Search Results (196)

Reinforced concrete buildings with masonry-induced soft-storey irregularities exhibit extreme seismic vulnerability, a critical risk often underestimated by conventional code-based design. Standard equivalent static methods typically fail to capture the intense concentration of seismic demand at the flexible ground level, leading to unconservative designs that do not meet performance objectives. This research proposes a corrective linear–static methodology to address this deficiency. A new Equivalent Lateral Force profile (ELF_i1) was developed, derived from modal analyses of 235 representative soft-storey archetypes to accurately account for stiffness heterogeneity. This profile was integrated with a realistic response modification coefficient (R_i1 = 5.04), determined to be 37% lower than the normative R-factor (R = 8) prescribed by code. Nonlinear static analyses confirmed that conventional design resulted in “irreparable” damage (mean Global Damage Index = 0.82). In contrast, redesigning the structure using the proposed ELF_i1 and R_i1 methodology successfully mitigated damage concentration, upgrading structural performance to a “repairable” state (mean Global Damage Index = 0.52). Finally, Incremental Dynamic Analysis validated the approach; the redesigned structure satisfied FEMA P695 collapse prevention criteria, achieving an Adjusted Collapse Margin Ratio (ACMR) of 2.10. This study confirms the proposed method is a robust and practical design alternative for soft-storey mechanisms within a simplified linear framework. Full article

The end-of-life phase of a building, which includes demolition and waste disposal, represents a crucial aspect of sustainable construction. In Europe, construction and demolition (C&D) waste accounts for approximately 40% of the total waste generated in the EU, making its management a global challenge. The EU Construction & Demolition Waste Management Protocol (2024) emphasizes the importance of evaluating, before proceeding with the demolition of a building, whether renovation could be a more efficient solution, considering economic, environmental, and technical aspects. From an economic perspective, demolition costs vary depending on several factors, including project size, structural complexity, techniques employed (conventional or non-conventional), materials to be removed, and local regulations. In addition to the direct costs of the intervention, it is essential to consider indirect impacts, such as the management of construction and demolition (C&D) waste, the removal of hazardous substances, and potential environmental damage to be mitigated. This study analyzes a case located in Italy, in the municipality of Caivano (Metropolitan City of Naples, in Campania region), concerning a building that required energy efficiency improvements and seismic upgrades. The decision to demolish and rebuild proved to be economically more advantageous than renovation, while also allowing a 35% increase in volume, enabling the creation of a greater number of housing units. Through the analysis of this real case study, the aim is to highlight how investments in demolition, if properly planned, designed, assessed, and managed, can effectively contribute to building redevelopment, supporting the transition towards a sustainable construction model in line with the principles of the circular economy. Full article

The widespread adoption of high-strength steel reinforcement in China has driven a growing demand for 600 MPa grade and higher-strength stirrups in engineering applications. This study experimentally investigates the seismic performance of concrete columns reinforced with 630 MPa high-strength steel stirrups. Six concrete columns were designed and fabricated, incorporating key variables including concrete strength, stirrup strength, and stirrup spacing ratio. Low-cycle reversed loading tests were subsequently conducted on these specimens, enabling a thorough evaluation of their seismic characteristics. Additionally, the study examines the cumulative damage effects and confining influence of 630 MPa high-strength stirrups on the core concrete. The findings reveal that concrete columns with a low ratio of 630 MPa high-strength stirrups exhibit enhanced seismic performance when the concrete strength is relatively low. However, with increasing concrete strength, the confinement efficiency of 630 MPa ultra-high-strength stirrups diminishes, leading to accelerated damage progression and reduced ductility. Both low- and high-strength concrete columns benefit from a high stirrup ratio, which provides effective confinement. Furthermore, 630 MPa high-strength stirrups help mitigate damage accumulation while enhancing yield displacement, peak displacement, ultimate displacement, ductility, and energy dissipation capacity. The use of 630 MPa high-strength stirrups not only ensures superior seismic performance but also reduces reinforcement requirements and improves construction efficiency. Full article

Ground settlement is a multifaceted geological phenomenon driven by natural and man-made forces, posing a significant impediment to sustainable urban development. Thus, ground settlement susceptibility (GSS) mapping has emerged as a critical tool for understanding and mitigating cascading hazards in seismically active and anthropogenically modified sedimentary basins. Here, we develop an integrated framework for assessing GSS in the Pohang region, South Korea, by integrating Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR)-derived vertical land motion (VLM) data with seismological, geotechnical, and topographic parameters (i.e., peak ground acceleration (PGA), effective shear-wave velocity (V_s³⁰), site period (T_s), general amplification factor (A_F), seismic vulnerability index (K_g), soil depth, topographic slope, and landform classes) through ensemble machine learning models such as Random Forest (RF), XGBoost, and Decision Tree (DT). Analysis of 56 Sentinel-1 SLC images (2017–2023) revealed persistent subsidence concentrated in Quaternary alluvium, reclaimed coastal plains, and basin-fill deposits. Among the tested models, RF achieved the best performance and strongly agreed with field evidence of sand boils, liquefaction, and structural damage from the 2017 Pohang earthquake. The very-high-susceptibility zones exhibited mean subsidence rates of −3.21 mm/year, primarily within soft sediments (V_s³⁰ < 360 m/s) and areas of thick alluvium deposits. Integration of the optimal RF-based GSS index with regional building inventories revealed that nearly 65% of existing buildings fell within high- to very-high-susceptibility zones. The proposed framework demonstrates that integrating PSInSAR and ensemble learning provides a robust and transferable approach for quantifying ground settlement hazards and supporting risk-informed urban planning in seismically active and complex geological coastal environments. Full article

The optimal performance of buildings strongly depends on their structural configuration, as it influences the structural response to expected loads during life service. For instance, structural arrangements oriented to reduce torsional effects increase performance and, in turn, mitigate vulnerability to seismic events. However, several structural analyses should be performed to ensure that these structural arrangements are robust This can be computationally expensive depending on the type of analysis. The objective of this research is twofold. The first objective is to compare the dynamic response of two reinforced concrete buildings that are almost identical in height and floor area but whose structural elements are placed differently. The dynamic response of both structures was calculated via nonlinear dynamic analysis (NLDA) by considering a large set of ground motion records. Second, NLDA results were compared with those stemming from a spectral-based methodology. The comparison is made on the basis of the fragility and damage functions given different return periods. The results show that an adequate spatial distribution of structural elements reduces materials and increases safety and stability, since the expected damage is lower. Likewise, it is observed that the results based on reduced-order procedures accurately represent those obtained from NLDA while entailing a significantly lower computational cost. Full article

This research examined the phenomenon of pounding between neighboring steel structures, both with and without tension-only braces, utilizing an extensive nonlinear time-history analysis. The evaluation of the structural response was conducted using essential engineering demand parameters such as inter-story drift ratio (IDR), residual inter-story drift ratio (RIDR), peak floor acceleration (PFA), base shear, and base moment. The findings indicated that the addition of tension-only braces plays a crucial role in diminishing the structural response during seismic activities. The tension-only brace effectively alleviates the negative impacts of structural pounding by offering supplementary restraint and energy dissipation mechanisms, which enhances the overall seismic performance of the steel frame structures. These results highlight the potential advantages of adopting tension-only braces as a passive control method to mitigate pounding-related structural damage in closely situated buildings. Full article

The effect of an earthquake on any structure is primarily determined by both its inherent properties and the surrounding environmental conditions. When seismic waves pass through different media, their characteristics and properties, such as amplitude, frequency content, and duration can change, thereby changing the seismic response of both soil and structures. The intensity and distribution of seismic waves can be influenced by several of key factors, including the local geology and stratigraphy, irregular topography, existence of man-made structures, and others. Relevant researches and studies have consistently emphasized the significance of the surrounding environment in seismic wave modification. Historical data also shows that similar types of earthquakes can result in varying degrees of damage depending on geographic location. Hence, a thorough understanding of the interaction between seismic waves and the surrounding environment is necessary for achieving precision in seismic design, risk assessment, and proper seismic mitigation strategies. An overview of contemporary research on seismic wave modification and the resulting interaction effects, presenting significant findings and analytical techniques related to phenomena such as soil-structure interaction (SSI) and its extended forms, including structure–soil–structure interaction (SSSI), soil–structure–cluster interaction (SSCI), and site–city interaction (SCI), is presented in this review article. The underlying mechanisms of these interactions are explored in this study and a detailed assessment of fundamental concepts, practical challenges, and methodologies for preventing and mitigating their effects in site-dependent settings is provided. Further, Topographic soil–structure interaction (TSSI) and topographic–structure–soil–structure interaction (TSSSI) are also discussed within a unified framework that considers the combined influence of topography and SSI extensions. This study focuses on the importance of the surrounding environment in influencing ground motion during earthquakes by identifying the complex interactions that affect the seismic response of both surface and underground structures. Some illustrative figures were generated with Microsoft Copilot and subsequently edited and validated by the authors. Full article

This study presents a novel structural framing solution designed to improve seismic energy dissipation and limit displacements, aiming to serve as an effective alternative to traditional precast systems employing pendulum-based isolation. While pendulum mechanisms mitigate seismic forces by decoupling the superstructure from ground motion, they are typically characterized by high implementation costs, mechanical complexity, and post-event maintenance challenges. In contrast, the proposed approach integrates seismic performance enhancements within the structural frame itself, removing the dependency on external isolation components. The system leverages a combination of pinned and semi-rigid beam-to-column joints that are tailored for use within dry precast construction technologies. These connection types not only support rapid and labor-efficient assembly but also, when properly detailed, offer robust hysteretic behavior and deformation control under dynamic loading. The research includes both experimental testing and numerical simulations focused on the cyclic response of these connections, enabling a comprehensive understanding of their role in dissipating energy and delaying damage progression. Recognizing the industry’s frequent emphasis on construction speed and upfront cost-efficiency, often at the cost of long-term reparability, this work introduces an alternative framework that emphasizes resilience without compromising construction practicality. The resulting system demonstrates improved post-earthquake functionality and reduced downtime, making it a promising and economically viable option for seismic applications in precast construction. This advancement supports current trends toward performance-based design and enhances the structural reliability of dry-assembled systems in seismic regions. Full article

This paper presents an approach to risk mitigation strategies through seismic vulnerability of buildings’ non-structural elements (NSEs) proposing practical and accessible strategies for risk reduction aligned with the United Nations Sustainable Development Goals (SDG) framework. NSEs play a crucial role in the overall safety and resilience of built environments during seismic events. However, their vulnerability is often underestimated, despite their potential to cause significant human, economic, and social losses. Moreover, NSEs remain widely overlooked in both seismic risk assessments and mitigation strategies, including risk education. This issue directly impacts multiple SDGs. NSE damage exacerbates poverty by increasing financial burdens due to repair and recovery costs. It also affects access to quality education, not only by disrupting school infrastructure but also by limiting access to knowledge, which is essential for strengthening the coping capacity of communities. Furthermore, seismic risk mitigation must be inclusive to reduce inequalities, ensuring that safety is not a privilege but a right for all. Lastly, NSE vulnerability directly influences the resilience and sustainability of cities and communities, affecting urban safety and disaster preparedness. Simple mitigation actions, such as proper anchoring, reinforcement, or improved design guidelines, could drastically reduce their vulnerability and related consequences. Raising awareness of this underestimated issue is essential to foster effective policies and interventions. Full article

Simulation of damage scenarios is an important tool for seismic risk mitigation. While a detailed analysis of each building would be preferable to assess their vulnerability to seismic hazard, simplified yet robust methodologies are necessary at a large urban scale to overcome computational costs or data unavailability. Moreover, most damage assessments simulate single seismic shocks, though in many real sequences, with a series of aftershocks following the mainshocks, it is observed that buildings endure damage accumulation, which increases their vulnerability over time. The present study builds on a recently developed methodology for simulating urban-scale damage scenarios across seismic sequences, explicitly accounting for damage accumulation and the evolution of vulnerability. In particular, the availability of a dataset reporting the damage observed in the L’Aquila area (Italy) during the severe earthquake sequence of 2009, in combination with the georeferenced maps representing the spatial distribution of the ground motion, allows for the calibration of the methodology through the comparison between the simulations’ results and the sequence’s real data. Although calibrated on the L’Aquila dataset, the proposed procedure could also be applied to different urban areas, with both real and synthetic seismic sequences, enabling the forecasting of damage scenarios to support the development of effective strategies for seismic risk mitigation. Full article

To mitigate and control the seismic damage risk of high-speed railway bridges and enhance their post-earthquake reparability, a prefabricated multi-layer parallel-connected slit steel plate shear damper is proposed by utilizing the energy absorption capacity of flexure–shear coupled deformation in dampers. A theoretical model for calculating the stiffness and load-bearing capacity of the proposed damper was established and validated through detailed finite element simulations. The results demonstrate that the damper exhibits stable energy dissipation efficiency under cyclic loading, along with a gradual reduction in post-yield stiffness. Subsequently, a numerical model of the high-speed railway track–bridge-damper systems (HSRTBDS) was developed, incorporating the contribution of the proposed damper to quantify its control over the seismic response of the HSRTBDS. The findings indicate that the damper effectively reduces the seismic responses of the girders, rail fasteners, and track slabs, with a maximum deformation reduction exceeding 30% in the supporting structures. However, the deformation and damage of the bridge piers slightly increased, though they remained within acceptable safety limits. The damper showed limited influence on the damage to rails, fasteners, and shear key slots. Overall, the effectiveness of the proposed damper in controlling the structural response of HSRTBD has been demonstrated and validated, providing insights for the seismic design of high-speed railway bridges in high-intensity seismic zones. Full article

Liquefaction-induced failure of pile foundations remains a critical challenge in seismic bridge engineering, particularly for large-diameter variable-section piles widely used in deep foundations. To address the limited understanding of their dynamic behavior in liquefiable soils, this study conducted large-scale shaking table tests on single and group pile foundations at the Xiang’an Bridge site in Xiamen. The model reproduced a stratified saturated sandy soil profile to examine pore pressure evolution, acceleration response, horizontal displacement, and bending moment under seismic intensities of 0.15 g, 0.25 g, 0.35 g, and 0.45 g. The experimental results validated the model’s reliability and revealed clear performance distinctions between the two pile types. As seismic intensity increased, the stable pore pressure ratio rose from 0.72 to 0.86, indicating progressive liquefaction. Compared with the single pile, the pile group exhibited 15–25% lower peak acceleration and displacement, and a delayed occurrence of maximum response by about 1.3 s. Damage occurred at 0.35 g for the single pile but only at 0.45 g for the pile group, accompanied by a more minor reduction in fundamental frequency (32.44% vs. 52.90%). These results demonstrate that the pile group effect mitigates the impact of liquefaction and enhances seismic resistance. The study provides experimental validation and quantitative insight into the dynamic response mechanisms of variable-section pile group foundations, contributing novel guidance for the seismic design of bridge foundations in liquefaction-prone regions. Full article

Many immersed tunnels are constructed in alluvial formations within earthquake-prone regions, making seismic resistance a critical aspect of their safety design. During an earthquake, tunnel displacements can lead to slippage between the tunnel and surrounding soil and may be further amplified by liquefaction. This phenomenon can cause severe structural damage, including tunnel flotation. This paper examines the seismic performance of immersed tunnels, starting with an overview of the deformation mechanisms affecting tunnels, including those induced by ground shaking and failure. Given its significance in large foundation deformations and its impact on tunnel integrity, liquefaction is analyzed alongside potential mitigation strategies. The seismic design process for immersed tunnels is discussed in detail, covering analytical approaches, numerical modeling techniques (such as finite element and finite difference methods), and physical modeling. Real-world examples are provided to illustrate key concepts. Finally, this paper summarizes the core factors influencing the seismic response of immersed tunnels and highlights future research directions to enhance their resilience in seismic environments. Full article

On 10 August 2025, a powerful earthquake (M_w = 6.1) occurred in Balıkesir, located within the Aegean Graben System, one of Türkiye’s major tectonic elements, and was felt across a very wide region. This study presents a comprehensive assessment of the seismotectonic characteristics, recorded ground motions, and observed structural performance during this earthquake, focusing specifically on implications for regional seismic hazard assessment. Peak ground acceleration values obtained from local accelerometer stations were compared with predicted peak ground accelerations. The study also conducted comparisons for Balıkesir districts using the two most recent earthquake hazard maps used in Türkiye. Comparative hazard analyses revealed whether existing seismic hazard maps adequately represent Balıkesir. The findings highlight the need for region-specific hazard model updates, improved implementation of earthquake-resistant design rules, and targeted retrofit strategies to mitigate future earthquake risk. The methodology adopted in this study involved comparative hazard analysis using the last two seismic hazard maps, evaluation of PGA’s across 20 districts of Balıkesir Province, and a field-based survey of structural damage. This integrative approach ensured that both seismological and engineering perspectives were comprehensively addressed. Full article

Widespread casualties and property damage due to structural failures following devastating earthquakes have once again highlighted the critical significance of evaluating the seismic performance of existing buildings. In this context, a fundamental part of modern pre-disaster management is to evaluate the potential seismic risks of existing structures and implementing the necessary precautions. This study focuses on determining regional risk priorities using a rapid assessment methodology applied to a sample of reinforced-concrete (RC) structures in the Centre of Bitlis city, situated in the high-seismic-risk Lake Van Basin. Risk prioritization was made among the buildings based on the Turkish Rapid Assessment technique revised in 2019 for 100 different RC buildings with one to seven stories. The negative parameters utilized in this method were analyzed both in relation to the 6 February 2023, Kahramanmaraş earthquakes and the assessed building stock. Additionally, the study provides a comprehensive review of the existing building inventory across the region and offers recommendations for potential precautions to mitigate earthquake risks. Full article