Search Results (47)

Afghanistan experiences frequent damaging earthquakes, and the widespread use of unreinforced adobe and Pakhsa construction leads to high casualty rates and severe housing losses. Traditional earthen buildings exhibit low tensile capacity, rapid stiffness degradation, and brittle failure, often collapsing at drift levels below 0.5–0.6% or at modest ground motions. Reinforcement techniques evaluated in international experimental studies—such as timber confinement, flexible steel wire mesh, geogrids, and high-quality plastic fencing—have demonstrated measurable improvements, including 30–200% increases in lateral strength, three- to seven-fold increases in ductility, and out-of-plane capacity enhancements of more than two-fold when properly anchored. This study synthesises research findings and global earthen building codes and guidelines to develop a practical, context-appropriate benchmark house model for Afghanistan. The proposed model integrates representative wall geometries, concentrated flat-roof loading, and realistic construction capabilities observed across the country. Three reinforcement alternatives are presented, each designed to be low-cost, compatible with locally available materials, and constructible without specialised equipment. By linking quantitative performance evidence with context-specific construction constraints, the study provides a technically grounded and implementable pathway for improving the seismic safety of rural earthen dwellings in Afghanistan. The proposed benchmark model offers a robust foundation for future national guidelines and for the design and retrofitting of safer, more resilient housing. Full article

This study presents a multi-factor coupled assessment of seismic disaster risk for approximately 635,000 individual building units in Ankang City, Shaanxi Province, China, utilizing a high-resolution dataset. The assessment methodology innovatively integrates the three core components of risk: seismic vulnerability V of load-bearing structures, site-specific seismic hazards R, and potential consequences C of damage, to formulate the Seismic Resilience Index I_SR = C·R·V. Crucially, the approach advances established risk assessment frameworks by enhancing the spatial resolution of the site influence coefficient R using a high-resolution national site classification map and detailed local geological data. The results reveal that the areas with the lowest I_SR values (indicating the lowest resilience and thus the highest risk) are predominantly concentrated in older residential districts of counties such as Ningshan, Hanyin, and Ziyang, where unreinforced masonry structures built prior to 1989 are widespread. The model assessment results align with expected structural performance characteristics, and the study concludes by offering quantified, priority-based recommendations for targeted structural intervention and seismic retrofitting in the identified highest-risk regions and building typologies. Full article

Steel moment-resisting frames rely on strength and ductility to perform under seismic loads. Conventional techniques such as reduced beam section (RBS) and reduced web section (RWS) improve ductility by relocating plastic hinges but can suffer from local buckling, fabrication challenges, and costly post-earthquake repairs. This study proposes a sacrificial steel sleeve fuse system for bolted endplate connections, designed to concentrate inelastic deformation within a replaceable sleeve while preserving the primary structural components. Experimental tests included standalone sleeve compression, bolted sleeve assemblies, and T-stub connections with and without sleeves, all validated with finite element models. A parametric study evaluated two sleeve geometries—circular wave (CW) and U-shaped (US)—and compared the sleeve fuse system’s monotonic performance with RWS and standard connections. Results indicate that properly designed sleeve fuses significantly enhance ductility and energy dissipation without compromising initial stiffness or strength, achieving up to 1.8 times the ductility and 25.9% higher energy absorption relative to RWS connections. The findings highlight the sleeve fuse as an innovative, easily replaceable, and resilient solution for seismic applications, offering a practical path for both retrofitting existing frames and designing new structures. Full article

This study presents a comprehensive methodological framework that encompasses all stages required to evaluate the structural response to potential seismic motions. The proposed approach involves the estimation of seismic hazard at the site of interest, the disaggregation and definition of control earthquakes, the characterization of local site effects, the assessment of possible resonance phenomena, and the comparison between response spectra derived from probable seismic scenarios and the design spectra of the buildings, leading to conclusions regarding structural safety. The methodology integrates instrumental measurements of soil and building vibration periods with analytical procedures to define response spectra consistent with expected seismic scenarios. It was applied to buildings of special importance located in Guatemala City, particularly within the University of San Carlos of Guatemala (USAC) campus, with the aim of evaluating their structural safety and developing retrofitting criteria when necessary. The implementation began with a probabilistic seismic hazard analysis (PSHA) to identify control earthquakes that make the largest contribution to hazard for a 475-year return period, followed by the estimation of rock response spectra. A seismic microzonation study was then conducted to characterize local site conditions. Instrumental vibration measurements of the soil and structures were obtained, and a soil–structure interaction analysis was carried out to evaluate potential resonance effects. The results showed no evidence of resonance. Finally, soil response spectra derived from the control earthquakes were compared with the design spectra defined by the AGIES 2024 structural safety standards. The results confirmed that the design spectra adequately envelope the computed response spectra for all soil–structure combinations. The proposed methodology is replicable and can be used to assess the seismic design adequacy of other buildings, providing a rational basis for retrofitting decisions when design spectra do not fully encompass the expected seismic response. Full article

This paper presents a global performance-based seismic assessment of an existing reinforced concrete hospital building retrofitted with dissipative bracing systems. The study aims to evaluate the overall effectiveness of different dissipative configurations, two traditional systems and one innovative low-activation solution in enhancing the seismic performance of the structure in compliance with the Italian Building Code (NTC 2018). The analyses were carried out using nonlinear static (pushover) procedures to determine the global capacity, equivalent damping, and displacement demand at the Life Safety (SLV) and Near Collapse (SLC) limit states. The retrofitting interventions were modeled assuming elastic connections between the existing RC frames and the added steel members, consistent with standard design practice in which connections are dimensioned with overstrength to avoid premature failure. The results demonstrate that the integration of dissipative systems significantly increases stiffness and damping, effectively reducing lateral displacements and improving the seismic safety index above the 60% threshold required for strategic facilities. The study highlights the importance of global assessment methodologies in guiding the seismic upgrading of hospitals and other critical infrastructures, while local detailing and device-level optimization are identified as topics for future research. Full article

Mixed structures with lightweight steel added stories are particularly vulnerable to damage and failure at the joints during seismic events. To evaluate the secondary seismic behavior of the joints in lightweight steel added stories after seismic damage repair, a low-cycle load test was conducted in this study. Following the initial damage, carbon fiber-reinforced polymer (CFRP) was applied for reinforcement, along with epoxy resin for the repair of concrete cracks. The experimental analysis focused on the structural deformation, failure characteristics, and energy dissipation capacity in both the original and repaired joint states. On the basis of the experimental findings, finite element analysis was carried out to examine the influence of varying CFRP layer configurations on the seismic performance of the repaired joints. The results revealed a significant change in the damage pattern of the repaired specimen, shifting from secondary surface damage to significant concrete deterioration localized at the bottom of the column. The failure mechanism was characterized by the CFRP-induced tensile forces acting on the concrete at the column base, following considerable deformation at the beam’s end. When compared to the original joint, the repaired joints exhibited markedly improved performance, with a 33% increase in horizontal ultimate strength and an 85% increase in energy dissipation capacity at failure. Additionally, the rotation angle between the beams and columns was effectively controlled. Joints repaired with two layers of CFRP demonstrated superior performance in contrast to those with a single layer. However, once the repaired joints met the required strength, further increasing the number of CFRP layers had a minimal influence on the mechanical properties of the joints. The proposed CFRP-based seismic retrofit method, which accounts for the strength degradation of concrete in damaged joints due to earthquake-induced damage, has proven to be both feasible and straightforward, offering an easily implementable solution to improve the seismic behavior of structures. 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

This study offers a quantitative performance assessment of integrated seismic retrofit designs applied to an in-service 1960s reinforced concrete school structure in Central Italy. The research combines in-depth experimental material characterization with complex numerical simulations in order to estimate both the independent and interaction effects of external steel exoskeletons in conjunction with localized CAM (Cucitura Attiva dei Materiali) strengthening. The experimental investigation includes extensive material characterization through core drilling and non-destructive pacometric inspections to accurately define the existing concrete properties. The numerical analysis is performed with Finite Element modeling to estimate four different structural conditions: the original state, the condition with static strengthening, the condition with additional steel exoskeletons, and the condition with both exoskeletons and localized CAM reinforcements. The results quantitatively estimate the specific performance gains from the individual retrofit strategies. The steel exoskeletons show effective reduction in inter-story drifts but negligible effect on strength-oriented failure mechanisms. Localized CAM strengthening therefore stands out as necessary in reaching adequate safety levels in all the failure mechanisms. Economic analysis reveals that while steel exoskeletons provide the major cost component, the integrated approach with localized strengthening is essential for achieving comprehensive seismic safety enhancement. Full article

This study presents a high-performance external strengthening strategy for reinforced concrete (RC) beam–column joints, integrating near-surface mounted (NSM) Carbon Fiber Reinforced Polymer (C-FRP) ropes with externally bonded C-FRP sheets. The X-shaped ropes, anchored diagonally on both principal joint faces and complemented by vertical ropes at column corners, provide enhanced core confinement and shear reinforcement. C-FRP sheets applied to the beam’s plastic hinge region further increase flexural strength and delay localized failure. Three full-scale, shear-deficient RC joints were subjected to cyclic lateral loading. The unstrengthened specimen (JB0V) exhibited rapid stiffness deterioration, premature joint shear cracking, and unstable hysteretic behavior. In contrast, the specimen strengthened solely with X-shaped C-FRP ropes (JB0VF2X2c) displayed a markedly slower rate of stiffness degradation, delayed crack development, and improved energy dissipation stability. The fully retrofitted specimen (JB0VF2X2c + C-FRP) demonstrated the most pronounced gains, with peak load capacity increased by 65%, equivalent viscous damping enhanced by 55%, and joint shear deformations reduced by more than 40%. Even at 4% drift, it retained over 90% of its peak strength, while localizing damage away from the joint core—a performance unattainable by the unstrengthened configuration. These results clearly establish that the combined C-FRP rope–sheet system transforms the seismic response of deficient RC joints, offering a lightweight, non-invasive, and rapidly deployable retrofit solution. By simultaneously boosting shear resistance, ductility, and energy dissipation while controlling damage localization, the technique provides a robust pathway to extend service life and significantly enhance post-earthquake functionality in critical structural connections. Full article

Masonry industrial buildings, common in the 19th and 20th centuries, represent a significant architectural typology. These structures are crucial to the study of industrial archeology, which focuses on preserving and revitalizing historical industrial heritage. Often left neglected and deteriorating, they hold great potential for adaptive reuse, transforming into vibrant cultural, commercial, or residential spaces through well-planned restoration and consolidation efforts. This paper explores a case study of such industrial architecture: a decommissioned factory near Naples. The complex consists of multiple structures with vertical supports made of yellow tuff stone and roofs framed by wooden trusses. To improve the building’s seismic resilience, a comprehensive analysis was conducted, encompassing its historical, geometric, and structural characteristics. Using advanced computer software, the factory was modelled with a macro-element approach, allowing for a detailed assessment of its seismic vulnerability. This approach facilitated both a global analysis of the building’s overall behaviour and the identification of potential local collapse mechanisms. Non-linear analyses revealed a critical lack of seismic safety, particularly in the Y direction, with significant out-of-plane collapse risk due to weak connections among walls. Based on these findings, a restoration and consolidation plan was developed to enhance the structural integrity of the building and to ensure its long-term safety and functionality. This plan incorporated metal tie rods, masonry strengthening through injections, and roof reconstruction. The proposed interventions not only address immediate seismic risks but also contribute to the broader goal of preserving this industrial architectural heritage. This study introduces a novel multidisciplinary methodology—integrating seismic analysis, traditional retrofit techniques, and sustainable reuse—specifically tailored to the rarely addressed typology of masonry industrial structures. By transforming the factory into a functional urban space, the project presents a replicable model for preserving industrial heritage within contemporary cityscapes. Full article

Many urbanised areas of the Apennines, in Italy, have complex soil stratifications. A typical example is the outskirts of the city of L’Aquila, which is founded on highly heterogeneous soil layers and was severely affected by a strong earthquake in 2009. In such conditions, shear wave velocity profiles (V_S) obtained from in situ tests such as the Seismic Dilatometer Marchetti Test (SDMT) provide reliable analyses of the local seismic response. This article presents the mono-dimensional (1D) and two-dimensional (2D) seismic response analyses conducted to characterise the soil foundation of the hospital complex and adjacent university buildings in L’Aquila before their seismic retrofitting. This study emphasises the importance of accurate soil characterisation prior to repair interventions, especially in deposits where there are V_S inversions and in the presence of geometrically irregular and large structures. Under these conditions, estimating the motion amplitudes of the deposit’s higher modes beyond the fundamental level is essential in accurately characterising the seismic response, especially for buildings where higher structural modes play a significant role. The results show that approximating the V_S profile with simplified procedures, as proposed by the Italian Building Code of 2018 (equivalent V_S, similar to average), leads to incorrect estimates of seismic action. Full article

The process of seismic retrofitting for inadequate RC frames is vital for enhancing structural integrity in areas susceptible to earthquakes. This research investigates a novel tube-in-tube (TnT) buckling restrained brace (BRB) system aimed at improving the seismic performance of these substandard RC frames. By targeting significant weaknesses inherent in older RC constructions, the TnT BRB introduces a lightweight, all-steel configuration that eliminates the need for traditional mortar or concrete infill materials. Experimental shake table testing on two one-third scaled RC frame models was conducted to compare the seismic performance of an unretrofitted control frame and a frame retrofitted with the TnT BRB system. Results indicate significant enhancements in lateral strength, ductility, and energy dissipation capacity in the retrofitted frame, demonstrating stable and symmetrical hysteresis loops and reduced stiffness degradation compared to conventional X-braced systems. Analytical modeling corroborated these experimental findings, confirming the TnT BRB’s superior capability in absorbing seismic energy and preventing premature structural failures. This investigation emphasizes both the practical and financial benefits of integrating the TnT BRB into seismic retrofitting strategies while recommending further research to optimize the system, specifically addressing issues related to local denting, frictional wear, and alignment to bolster its effectiveness in practical applications. Full article

Italy is internationally renowned for its cultural heritage, a testament to its rich history. Many of these structures, built before the advent of modern engineering principles, were constructed based on empirical knowledge and lack seismic design considerations, making them highly vulnerable to earthquakes. This vulnerability presents a significant challenge to preserving Italy’s architectural legacy. A notable example is Villa Vannucchi, located in the seismically active Vesuvius region. Given its historical and cultural significance, enhancing its structural resilience while preserving its architectural authenticity is imperative. This study investigates the seismic vulnerability of Villa Vannucchi through a comprehensive analysis of its structural deficiencies and proposes a targeted retrofitting strategy in accordance with the Italian Guidelines for Cultural Heritage (IGCH). The evaluation is conducted in three phases: 1 Preliminary structural assessment—Calculation of two critical safety factors to evaluate the villa’s overall stability. 2 Local collapse mechanism analysis—Examination of the structure’s susceptibility to localized failures. 3 Advanced computational modelling—Detailed simulations revealing critically low seismic coefficients. Based on these findings, a consolidation plan is developed, integrating traditional and minimally invasive techniques. Key interventions include reinforcing the masonry and reducing floor deformability to improve overall structural stability. The implementation of these retrofitting measures significantly enhances the villa’s seismic resilience, as evidenced by the increased safety coefficients. This reduction in vulnerability not only ensures the preservation of Villa Vannucchi, but also safeguards its cultural and historical legacy for future generations. Full article

Addressing the critical seismic vulnerabilities of reinforced concrete (RC) beam-column joints remains an imperative research priority in earthquake engineering. This study presents an experimental and analytical investigation into the seismic performance enhancement of non-ductile RC frames using an innovative all-steel Tube-in-Tube Buckling-Restrained Brace (TnT BRB) system. Shake table tests were performed on one-third scale RC frame specimens, including a baseline structure representing conventional substandard design and a counterpart retrofitted with the proposed TnT BRBs. Experimental results revealed that the unretrofitted specimen experienced pronounced brittle shear failures, excessive lateral deformations, and significant degradation of beam-column joints under cyclic seismic loading. In contrast, the TnT BRB-retrofitted specimen exhibited substantially improved seismic behavior, characterized by enhanced energy dissipation, controlled inter-story drifts, and preserved joint integrity. Advanced fiber-based finite element modeling complemented the experimental efforts, accurately capturing critical nonlinear phenomena such as hysteretic energy dissipation, stiffness degradation, and localized damage evolution within the structural components. Despite inherent modeling limitations regarding bond-slip effects and micro-level cracking, strong correlation between numerical and experimental results affirmed the efficacy of the TnT BRB retrofit solution. This integrated experimental-analytical approach offers a robust, cost-effective pathway for upgrading seismically deficient RC structures in earthquake-prone regions. Full article

Old Cairo, also known as Islamic Cairo, is a UNESCO World Heritage Site representing a rich tapestry of history and culture. Today, among various significant aspects, its cultural heritage necessitates the elaboration of a proactive conservation strategy, which should take advantage of the intrinsic support provided by the efforts documented in the literature that have been made in several scientific fields, disciplines, and directions over the years. Most historic religious monumental buildings in Old Cairo, in particular, not only face the effects of local seismic hazards, which are emphasized by damage by past earthquakes, but also suffer the consequences of several influencing parameters that are unique to the Cairo city context. In this sense, it is known that the structural retrofitting of these monumental buildings requires sound knowledge of technical details and criticalities, based on inspections, numerical simulations, the in-field integration of technologies, and laboratory tests. Many other gaps should also be addressed, and a sound conservation strategy should be elaborated on the basis of a multi-target approach, which could account for the structural engineering perspective but also contextualize the retrofit within the state of the art and the evolution of past events. This is the target of the contemporary “Particular Relevance” bilateral Italy–Egypt “CoReng” project, seeking to define a multidisciplinary strategy for conserving Old Cairo’s cultural heritage and focusing primarily on the case study of the Religions Complex. To this end, a review analysis of major oversights and challenges relating to historic monuments in Old Cairo is presented in this paper. Learning from past accidents and experiences is, in fact, the primary supporting basis for elaborating new operational steps and efficient approaches to mitigating challenges and minimizing the consequences of emergency events. As such, this review contribution specifically focuses on the structural vulnerability of historic monumental buildings in Old Cairo, reporting on past efforts, past strategy proposals, research experiences, and trends. Full article