Mestrado em Engenharia Civil
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- ItemAnálise da autocicatrização de diferentes tipos de concretos com vistas à durabilidade, por meio do ensaio de migração acelerada de íons cloreto(Universidade Federal do Espírito Santo, 2025-09-30) Paigel, Gabriel Agrisi; Vieira, Geilma Lima; https://orcid.org/0000-0001-6148-3307; http://lattes.cnpq.br/5783172236615493; https://orcid.org/0009-0001-0380-6275; http://lattes.cnpq.br/1550296610058631; Araújo, Georgia Serafim; https://orcid.org/0000-0002-2029-6334; http://lattes.cnpq.br/4707150428037806; Zuchetti, Laís; https://orcid.org/0000-0001-9328-3350; http://lattes.cnpq.br/This study evaluates the phenomenon of self-healing in concrete with mineral additions and a crystalline admixture to understand its impact on durability, especially in aggressive conditions like those exposed to chloride ions. Mix designs with ground granulated blast-furnace slag, fly ash, a crystalline admixture, and a reference mix with high-early-strength Portland cement were analyzed in both uncracked and cracked samples, with crack widths less than 0.2 mm and between 0.3 and 0.4 mm. The methodology included chloride migration tests (NT BUILD 492), electrical resistivity measurements, stereoscopic microscopy, and, as a complement, X-ray diffraction (XRD) analyses to verify the ability of these materials to resist the penetration of deleterious agents and promote crack sealing. The results indicated that all materials showed some degree of visible self-healing. Concrete with blast-furnace slag stood out for its high resistance to chloride penetration, with a reduction of about 40% in penetration depth compared to the concrete with the crystalline admixture, in addition to showing higher electrical resistivity. In terms of self-healing, the concretes with fly ash and the crystalline admixture showed the best performance, while the slag demonstrated an intermediate behavior. The combined analysis of microscopy and XRD confirmed the formation of calcium carbonate (CaCO₃) as the main sealing product. The statistical analysis showed that the concrete's composition significantly influences its resistance to chloride penetration, while the crack width, within the studied ranges, did not have a relevant impact on the healing capacity. It is concluded that the use of mineral additions and specific admixtures is an effective strategy for producing more durable, resilient, and sustainable concrete.
- ItemAvaliação global-local da vida em fadiga de ligações soldadas em pontes ferroviárias de carga(Universidade Federal do Espírito Santo, 2025-10-13) Ferro, Karina Barth; Dias, João Victor Fragoso; https://orcid.org/0000-0003-1455-1519; http://lattes.cnpq.br/0090215976146284; https://orcid.org/0000-0001-6910-6362; http://lattes.cnpq.br/2043581822614372; Calenzani, Adenilcia Fernanda Groberio; https://orcid.org/0000-0002-0936-9950 ; http://lattes.cnpq.br/9959808218883879; Carvalho, Hermes; https://orcid.org/0000-0002-4652-8068; http://lattes.cnpq.br/7254461558501100In cargo transportation, railways play a complementary role in logistics by enabling the transport of large volumes with lower energy consumption. To serve this purpose, railway bridges have been constructed over the years using various materials, among which steel has gained prominence due to its versatility and the ability to span long distances with lightweight structures. In these bridges, structural details such as welded connections can feature various geometric configurations that result in stress concentration points. When combined with dynamic loading and second-order effects, these stress concentrations make fatigue one of the primary causes of failure in steel bridges. However, assessments for this type of limit state can be complex, and more accurate approaches, such as the global-local methodology, can be employed. Within this context, a fatigue life assessment is conducted on a welded connection of a railway bridge with a composite steel-concrete structure. The analysis is carried out using finite element models in the commercial software Ansys Mechanical APDL v. 2020R1, considering two modeling scales – global and local. Fatigue life is estimated using both the nominal stress method and the hot-spot stress method. Damage per vehicle passage is computed based on the stress history, followed by the estimation of the number of load cycles the structure can withstand, in accordance with the recommendations of the International Institute of Welding (IIW) and EN 1993-1-9:2005. The results indicate that for the evaluated detail, fatigue life is not infinite, even when considering the passage of the lightest type of vehicle operating on the track. Furthermore, it is evident that increases in vehicle weight and traffic speed have a significant impact on the fatigue life of the detail. Regarding standards and methodologies, the nominal stress method was found to be non-conservative for fatigue life prediction, whereas the IIW methodology yielded more conservative results than those provided by EN 1993-1- 9:2005.
- ItemInfluência da granulometria, expansão volumétrica e teor de cal livre na tensão de expansão de escória LD confinada e em ambiente termicamente controlado(Universidade Federal do Espírito Santo, 2024-09-30) Saquetto Junior, Arnaldo; Co-orientador1; https://orcid.org/; http://lattes.cnpq.br/; Pires, Patrício José Moreira; https://orcid.org/; http://lattes.cnpq.br/; https://orcid.org/; http://lattes.cnpq.br/; 1º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 2º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 3º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 4º membro da banca; https://orcid.org; http://lattes.cnpq.br/Due to the need to analyze the load produced by the expansion in confinement of LD steel slag for its use in engineering, this work aims to measure this load through the development of an experimental apparatus with thermally controlled hydration, at volumetric expansion levels above 3% and below 3%, measured by the Modified PTM – 130 test, according to the DNIT 113/2009 – ME standard, as well as different particle size ranges. The loads detected by the developed test were expressed in terms of stress in kPa, with the highest recorded stress being 329.28 kPa, for a sample with a particle size distribution between 0 mm and 4.75 mm and a volumetric expansion of 4.67%. It was found that applying a pre-load of 5.42 kPa (10 kgf) to the sample, before conducting the test, can increase the final stress by 75% compared to samples without the application of this pre-load. The lowest confinement expansion stress level was 10.21 kPa, measured in a sample with volumetric expansion below 3%, already pre-cured and without pre-load applied at the start of the test. It was possible to correlate the results obtained with values of void ratio and the free lime content in the sample. The correlation between void ratio and volumetric expansion, and the measured expansion load was very strong and inversely proportional, where lower void ratios resulted in higher measured values. It was verified that the developed equipment is indeed capable of performing this measurement, and it was concluded that the expansion load is closely correlated with volumetric expansion parameters, and that voids influence this expansion load in a confinement situation
- ItemOtimização topológica de pisos em treliças mistas tubulares com lajes mistas : análise de custos e emissões de CO2(Universidade Federal do Espírito Santo, 2025-08-22) Silva, Chayana Morgner Gomes da; Calenzani, Adenilcia Fernanda Grobério ; https://orcid.org/0000-0002-0936-9950; http://lattes.cnpq.br/9959808218883879; Alves, Élcio Cassimiro ; https://orcid.org/0000-0001-6971-2645; http://lattes.cnpq.br/6509450210637509; https://orcid.org/0009-0001-5367-2957; http://lattes.cnpq.br/5148699094876758; Melo, Antônio Macário Cartaxo de ; https://orcid.org/0000-0003-0398-4124; http://lattes.cnpq.br/2798137522735300; Silva, André Tenchini da ; https://orcid.org/0000-0003-0925-1159; http://lattes.cnpq.br/7036280752466413The objective of this study is to optimize the costs and CO₂ emissions of composite floor systems supported by composite tubular trusses, with and without concrete filling in the upper chord, considering the effect of vibrations induced by human walking. For the optimization problem, constraints related to the ultimate and service limit states of the composite slabs after concrete curing, and of the composite trusses before and after curing, were implemented. The optimization problem considered twenty-one design variables, including: circular profiles of the lower, upper, and diagonal members of the internal, edge, and main trusses; concrete strength (𝑓𝑐𝑘) of the slab; thickness of the steel deck; thickness of the concrete slab; number of truss panels; truss height; concrete strength (𝑓𝑐𝑘) of the filling in the upper chord of the internal, edge, and main trusses; span between internal trusses; and additional reinforcement. The Particle Swarm Optimization (PSO) algorithm was used to search for the optimal solution. To validate the implemented computational code, comparative analyses were first carried out with problems from the literature to verify the effectiveness of the proposed formulation. Subsequently, a parametric analysis was performed by varying the live loads and spans to identify the most influential factors in the solution. Finally, the effects of considering the comfort limit state of users related to human walking, and the influence of concrete filling in the upper chords of the trusses, were analyzed in the search for the optimal floor solution. It was concluded that concrete filling in the upper chords of the trusses contributes to reducing the number of truss panels and the cross-sectional area of the profiles, resulting in lower emissions and costs compared to full web beams. The analysis of floor vibration effects directly influenced the geometry of the internal and main truss sections, due to the need to provide greater structural stiffness
- ItemOtimização multiobjetivo no projeto de lajes mistas de aço e concreto(Universidade Federal do Espírito Santo, 2025-08-14) Silva, Isabela Oliveira Maia da; Alves, Élcio Cassimiro; https://orcid.org/0000-0001-6971-2645; http://lattes.cnpq.br/6509450210637509; Calenzani, Adenilcia Fernanda Grobério ; https://orcid.org/0000-0002-0936-9950; http://lattes.cnpq.br/9959808218883879; https://orcid.org/0009-0003-0976-9510; http://lattes.cnpq.br/2866501864088026; Dias, João Victor Fragoso; https://orcid.org/0000-0003-1455-1519; http://lattes.cnpq.br/0090215976146284; Kripka, Moacir; https://orcid.org/0000-0002-1997-3414; http://lattes.cnpq.br/7554233520986997The composite steel and concrete slabs have been used as a more economical and sustainable structural alternative since they offer advantages that outweigh other structural systems. Dispensing with formwork and shoring, high construction speed, and reduction in concrete and tensile reinforcement consumption are advantageous features of composite slabs. In this context, the aim of this study is to present the formulation of a multi-objective problem for composite slabs, considering the minimization of CO₂ emissions and final costs, as well as the maximization of load capacity. The design constraints followed the prescriptions of Brazilian standards for both construction and service phases. For the initial phase (before concrete curing), the design consists of verifying the steel formwork supporting the applied loads alone, using the Effective Width Method (EWM) as prescribed by ABNT 14762:2010. For the service phase (after concrete curing), the design was based on ABNT NBR 8800:2024, considering the composite steel system resisting the slab loads. To solve the optimization problem, the MOPSO (Multi-Objective Particle Swarm Optimization) algorithm was used to generate and analyze results through Pareto Fronts. For program validation, a verification of the cataloged slabs was conducted, maintaining their geometric and material properties, and investigating the possibility of loads exceeding those specified in the manufacturer's tables. Solutions were presented that are capable of supporting up to 1.54 times the load indicated by the manufacturer. The formulation was validated using problems from the literature, and an analysis of manufacturer-proposed solutions for different spans was conducted. Additionally, an equation was proposed to relate CO₂ emissions to cost. The results indicate that MOPSO was efficient in finding optimal solutions, yielding results very close to those in the literature using single objective formulations. With the proposed formulation, solutions were achieved with up to 2.4 times the design load proposed in catalogs, and up to 35% lower CO₂ emissions and 30% lower cost due to additional reinforcement. Moreover, solutions were obtained for spans exceeding the maximum limits provided by manufacturers by using concrete with compressive strength greater than 30 MPa. According to the results, the problem constraints are: verification of the steel formwork for bending moments before concrete curing, and verification of the composite section for longitudinal shear after curing