Computational mechanics, particularly the Finite Element Method, has become an essential tool for engineers to simulate the behavior of structures under various conditions. Additionally, hyperelastic models are commonly used to represent the behavior of highly deformable materials, such as elastomers and polymers, which are increasingly utilized in engineering applications. The use of hyperelastic models is suitable for capturing nonlinear stress-strain relationships of materials, but the accuracy of these models may vary depending on material properties and deformation regimes. Therefore, it is important to select an appropriate model for specific conditions of interest. In this context, hyperelastic models including Mooney-Rivlin, Neo-Hookean, Ogden, and Yeoh were implemented in a computational code in FORTRAN using the Finite Element Positional Method along with Reissner's kinematics and the Newton-Raphson method for nonlinear analysis of plane frames with samples of elastomers containing varying percentages of carbon black. Subsequently, the Method of Least Squares was employed to determine the constitutive coefficients of hyperelastic models. The performance of each model was then evaluated by comparing the force vs. displacement curve of the material under study. Ultimately, it was concluded that the Yeoh and Ogden models exhibited consistent values, while the Neo-Hookean and Mooney-Rivlin models deviated. This observation was attributed to the number of constants in the formulation of these models. Furthermore, it can be stated that the use of the positional finite element method for nonlinear analysis of plane frames with hyperelastic models performs well, especially after the modifications proposed in this work to the formulations of hyperelastic models. These modifications consisted of adding the first invariant of deformation from the simple shear formulation to include the consideration of distortion in the specific energy of deformation of hyperelastic models.

In an increasingly evident and fundamental way is the search for the conservation of cultural heritage, as a way of maintaining and preserving the identity of a society. Historic buildings are an integral part of this heritage and the best way to conserve and safeguard them is to analyze and understand the materials and methods used during the period of their construction, in order to carry out a more harmonious and efficient restoration, with materials similar to the originals. In this context, this work aims to characterize and study the mortar covering the ruins of the Church of Santa Rita de Cássia, in the city of Pedro Velho/RN - Brazil. To this end, on-site visits were carried out for visual observations and photographic records of the historic building, collecting a total of 30 (thirty) samples of coating mortar for subsequent physical-chemical characterization through visual, tactile analysis and analytical techniques carried out in the laboratory, FRX, DRX, mortar content (binder:aggregate) tests by acid attack and granulometric analysis were developed. From these analyzes it was found that the mortars analyzed are rich in lime, with a binder of a calcitic nature and sand of siliceous origin, as aggregate, with the presence of clay in their composition, presenting different binder:aggregate ratios in almost all cases. mortars, ranging from 1:3 to 1:13, proving their production without any technological control. Therefore, for possible future restoration, it must be done with mortar made of lime and sand with different traits.

This research aimed to analyze the behavior of a reinforced concrete two pile caps with embedded socket and shear keys in the presence of additional reinforcement. A numerical model was developed in the ABAQUS software, based on the finite element method. The numerical models were calibrated and validated based on experimental tests by Barros (2013).
A parametric analysis of the models was carried out in two stages, which also included the variation in the compressive strength of the concrete of the pile caps. The first step consisted of varying the steel area and arrangements of the additional reinforcement proposed by Barros (2013). The second stage included the variation in angle and configuration of the additional reinforcement. It was observed throughout the parametric analyzes that the compressive strength of the pile caps was the parameter that most influenced the load capacity of the models by providing greater resistance to the compression struts, since the models' collapse occurred due to the crushing of the concrete in the struts in the connection region. The results of the first stage showed that the additional reinforcement, originally proposed by Barros (2013), does not influence the load capacity of the pile caps and crack control. The analyzes of the second stage showed that the new proposed configurations A1, A2 and A1+A2 enabled better control of the cracking of the pile caps. Reinforcement A1 acted to control diagonal cracking of the pile caps strut, resulting in an increase in load capacity between 0.94% and 2.55%, varying according to the pile caps’ compressive strength. The A2 model was more efficient, controlling central cracking and diagonal cracking of the pile caps struts, resulting in an increase in load capacity between 5.31% and 10.19%. The A1+A2 model presented practically a superposition of effects, controlling both diagonal cracking and central cracking. It was the arrangement that provided the greatest increases in load capacity, which varied between 6.77% and 12.48%. Thus, the importance of reinforcement for controlling cracking in pile caps with embedded socket with shear keys is demonstrated. Since, in addition to resulting in better behavior in service and greater durability of the structural element, they can also act by delaying the collapse mechanisms of the pile caps and, thus, increasing their load capacity, as was observed more significantly on models A2 and A1+A2.

The coagulation process involves the destabilization of colloidal particles (including microorganisms) and suspended matter in water, for subsequent removal in separation units, through the addition of coagulants. Coagulation is one of the tools used in the mitigation of eutrophication, capable of removing algal biomass from water bodies. Additionally, coagulation plays a fundamental role in water treatment for supply, being an essential step in removing suspended particles and impurities, thus ensuring the quality and safety of the drinking water provided to the population. Therefore, this dissertation aimed to evaluate the use of organic coagulants of plant origin in the mitigation of eutrophication and the treatment of water from eutrophicated sources in the Brazilian semiarid region. The first chapter focused on eutrophication mitigation, evaluating the use of three organic plant-based coagulants in the Floc & Sink technique, which involves the coagulation and sedimentation of algal biomass and has been used as a means to mitigate the effects of eutrophication. The three tested coagulants are composed of extracted tannins, chemically modified through the cationization process, from the bark of three different trees: cashew (Anacardium occidentale), black jurema (Mimosa tenuiflora), and Tanfloc SG, obtained from black wattle (Acacia mearnsii). Three different doses of each coagulant (50, 100, and 200 mg.L-1) were applied to water samples from four reservoirs in the tropical semiarid region. The results showed that all treatments were capable of removing algal biomass and turbidity, except for the 50mg/L dose of cashew. Increased doses of coagulants resulted in greater removal of biomass and turbidity. Tannin-based coagulants were able to approach the zeta potential to the isoelectric point (0 mV), favoring the neutralization of surface charges of suspended particles. Additionally, no significant changes in water pH were observed after the application of coagulants. Thus, plant-based coagulants emerge as promising alternatives to inorganic coagulants in the Floc & Sink technique, aiming to mitigate the effects of eutrophication in the semiarid region. They represent a potentially more sustainable solution for removing algal biomass in future large-scale applications. The second chapter aimed to evaluate the use of natural tannins as an alternative to metallic coagulants in the treatment of water from eutrophicated reservoirs in the semiarid region for supply. In this chapter, jar test assays were performed with water samples from two semiarid reservoirs. The assays were conducted with 3 tannin-based coagulants: from cashew (Anacardium occidentale), black jurema (Mimosa tenuiflora), and Tanfloc SG, obtained from black wattle (Acacia mearnsii). Four doses (10, 25, 50, and 100 mg.L-1) of each coagulant were used. All analyzed coagulants demonstrated a reduction in both turbidity and chlorophyll-a. As the doses of coagulants increased, greater removal of algal biomass and turbidity was observed. The approximation of the zeta potential to the isoelectric point (0 mV) favored the tannins' ability to neutralize the surface charges of suspended particles. Overall, tannins did not cause significant changes in water pH. Although tannin-based coagulants removed algal biomass and turbidity from water, they failed to remove color satisfactorily, making them less promising alternatives for the treatment of water from the studied reservoirs. Our study demonstrated that the tested tannin-based coagulants are potential products for the mitigation of eutrophication in semiarid reservoirs due to their high capacity for removing algal biomass and turbidity. However, their use in water treatment plants for supply is compromised due to their low capacity for color removal.

Earth construction is one of the oldest and most widespread vernacular building techniques, as it is an ecological, sustainable, affordable material, which reduces the impact of greenhouse gases for the house-building industry. The aim of this work is to analyse a soil classified as sandy-silt and see if it is compatible with the 3D printing process, stabilizing it with Portland Cement using chemical additives to provide the pumpability required for printing, partially replacing the cement with mineral additions (metakaolin and limestone filler), so that the 3D printing mixture in cement-stabilized soil (3DTC) has a paste volume suitable for the printing system, but with low Portland Cement contents. The experimental program began with an empirical analysis of the mixtures, starting with the 1:1 cement:soil mixture, known as the reference (REF), in order to obtain a 3DTC mixture with a consistency compatible with the extrusion method of the 3D printer available at UFRN, in order to establish the chemical additive contents and the water/dry material ratio compatible with the printing speed and nozzle height conditions. From this mixture, the reduction in cement consumption of the REF mixture was analyzed, in two mixtures called T15%C and T20%C with proportions of 0.15:0.85:1 and 0.2:0.80:1 (cement:mineral additions:sand). The number of possible layers for printing 3DTC blocks to be built continuously and without crumbling was then determined using a constant printing speed of 80 mm/s with a deposition height of 1 cm. With these printing conditions established, 6 3DTC blocks were printed, of each composition, with dimensions of 14 cm x 14 cm in cross section and 16 cm in height, where 3 blocks were subjected to dimensional analysis and then the axial compressive strength was determined, and 3 blocks were used to extract small pieces (40x40x160 mm) to carry out compressive strength and flexural tensile strength tests. With the mixtures analyzed, it was possible to build 3DTC blocks with cement consumption in the T15%C -113.60 kg/m³ and T20%C - 152.78 kg/m³ mixtures and make them printable with cement reduction levels of 87% and 82%, respectively, compared to the reference mixture (REF), which used only cement and soil in a 1:1 ratio by mass. The reference 3DTC block had the highest compressive strength (19.8 MPa) of the three mixes evaluated, due to the high cement content in the mix. The T15%C and T20%C mixtures had block strengths of 3.1 MPa and 3.0 MPa, respectively, making them suitable for masonry construction.

Purpose: The study aims to identify areas vulnerable to soil loss in the Potengi River hydrographic basin (BHRP) in Rio Grande do Norte, through a multicriteria analysis involving various geo-environmental attributes, in order to guide efforts towards efficient actions for the Recovery of Degraded Areas (RAD). 

Methodology: Data on geology, climate, geomorphology, pedology, hydrographic network, and interpretation of land cover and land use were collected. Through map algebra, it was possible to model the landscape of the basin and locate the areas most vulnerable to soil loss. 

Originality/Relevance: After the investigation using geoprocessing, the results generated in the form of cartographic products were evaluated and validated through field inspections to verify all situations identified as critical and assess the accuracy of the method used. It is important to note that in other studies conducted in BHRP, there was no specific objective of evaluating and validating the reality. 

Results: It was found that approximately 76% of the 4,170 km² area of the basin is moderately vulnerable to erosion, with nine critical areas of very high vulnerability identified, which need to reduce soil loss to avoid future effects such as drainage siltation and transport of soil nutrients. 

Social/Managerial contributions: Mapping the current state of land cover, land use, and preservation areas is essential to develop protection and monitoring measures. This allows for the implementation of initiatives such as Payment for Environmental Services (PSA) and the creation of a bank of priority areas, aiming to preserve water resources, especially in the semiarid region of Northeast Brazil.

Expansive soils present volumetric instability when experiencing moisture variations. It is important to understand this expansion mechanism and the stabilization techniques for this type of soil, aiming to minimize losses in civil construction. Among the possibilities of techniques for improving expansive soil, the following research highlights chemical stabilization, commonly carried out with the addition of portland cement or hydrated lime. The costs and environmental impact of producing these materials have encouraged researchers to use solid waste as stabilizers, as they are produced abundantly in industries and in most cases are disposed of irregularly. This work aims to analyze the stabilization of an expansive soil with ornamental rock processing residue, observing the improvement of mechanical, hydraulic and deformability properties of the soil. For this, the expansive soil will be collected in mossoró-rn and stabilized with additions of processing residue of 10%, 20% and 30%. The soil, ornamental rock processing residue and soil-residue mixtures will be analyzed, initially, by preliminary tests: granulometric analysis by sieving and sedimentation, atterberg limits and real grain density, later the chemical characterization tests will be carried out: fluorescence of x-ray (xrf), x-ray diffraction (xrd) and energy dispersive x-ray spectroscopy (eds) integrated with the scanning electron microscope (sem) and finally the mechanical characterization tests: simple compression, free expansion and compression triaxial.

The civil construction represents one of the sectors of the economy that most contributes to the degradation of the environment, however, it also has a high potential for the application of new materials that add parameters of sustainable development, such as functionality and sustainability. For this reason, this research seeks to produce an ecological material, that is, a solid brick of arisco, predominantly sandy soil with little clay fraction, with cement contents and the incorporation of other components, aiming at the partial replacement of Portland cement, high energy cost input and carbon dioxide generator, by salinization residue, such as carago or binder such as hydrated lime, or pozzolanic additive such as metakaolin. 32 bricks were produced with variations of substitutions between the materials mentioned above. In the initial stage, the characterization of the arisco was carried out, in addition to DRX and FRX tests of the raw materials and thermogravimetric analysis of the carago. After manufacturing the brick, the physical and mechanical properties were evaluated, through resistance to resistance, water absorption and durability. Once this step was completed, samples taken from the collapse of the bricks were subjected to microstructural tests such as XRD and SEM, seeking out to understand the interaction mechanism between the constituents of the hidden mixtures. Finally, it was found that the reference composition reached the highest mechanical strength, while the mixture that used only carago showed the highest water absorption and the one that included carago and metakaolin had the highest mass loss. The mixtures behaved within the requirements of Brazilian technical standards and can be used in non-structural masonry.

As economic development drives the accelerated pace of construction, it is known that it projects a global environmental crisis as a result of the waste of natural resources from non-renewable sources, thus arousing the search for alternatives for reuse of construction and demolition waste (CDW). In this study, the influence of incorporating recycled aggregates of CDW, sand and gravel, on the durability parameters in mixtures of self-compacting concrete (SCC), with and without the addition of metakaolin, submitted to two exposure conditions: in open air and in chloride ion attack cycles, was verified. Five mixtures were produced: (1) reference SCC, with natural sand and gravel; (2) SCC with recycled sand and gravel; (3) SCC with recycled sand and gravel and addition of 10% MK; (4) SCC with recycled sand, natural gravel and addition of 10% MK and (5) SCC with natural sand, recycled gravel and addition of 10% MK. The water/cementitious material ratio was kept constant for all mixtures and the additive dosage was adjusted according to the variation in the use of aggregates. The evaluation of mechanical properties and durability was performed from tests of axial compressive strength, ultrasonic pulse velocity, chloride penetration, chloride ion diffusion, electrical resistivity and corrosion potential. The results showed that the SCC properties were reduced with the use of recycled CDW aggregates. However, for some durability indicators, SCC with recycled aggregate behaved similarly to SCC with natural aggregates. The addition of metakaolin compensated for the decrease in quality of the SCC with the use of recycled aggregates. The SCC mixture with recycled sand and metakaolin stood out positively in relation to the others, with better results than the reference mixture.

High concentrations of nutrients, mainly phosphorus, trigger the eutrophication of lentic water sources. Thus, the reduction of external sources does not reduce eutrophication efficiently, since the nutrients accumulated in the sediment can be released into the water column, depending on the physical and chemical conditions of the system, favoring internal fertilization. Linked to this, the tropical semi-arid region of Brazil presents reduced precipitation and high temperatures, conditions that result in high evaporation and decrease in the water level of reservoirs used for supply, thus favoring resuspension by the wind. This, in turn, intensifies internal fertilization and the eutrophication process. Thus, this work will analyze the influence of wind resuspension on the release of phosphorus from the sediment to the water column, on a laboratory scale, using material from a shallow reservoir in the Brazilian tropical semi-arid region. In this study, resuspension simulations will be performed in microcosms to evaluate the release of phosphorus at the water-sediment interface. Based on the water-soluble reactive phosphorus concentrations of the microcosms, it will be possible to calculate the rate of P release from the sediment to the water column before and after resuspension events.

The use of large crawler cranes in engineering projects introduces several complexities to the scope of the projects. In this context, the preparation of operational platforms capable of providing the necessary safety and functionality for the equipment to perform its activities stands out. These platforms must be constructed based on specific geotechnical analyses. International practice demonstrates that such analyses are developed by considering the crane's load on soil layers as similar to the case of direct foundations resting on the surface of a terrain. Thus, geotechnical investigation and design methods are adapted from foundation engineering. However, in Brazil, projects of this nature are usually developed from a perspective derived from highway engineering, which is not the most suitable for this type of situation. In this context, this thesis presents a discussion about the main aspects associated with international and national practices regarding the design and execution of platforms for operating large crawler cranes. It particularly focuses on the most commonly used geotechnical investigation and design methods. Based on these discussions, a methodology is proposed for the development of geotechnical investigation plans and design methods applicable to operational platforms for large crawler cranes, specifically adapted to the Brazilian context. Additionally, two examples of design sequences are presented using the proposed methodology. These examples illustrate how aspects such as the magnitude of the load and the geometry of the support elements influences the analyses.

Water scarcity is a recurring problem in semi-arid regions, mainly due to the low incidence of precipitation and high evapotranspiration, which result in reduced water availability and low reliability for the supply of water demands. In this scenario, water transposition projects between hydrographic basins are an important solution to guarantee access to water for the population of these regions. The present work aims to define technical criteria for the operation of water systems that receive water from transposition projects, in semi-arid regions, in order to achieve greater guarantee in meeting the demands for water with the lowest input of exogenous waters. For this, the hydrological states of the reservoirs that make up the water system under study and that trigger the need for water transfer will be defined, in addition to optimizing the transferred volumes that result in the greatest synergistic gain in the use of water resources in the system. This research will be developed in a stretch of the Apodi-Mossoró river, between the water delivery portal of the São Francisco River Integration Project (PISF) and the Santa Cruz do Apodi dam, in the state of Rio Grande do Norte. Different scenarios of operation of the reservoirs that make up this water system will be simulated, adopting the operating rule of the Guide Curve method based on zones. Thus, it is expected with this research to define operating rules that best suit the proposed scenarios for the water system, in order to enable the minimization of deficits in meeting the demands requested in this region, as well as the reduction of losses due to overflow and evaporation. in the reservoirs, generating benefits in terms of access to water in this semi-arid region.

The civil construction sector has continuously sought materials that have a lower impact on the built environment, for this reason the use of wood has become attractive because it is a natural and renewable material. Knowledge of physical and mechanical properties is essential to classify new species and indicate their constructive component use. In the Northeast region of Brazil, the Caatinga biome stands out for its biodiversity as the only fully national biome. However, the physical and mechanical properties of the local species are little known and investigated and therefore their application becomes limited, being commonly used for energy purposes. With this, the study seeks to characterize the species Mimosa Tenuiflora and Aspidosperma Piryfolium native to the Caatinga biome and indicate potential uses in civil construction. Physical tests were performed to determine moisture (U), density ( ), apparent density ( ), dimensional stability ( , ΔV) and thermal conductivity; mechanical tests of compression parallel to the fibers (f_c0), parallel and perpendicular shearing (fv_0, fv₉₀), traction parallel and perpendicular to the fibers (ft_0, ft₉₀), Janka hardness parallel and perpendicular (fH_0, fH₉₀), static bending (fM₀) and elastic modulus test by non-destructive methods by ultrasound, stress waves and longitudinal and flexural excitation. The Shapiro-Wilk test and the Pearson correlation between physical and mechanical properties were used. The indication of applications of the species was carried out through the classification proposed by the IPT (2013) and IPT/SUDAM (1981), using the criteria of Nahuz (1974) and Nogueira (1991). The results show the species Mimosa Tenuiflora with 13 correlations and Aspidosperma Piryfolium with 19 representative correlations between physical and mechanical properties. Both species have equivalent properties to the commercialized species for constructive use, Aspidosperma Piryfolium can be used in light civil construction. Meanwhile, Mimosa Tenuiflora can be used in light and heavy civil construction.

The presence of natural organic matter (NOM) in water sources used for public supply influences the performance of water treatment units (oxidation, coagulation and adsorption). The quantity, characteristics and properties of NOM vary among waters from different sources and depend on the biogeochemical cycles of the surrounding environments. Water sources such as Brazilian coastal lagoons typically have low turbidity, so NOM is a determining factor in the coagulant dose. In these water sources, water treatment in a complete cycle is generally not efficient, as the flocs produced in the coagulation/flocculation are light, and the technologies of downflow direct filtration or upflow direct filtration are more suitable. Despite this, some tropical coastal lagoons may have high turbidity (and color) values, due to intense tropical rains and the anthropic degradation of the basin of these water sources, so the use of double filtration can be advantageous, as it can provide greater capacity to retain particles and NOM, increasing the robustness of the treatment system. However, the operation of more filtration units implies higher operational demand, higher consumption of washing water, electricity, etc., which may result in higher treatment costs. In this research, laboratory-scale and pilot-scale treatability tests of downflow direct filtration and double filtration with water from a tropical coastal lagoon will be carried out, with the objective of comparing these two systems for water treatment with emphasis on the NOM removal.

Os sistemas de drenagem urbana convencionais não são construídos para acompanhar a urbanização rápida e descontrolada, tornando-se ineficientes na coleta e descarga do escoamento produzido por eventos de chuvas intensas, fazendo com que ocorram inundações. Além disso, as chuvas intensas provavelmente sofrerão interferências das mudanças climáticas em longo prazo, de modo que existe a necessidade de revisão dos critérios de projeto para sistemas de drenagem urbana de acordo com os cenários climáticos esperados. A fim de mitigar as falhas nos dispositivos de drenagem convencionais e garantir uma maior resiliência da drenagem urbana frente às mudanças climáticas vem-se empregando uma concepção descentralizada de infraestrutura de drenagem urbana: os dispositivos urbanos de baixo impacto (Low Impact Development – LID) como telhados verdes, pavimentos permeáveis, trincheiras de infiltração e micro reservatórios, que objetivam simular o comportamento hidrológico natural da bacia para controlar as vazões de pico no escoamento superficial. Embora os benefícios hidrológicos dos LIDs tenham sido amplamente documentados, os potenciais impactos das mudanças climáticas no desempenho desses dispositivos, permanecem desconhecidos nas modelagens, gerando conclusões parciais e isoladas sobre o comportamento futuro de dispositivos da drenagem urbana. Dessa forma, este trabalho tem como objetivo avaliar a aplicabilidade da associação dos LIDs aos sistemas de drenagem convencionais em mitigar inundações em bacias urbanas tropicais. 

Dams are water structures that contribute to the socioeconomic development of a region. However, the absence of adequate safety procedures increases the risk of failures with the potential to cause significant impacts to downstream areas. This work developed a fuzzy safety risk assessment methodology for water accumulation dams located in the semi-arid region of Brazil. The fuzzy hierarchical analytical process (FAHP) was used to obtain the weight of the indicators and the aggregated scores corresponding to the vulnerability and potential harm criteria. In the fuzzy inference phase, the system was divided into two stages to obtain a more representative model. In the first step, vulnerability was estimated using conditional IF-THEN statements to estimate the combined effect of technical characteristics, conservation status, and security plan. Then, the defuzzified vulnerability values were combined with the potential harm to estimate the resulting potential risk. When comparing the results obtained by the proposed model with the CNRH classification regarding the CRI, it was observed that the studied dams were categorized into equivalent classes. As for the periodicity, deadlines and frequency based on the proposed danger scale, they were more rigorous than those of the ANA and allowed the establishment of priorities for safety procedures, such as monitoring and sensing, appropriate to the situations encountered in the field. Therefore, the proposed model allowed incorporating the uncertainties of the specialists' subjective judgments into the decision-making process and can be inserted as an improvement in the normative assessment to estimate the risk of dams with similar characteristics.

In accordance with recent changes in Brazilian legislation, all production processes are now required to account for the byproducts resulting from their operations and consider potential alternatives for appropriate disposal before resorting to sanitary landfills. Under this principle, the current study has delved into examining the properties of incineration bottom ashes from Healthcare Waste in a facility located in Paraíba. The aim is to assess the viability of utilizing these ashes in the impermeable barrier layers of the final cover of sanitary landfills.

To achieve this objective,  geotechnical and chemical-mineralogical composition tests were conducted to determine whether the material meets the necessary criteria for the proposed application. Mixtures were prepared using the soil typically used for the final cover of sanitary landfills, incorporating varying mass proportions of HMW ashes. Notably, all these mixtures displayed a saturated permeability coefficient in the order of 10^-7 m/s, approximating the hydraulic conductivity values to those recommended in the existing literature.