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Can FRP Reinforcement Reduce Vibrations of CLT Floors?
No full textDesign of long-span building floors has been governed by vibration serviceability criteria, and cross-laminated timber (CLT) floors are no exception. High stiffness to mass ratio makes them highly susceptible to excessive vibrations induced by pedestrians walking, which is by no surprise the most frequent load case scenario in buildings occupied by people. Typically composed of multiple prefabricated CLT panels assembled on a building site, CLT floors have been an increasingly popular greener and build faster alternative to the traditional concrete and composite floors. This paper presents an experimental and preliminary numerical research designed to study potential benefits of reinforcing CLT panels with fiberglass reinforced polymer (FRP) bars on vibration performance of the floor assembly
EUROCODE 2: Cracking in prestressed concrete
No full textEurocode 2 (EN 1992-1-1:2004) provides instructions for the SLS design of prestressed concrete
structures with cracks. Regarding requirements, there is a difference between bonded and unbonded tendons. The limitations for elements with unbonded tendons are the same as for reinforced concrete elements, regardless of the environmental conditions. These limitations are usually already fulfilled by
ULS design.
Requirements for elements with bonded tendons are much stricter. Narrow cracks without additional
restrictions are allowed only for mild environments (X0, XC1). For the remaining environments, under
service load, it is necessary for the tendons to be within the concrete in compression (“decompression
limit”).
The paper refers to the structural efficiency of prestressed concrete elements that are constructed using bonded tendons. The consequences of the design requirements set for prestressed elements with cracks are discussed. Emphasis is placed on requirements that have an adverse impact on design. The considerations are illustrated with a design example. The general conclusion is that uncracked elements provide more favorable results when using bonded tendons
Poisson’s ratio and stress-transfer mechanism of triangular-shaped ten-wire prestressing strand
No full textThis study investigates the Poisson’s ratio and deformation behavior of a triangular ten-wire prestressing strand in comparison to conventional seven-wire strand. Experimental tests were conducted under controlled loading to evaluate axial and lateral strains, allowing the determination of strand Poisson’s ratios. The results show that ten-wire strands exhibit consistently higher Poisson’s ratios (≈0.44) than seven-wire strands (≈0.33), representing an increase of approximately 25% in lateral strain response. This behavior is attributed to the triangular arrangement of wires, which provides additional wire-to-wire contacts and annular spaces, enhancing confinement and strand–concrete interaction. The findings highlight the significant influence of strand geometry on bond efficiency, transfer length, and mechanical response, providing valuable guidance for the design, calibration, and assessment of pretensioned prestressed concrete members. These results support improved predictive modeling of stress transfer and deformation behavior, contributing to more efficient and reliable prestressed concrete design
Priliv čistih voda u kanalizaciju – uzroci i uticaji na prečišćavanje otpadnih voda
No full textU radu su predstavljeni uzroci i posledice priliva čistih voda u kanalizacioni sistem, sa
posebnim osvrtom na njihov uticaj na funkcionisanje kanalizacije i efikasnost procesa
prečišćavanja otpadnih voda. Posebno je ukazano na neophodnost da se ovoj problematici
hitno i sistematski posveti odgovarajuća pažnja u Republici Srbij
An innovative hybrid paradigm on “nature” consideration in the water-energy-food Nexus
No full textIntegrated approaches and solutions for effective governance and positive management of natural resources need to consider the rising global trends and challenges influenced by the increasing demands for water, energy, food and materials from primary sectors, while maintaining the integrity of ecosystems, and ensuring resource security, justice and equitable access to resources. The Water-Energy-Food (WEF) Nexus has been proposed as a cross-sectoral approach to promote resource use efficiency, manage trade-offs, and exploit arising synergies across these sectors; whilst improving governance coherence and increasing sustainability and systems resilience. The WEF Nexus has evolved from productivity and sustainability perspectives on natural resources uses – recognising and understanding the water, energy, and food sectors’ interconnectedness – to be flexibly expanded to other components such as climate, biodiversity, land, health, transport and ecosystems. Ecosystems provide invaluable services to the WEF Nexus – e.g., water flows regulation, food and biomass production, energy efficiency and recovery – supporting human health and well-being; however, until now there is limited consensus by researchers and practitioners on how to integrate the recognised role of nature and ecosystems as a component of the complex Nexus system.
The present communication will describe and compare conceptual paradigms, discuss the fundamental concepts and diverging perceptions implied in the analysis of integrating “nature” in the WEF Nexus, and propose a novel forward-looking conceptualisation of the so-called WEF-ecosystems (WEFE) Nexus, and research directions.
To converge existing approaches that integrate the term “nature” into the WEF Nexus approach, and suggest a common framework, an interdisciplinary group of natural resources management researchers and systems thinking experts from different scientific disciplines and expertise, and members of the European research network NEXUSNET – 37 of the total participants are co-authors of this communication –, followed a collaborative process of knowledge co-creation combining literature review, elicitation of expert opinion and collaborative writing. The synthesis of existing scientific literature was assessed to identify the multiplicity of different most used concepts, semantics, definitions, and true perspectives and modes of representing “nature” in the Nexus, including social and ecological systems.
The results reveal a collection of concepts utilised in the literature to characterise, partially or fully, “nature” and ecological systems in the Nexus – which include mainly those from an anthropogenic view –, such as “environment”, “environmental impact”, “ecosystems”, “ecosystem services”, “social-ecological systems”, “land use”, “natural resources”, “nature-based solutions”, and “biodiversity”. Inconsistencies were also found in the role attributed to nature, exemplified by three key conceptual hybrid paradigms: (Paradigm 1) Ecosystems as the fourth “pillar” / component of an expanded WEF Nexus; i.e., the WEFE Nexus; (Paradigm 2) Ecosystems and their services as a foundational layer to the WEF Nexus, to highlight their role in delivering resources and services to the water, energy, and food sectors; and (Paradigm 3) the WEF Nexus integration as a central component of the social systems (SES) framework, acknowledging the human/natural systems relation. By creating a hybrid approach that brings together the benefits and disadvantages of the respective existing paradigms, this communication will present a forward-looking WEFE Nexus conceptualisation towards a holistic and comprehensive thinking on the water, energy, food, and ecosystem systems’ interplays. This paradigm expands and emphasises the mutual interlinkages among water, energy and food to the entirety of ecosystems and the SES – which would act as a fourth node. Thus, acknowledging the social-ecological processes that are affected by and potentially affect the WEF Nexus – e.g., to address resource use optimisation and recommendations, including technological and social innovations.
This hybrid WEFE Nexus paradigm can include greater requirements regarding its operationalisation. Therefore, the authors emphasise the main ‘good practices’ in this regard. The first is the creation of such a work plan that can ensure better adaptation to unforeseen challenges and changes, continuous communication between different working parts, as well as their interdisciplinarity. The second is that policy analysts should focus on multiple tasks, some of which are: predicting policy coherence and identifying existing policy compromises and synergies; assessments that will extend to policy areas outside the Nexus sector being investigated to assess their potential impact on decision-making processes within the Nexus; subsequent evaluations of the impact of Nexus policies to ensure that policies across different sectors are achieving their intended outcomes; the uptake of Nexus research results into policy making.
The results of this collaborative research piece intend to make available researchers and stakeholders with the basis to better understand and ultimately manage Nexus challenges in transdisciplinary frameworks, combining social and ecological processes, towards a transformative change based on the WEF - “nature” Nexus space
Behavior of Demountable Connections with Taper Threaded Mechanical Coupler (TTC) and Rebar Anchor Under Tension Load
No full textComposite and mixed steel-concrete buildings, apart from high structural efficiency, have great potential in terms of reuse of structural elements at the end of the life of the buildings. The use of most demountable connectors can assure the reuse of steel elements; however, the reuse of reinforced concrete (RC) elements and embedded connectors remains relatively uncertain due to potential damage of connectors during disassembly. One of the possible solutions to assure the reuse of all components could be to use demountable connectors assembled from a demountable bolt and an embedded mechanical coupler with a rebar anchor. The key challenge for practical implementation of this type of demountable connector is adequate analysis under tension loads, due to a lack of design recommendations. This paper presents experimental investigations of the
connection with demountable connectors with mechanical couplers and rebar anchors, located close to the concrete edge, under pure tension load. Nine pull-out tests on single connectors embedded in the RC element and six in-air tests on bare connectors were conducted in order to define the global behavior of the connection and the local behavior of the connector, respectively. The influence of concrete strength (concrete class C20/25 and C30/37), connector diameter (with M16 and M20 bolts), and bolt grade (grades 5.8 and 8.8) on the connection behavior was discussed in terms of resistance, stiffness, deformation capacity, and failure modes. Ultimate resistance varied from 77 kN to 135 kN, with failure modes shifting from taper thread stripping to bolt fracture based on bolt grade. Based on the obtained test results, analytical equations for the calculation of tension resistance and overall deformation capacity of the connection were proposed
Sustainable Lightweight Concrete Designed with Modified Solidified Wastewater Sludge as Partial Replacement of Cement
No full textThe requirement for high-quality drinking water and the treatment of wastewater
prior to discharge into the environment results in the generation of sludge. As with
any high-volume materials, beneficial reuse applications are being sought to promote
sustainable environmental solutions. This research examined the possibilities of producing
sustainable lightweight concrete using modified solidified wastewater sludge as a partial
replacement of cement. Wastewater sludge was modified by the addition of aluminum
oxide and magnesium silicate hydrate. The properties of the modified wastewater sludge
were examined, as well as the influence of the partial cement replacement with the sludge in
lightweight concrete. Besides testing the physical and mechanical properties of four mortar
mixtures, an additional analysis of the willingness of final users to accept novel material
containing wastewater sludge was addressed. The results obtained for the mortar samples
indicate that 20% cement replacement is the upper limit for the modified sludge’s
application. The lightweight concrete prepared with the modified sludge (in the amount
of 20%) was tested in a hardened state. The water permeability was reduced by 33.3%
with the addition of the modified sludge. Both tested concrete mixtures showed good
frost resistance. The maximal measured reduction in the compressive strengths was 7.6%.
Citizens’ perceptions and responses regarding the beneficial reuse of materials emphasize
the importance of comprehensive education for their future acceptance
Rapid Earthquake Loss Assessment Framework: RELAR Project and Its Application on the Data Set From the Kraljevo (Serbia) Earthquake in 2010
No full textRapid earthquake damage and loss assessment is a critical process for evaluating the immediate impacts of seismic events on infrastructure and populations. It involves the quick analysis of structural damage and economic losses. The goal is to provide timely information to emergency responders, government agencies, and decision-makers, enabling efficient resource allocation and disaster response. Advanced technologies such as machine learning, remote sensing, and real-time data analytics have improved the accuracy and speed of these assessments, helping to mitigate the effects of earthquakes and support recovery efforts. This paper presents the RELAR project, funded by the Science Fund of the Republic of Serbia, which aims to improve earthquake loss assessment and recovery processes. By integrating Machine Learning and Image Recognition, the project accelerates response times and enhances the accuracy of damage estimation and repair cost assessments. Traditional methods often suffer from delays and inaccuracies due to data limitations and lack of flexibility. RELAR offers innovative solutions for providing reliable, timely information, even in the absence of ground motion data. The project’s objectives include developing practical ML algorithms, validating assessment models, and establishing proactive risk mitigation strategies. Within the paper, a brief overview of the first results of the framework applied to the case of Kraljevo 2010 earthquake is given, showing the methodology of the approach
Methodology for Implementing Monitoring Data into Probabilistic Analysis of Existing Embankment Dams
No full textMonitoring data provide valuable information on embankment dam behavior
but are typically not integrated into a classical probabilistic safety assessment. This paper
introduces a Bayesian-inspired methodology to directly integrate actual dam monitoring
records into a Monte Carlo probabilistic safety assessment using a finite element framework,
without recalibrating the original input parameters ‘distributions. After the baseline
(unweighted) set of simulations is generated, the method assigns a weight coefficient to
each simulation outcome based on the likelihood of matching monitoring data, effectively
updating the baseline probabilistic analysis results. Therefore, such “weighted” analysis
produces an updated probability distribution of the dam’s factor of safety (FS) that reflects
both prior uncertainty of model parameters and actual monitoring data. To illustrate the
approach, a case study of a rockfill triaxial test specimen is analyzed: a baseline probabilistic
analysis yields a mean FS ~1.7, whereas the weighted analysis incorporating monitoring
data reduces the mean FS to ~1.5 and narrows the variability. The weighted analysis
suggests less favorable conditions than the baseline projections. This methodology offers
a transparent, computationally tractable route for embedding monitoring evidence into
reliability calculations, producing more reflective safety estimates of actual dam behavior
Drought propagation in high-latitude catchments: insights from a 60-year analysis using standardized indices
No full textDroughts, traditionally less associated with highlatitude regions, are emerging as significant challenges due to changing climatic conditions. Recent severe droughts in Europe have exposed the vulnerability of northern catchments, where shifts in temperature and precipitation patterns may intensify drought impacts. This study investigates the dynamics of drought propagation in high-latitude regions, focusing on four key aspects: (1) the typical lag time for drought conditions to propagate from initial precipitation deficits to impacts on soil moisture, streamflow, and groundwater systems; (2) the probability of precipitation deficits leading to these droughts; (3) the key catchment characteristics influencing drought propagation; and (4) the way in which drought propagation has evolved under changing climate conditions. By analyzing long-term observational records from 50 Swedish catchments, the study reveals that drought propagation is highly variable and influenced by a complex interplay of catchment characteristics, hydroclimatic conditions, and soil properties. Soil moisture exhibits the shortest propagation times, often responding within a month to precipitation deficits, while groundwater shows the longest and most variable response times, sometimes exceeding several months. The probability of precipitation deficits propagating into soil moisture droughts is highest, followed by streamflow and groundwater, with these probabilities increasing over time. Across all drought types, annual precipitation and streamflow emerge as the most influential factors governing both propagation time and probability. Although most catchments have become wetter year-round due to climate change, southern catchments are increasingly vulnerable to spring droughts (particularly soil moisture drought), driven by increasing evaporative demand. Despite these hydroclimatic shifts, no significant long-term trends in propagation times or probabilities have been observed over the past 60 years. These findings highlight the need for tailored region-specific water management strategies to address seasonal and regional variations in drought risks, particularly as climate change continues to reshape hydrological regimes