Catastrophic Collapse Research Articles

Permafrost Food Storage Monitoring and Vulnerability Assessment in Utqiaġvik, Alaska

Traditional Iñupiaq sigḷuaq are cellars excavated into permafrost for storage of large quantities of game, fish, and other foodstuffs harvested for subsistence. Permafrost provides both a cultural and regulatory ecosystem service to Arctic peoples. A cellar thermal monitoring program in Utqiaġvik (formerly Barrow), Alaska, documented catastrophic flooding, collapses, and other issues in these cellars related to warming climatic conditions, community functions, and development. This paper provides an update on the Utqiaġvik monitoring program, which was operational from 2005 to 2019. All five monitored cellars exhibited stable to warming mean annual internal temperatures over the period of observation. Two cellars flooded, another was abandoned because of sloughing walls, and two were functioning until the COVID-19 pandemic. Based on experiences gained from the 14-year Utqiaġvik monitoring program, we conduct a vulnerability assessment using the source-pathway-receptor-consequence (SPRC) model and identify several vulnerability reduction measures. We recommend the SPRC model to aid evaluation of specific vulnerabilities of cellars and other traditional frozen infrastructure, and to improve future monitoring methods and products through increased community participation. Any attempt to provide data for community-resilience decisions should start with identifying and communicating process components, thereby bridging stakeholder learning and responses (their “heuristics” in the SPRC model) and science-based knowledge.

Metaheuristic optimization of extreme gradient boosting machine for enhanced prediction of lateral strength of reinforced concrete columns under cyclic loadings

The estimation of lateral strength in reinforced concrete (RC) columns subjected to cyclic loads is crucial in structural design. The failure of RC columns under lateral forces can lead to catastrophic structural collapses. This fact emphasizes the need for accurate assessments of their dynamic behavior. This paper proposes a data-driven model for estimating the lateral strength of RC columns. A historical dataset comprising 12 predictor variables and 247 samples has been compiled to train and validate of the proposed approach. The extreme gradient boosting machine (XGBoost) is employed to establish a predictive relationship between the lateral strength of RC columns and their influencing factors. Since model selection is critical for constructing a reliable prediction mode, this study relies on utilizing metaheuristic approaches, including Genetic Algorithm, Particle Swarm Optimization, Artificial Bee Colony, and Ant Colony Optimization, to optimize the performance of the XGBoost model. Experimental results show that the integration of Ant Colony Optimization and XGBoost can help attain outstanding prediction accuracy with a correlation of determination (R2) of 0.95. Additionally, an asymmetric squared error loss function is utilized to reduce overestimations by 12 %. The newly developed method can be utilized in practical applications where reliable predictions of the lateral strength of RC columns under cyclic loads are required.

Numerical Study on the Shear Capacity-Curvature Ductility Relationship of High Strength Reinforced Concrete Beams under Different Failure Modes Using ABAQUS

Studying shear capacity in reinforced concrete beams is vital for structural safety and integrity. Preventing sudden shear failure is essential to avoid catastrophic collapses and ensure reliable construction performance. ABAQUS is vital for the thorough analysis of concrete specimens, offering deeper insights into their behavior under different experimental conditions. This paper explored the correlation between shear capacity and curvature ductility in high-strength reinforced concrete cantilever beams subjected to monotonic loading, involving tests on six cantilever beams with cross sections measuring 200 mm by 300 mm. The study examined how span-to-effective depth ratios ("a/d") and stirrup spacing influence beam behavior at the plastic hinge under various failure modes: flexural, shear, and combined. The specimens were categorized into two groups, with each group comprising 3 beams and 3 values for each variable. In the first test group, as the a/d ratio increased from 750 to 850 and then to 1150 mm, shear capacity increased by 99.3% and 16.3%, while curvature ductility improved by 45.5% and 29.7%. The failure modes included shear, combined, and flexural, indicating a direct yet non-linear relationship between curvature ductility and shear capacity. Increasing stirrup spacing from 100 to 150 and then to 300 resulted in a 37.3% and 59.2% decrease in shear capacity and an 18% and 58.8% reduction in curvature ductility. This demonstrates an inverse non-linear relationship and a shift in failure mode from flexural to combined and then to shear.

Advancing stem cell technologies for conservation of wildlife biodiversity.

Wildlife biodiversity is essential for healthy, resilient and sustainable ecosystems. For biologists, this diversity also represents a treasure trove of genetic, molecular and developmental mechanisms that deepen our understanding of the origins and rules of life. However, the rapid decline in biodiversity reported recently foreshadows a potentially catastrophic collapse of many important ecosystems and the associated irreversible loss of many forms of life on our planet. Immediate action by conservationists of all stripes is required to avert this disaster. In this Spotlight, we draw together insights and proposals discussed at a recent workshop hosted by Revive & Restore, which gathered experts to discuss how stem cell technologies can support traditional conservation techniques and help protect animal biodiversity. We discuss reprogramming, in vitro gametogenesis, disease modelling and embryo modelling, and we highlight the prospects for leveraging stem cell technologies beyond mammalian species.

Curvature-Assisted Vesicle Explosion Under Light-Induced Asymmetric Oxidation.

Exposure of cell membranes to reactive oxygen species can cause oxidation of membrane lipids. Oxidized lipids undergo drastic conformational changes, compromising the mechanical integrity of the membrane and causing cell death. For giant unilamellar vesicles, a classic cell mimetic system, a range of mechanical responses under oxidative assault has been observed including formation of nanopores, transient micron-sized pores, and total sudden catastrophic collapse (i.e., explosion). However, the physical mechanism regarding how lipid oxidation causes vesicles to explode remains elusive. Here, with light-induced asymmetric oxidation experiments, the role of spontaneous curvature on vesicle instability and its link to the conformational changes of oxidized lipid products is systematically investigated. A comprehensive membrane model is proposed for pore-opening dynamics incorporating spontaneous curvature and membrane curling, which captures the experimental observations well. The kinetics of lipid oxidation are further characterized and how light-induced asymmetric oxidation generates spontaneous curvature in a non-monotonic temporal manner is rationalized. Using the framework, a phase diagram with an analytical criterion to predict transient pore formation or catastrophic vesicle collapse is provided. The work can shed light on understanding biomembrane stability under oxidative assault and strategizing release dynamics of vesicle-based drug deliverysystems.

An index-based multi-hazard risk assessment method for prioritisation of existing bridge portfolios

In recent years, several catastrophic collapses of existing bridges have highlighted the need for rapid risk analysis methods aimed at supporting infrastructure managers in the prioritisation of detailed assessments and, if any, risk mitigation actions. A large percentage of existing road bridges were built between the 1960s and 1980s, having thus already reached or even exceeded their design lifetime. Several studies have also shown that bridges often collapse due to either natural or human-related events, such as floods, collisions or overloading that, in addition to earthquakes, should be duly considered in risk assessment. This calls for multi-hazard approaches that provide an integrated perspective of the risk of bridge portfolios, to identify critical structures to support decision-makers. This study proposes a multi-hazard risk-based prioritisation methodology for application to a large number of bridges under limited level of knowledge. Specifically, the risk level is quantified through indices, accounting for uncertainties, that are used for comparative purposes among bridges. The methodology is applied to a highway bridge portfolio located in northern Italy, producing a risk-based ranking that is critically discussed. Analysis results are then compared with the outcome of the current Italian guidelines for safety assessment and maintenance of existing bridges.

Experimental Study of Sinkhole Propagation Induced by a Leaking Pipe Using Fibre Bragg Grating Sensors.

Sinkhole formation caused by leaking pipes in karst soluble rocks is a significant concern, leading to infrastructure damage and safety risks. In this paper, an experiment was conducted to investigate sinkhole formation in dense sand induced by a leaking pipe. Fibre Bragg grating (FBG) sensors were used to record the strain. A balloon was gradually deflated within a bed of wet silica sand to create an underground cavity. Eighteen FBG sensors, with a wavelength range between 1550 nm and 1560 nm, were embedded horizontally and vertically in the physical model at different levels to monitor deformation at various locations. A leaking pipe was installed to induce the collapse of the formed arch above the cavity. The strain measurements suggested the following four phases in the sinkhole formation process: (1) cavity formation, (2) progressive weathering and erosion, (3) catastrophic collapse, and (4) subsequent equilibrium conditions. The results showed differences in the strain signatures and distributions between the horizontal and vertical measurements. During the critical phase of the sinkhole collapse, the horizontal measurements primarily showed tension, while the vertical measurements indicated compression. This investigation demonstrates the effectiveness of FBGs as advanced monitoring tools for sinkhole precursor identification. The study also suggests using FBGs in geotechnical monitoring applications to improve the understanding and mitigation of sinkholes and related geohazards.

Investigating the impact of corrosion on behavior and failure modes of reinforced concrete slabs: An experimental and analytical study

Corrosion of steel reinforcement significantly reduces the load-carrying capacity of reinforced concrete (RC) flat slabs, making them more vulnerable to punching shear failure. This type of failure can lead to sudden and catastrophic collapse of the structure. Despite its critical implications, research on this topic remains limited, and a mechanical model to estimate the load-displacement behavior of RC flat slabs with corroded reinforcements is currently lacking. In this paper, experimental work on corroded RC slabs under punching shear loading was conducted. To investigate the impact of corrosion on the structural behavior of reinforced concrete (RC) flat slabs, eight specimens, including both corroded and uncorroded controls, were subjected to load testing. The study focused on key performance indicators including punching shear strength, stiffness, crack patterns, failure modes, and energy dissipation capacity. Additionally, an analytical study based on the newly developed Critical Shear Crack Theory (CSCT) was conducted to understand the behavior of corroded RC slabs. Experimental results indicated a significant reduction in the punching shear strength of corroded slabs. Moreover, as corrosion progressed, a notable shift in failure mode from punching shear to flexural failure was observed. The proposed CSCT model demonstrated good agreement between the experimentally obtained and analytically predicted load-displacement curves.

The evolution of accreting population III stars at 10−6–103 M⊙ yr−1

Context. The first stars formed over five orders of magnitude in mass by accretion in primordial dark matter halos. Aims. We study the evolution of massive, very massive and supermassive primordial (Pop III) stars over nine orders of magnitude in accretion rate. Methods. We use the stellar evolution code GENEC to evolve accreting Pop III stars from 10−6–103 M⊙ yr−1 and study how these rates determine final masses. The stars are evolved until either the end central Si burning or they encounter the general relativistic instability (GRI). We also examine how metallicity affects the evolution of the star at one accretion rate. Results. At rates below ∼2.5 × 10−5 M⊙ yr−1 the final mass of the star falls below that required for pair-instability supernovae. The minimum rate required to produce black holes with masses above 250 M⊙ is ∼5 × 10−5 M⊙ yr−1, well within the range of infall rates found in numerical simulations of halos that cool via H2, ≲10−3 M⊙ yr−1. At rates of 5 × 10−5 M⊙ yr−1 to 4 × 10−2 M⊙ yr−1, like those expected for halos cooling by both H2 and Lyα, the star collapses after Si burning. At higher accretion rates the GRI triggers the collapse of the star during central H burning. Stars that grow at above these rates are cool red hypergiants with effective temperatures log(Teff) = 3.8 and luminosities that can reach 1010.5 L⊙. At accretion rates of 100–1000 M⊙ yr−1 the gas encounters the general relativistic instability prior to the onset of central hydrogen burning and collapses to a black hole with a mass of ∼106 M⊙ without ever having become a star. Conclusions. Our models corroborate previous studies of Pop III stellar evolution with and without hydrodynamics over separate, smaller ranges in accretion rate. They also reveal for the first time the critical transition rate in accretion above which catastrophic baryon collapse, like that which can occur during galaxy collisions in the high-redshift Universe, produces supermassive black holes via dark collapse.

A p62-dependent rheostat dictates micronuclei catastrophe and chromosome rearrangements.

Chromosomal instability (CIN) generates micronuclei-aberrant extranuclear structures that catalyze the acquisition of complex chromosomal rearrangements present in cancer. Micronuclei are characterized by persistent DNA damage and catastrophic nuclear envelope collapse, which exposes DNA to the cytoplasm. We found that the autophagic receptor p62/SQSTM1 modulates micronuclear stability, influencing chromosome fragmentation and rearrangements. Mechanistically, proximity of micronuclei to mitochondria led to oxidation-driven homo-oligomerization of p62, limiting endosomal sorting complex required for transport (ESCRT)-dependent micronuclear envelope repair by triggering autophagic degradation. We also found that p62 levels correlate with increased chromothripsis across human cancer cell lines and with increased CIN in colorectal tumors. Thus, p62 acts as a regulator of micronuclei and may serve as a prognostic marker for tumors with high CIN.

Bio-Inspired Curved-Elliptical Lattice Structures for Enhanced Mechanical Performance and Deformation Stability.

Lattice structures, characterized by their lightweight nature, high specific mechanical properties, and high design flexibility, have found widespread applications in fields such as aerospace and automotive engineering. However, the lightweight design of lattice structures often presents a trade-off between strength and stiffness. To tackle this issue, a bio-inspired curved-elliptical (BCE) lattice is proposed to enhance the mechanical performance and deformation stability of three-dimensional lattice structures. BCE lattice specimens with different parameters were fabricated using selective laser melting (SLM) technology, followed by quasi-static compression tests. Finite element (FE) numerical simulations were also carried out for validation. The results demonstrate that the proposed BCE lattice structures exhibit stronger mechanical performance and more stable deformation modes that can be adjusted through parameter tuning. Specifically, by adjusting the design parameters, the BCE lattice structure can exhibit a bending-dominated delocalized deformation mode, avoiding catastrophic collapse during deformation. The specific energy absorption (SEA) can reach 24.6 J/g at a relative density of only 8%, with enhancements of 48.5% and 297.6% compared with the traditional energy-absorbing lattices Octet and body-center cubic (BCC), respectively. Moreover, the crushing force efficiency (CFE) of the BCE lattice structure surpasses those of Octet and BCC by 34.9% and 15.8%, respectively. Through a parametric study of the influence of the number of peaks N and the curve amplitude A on the compression performance of the BCE lattice structure, the compression deformation mechanism is further analyzed. The results indicate that the curve amplitude A and the number of peaks N have significant impacts on the deformation mode of the BCE lattice. By adjusting the parameters N and A, a structure with a combination of high energy absorption, high stiffness, and strong fracture resistance can be obtained, integrating the advantages of tensile-dominated and bending-dominated lattice structures.

"The catastrophic collapse of collective farms": diaries of the student practice of Leningrad Branch of the Communist University of National Minorities of the West in 1930 as a source for studying collectivization

The urgent task of historical science is to identify and include new sources in the research turnover. This article is devoted to a little-studied type of sources, which are the accounting documents of university practice, which students of communist universities of the USSR necessarily passed in the 1930s. As an example, diaries compiled by students of the Leningrad Branch of the Communist University of the National Minorities of the West during the period of party practice in the spring of 1930 are used. The purpose of the work is to present these materials to the scientific community. In this regard, the article includes the texts of two student diaries prepared according to the methodological recommendations for the publication of archival documents in printed form. The author is convinced that these materials are capable of qualitatively supplementing the source base of scientific research on the problems of collective farm construction in the USSR. The information contained in the diaries shows the process of collectivization from the point of view of Soviet activists. This not only contributes to a better understanding of the processes that the socialist restructuring of the village caused, but also allows you to study in detail the peculiarities of the work of collectivizers. This determines the novelty and relevance of this work. The prospects for the methodological development of these sources are due to the development of an anthropological paradigm that expands the subject field of historical science and suggests new approaches to the study of already known issues. In this case, we can talk about the increment of scientific knowledge in the field of collectivization by studying the facts of everyday life of collective farm peasants and trainees engaged in artel construction. A high degree of informational impact of student diaries can be provided within the framework of such research areas as the history of everyday life and microhistory. Насущной задачей исторической науки является выявление и включение в исследовательский оборот новых источников. Данная статья посвящена мало изученному виду источников, каковым являются отчётные документы университетской практики, которую в обязательном порядке проходили студенты коммунистических вузов СССР в 1930-е гг. В качестве примера использованы дневники, составленные учащимися Ленинградского отделения Коммунистического университета национальных меньшинств Запада в период партийной практики весной 1930 г. Цель работы – представить указанные материалы научному сообществу. В этой связи статья включает тексты двух студенческих дневников, подготовленных согласно методическим рекомендациям по публикации архивных документов в печатном виде. Автор убеждён, что данные материалы способны качественно дополнить источниковую базу научных исследований проблем колхозного строительства в СССР. Информация, содержащаяся в дневниках, показывает процесс коллективизации с точки зрения советских активистов. Это не только способствует лучшему пониманию процессов, которые вызвала социалистическая перестройка деревни, но также позволяет подробно изучить особенности труда коллективизаторов. Этим определяются новизна и актуальность настоящей работы. Перспективность методологического освоения названных источников обусловлена развитием антропологической парадигмы, расширяющей предметное поле исторической науки и подсказывающей новые подходы к изучению уже известной проблематики. В данном случае речь может вестись о приращении научного знания в области коллективизации за счёт изучения фактов обыденной жизни колхозных крестьян и практикантов, занимавшихся артельным строительством. Высокая степень информационной отдачи студенческих дневников может быть обеспечена в рамках таких исследовательских направлений, как история повседневности и микроистория.

Natural coral recovery despite negative population growth.

Demographic processes that ensure the recovery and resilience of marine populations are critical as climate change sends an increasing proportion on a trajectory of decline. Yet for some populations, recovery potential remains high. We conducted annual monitoring over 9 years (2012-2020) to assess the recovery of coral populations belonging to the genus Pocillopora. These populations experienced a catastrophic collapse following a severe typhoon in 2009. From the start of the monitoring period, high initial recruitment led to the establishment of a juvenile population that rapidly transitioned to sexually mature adults, which dominated the population within 6 years after the disturbance. As a result, coral cover increased from 1.1% to 20.2% during this time. To identify key demographic drivers of recovery and population growth rates (λ), we applied kernel-resampled integral projection models (IPMs), constructing eight successive models to examine annual change. IPMs were able to capture reproductive traits as key demographic drivers over the initial 3 years, while individual growth was a continuous key demographic driver throughout the entire monitoring period. IPMs further detected a pulse of reproductive output subsequent to two further Category 5 typhoon events during the monitoring period, exemplifying key mechanisms of resilience for coral populations impacted by disturbance. Despite rapid recovery, (i.e., increased coral cover, individual colony growth, low mortality), IPMs estimated predominantly negative values of λ, indicating a declining population. Indeed, while λ translates to a change in the number of individuals, the recovery of coral populations can also be driven by an increase in the size of surviving colonies. Our results illustrate that accumulating long-term data on historical dynamics and applying IPMs to extract demographic drivers are crucial for future predictions that are based on comprehensive and robust understandings of ecological change.

Analytical vulnerability functions for assessing fatalities in masonry buildings

AbstractThe assessment of human losses and injuries due to earthquakes is critical for the development of risk reduction measures. Yet, most vulnerability studies have focused on the derivation of fragility functions for structural damage, neglecting the evaluation of the human impact. In this study, we implemented a fatality vulnerability assessment procedure based on advanced structural modelling, with an application to typical limestone and granite masonry buildings in Portugal. We performed nonlinear time‐history analysis on 3D numerical models whose characteristics were sampled from statistical models representing the geometric and mechanical properties of this type of construction. Engineering demand parameters, such as volume of loss and volume of survivable space, were estimated and converted into a fatality rate based on observations from past fatal earthquakes. We compared these vulnerability functions with other proposals from the literature in which conventional fragility functions are directly combined with collapse and fatality rates. Finally, the resulting vulnerability functions were tested for two earthquake scenarios for Portugal. The results from this study indicate that the conventional approach for fatality modelling tends to underestimate human losses for strong ground shaking due to the inability to account for catastrophic structural collapses. The fatality vulnerability functions developed in this work can be directly used in probabilistic seismic risk analysis or the assessment of earthquake scenarios.

Multi-Task AI-driven undetermined blind source identification for modal identification of large scale structures

The effective management of aging infrastructure represents a critical concern globally, exerting profound socio-economic influences and occupying a prominent position on the political agenda. The escalating occurrences of catastrophic collapses in recent years underscore the pressing requirement for efficient Structural Health Monitoring (SHM) strategies. These strategies play a pivotal role in aiding decision-making processes related to prioritizing interventions and rehabilitation efforts. Among SHM systems, those utilizing Operational Modal Analysis (OMA) through vibration-based techniques have gained popularity due to their non-destructive nature, comprehensive damage assessment capabilities, and relative ease of automation. Despite their advantages, current OMA methods encounter significant scalability challenges, primarily attributable to extensive computational demands and the necessity for substantial expert involvement. In this context, recent advancements in the field of artificial intelligence (AI) present a promising solution to address these scalability issues, opening the door for the development of next-generation SHM systems. This study introduces an innovative Multitask Learning Deep Neural Network (MTL-DNN) model designed for rapid and automated blind source modal identification of structures. Integrating the concepts of undetermined second-order blind source identification (SOBI) into the architecture of the network, the proposed model can reveal the independent modal components present in the raw response acceleration data with minimum computational burden. The presented results demonstrate the quasi-instantaneous modal identification capabilities of the proposed architecture, enabling the estimation of more components than the number of sensors.

Achieving high strength and energy absorption of novel 3D printed helical layered square honeycombs

Bionics shape design of cellular structures has the potential advantage of improving their both mechanical properties and energy absorption capabilities to the conventional honeycomb structures. In this article, inspired by square porous wood and DNA double helix, we demonstrate the creation of the novel helical layered square honeycombs (HLSHs) that simultaneously exhibit high strength and excellent energy absorption capacity. In-plane compression experiments and finite element simulations revealed that helical structure can effectively strengthen every unit cell to resist local stress concentration which always leads to rapid strain localization and finally followed by catastrophic collapse. Furthermore, the stiffness, strength and energy absorption capability can be continuously improved by increasing the number of helical layers. More specifically, the HLSH-4L (4 layers) exhibits higher collapse stress (∼176 %) and specific absorption energy (∼502 %) compared with that of regular square honeycomb (RESH). The investigation of deformation and failure behavior show that the helical structure can supply high cell-buckling resistance and facilitate the “X” shape deformation band. Besides, the helical structure also caused the transition of failure mechanisms from printing fibers tearing in RESH to layer cracking in HLSHs. This study can present insight into the design of lighter and stronger honeycomb.

Enhancing pier local scour prediction in the presence of floating debris

AbstractLocal scour poses a grave threat to bridge foundations, potentially causing catastrophic collapses. This study uses FLOW-3D with the Reynolds-Averaged Navier-Stokes model to analyze pier scour and dune formation under bridges. It focuses on submerged debris shapes near the water's surface. Results closely match experiments when specific conditions are met. The study introduces an innovative approach to debris impact assessment. Instead of traditional methods, it proposes a novel equation accounting for debris's effective area and elevation. This enhances reliability by over 20%, improving scour depth assessment in debris-laden scenarios. This advances the understanding of debris's role in local scour, benefiting bridge design and management practices.

Island-wide characterization of agricultural production challenges the demographic collapse hypothesis for Rapa Nui (Easter Island).

Communities in resource-poor areas face health, food production, sustainability, and overall survival challenges. Consequently, they are commonly featured in global debates surrounding societal collapse. Rapa Nui (Easter Island) is often used as an example of how overexploitation of limited resources resulted in a catastrophic population collapse. A vital component of this narrative is that the rapid rise and fall of pre-contact Rapanui population growth rates was driven by the construction and overexploitation of once extensive rock gardens. However, the extent of island-wide rock gardening, while key for understanding food systems and demography, must be better understood. Here, we use shortwave infrared (SWIR) satellite imagery and machine learning to generate an island-wide estimate of rock gardening and reevaluate previous population size models for Rapa Nui. We show that the extent of this agricultural infrastructure is substantially less than previously claimed and likely could not have supported the large population sizes that have been assumed.

Resilient and Sustainable Structures through EMI-Based SHM Evaluation of an Innovative C-FRP Rope Strengthening Technique

Reinforced Concrete (RC) members in existing RC structures are susceptible to shear-critical due to their under-reinforced design. Thus, implementing a retrofitting technique is essential to eliminate the casualties that could arise from sudden and catastrophic collapses due to these members’ brittleness. Among other proposed techniques, using Carbon-Fiber Reinforced Polymers (C-FRP) ropes to increase the shear strength of RC structural elements has proved to be a promising reinforcement application. Moreover, an Electro-Mechanical Impedance (EMI-based) method using Lead Zirconate Titanate (PZT-enabled) was employed to assess the efficiency of the strengthening scheme. Initially, the proposed technique was applied to C-FRP rope under the subjection of pullout testing. Thus, a correlation of the rope’s tensile strength with the EMI responses of the PZT patch was achieved using the Root Mean Square Deviation (RMSD) metric index. Thereafter, the method was implemented to the experimentally acquired data of C-FRP ropes, used as shear reinforcement in a rectangular deep beam. The ropes were installed using the Embedded Through Section (ETS) scheme. Furthermore, an approach to evaluate the residual shear-bearing capacity based on the EMI responses acquired by being embedded in and bonded to the ropes’ PZTs was attempted, demonstrating promising results and good precision compared to the analytical prediction of the C-FRP ropes’ shear resistance contribution.

Competing climate feedbacks of ice sheet freshwater discharge in a warming world

Freshwater discharge from ice sheets induces surface atmospheric cooling and subsurface ocean warming, which are associated with negative and positive feedbacks respectively. However, uncertainties persist regarding these feedbacks’ relative strength and combined effect. Here we assess associated feedbacks in a coupled ice sheet-climate model, and show that for the Antarctic Ice Sheet the positive feedback dominates in moderate future warming scenarios and in the early stage of ice sheet retreat, but is overwhelmed by the negative feedback in intensive warming scenarios when the West Antarctic Ice Sheet undergoes catastrophic collapse. The Atlantic Meridional Overturning Circulation is affected by freshwater discharge from both the Greenland and the Antarctic ice sheets and, as an interhemispheric teleconnection bridge, exacerbates the opposing ice sheet’s retreat via the Bipolar Seesaw. These results highlight the crucial role of ice sheet-climate interactions via freshwater flux in future ice sheet retreat and associated sea-level rise.