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Water bound to various hydrous minerals can be transported deep into the mantle by slab subduction. Serpentine is one of most important hydrous minerals in the crust and shallow upper mantle. A partially serpentinized slab mantle limits the amount of water that can enter deep into the mantle. The partitioning of water between hydrous minerals and nominally anhydrous minerals (NAMs) is a crucial factor in controlling the physical properties and dynamics of slabs. Recent experiments on water partitioning have revealed that water strongly partitions to coexisting hydrous minerals. NAMs, such as olivine and its high-pressure polymorphs, have limited water content in water-undersaturated wet slabs. Metastable olivine wedges are not a feature of dry slabs, but can be of wet slabs that are not saturated with water. The transformation kinetics of the dry state, which generates deep-focus earthquakes and produces significant deformation in the slab, can work under wet slabs. Water bound to hydrous minerals is transported by the slab to the mantle transition zone and lower mantle. Hydrous minerals in stagnant slabs over 660 km depth release water as the slab warms, producing locally hydrated mantle transition zones and dense water-bearing magmas at the base of the upper mantle, and generating intraplate volcanism, which are referred to as the big mantle wedge model. Seismic scatterers are observed in the lower mantle at depths from 700 to 1900 km. These scatterers may be caused by water release at the top of the lower mantle by dehydration of hydrous minerals such as dense hydrous magnesium silicates. The shear instability due to the second order phase transformation from stishovite to CaCl2-type phase in hydrous aluminous SiO2 also causes the depth variation of seismic scatterers in the lower mantle. The high-pressure polymorphs of aluminous SiO2 contain a large amount of water more than 1 wt%, which can be important water carriers under lower mantle conditions. [ABSTRACT FROM AUTHOR]

Purpose: Explosions, historically associated with military engineering, are now pertinent to structural engineering due to increased subversive blasts, global conflicts, civil disturbances, geopolitical volatility, and industrial accidents. Despite numerous studies using various explosives, a comprehensive comparative analysis of their geometric effects on structural damage is lacking. The rationale behind researchers' choices of geometric forms and orientations remains questionable. The main purpose of this study is to investigate the effect of geometric shape and orientation of an equivalent TNT dose on a reinforced concrete (RC) square slab under contact explosion, with specific focus on understanding the mechanism of damage and cracks propagation. The research question addressed is whether the geometric characteristics and orientation of the explosive significantly influence the type and extent of damage on the slab, in comparison to the boundary conditions (BCs) imposed. Methods: The investigation employs computational simulations using the Abaqus software, considering twenty-six cases with five different geometric forms of the TNT dose: brick, simple cube, spherical, hemispherical, and cylindrical. Both clamped and simple boundary conditions are studied. The integration of the Eulerian-Lagrangian methodology, in conjunction with the finite element technique within the framework of Abaqus, has been employed for the purpose of simulating explosive events. Experimental data from relevant literature are utilized to validate the computational predictions. Results: The findings reveal that the type and extent of damage inflicted on the slab are predominantly influenced by the geometric form and orientation of the TNT dose, rather than the boundary conditions. The study elucidates that slab damage is contingent upon the geometric characteristics and alignment of the explosive relative to the BCs. The order of damage severity among the considered geometric forms and orientations is highlighted. Conclusion: The study underscores the significance of considering both the geometric form and orientation of the explosive in relation to the slab's geometry and boundary conditions. Perforation with prevailing flexure mode of damage is observed under clamped BC, while a combination of flexure and shear occurs under simple BC. Slabs with simple BC exhibit higher damage with more cracks compared to those with clamped BC. [ABSTRACT FROM AUTHOR]

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Recycling of concrete generated from construction and demolition waste as coarse aggregates in concrete has been a focus of several studies for the evolution of the green concrete and conservation of natural resources. This investigation, therefore, focusses on the study of the behavior of RC beams strengthened with externally bonded CFRP wraps, cast with both natural and recycled aggregates concrete. Furthermore, one-way slabs were strengthened with Near Surface Mounted (NSM) bars, while two-way slabs were strengthened with CFRP strips. One-way and two-way slabs used in the study were cast with both natural and recycled aggregate concrete (RAC). In RAC, natural aggregates were replaced by 30% recycled concrete aggregates. All beams and slabs were cast with concrete mix design of 1:1.24:2.6 and w/c ratio of 0.43. Beams and one-way slabs, control and strengthened, were tested under four-point bending. Whereas, two-way slabs were tested in punching. A significant increase in the load-carrying capacity was observed for both natural and recycled aggregates concrete beams without shear reinforcement and two-way slabs, indicating the effectiveness of strengthening scheme. Increase of 20.5% and 12.6%, respectively, was found in the load-carrying capacities for the cases of both and natural and RAC beams with natural aggregate concrete (NAC) and RAC beams when results were compared for the case of shear deficient control and strengthened RC beams with CFRP wraps. Furthermore, increase of 27 − 37% was noted in load-carrying capacities of both natural and RAC two-way slabs when results were compared for the case of control and strengthened NAC and RAC slabs. [ABSTRACT FROM AUTHOR]

Abstract Water bound to various hydrous minerals can be transported deep into the mantle by slab subduction. Serpentine is one of most important hydrous minerals in the crust and shallow upper mantle. A partially serpentinized slab mantle limits the amount of water that can enter deep into the mantle. The partitioning of water between hydrous minerals and nominally anhydrous minerals (NAMs) is a crucial factor in controlling the physical properties and dynamics of slabs. Recent experiments on water partitioning have revealed that water strongly partitions to coexisting hydrous minerals. NAMs, such as olivine and its high-pressure polymorphs, have limited water content in water-undersaturated wet slabs. Metastable olivine wedges are not a feature of dry slabs, but can be of wet slabs that are not saturated with water. The transformation kinetics of the dry state, which generates deep-focus earthquakes and produces significant deformation in the slab, can work under wet slabs. Water bound to hydrous minerals is transported by the slab to the mantle transition zone and lower mantle. Hydrous minerals in stagnant slabs over 660 km depth release water as the slab warms, producing locally hydrated mantle transition zones and dense water-bearing magmas at the base of the upper mantle, and generating intraplate volcanism, which are referred to as the big mantle wedge model. Seismic scatterers are observed in the lower mantle at depths from 700 to 1900 km. These scatterers may be caused by water release at the top of the lower mantle by dehydration of hydrous minerals such as dense hydrous magnesium silicates. The shear instability due to the second order phase transformation from stishovite to CaCl2-type phase in hydrous aluminous SiO2 also causes the depth variation of seismic scatterers in the lower mantle. The high-pressure polymorphs of aluminous SiO2 contain a large amount of water more than 1 wt%, which can be important water carriers under lower mantle conditions.

In the present study, nylon waste fibers (NWF) were utilized for the first time to improve the impact resistance of self-compacting concrete (SCC) slabs against pistol shooting. Six ratios of NWF were used in the range of (0.25- 1.5 at an increment of 0.25) % with three different lengths (50, 70, and 90) mm for each ratio. The fresh properties, compressive strength, and Utara sonic pulse velocity (UPV) of SCC were also measured. The results indicate the positive role of NWF in improving compressive strength. However, the fresh properties are affected negatively by using NWF. The best impact resistance of the slab occurred when 1% of NWF with a length of 90 mm was utilized. [ABSTRACT FROM AUTHOR]

Abstract Reinforced concrete (RC) slabs often require strengthening due to deterioration, increased loads, or design changes. Concrete overlay is a commonly used technique for strengthening, but predicting the behavior of overlays can be challenging. To address this challenge, this study presents a three-dimensional non-linear finite element model using Abaqus/CAE to analyze the structural performance of one-way reinforced concrete (RC) slabs strengthened with concrete overlays. The model considers three different bonding conditions at the interface: friction, epoxy, and shear connectors. The predictions of the model were compared to experimental results, and it was found that the model accurately captures the load–deflection response, cracking behavior, and interfacial slip in the strengthened slabs. Additionally, the model accurately predicts the new structural capacity of the strengthened slabs, showing good agreement with experimental data. These findings offer valuable insights into the effectiveness of concrete overlays as a traditional strengthening technique for RC slabs. Moreover, the developed finite element model provides a useful tool for optimizing the design of these overlays.

Secondary cooling electromagnetic stirring (S-EMS) significantly impacts the internal quality of continuous casting slabs. In order to investigate the effects of S-EMS modes on segregation in slabs, a three-dimensional numerical model of the full-scale flow field, solidification, and mass transfer was established. A comparative analysis was conducted between continuous electromagnetic stirring and alternate stirring modes regarding their impacts on steel flow, solidification, and carbon segregation. The results indicated that adopting the alternate stirring mode was more advantageous for achieving uniform flow fields and reducing the disparity in solidification endpoints, thus mitigating carbon segregation. Specifically, the central carbon segregation index under continuous stirring at 320 A was 1.236, with an average of 1.247, while under alternate stirring, the central carbon segregation index decreased to 1.222 with an average of 1.227. [ABSTRACT FROM AUTHOR]

Seismic tomography of Earth's mantle images abundant slab remnants, often located in close proximity to active subduction systems. The impact of such remnants on the dynamics of subduction remains underexplored. Here, we use simulations of multi‐material free subduction in a 3‐D spherical shell geometry to examine the interaction between visco‐plastic slabs and remnants that are positioned above, within and below the mantle transition zone. Depending on their size, negatively buoyant remnants can set up mantle flow of similar strength and length scales as that due to active subduction. As such, we find that remnants located within a few hundred km from a slab tip can locally enhance sinking by up to a factor 2. Remnant location influences trench motion: the trench advances toward a remnant positioned in the mantle wedge region, whereas remnants in the sub‐slab region enhance trench retreat. These motions aid in rotating the subducting slab and remnant toward each other, reducing the distance between them, and further enhancing the positive interaction of their mantle flow fields. In this process, the trench develops along‐strike variations in shape that are dependent on the remnant's location. Slab‐remnant interactions may explain the poor correlation between subducting plate velocities and subducting plate age found in recent plate tectonic reconstructions. Our results imply that slab‐remnant interactions affect the evolution of subducting slabs and trench geometry. Remnant‐induced downwelling may also anchor and sustain subduction systems, facilitate subduction initiation, and contribute to plate reorganization events. Plain Language Summary: Subduction, the process where cold oceanic lithosphere descends into the mantle, is a time‐dependent process: old subduction zones cease while new subduction zones initiate, in cycles of tectonic plate motions. The cessation of subduction is accompanied by break‐off of the subducting slab from the surface plate, forming a slab remnant. The remnant continues sinking into the mantle and, in doing so, generates a flow field that may influence adjacent subduction systems. In this study, we present numerical simulations of subduction in a 3‐D spherical shell domain, and examine how subduction systems interact with a range of slab remnants. Our models show that sinking remnants can significantly enhance the sinking velocity of slabs within a few 100–1,000 km of the remnants, and can influence the spatial and temporal evolution of trench shape. Our results suggest that the existence of slab remnants may help to anchor and sustain subduction systems, and lead to an environment more favorable for the initiation of new subduction zones. Since such events are closely linked to reorganizations in global plate motions, we suggest that the location of pre‐existing remnants influences tectonic plate movements and, potentially, super continent cycles. Key Points: Subducted slab remnants can enhance the sinking velocities of actively subducting plates by up to a factor 2Slab remnants strongly influence trench motions and the evolution of trench shape at subduction zones located within a few 100–1,000 s of kmThe flow fields interact such that the slab tip and remnant approach, thus strengthening mantle flow that can anchor subduction location [ABSTRACT FROM AUTHOR]

Reinforced concrete (RC) slabs often require strengthening due to deterioration, increased loads, or design changes. Concrete overlay is a commonly used technique for strengthening, but predicting the behavior of overlays can be challenging. To address this challenge, this study presents a three-dimensional non-linear finite element model using Abaqus/CAE to analyze the structural performance of one-way reinforced concrete (RC) slabs strengthened with concrete overlays. The model considers three different bonding conditions at the interface: friction, epoxy, and shear connectors. The predictions of the model were compared to experimental results, and it was found that the model accurately captures the load–deflection response, cracking behavior, and interfacial slip in the strengthened slabs. Additionally, the model accurately predicts the new structural capacity of the strengthened slabs, showing good agreement with experimental data. These findings offer valuable insights into the effectiveness of concrete overlays as a traditional strengthening technique for RC slabs. Moreover, the developed finite element model provides a useful tool for optimizing the design of these overlays. [ABSTRACT FROM AUTHOR]

The objective of this study is to evaluate the mechanical behavior of GRFP in massive concrete slabs. The use of glass fiber reinforced polymer (GFRP) rebars in construction design has been an alternative technique to provide more durable structures. However, there is a need to evaluate the behavior of GFRP reinforced slabs under flexure and to compare the service state (SS) and ultimate service state (USS) of the loaded element. Thus, reinforced concrete slabs of varying thicknesses were constructed with steel and GFRP rebars. Results show that the applied load for maximum span deflection of the GFRP slab under SS was 50% lower than for the one with steel reinforcement. The maximum span deflection of the GFRP slab under USS was also 282% larger than for steel rebars reinforcement.

This research explores the dynamic responses of reinforced concrete (RC) slabs under high-velocity impacts. The study utilizes advanced numerical simulations to investigate the effects of varied impact loading and slab depths, unveiling complex rate-dependent behaviors (i.e., impact forces, reactions, accelerations, and displacements) across a diverse range of velocities. The alignment of simulation results with experimental data validates the robustness and accuracy of the employed approach. Additionally, an analytical model predicting the load-carrying capacity and deflection of these slabs under high-velocity loads is proposed. The results indicated that higher loading rates correlate with increased forces and damage until perforation. Analytical models exhibit strong performance within a ±10% error margin, and response surface analysis quantifies the impactor velocity's influence on load for a constant thickness. Overall, this investigation sheds light on the dynamic complexities of RC slabs subjected to high-velocity impacts, providing valuable insights for structural design considerations. [ABSTRACT FROM AUTHOR]

Ferrocement is extensively utilized in construction as a structural material, given its exceptional mechanical properties and impact strength. This study aimed to analyze the performance of ferrocement that is reinforced with recycled steel wire tires under static loads. This current study a comparative investigation of behavior of compressive strength of ferrocement cubes and flexural behavior of ferrocement panels and behavior of ferrocement panels reinforced with tire Steel wire tires under static loads. Ferrocement slabs sample was (L 500 x W 500 x t 50mm) in size, and 15 slabs were subjected to static point load. The number of wire mesh layers, which was replaced by recycling tire steel wire as a ratio of the volume of wire mesh, was the main parameter in the current study. The percentage of recycle steel wire tires are 33% and 66% and 99% from of steel wire mesh for reinforcements of ferrocement panels. The results presented, the behavior of panels under static load at ultimate failure and first crack. It showed that ferrocement have 99.0% steel wire tires gave a good performance under static loading which were required to increase the load value to make the first crack and ultimate failure, and causing late of the failure and less deflection. [ABSTRACT FROM AUTHOR]

Bamboo is a naturally sustainable material that has been used in construction for a very long time. Investigations on the feasibility of using bamboo for reinforcing concrete have been carried out by various researchers. However, the lack of construction codes and design procedures for bamboo-reinforced concrete (BRC) structures is preventing structural engineers and construction firms from using bamboo in construction. The aim of this work was therefore to review various BRC structural elements, including beams, columns, slabs and walls, in order to develop guidelines for using them confidently. [ABSTRACT FROM AUTHOR]

This study presents the results of an investigation of the effect of biaxial geogrid reinforcement on the load-carrying capacity of rigid pavement slabs. Six concrete slabs having dimensions of 800 × 800 × 50 mm were prepared and tested under static loads at three different locations: interior, edge and corner of the slab. Three of the slabs were unreinforced and taken as references. The other three slabs were reinforced with a biaxial geogrid layer. Study parameters investigated in this study included the load-carrying capacity, ductility and failure modes of the slabs. The experimental results were verified theoretically using the finite-element software ABAQUS. The findings indicated that the load-carrying capacity and ductility of the concrete slabs reinforced with the biaxial geogrid can be improved. Test results obtained indicated that the maximum load-carrying capacity of the concrete slabs reinforced with the biaxial geogrid was increased by 25%, 26% and 29% for interior, edge and corner loading locations, respectively. [ABSTRACT FROM AUTHOR]

A high proportion of the CO2 emissions worldwide are caused by the construction sector or are associated with buildings. Every part of the industry needs to reduce its share of emissions, so the building sector must also do its part. One possible solution for achieving this reduction in the field of load-bearing structures is the use of adaptive structures. This research focuses on adaptive slab structures, which require specific actuators to be integrated into the system. Conventional actuators are not suitable due to the prevailing requirements, namely installation space and performance. For this investigation, the actuator is divided into different functional components. A rough description of the requirements for one component, namely the energy converter, is given. Different concepts are developed, tested, and compared with numerical results. Due to the requirements, the concepts are limited to hydraulics. The authors then present a comparison of different simulation strategies for the energy converter. Overall, this paper provides a new contribution to the design of energy converter concepts for integrated hydraulic actuators in slabs, along with experimental verification of the working principle of the energy converters to meet the requirements. A simplified numerical model is proposed to estimate the behavior of the energy converter during the early design phase. [ABSTRACT FROM AUTHOR]

Abstract Seismic tomography of Earth's mantle images abundant slab remnants, often located in close proximity to active subduction systems. The impact of such remnants on the dynamics of subduction remains underexplored. Here, we use simulations of multi‐material free subduction in a 3‐D spherical shell geometry to examine the interaction between visco‐plastic slabs and remnants that are positioned above, within and below the mantle transition zone. Depending on their size, negatively buoyant remnants can set up mantle flow of similar strength and length scales as that due to active subduction. As such, we find that remnants located within a few hundred km from a slab tip can locally enhance sinking by up to a factor 2. Remnant location influences trench motion: the trench advances toward a remnant positioned in the mantle wedge region, whereas remnants in the sub‐slab region enhance trench retreat. These motions aid in rotating the subducting slab and remnant toward each other, reducing the distance between them, and further enhancing the positive interaction of their mantle flow fields. In this process, the trench develops along‐strike variations in shape that are dependent on the remnant's location. Slab‐remnant interactions may explain the poor correlation between subducting plate velocities and subducting plate age found in recent plate tectonic reconstructions. Our results imply that slab‐remnant interactions affect the evolution of subducting slabs and trench geometry. Remnant‐induced downwelling may also anchor and sustain subduction systems, facilitate subduction initiation, and contribute to plate reorganization events.

Introduction. The development of methods for determining the frequencies and forms of vibrations, as well as dynamic reactions of thin slabs with different support systems, including those supported on point supports, is an urgent task, the solution of which is the subject of this paper.The aim of the work is to develop experimental methods for determining the frequencies and forms of natural vibrations of thin point-supported square solid slabs and slabs with holes.Materials and methods. The methodology and analysis of experimental results of dynamic characteristics of square solid slabs and slabs with holes are presented.Results. In this work, the frequencies of natural vibrations of square slabs with free edges resting on point supports are determined; the dependences of frequencies of slabs vibrations on coordinates of point supports and sizes of symmetrically located holes are obtained; the location of point supports at which the fundamental frequency of slabs free vibrations is maximum, is determined; frequencies, forms and decrements of vibrations of square slabs resting on four point supports are experimentally determined, as well as the influence of presence of holes and the degree of pinching of the supports on the dynamic characteristics of these slabs.Conclusions. Comparison of experimental and theoretical values of natural vibration frequencies of the slabs showed good similarity. The results obtained in this paper can be appplied to dynamic and seismic calculations of point-supported square slab coverings.

Several existing reinforced concrete structures (RC) requires improvement in performance for reasons of deterioration. This is due to many factors such as change in code requirements. The current study was assisted by experimental models to investigate the behavior of RC slabs strengthened with carbon fiber reinforced polymer (CFRP) laminates and sheets. Seven RC slabs strengthened with CFRP (laminates and sheets) were tested. The slabs were divided into four groups. The first phase includes one slab without strengthening (reference slab), the second phase includes one slab strengthened with CFRP laminates, and the third phase includes one slab strengthened with CFRP sheets. The fourth phase includes four slabs strengthened with different areas of sheets. The major test parameters included the different types of strengthening materials and the corresponding types of epoxy used for each type of CFRP. A comparison between the two types of CFRP was conducted. The load deflection, load strain and mode of failure were investigated. Test results demonstrated that the flexural strength increased and the ductility reduced with the increase in the area of CFRP sheets. for almost equivalent applied area, CFRP Sheets has more significant influence on the behavior of the strengthened slabs than laminates. Strengthening of RC slabs with CFRP improves the flexural strength capacity for both types. For the same CFRP strength, the sheets showed a cost reduction of 70%. The difference is attributed to the difference in the mechanical properties and the bonding quality of the CFRP material.

Classical models for the passive myocardium, such as the Fung and Holzapfel-Ogden models, are known to have high degeneracy as well as numerous mechanical and mathematical limitations, preventing their utility in microstructural experiments and precision medicine. Hence, the upper triangular (QR) decomposition and orthogonal strain attributes were leveraged to develop a new model using published biaxial data on slabs of left myocardium, resulting in a separable strain energy function. This new model, the Criscione-Hussein model, was compared with both the Fung and Holzapfel-Ogden models by quantifying the uncertainty, computational efficiency, and material parameter fidelity for all three models. As a result, the Criscione-Hussein model was found to significantly reduce the uncertainty and computational time (p < 0.05) and enhance the fidelity of the material parameters. Hence, the Criscione-Hussein model enhances the predictability for the passive behavior of the myocardium and may serve a role in creating more accurate computational models that provide better visualizations for the mechanical behavior of the heart and enable the experimental connection between the model and the myocardial microstructure. [ABSTRACT FROM AUTHOR]

This paper aims to explore the structural performance of 3D-printed and casted cement-based steel-reinforced concrete beams and one-way slabs incorporating short carbon fibre and activated carbon powder, which have been shown to enhance concrete's flexural strength and reduce its electrical resistivity. The samples are cast and printed in 250 × 325 × 3500 mm beams and 150 × 400 × 3500 mm one-way slabs and mechanical, electrical, and piezoresistivity properties were measured. This length of beams and one-way slabs with rebars have been considered as they can magnify the flexural and cracking behaviour and make them easier to be monitored and analysed. The samples were loaded up to 80% of maximum stress. Crack propagation and strain was assessed using the 2D digital image correlation (DIC) method. The results compared samples under continuously increasing loads between 3D-printed and cast samples. The 3D-printed composites had a better piezoresistive response due to the enhanced anisotropic behaviour. DIC analysis illustrated similar results among different samples, while 3D-printed blocks had lower cracking performance due to the horizontal case fracture in lower stress. [ABSTRACT FROM AUTHOR]

In the state of Paraná, strawberry farming is relevant, however, it is still an expanding market. Understanding and determining the main economic aspects related to cultivation becomes essential for the success of the enterprise. The objective of this study was to survey the main costs of establishment, management, and economic viability of organic strawberry farming in a soilless substrate system in Laranjeiras do Sul-PR. The study was conducted in the 2022 crop season and divided into three stages. The first stage involved a literature review of all aspects of organic strawberry farming in a soilless substrate system. The second stage consisted of a case study, and the third stage involved the analysis of production costs and economic viability of the crop. The total costs of managing and establishing a 250 m² greenhouse with 1800 strawberry plants reached R$ 39,147.00, with the most significant cost components being related to the structure, especially eucalyptus poles. The following financial viability indices were used: Net Present Value (NPV), Internal Rate of Return (IRR), and Discounted Payback Period. The results obtained indicate financial viability in production, as the NPV was R$ 69,509.88; the IRR was 57%; the profitability was R$ 25.097,00 per year in a 250 m² greenhouse, and the Payback Period was 1.6 years. Analyzing these indices confirms that the investment is viable and promising. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of fiber on the behavior of punching shear slabs; a finite element modeling approach is used to simulate the case study. The proportion mix of hybrid fiber-reinforced concrete, which contains 0.2 percent macro synthetic fibers and 0.68, 0.8, and 0.96 percent steel fibers, compressive strengths of 50 MPa, different longitudinal reinforcement used, and slab thicknesses of 150, 200, and 250 mm are all joined and investigated in this study. The ATENA software is used to perform nonlinear finite element analysis. The slab results validation was done similarly to previous experimental work, and the acquired results indicated a significant agreement. Thirty-six two-way specimen slabs with dimensions of 1900 × 1900mm were modeled in this investigation. All four sides of the slabs are supported. The results showed that the slabs' ultimate shear capacity increases with increasing the hybrid steel fiber. Nevertheless, the ultimate capacity of the slabs has decreased due to an increase in the reinforcement ratio and slab thickness. [ABSTRACT FROM AUTHOR]

No estado do Paraná a cultura do morangueiro é relevante, contudo, é um mercado que ainda está se expandindo. Conhecer e determinar os principais aspectos econômicos relacionados ao cultivo se torna essencial para o sucesso do empreendimento. O objetivo neste trabalho foi realizar um levantamento dos principais custos de implantação, condução e a viabilidade econômica da cultura do morangueiro em sistema orgânico de produção fora do solo em substrato em Laranjeiras do Sul-PR. O estudo foi realizado na safra de 2022. A pesquisa foi dividida em três etapas. A primeira foi realizada através de pesquisa bibliográfica de todos os aspectos do sistema orgânico de morangueiro fora do solo em substrato. A segunda etapa se constitui de um estudo de caso e a terceira etapa, referente às análises dos custos de produção e da viabilidade econômica da cultura. Os custos totais de condução e implantação de uma estufa de 250 m² de morangueiros com 1800 plantas atingiram R$ 39.147,00, cujos componentes mais significativos na composição dos custos foram os gastos com a estrutura, especialmente com postes de eucalipto. Para a análise de viabilidade se utilizou os seguintes índices: Valor Presente Líquido (VPL), Taxa Interna de Retorno (TIR) e Payback descontado. Os resultados obtidos identificam viabilidade financeira na produção, pois o VPL foi de R$ 69.509,88; a TIR de 57%; a rentabilidade foi de R$ 25.097,00/ano em uma estufa de 250 m²; e o Payback foi de 1,6 anos. Analisando esses índices se afirmar que o investimento é viável e promissor.

Abstract Reinforced concrete structures, when subjected to fire, have their mechanical resistance reduced related to the behavioral change of the material. Many experimental and numerical research on the behavior of concrete exposed to fire have been carried out on beams and columns, with slabs being studied less frequently, mainly due to its size and consequently higher research costs. This paper carried out a numerical analysis of the thermomechanical behavior of reinforced concrete slabs exposed to fire, using finite element modeling. The parametric analysis carried out changing the aggregate type of concrete showed that when exposed to ISO834 fire curve, the displacement in the center of slab with siliceous aggregate was 47% higher than the slab with calcareous aggregate. Analyzing the crack opening, for slabs exposed to ISO834 fire curve, the first 1mm-cracks were noticed at 18min when using calcareous aggregate, while the slabs with siliceous aggregate started at 13min.

A mechanical model has been developed by the authors in order to predict the shear strength of reinforced concrete slabs under concentrated loads close to linear supports. The model takes into account a significant number of variables involved in the phenomenon, such as the clear shear span, the concrete compressive strength, the reinforcement ratio, the effective depth, the load spreading angle, the size effect and the size of the loaded area. It is applicable to simply supported slabs, cantilever slabs and situations with partial restraint to the rotation, such as intermediate supports. It has been validated with a database of 90 shear test in slabs subjected to a single concentrated load in different supporting conditions, yielding results on the safe side and showing low scatter. A parametric analysis of the model is also presented, detailing how the different involved variables affect the shear strength. These results, along with the simplified expressions for the shear strength calculation, provide a useful tool for the assessment of the shear strength of reinforced concrete solid slabs in daily engineering. [ABSTRACT FROM AUTHOR]

Several existing reinforced concrete structures (RC) require improvement in performance for reasons of deterioration. This is due to many factors such as the change in code requirements. The current study was assisted by experimental models to investigate the behavior of RC slabs strengthened with carbon fiber reinforced polymer (CFRP) laminates and sheets. Seven RC slabs strengthened with CFRP (laminates and sheets) were tested. The slabs were divided into four groups. The first phase includes one slab without strengthening (reference slab), the second phase includes one slab strengthened with CFRP laminates, and the third phase includes one slab strengthened with CFRP sheets. The fourth phase includes four slabs strengthened with different areas of sheets. The major test parameters included the different types of strengthening materials and the corresponding types of epoxies used for each type of CFRP. A comparison between the two types of CFRP was conducted. The load deflection, load strain and mode of failure were investigated. Test results demonstrated that the flexural strength increased, and the ductility reduced with the increase in the area of CFRP sheets. for almost equivalent applied area, CFRP Sheets has more significant influence on the behavior of the strengthened slabs than laminates. Strengthening of RC slabs with CFRP improves the flexural strength capacity for both types. For the same CFRP strength, the sheets showed a cost reduction of 70%. The difference is attributed to the difference in the mechanical properties and the bonding quality of the CFRP material. [ABSTRACT FROM AUTHOR]

Eucalyptus saligna, is currently gaining significance in lumber production and for construction purposes in Ethiopia. The objective of the study was to investigate the lumber recovery rate of Eucalyptus saligna and the factors influencing it. The operation yielded 47.33 m3 of lumber, accounting for 53.51% of the total lumber recovery rate. Furthermore, 25.49 m3 (28.81%) of slabs and 15.65 m3 (17.69%) of saw dusts were obtained. Lumber recovery rate was recorded 42.86% using through and through (under 35 cm of diameter classes), while 56.31% of lumber recovery rate were achieved using quarter sawing method (above 35 cm of diameter classes). The magnitude of the rate of lumber recovery was reduced by several factors such as end-splitting and brittle-heart. It was observed that cutting use of wider saw kerf was caused a reduction in the rate of lumber recovery owing to generation of increased quantity of sawdust. [ABSTRACT FROM AUTHOR]

Concrete is brittle; hence, it is incredibly likely that concrete buildings may fail in both local and global ways under dynamic and impulsive stresses. An extensive review investigation was carried out to examine reinforced concrete (RC) slab behavior under low-velocity impact loading. Significant past research studies that dealt with experimental and numerical simulations and analytical modeling of the RC slabs under impact loading have been presented in this work. As a result, numerous attempts to define failure behavior and to assess concrete structures' vulnerability to lateral impact loads have been made in the literature. Based on analytical, numerical, and experimental studies carried out in previous research, this article thoroughly reviewed the current state of the art regarding the responses and failure behaviors of various types of concrete structures and members subjected to low-velocity impact loading. The effects of different structural and load-related factors were examined regarding the impact strength and failure behavior of reinforced concrete slabs reinforced with various types of strengthening procedures and exposed to low-velocity impact loads. The reviews suggested that advanced composite materials, shear reinforcement, and hybrid techniques are promising for effectively strengthening concrete structures. [ABSTRACT FROM AUTHOR]

Flexural shear behavior, which mainly concerns reinforced concrete (RC) slabs without shear reinforcement, is usually investigated by means of simply supported, beam‐shaped specimens. Only few tests are available where the cross‐section properties correspond to a slab (b ≫ h) or the support conditions lead to moment and shear force distributions of multi‐span slab systems. The moment distribution in the vicinity of inner supports can decrease shear slenderness and, hence, increase shear strength. An increase in member width is also often associated with a beneficial effect on load bearing behavior. Firstly, the course of the shear crack changes along the width which, both, increases the crack face area, and potentially allows for an increased interlocking effect of the two crack faces. Secondly, a (wide) slab's ability to redistribute inner stresses in lateral direction can compensate inner irregularities. However, the likelihood of irregularities to occur after all, increases with increasing concrete volume, so larger member widths. A comparison of existing investigations shows that the findings are partly inconclusive. Also, no studies addressing the influence of the member width exist with tests in the vicinity of intermediate supports despite being the typical shear‐critical section in actual members. To address related open questions, an experimental campaign comprising 20 shear tests on slab segments without shear reinforcement was conducted. Essentially, member width (b = 0.3 or 2.4 m) and support conditions were varied within the test program. Main goal of the experimental campaign was finding answers to the question whether one‐way flexural shear strength is influenced by the member's width. This has been addressed by generating results from pairs of tests which differed only in their width while having otherwise equal properties (b/h ≈ 1.0 and b/h ≈ 8.5). Eight such pairs were tested featuring different shear span lengths, rotational restrains at the support and longitudinal reinforcement ratios. In contrast to other experimental campaigns, shear tests near inner supports were incorporated in the experimental program. On average, the gain in shear capacity of the wide members compared to the reference linear member was proportional to the increase in width. It can thus be concluded that linear (beam‐shaped) specimens are suitable for representing one‐way shear capacity of RC slabs. Enhanced shear response of actual slabs can rather be ascribed to beneficial effects from loading and support conditions which enable to partially activate two‐way stress distribution or compressive membrane action. Additionally, rare occurrence of damages in RC slabs is not only to be attributed to an underestimation of capacity but probably also to an overestimation of design load. [ABSTRACT FROM AUTHOR]

A high proportion of the CO2 emissions worldwide are caused by the construction sector or are associated with buildings. Every part of the industry needs to reduce its share of emissions, so the building sector must also do its part. One possible solution for achieving this reduction in the field of load-bearing structures is the use of adaptive structures. This research focuses on adaptive slab structures, which require specific actuators to be integrated into the system. Conventional actuators are not suitable due to the prevailing requirements, namely installation space and performance. For this investigation, the actuator is divided into different functional components. A rough description of the requirements for one component, namely the energy converter, is given. Different concepts are developed, tested, and compared with numerical results. Due to the requirements, the concepts are limited to hydraulics. The authors then present a comparison of different simulation strategies for the energy converter. Overall, this paper provides a new contribution to the design of energy converter concepts for integrated hydraulic actuators in slabs, along with experimental verification of the working principle of the energy converters to meet the requirements. A simplified numerical model is proposed to estimate the behavior of the energy converter during the early design phase.

Previous work has shown that floor slabs make up most of the material mass of building structures and are typically made of reinforced concrete. Considering the associated resource consumption and greenhouse gas emissions, new approaches are needed in order to reduce the built environment’s impact on the ongoing climate crisis. Various studies have demonstrated that adaptive building structures offer a potential solution for reducing material resource consumption and associated emissions. Adaptive structures have the ability to improve load-bearing performance by specifically reacting to external loads. This work applies the concept of adaptive structures to reinforced concrete slabs through the integration of fluidic actuators into the cross-section. The optimal integration of actuators in reinforced concrete slabs is a challenging interdisciplinary design problem that involves many parameters. In this work, actuation influence matrices are extended to slabs and used as an analysis and evaluation tool for deriving actuation concepts for adaptive slabs with integrated fluidic actuators. To define requirements for the actuator concept, a new procedure for the selection of actuation modes, actuator placement and the computation of actuation forces is developed. This method can also be employed to compute the required number of active elements for a given load case. The new method is highlighted in a case study of a 2 m × 2 m floor.

This paper focuses on the investigation of the flexural behaviour of steel-concrete composite beams through non-linear finite element analysis. Both geometries, as well as material non-linearity, are considered. Steel-concrete composite beams are typically made consisting of a hot-rolled I-section steel beam and a concrete slab that is connected monolithically by using a shear connector. A shear connector is one of the key elements for developing the composite action used in steel-concrete composite structures. This paper deals with the flexible shear connectors such as studs and channels designed as per the Indian standards 11384. Initially, the FE models are validated by making comparisons with the experimental test results obtained by previous researchers, as available in the literature. In the present study, thirty three-dimensional simply supported composite beams are created and analysed using finite element commercial software package ANSYS15 workbench version subjected to two-point loads. The degree of shear connection, the strength of steel section and the geometry of stud and channel connectors are the primary parameters considered for the present research work, and the results are compared. The overall flexural response is provided, including failure modes, load-central deformation behaviour, and interface slip, as well as the effects of yield strength of steel, the geometry of the stud and channel shear connector along with the degree of shear interaction, are evaluated. The results show that the degree of interaction, the geometry of shear connectors and steel yield strength have significant influence. Subjected to flexure, steel-concrete composite beam section with channel connector is less evaluated so far; therefore, in the present research work, channel shear connector is taken into account to evaluate the flexural behaviour with the consideration of varying grades of steel section along with the degree of interaction and to compare the results with a different section of shear connectors.

In Ethiopia, sawmills have poor capacity utilization primarily due to the outdated equipment that resulted in a low recovery rate and the production of a high amount of wastage. The lumber recovery rate is the output (lumber) of a log in the sawing process. In Ethiopia, Cupressus lusitanica is significantly used for lumber, for furniture production, construction, poles and posts. Sampled logs were processed according to the normal production rate and standard lumber dimension of the sawmill for the purpose of estimating the lumber recovery rate. The present study aimed to investigate the lumber recovery rate of C. lusitanica and the factors affecting it. A total of 26.93 m3 of lumber was produced by the sawmilling operation, representing 72.86% of the overall lumber recovery rate. Furthermore, the sawdust and slabs were recorded as 2.92 m3 (7.90%) of sawdust and 7.11 m3 (19.24%) of slabs, respectively. There were a number of factors that decreased the magnitude of the lumber recovery rate. It was observed that cutting using a wider saw kerf caused a reduction in the rate of lumber recovery owing to the generation of an increased quantity of sawdust. The lumbers were air-seasoned in the sawmill yard. Maximizing the volume of the lumber recovered from the logs can increase the sawmill profitability, lessen the effects of climate change, ensure the sustainable use of natural resources, enhance the energy efficiency and manage wood waste (e.g., recycling and prevention) for green economic development and industrial transformation. This species has a great demand in the wood industry of Ethiopia; hence, the plantation and yield of C. lusitanica must be expanded in order to provide sustainable forestry, protect valuable forest resources and safeguard the biodiversity in the country. [ABSTRACT FROM AUTHOR]

Vulnerability fixing is time-consuming, hence, not all of the discovered vulnerabilities can be fixed timely. In reality, developers prioritize vulnerability fixing based on exploitability. Large numbers of vulnerabilities are delayed to patch or even ignored as they are regarded as “unexploitable” or underestimated owing to the difficulty in exploiting the weak primitives. However, exploits may have been in the wild. In this paper, to exploit the weak primitives that traditional approaches fail to exploit, we propose a versatile exploitation strategy that can transform weak exploit primitives into strong exploit primitives. Based on a special object in the kernel named Thanos object, our approach can exploit a UAF vulnerability that does not have function pointer dereference and an OOB write vulnerability that has limited write length and value. Our approach overcomes the shortage that traditional exploitation strategies heavily rely on the capability of the vulnerability. To facilitate using Thanos objects, we devise a tool named TAODE to automatically search for eligible Thanos objects from the kernel. Then, it evaluates the usability of the identified Thanos objects by the complexity of the constraints. Finally, it pairs vulnerabilities with eligible Thanos objects. We have evaluated our approach with real-world kernels. TAODE successfully identified numerous Thanos objects from Linux. Using the identified Thanos objects, we proved the feasibility of our approach with 20 real-world vulnerabilities, most of which traditional techniques failed to exploit. Through the experiments, we find that in addition to exploiting weak primitives, our approach can sometimes bypass the kernel SMAP mechanism (CVE-2016-10150, CVE-2016-0728), better utilize the leaked heap pointer address (CVE-2022-25636), and even theoretically break certain vulnerability patches (e.g., double-free). [ABSTRACT FROM AUTHOR]