 22 May 2021, an Ms 7.4 earthquake with a focal depth of 17 km struck the Maduo region of Qinghai province, breaking a 3.8-year quiescence of strong earthquakes (magnitude >7.0) in mainland China. This event has increased stress on the Maqin–Maqu segment of the Kunlunshan fault, heightening the potential for a large earthquake in the region. In this study, we employed the epidemic-type aftershock sequence (ETAS) model and Reasenberg–Jones (R–J) model to fit the aftershock sequence following the mainshock, analyzing the temporal response and its ability to influence future generations. Concurrently, ensemble models were explored to leverage the strengths of both the ETAS and R–J models. Short-term forecasts of the probability and occurrence rate of aftershock events with varying magnitudes were conducted for the next three days. Then statistical methods, that is, receiver-operating characteristic diagrams and information gain, were used to evaluate the unconditional and relative performance. Our findings include that the ETAS model indicates a high decay rate with many aftershocks triggered by previous events, whereas the R–J model shows a normal decay rate with a higher proportion of strong aftershocks. The ETAS and R–J models perform better than random guesses for different aftershock magnitudes, but the ETAS model is somewhat affected by the problem of missing small earthquakes for a short period of time after the mainshock. The ensemble model that chooses the minimum strategy shows promise, especially in the early period, suggesting a reasonable and cautious decision approach should be chosen during the unstable stage. This study highlights the importance of short-term aftershock probability estimation for seismic research and decision-making. In the absence of more accurate models, current analytical approaches within the operational earthquake forecasting framework remain valuable. Continuous testing, feedback, and refinement of forecasting models, along with the development of ensemble models, are essential for enhancing seismic risk assessment and mitigation strategies.

Geomorphic expressions of active rifting reflect the role of structural inheritance: a new model for the evolution of the Shanxi Rift, northern China

Abstract. Many rifts are influenced by pre-existing structures and heterogeneities during their evolution, a process known as structural inheritance. During rift evolution, these heterogeneities may aid rift nucleation, rift growth, and the segmentation of faults; encourage the linkage of various segments; or even inhibit the formation of faults. Understanding how structural inheritance influences early rift evolution could be vital for evaluating seismic risk in tectonically active areas. The Shanxi Rift in the north of China is an active rift system believed to have formed along the trend of the Proterozoic Trans-North China Orogen; however, the influence of these pre-existing structures on the present-day rift architecture is poorly understood. Here, we use tectonic geomorphological techniques, e.g. the hypsometric integral (HI), channel steepness (ksn), and local relief, to study the evolution of the Shanxi Rift and identify areas of higher tectonic activity. We found that the HI was less sensitive to lithology and more valuable in evaluating the tectonic signal and that activity is concentrated in two rift interaction zones (RIZs) formed between the Xinding, Taiyuan, and Linfen basins. We then evaluated the relationship between the active faults and mapped pre-existing structures, finding that many faults formed parallel to inherited structures, while faults in the RIZs often cross-cut these structures. Based on these observations, we propose a new model for the evolution of the Shanxi Rift, where inherited structures play an important role in the initial segmentation of the rift, which, in turn, controls the development of the RIZ structures.

Multi-Scale Integrated Corrosion-Adjusted Seismic Fragility Framework for Critical Infrastructure Resilience

This study presents a novel framework for integrating corrosion effects into critical infrastructure seismic risk assessment, focusing on reinforced concrete (RC) structures. Unlike traditional seismic fragility curves, which often overlook time-dependent degradation such as corrosion, this methodology introduces an approach incorporating corrosion-induced degradation into seismic fragility curves. This framework combines time-dependent corrosion simulation with numerical modeling, using the finite–discrete element method (FDEM) to assess the reduction in structural capacity. These results are used to adjust the seismic fragility curves, capturing the increased vulnerability due to corrosion. A key novelty of this work is the development of a comprehensive risk assessment that merges the corrosion-adjusted fragility curves with seismic hazard data to estimate long-term seismic risk, introducing a cumulative risk ratio to quantify the total risk over the structure’s lifecycle. This framework is demonstrated through a case study of a one-story RC moment frame building, evaluating its seismic risk under various corrosion scenarios and locations. The simulation results showed a good fit, with a 3% to 14% difference between the case study and simulations up to 75 years. This fitness highlights the model’s accuracy in predicting structural degradation due to corrosion. Furthermore, the findings reveal a significant increase in seismic risk, particularly in moderate and intensive corrosion environments, by 59% and 100%, respectively. These insights emphasize the critical importance of incorporating corrosion effects into seismic risk assessments, offering a more accurate and effective strategy to enhance infrastructure resilience throughout its lifecycle.

THE POPULATION OF MILA FACING THE EARTHQUAKE OF AUGUST 07, 2020

The surge in urbanization within regions vulnerable to seismic activity poses a significant escalation in seismic risks. Effective mitigation strategies, reliant on improved architectural practices and behavioral adaptations, are imperative to curtail the toll of seismic events. Seismic vulnerability, intricately intertwined with seismic hazard, building conditions, and populace preparedness, underscores the need for comprehensive risk assessment. Although studies elucidating seismic risk knowledge and behaviors are scant in Algeria, they are more prevalent in Mediterranean regions. This paper delves into the examination of risk culture, discerning both direct and indirect causative factors behind the seismic disaster that befell Mila on August 7, 2020.Employing a research methodology that integrates the method Did You Feel It (DYFI USGS ) with a survey model used in Beirut, Lebanon.The findings offer notable insights for two principal reasons. Firstly, local perceptions of the seismic event's severity surpassed estimates by the US Geological Survey (USGS). Secondly, despite the relatively minor magnitude of seismic effects in the El Kherba neighborhood, the populace displayed inadequate preparedness for future earthquakes. Additionally, site-specific factors exerted substantial influence on crisis outcomes. In this context, the preparedness of Algerian society for seismic risks depends on understanding the phenomenon, recognizing associated hazards, and identifying available resources. Contribution: this study serves as a pivotal resource for fostering proactive local population preparedness and mitigating natural risks. Furthermore, it seeks to augment the efficacy of policies aimed at managing natural disaster risks in Algeria.

Seismic risk assessment of partially self-centering braced frames designed with multiple-objective-based method

Partially self-centering building structures are promising seismic resilient systems by balancing the reduction of residual deformations, nonstructural loss, and initial construction costs. This research seeks to establish a multiple-objective-design (MOD) approach for partially self-centering buckling restrained braced frames (PSBRBFs) and explore the risks associated with collapse, demolition, and nonstructural damage in PSBRBFs designed using the MOD approach. The peak displacement is set as an objective for achieving the desired collapse-prevention performance while the residual displacement is set as another objective to ensure the expected post-earthquake repairability. To this end, the step-by-step procedures of the MOD method are introduced based on the prediction models of peak and residual displacements of PSBRBFs. 6 building cases are designed with the MOD method. The dynamic results demonstrate that analyzed PSBRBFs can simultaneously achieve the targeted peak and residual displacements, validating the effectiveness of the MOD method. Seismic fragility assessments are conducted utilizing incremental dynamic analyses (IDAs) to investigate the influence of different performance objectives (i.e., different target peak and residual displacements) on the collapse, demolition, and nonstructural damage probabilities of PSBRBFs. And seismic risks of the designed PSBRBFs are investigated with the consideration of earthquake hazard risks. Results indicate that the demolition risks of the designed PSBRBFs are all larger than the corresponding collapse risks. Based on the analysis results, high PID and low RID design targets were recommended for practical applications to achieve excellent performance against demolition and comparable performance in avoiding collapse and nonstructural damage.

Evaluation of preventive information using alternative protocol: interactive play interactive play

Abstract To better understand individuals’ behaviour in the face of a natural disaster, and to evaluate the preventive information provided by French local authorities, the theatrical performance “Safe and Sound?” (“Sain et Sauf ?”), and its accompanying debriefing session, was tested in six French Alps municipalities in 2019 and 2020 several 2-day sessions in collaboration with local authorities. 200 people took part in this theatrical performance and interviews. The “Safe and Sound?” scheme is based on a 15-minute play, followed by the collection of data from watching the play and debriefing with an interviewer, during about 30 minutes. Two scenarios on flood risks and on seismic risks were narrated by an actor introducing dilemma. Interviews were transcribed and analysed to determine the level and sources of knowledge about the two natural hazards, and the behaviour during a simulation with an actor. Most participants immediately headed to safety only to later put themselves in danger when confronted with an insistent neighbour and the introduction of emotion-provoking characters, i.e. children. When making their choice at each stimulus, participants evoke different sources of reason. A little under half of participants mention common sense or instinct. Although the majority of participants claim they received preventive information from local authorities, this information is rarely applied. The media and own experience were mentioned more often. Lastly, the “Safe and Sound?” campaign was designed to assess behaviour, but findings show that it was also useful to raise awareness among the population.

Seismic assessment of SSSI effects between adjacent Cross-Laminated Timber (CLT) buildings

Urban building designs have been performed considering the behaviour of individual structures in isolation, neglecting potential seismic interactions with neighbouring buildings. In densely populated metropolitan areas, the Structure–Soil–Structure Interaction (SSSI) becomes a significant factor, capable of either amplifying or reducing the seismic response of buildings. This suggests that there is an unquantified seismic risk in densely packed urban areas, which will need to be estimated to obtain designs for more resilient infrastructure. Despite the increasing popularity of CLT as a structurally competitive material, limited attention has been given to investigating dynamic interactions between timber structures. The reduced weight of CLT structures compared to traditional materials necessitates a focused examination of the effects imposed by nearby buildings under varying soil conditions, challenging the fixed-base assumptions commonly applied in seismic analyses. This study investigates the impact of SSSI between pairs of cross-laminated timber (CLT) buildings. Three distinct building heights are considered, exploring differences in storey ratios, under five different ground motions to evaluate seismic performance comprehensively. Sixty detailed high-order three-dimensional models, treating soil and buildings as unified systems, are developed as numerical dynamic simulations. Results reveal that SSSI can significantly influence the displacement and acceleration demands of buildings, with a more pronounced effect observed in loose soil conditions. Particularly, the presence of adjacent higher buildings leads to an increase in the seismic response of the smaller structure, showing amplification effects in peak values but maintaining similar dynamic behaviour. There has been observed a clear trend of increase in the roof displacements of the smaller structure when the storey ratio of neighbouring structures increases; however, the trend of behaviour is not clear in the maximum accelerations. The study underscores the importance of understanding how nearby buildings, particularly those with more storeys, can impact the seismic response on CLT structures.

Normal fault architecture, evolution, and deformation mechanisms in basalts, Húsavik, Iceland: Impact on fluid flow in geothermal reservoirs and seismicity

Faults within layered basaltic sequences significantly influence hydrothermal fluid flow in shallow geothermal reservoirs and potentially during CO2 sequestration and storage. Nevertheless, their characterization regarding fault zone architecture, fluid flow, deformation mechanisms, and seismic potential remains underdeveloped. This study addresses this gap by integrating structural and microstructural observations with X-ray diffraction analyses of exposed normal-transtensional faults associated with the seismically active Húsavík-Flatey Fault in the Tjörnes Fracture Zone, Northern Iceland. Our findings demonstrate that the evolution of basalt-hosted normal-transtensional faults progresses through distinct stages: (1) low-displacement fault propagation from pre-existing cooling joints; (2) fault linkage via dilational jogs; (3) damage zone/fault core growth through brecciation and cataclastic processes; (4) shear localization along sharp slip surfaces; and (5) smearing of volcaniclastic interbeds along the principal fault plane. Evidence of shear localization, truncated clasts, and hydrothermal breccias/veins suggests repeated seismic slip events facilitated by overpressured fluids. Conversely, the presence of clay-rich foliated cataclasite indicates aseismic slips during interseismic periods. Slip along fault jogs, bends, geometric irregularities, and orientation changes causes the dilatant opening of the fault planes and extensional horsetail fractures at fault tips. These structures create main tabular zones for lateral movement of hydrothermal fluids parallel to the fault strike in shallow geothermal reservoirs situated in active extensional-transtensional tectonic settings. In addition, the dilational jogs and the intersection of horsetail veins with the hosting faults may define linear zones of high structural permeability and intense localized fluid flow parallel to the σ2 paleostress orientation and finally mineral precipitation. The results of this study can be utilized to improve models of geothermal fluid flow for enhanced recovery in basaltic reservoirs and assess seismic risk in basaltic faults.

Probabilistic Seismic Risk Assessment of Metro Tunnels in Soft Soils

Tunnels are of significant importance in the sustainable development of global urban areas, particularly in metropolitan areas. It is of the utmost importance to evaluate the seismic performance of tunnels across a wide spectrum of earthquake intensities. In order to address this, our study presents a framework for the assessment of seismic risk in tunnels. This study employs the city of Shanghai’s urban metro tunnels as case studies. The nominal values of seismic risk for the three main damage states—minor, moderate, and major—were calculated. Furthermore, the influence of utilizing disparate fragility functions on expected seismic risk assessments was investigated. In this framework, the probability density functions of the different fragility curve models are employed to treat the probability values associated with them as random variables. This approach aims to facilitate the propagation of IMV in seismic risk assessments. The results demonstrate that the Bayesian framework efficiently incorporates the full range of input model variability into risk estimation. The findings of this study offer a foundation for decision-making processes, seismic risk assessments, and the resilience management of urban infrastructure.

Numerical and experimental pseudo-static study on block arrangement effects in traditional dry-stone walls for out-of-plane mechanical behavior evaluation

In Lima’s slopes, the absence of urban planning has led to housing built on backfills contained by traditional dry-stone retaining walls, called “pircas,” which pose high seismic risk. A previous study [1], which combined numerical and experimental analyses, evaluated pircas through pseudo-static tests that reflected common construction methods in Lima’s eastern region. One recommendation from that study was to explore effective stone arrangements to enhance the seismic performance of pircas. Consequently, this study aims to examine how the construction process, particularly the arrangement of stones, impacts the out-of-plane behavior of pircas. The research focuses on identifying construction-feasible configurations that can effectively improve their seismic performance. For this purpose, natural-scale pseudo-static experimental studies and numerical modeling using the Discrete Element Method (DEM) were carried out. The experimental campaign consisted of nine pseudo-static tests on different wall arrangements. The pseudo-static numerical study included seventy wall arrangements. The geometry of the blocks was simplified to eliminate this component from the analysis, which focused on the arrangement of the wall. The numerical and experimental results showed the same trend. The study has demonstrated that the current construction technique can be significantly improved by regularly incorporating through-stones—tie stones that pass through the entire cross-section of the wall—and considering a cross-section with overlap. This approach leads to an increase of up to 50% in lateral strength compared to current practices, verifying the effectiveness of through-stones. The study does not intend to endorse the use of pirca for urban habitation in high seismic sectors. However, these traditional walls can be recommended for slope stability, environmental mitigation, urban agriculture, and protection of natural areas.

Life-Cycle Cost Assessment of the Base-Isolated-Reinforced Concrete Structure

Seismic isolation structures have excellent seismic mitigation effects, but implementing isolation measures may increase the initial cost of the structure. This paper presents a method to calculate the seismic loss and assess the life-cycle cost of isolated structures, which is convenient for owners to make decisions. The life-cycle cost assessment model is divided into two parts: initial cost assessment and seismic loss assessment over life-cycle period. Among them, the assessment method of the isolation layer is proposed, including the cost assessment of isolation bearings and dampers. The assessment method of seismic loss considers direct loss, indirect loss, casualties and integrating casualties into a unified assessment system. Direct loss includes building loss, indirect loss includes rental loss, relocation loss, income loss, personal property loss and business inventory loss. The seismic loss model is associated with seismic damage probability, which is obtained through seismic vulnerability and seismic probability risk assessment. The 8-story base-isolated-reinforced concrete structure illustrates the feasibility of the life-cycle-cost assessment model. The example shows that the initial cost of the isolated structure exceeds that of the nonisolated structure, however, the rental loss, income loss, personal property loss and casualties are much lower than those of nonisolated structures. The income loss of the isolated structure is the maximum proportion in life-cycle cost, and the casualty loss is the minimum proportion in the seismic loss, due to its excellent seismic mitigation effects.

Microzonation Approach for Analyzing Regional Seismic Response: A Case Study of the Dune Deposit in Concón, Chile

Urban areas located on complex geological formations, such as dune deposits, require detailed seismic risk assessments that extend beyond standard seismic codes. This study focuses on the city of Concón, Chile, where a significant portion of the urban area is situated on a coastal dune deposit. The research integrates seismic microzonation with a three-dimensional finite element model (3D FEM) to comprehensively evaluate the regional seismic response. Field data from 208 strategically distributed points were collected and combined with geotechnical and geomorphological information to construct a detailed 3D model of the region. This model allowed for the simulation of seismic behavior under various conditions, highlighting the limitations of general seismic codes in capturing local variations in seismic response. The results underscore the importance of considering local geological conditions in structural design, particularly in areas with irregular topography and complex subsurface conditions. This study concludes that incorporating microzonation into urban planning and seismic analysis can significantly enhance infrastructure resilience and disaster preparedness, providing a replicable approach for other cities facing similar geological challenges.

A simplified model for seismic risk assessment of three-dimensional irregular steel moment frame buildings

Seismic risk assessment of irregular buildings requires nonlinear dynamic analysis and three-dimensional (3D) models. However, creating and analyzing such models can be intricate and time-consuming, making the assessment process challenging. Furthermore, this complexity escalates when evaluating building stocks or generating a dataset of buildings with diverse attributes for use in learning algorithms. Therefore, this paper proposes an energy-based model for irregular steel moment-resisting frame buildings to simplify 3D models and improve the time efficiency of structural assessment compared to conventional 3D models. The proposed model is derived from the fish-bone model but has enhanced configuration, elastic, and inelastic properties. These improvements aim to broaden its applicability to encompass 3D irregular mid-rise buildings. Four-, six-, and nine-story irregular buildings in plan and height are utilized to validate the proposed model. The responses investigated in these buildings include eigenvalues, pushover curves, time history responses, incremental dynamic analysis results, fragility curves, and risk analysis outcomes. The findings demonstrate that the simplified model responses are in close agreement with those of 3D models. The comparison of results between the proposed simplified model and existing models indicates that the accuracy of the simplified model is at least 2.2 times that of the existing models. Moreover, it provides an average error reduction of 60 % in contrast to the existing models. These advancements have been achieved while the proposed simplified model maintains a level of time efficiency comparable to the current models. The results from the analysis of the created buildings using the proposed simplified model indicate that the model is suitable for application in the seismic risk assessment of building inventories and generating datasets for future research involving machine learning-based methodologies.

Operational status effect on the seismic risk assessment of oil refineries

The operational status of an oil refinery (type and scale of operations that take place at any time instance) largely determines the amount of fuel produced, circulated within the facility, and stored in tanks. This status is affected by seasonality, periods of peak or low demand, as well as periods of routine maintenance. However, it is an aspect that is typically neglected even though it stands out among the factors that determine the seismic performance of several critical industrial assets, such as the storage tanks, as well as the consequences of any potential failure. An open-source refinery testbed is employed herein to demonstrate the effect of the refinery's operational status on the seismic risk estimates. Alternative realistic operational scenarios are developed following typical industry practices and are arranged over a time period between two refinery major maintenance shutdown events. The most probable damage state is selected for each asset to identify the most vulnerable ones. Based on the type and importance of the impacted assets, the potential consequences are determined at the facility level. Resulting estimates are very different if an earthquake strikes during a regular/high/low-demand period, or a maintenance period. The framework can be utilized to identify the locations within the refinery that may trigger cascading failures and secondary damages, should their assets be damaged by a seismic event. The outcomes can be exploited by stakeholders, risk engineers, and emergency action planners for developing customized and businesslike procedures to enhance the seismic resilience of the facility.

A hybrid non‐parametric ground motion model of power spectral density based on machine learning

AbstractIn the fields of engineering seismology and earthquake engineering, researchers have predominantly focused on ground motion models (GMMs) for intensity measures. However, there has been limited research on power spectral density GMMs (PSD‐GMMs) that characterize spectral characteristics. PSD, being structure‐independent, offers unique advantages. This study aims to construct PSD‐GMMs using non‐parametric machine learning (ML) techniques. By considering 241 different frequencies from 0.1 to 25.12 Hz and evaluating eight performance indicators, seven highly accurate and stable ML techniques are selected from 12 different ML techniques as foundational models for the PSD‐GMM. Through mixed effects regression analysis, inter‐event, intra‐event, and inter‐site standard deviations are derived. To address inherent modeling uncertainty, this study uses the ratio of the reciprocal of the standard deviation of the total residuals of the foundational models to the sum of the reciprocals of the total residuals of the seven ML GMMs as weight coefficients for constructing a hybrid non‐parametric PSD‐GMM. Utilizing this model, ground motion records can be simulated, and seismic hazard curves and uniform hazard PSD can be obtained. In summary, the hybrid non‐parametric PSD‐GMM demonstrates remarkable efficacy in simulating and predicting ground motion records and holds significant potential for guiding seismic hazard and risk analysis.

Developing and evaluating a risk-informed decision support system for earthquake early warning at a railway bridge

Earthquake early warning (EEW) systems provide timely information on the arrival of strong seismic waves at a site. Such information can help mitigate the consequences of earthquakes on the operation of infrastructure assets. EEW-informed mitigation actions should stem from risk-based decision-making protocols, and EEW benefits should be evaluated for the range of possible rupture scenarios that affect an asset of interest. This paper addresses these challenges specifically for railway bridges by: (1) developing a risk-informed EEW decision support system (DSS) for these assets; and (2) quantifying the effectiveness of the proposed EEW-DSS in mitigating seismic risks for railway bridges across relevant rupture scenarios. The proposed EEW-DSS combines information on site-specific seismic hazard, time-dependent EEW algorithm outputs, probabilistic seismic demand modeling, damage/derailment fragilities, and seismic loss models. These modeling components compose a multi-criteria decision-making framework. Value of information theory is then proposed to estimate the loss-mitigation benefits of the EEW-DSS, accounting for varied stakeholder risk priorities as well as dynamic lead-time/accuracy tradeoffs related to EEW performance. A railway bridge with multiple piers is adopted for the case study, which demonstrates the importance of risk-based, uncertainty-informed decision-making to the overall effectiveness of EEW in potentially reducing seismic losses.

Historical earthquakes in the Holy Cross Mountains, Poland, true or false? Unveiling insights through archaeoseismology

The Holy Cross Mountains are an intraplate range with a limited historical seismicity record. The only documented earthquakes include the February 6, 1837 M 4.3 event, which caused ground cracks, and swarm events from February 1932 (M ∼ 3.5), likely triggered by the Holy Cross Fault (HCF) or sub-perpendicular faults. The apparent lack of older destructive earthquakes in historical catalogs motivated us to conduct archaeoseismological research to improve seismic hazard assessment, risk mitigation, and urban planning strategies, ultimately benefiting local communities. We focused on the 12th-century Collegiate church of Saint Martin in Opatów, located near the Holly Cross Fault (HCF). We report numerous damage features, such as leaning, bulging, and twisted walls, dropped keystones in Romanesque and Gothic portals, strike-slip displacements of these portals, surplus, oversized buttresses, and walled-up portals. While some deformations may result from humid loess instability and war destructions, our data, combined with historical records, suggest two to three seismic events in the past 800 years as a cause. We argue these deformations were co-seismically triggered by either large far-field events, like the 1259 AD earthquake, or local, shallow small-magnitude events significantly amplified by site effects. This indicates potential seismic activity in the Holy Cross Mountains during Medieval times. The absence of historical records does not imply the absence of earthquakes.

Multi-experimental seismic analysis of low-rise thin reinforced concrete wall building with unconnected elastomeric isolators using real-time hybrid simulations

In response to the pressing need for housing and streamlining construction processes, the building industry has embraced innovative construction techniques. One such method, known as the Industrialized Housing Construction (IHC) system, departs from traditional framing systems by utilizing thin-reinforced concrete walls (TRCW). These TRCWs, characterized by high flowability and rapid strength gain, enable quick and efficient monolithic construction of walls and slabs. However, challenges have arisen regarding the structural behavior of these elements, potentially compromising their seismic performance. Given the significant seismic risk, there is a compelling need to develop resilient buildings by using this cost-efficient structural system. This study proposes the use of passive control systems such as base isolation to address this problem. While base isolation has proven effective in other countries, its feasibility in structures using TRCW and its performance during actual seismic events warrants further investigation. This paper presents an innovative approach using Multi-Axial Real-Time Hybrid Simulation (M-RTHS), which combines numerical and experimental components to gain deeper insights into the seismic response of low-rise TRCW buildings with base isolation using unconnected fiber-reinforced elastomeric isolators (U-FREIs). The methodology is detailed and includes the division of the structure into numerical and experimental segments and the use of transfer systems to replicate real seismic excitations, including those from El Centro (USA, 1940), Pizarro (Colombia, 2004), Chihuahua (Mexico, 2013), Loma Prieta (USA, 1989), and Kobe (Japan, 1995), with a maximum amplitude of 7.36 [Formula: see text] (0.75 g). The results highlight a remarkable reduction in upper structure floor drifts of over 57.47%, the characterization of the behavior and energy dissipation of each experimental specimen, and the optimal evaluation of M-RTHS. This research paves the way for improving the seismic resistance of buildings in regions prone to seismic activity, especially those using innovative construction methods such as TRCW.

SEISMIC VULNERABILITY ASSESSMENT OF AN HISTORICAL UNREINFORCED MASONRY BUILDING OF THE XIXTH CENTURY: EL FETH HIGH SCHOOL IN BLIDA, ALGERIA

Schools In Algeria, built in the XIXth and XXth centuries, are not only places of education and learning, but make up a rich cultural heritage of architectural techniques and traditional know-how. However, their seismic vulnerability risks the safety of their occupants. They were built of masonry before seismic regulations were put into place, which increases their sensitivity to seismic hazard. Algeria is situated in a well-known zone of high seismic activity and the risk to these buildings challenges their structural behaviour. This study focuses on an assessment of seismic vulnerability on a specimen built entirely in hollow brick which wonderfully represents this architectural heritage leading to a better understanding of the potential risks for these buildings, at a structural level. Macro element models, using the Tremuri software, are subjected to a non-linear “Pushover” analysis in order to determine the degree of vulnerability and locate the weak sections of the structure which could collapse during seismic action. This study aims to highlight the seismic risks of these types of structures and also offer appropriate guidelines and recommendations that could be of use during a possible rehabilitation or conservation program of this built heritage site.