Faculdade de Engenharia Civil - FEC/ITEC

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2788

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Agora exibindo 1 - 20 de 29

Acesso aberto (Open Access)
Análise computacional do fenômeno de transferência de calor em paredes divisórias do tipo dry wall
(2007-06) ALVES, Maurício Coelho; BATISTA, Eduardo de Miranda
The present work aims to give a contribution to the study of cold–formed steel members under fire condition. Specifically, the heat transfer in light steel framed walls with or without thermal insulation was studied. For this, computational models are applied to obtain, with acceptable precision, the values of temperature in any position of the structural system. In this way, it will be possible to describe the temperature distribution (uniform or non–uniform) over the cross–section of the studs that constitute the panel, giving subsidies for stability and pos–buckling analyses of the structural members. The numerical simulations of heat transfer are developed with the aid of computational programs ABAQUS and SAFIR, both based on the finite element method.
Acesso aberto (Open Access)
Análise do desenvolvimento de competências gerenciais na construção civil através do modelo da Aprendizagem Baseada em Problemas adaptado ao contexto organizacional
(2014-03) MARTINS, Vitor William Batista; NEVES, Renato Martins das; MACÊDO, Alcebíades Negrão
Continuous changes in the civil engineering scenario, and consequently in construction production management require engineers with a different profile, resulting in the need of new competences, related to innovation, customer focus, planning and control, quality management systems, sustainability and a humanistic vision. The main goal of this article is to identify the competences developed in a construction company through the implementation of problem-based learning adapted to the organizational context. The strategy applied in this study was action research, in which researchers work with practitioners to improve the way they understand and solve problems. The results obtained involve the development of competences related to the organizational context, individual, collective and organizational learning process, pointing out problems and possible managerial solutions in the company. By developing managerial competences, a sustainable and humanistic vision, with client focus was stimulated, besides improvements in the quality management system. Some problems were identified in the organizational management system, making evident the need to create an environment that facilitates information exchange among the different sectors of the company.
Acesso aberto (Open Access)
Análise estática e dinâmica de uma ponte ferroviária em concreto armado localizada na Estrada de Ferro Carajás
(Instituto Brasileiro do Concreto, 2010-09) TEIXEIRA, Ritermayer Monteiro; AMADOR, Sandro Diord Rescinho; OLIVEIRA, Dênio Ramam Carvalho de
This work presents results of static and dynamic analysis carried out on 593 m length bridge along Carajás railroad in Maranhão state. The bridge's behavior became important due to some changes over the static and dynamic loads once the future train will be heavier. Thus, a mathematic model was developed using the finite element method basis to evaluate its behavior and "in loco" structural moni- toring to get data as strains and vibrations when the trains go through. Several high precision accelerometers and strains gauges were placed along the slab, beams and columns. Numerical and experimental results are shown and the main conclusions validating the applied methodology are presented as well.
Acesso aberto (Open Access)
Behavior prediction models and control charts for safety control of concrete dams
(Universidade Federal do Pará, 2012-06) LOPES, Romulo Antonio Chaves; SANTOS, Eurípedes Pinheiro dos; VELOSO, Luís Augusto Conte Mendes
This paper presents a study for improving measurement procedures on concrete dams based on the development of behavior prediction models using multiple regression and control charts. The series of displacements of the TA-2 concrete block crest of the Tucuruí Hydroelectric Power Plant, the largest Brazilian hydroelectric power plant, was taken as an example of application. The methodology that was used generated a behavior prediction model that is in good agreement with the measured displacements. Two types of control charts were tested, both of which identified the change in structural behavior of the block.
Acesso aberto (Open Access)
Caracterização da cinza de caroço de açaí residual para adição ao concreto
(Universidade Federal do Pará, 2019-05) CORDEIRO, Luciana de Nazaré Pinheiro; PAES, Isaura Nazaré Lobato; SOUZA, Paulo Sérgio Lima; AZEVEDO, Caroline Menezes
Environmental problems are a reality in today's world and are associated with urban and population growth, with little or no planning. The construction industry is one of the largest consumers of natural resources and generator of solid waste. Thus, it is interesting to think of a way to incorporate materials that are now considered waste, to the constructive process and reduce the consumption of natural materials. In this section, we have the ashes of açaí stone, residue of ceramic kilns, that today do not present an adequate destination. Thus, this research has the main objective to characterize residual ash of açaí (CCAR), in order to make possible its reuse as an input of the civil construction. In order to achieve this objective, a milling study was carried out in order to determine the optimum material processing time, characterization from the chemical, physical and mineralogical point of view, and the pozzolanic potential analysis to evaluate the residual ash reactivity. The results show that ash has physical characteristics that allow it to be used as an addition to concrete. There was a decrease in the axial compressive strength and an increase in the water absorption of concrete with additions, in relation to the reference concrete. In spite of these effects, a certain densification of the cementitious matrix was observed, probably due to the variation of the particle size that may provide greater compactness with optimization of grain packing.
Acesso aberto (Open Access)
Chapas de cimento-madeira com resíduos da indústria madeireira da Região Amazônica
(2012-06) MACÊDO, Alcebíades Negrão; SOUZA, Alberto Alexandre Costa e; POMPEU NETO, Bernardo Borges
The aim of this study was to to evaluate the use of waste from the timber industry of the Brazilian Amazon Region in the production of wood-cement composites. The compatibility of six Amazon hardwood native species with cement CP V ARI was assessed through axial compression tests in cylindrical specimens. The waste was used was only treated by washing in hot water for two hours. The ratio cement/wood was 3:1 in mass, along with aluminum sulfate curing accelerators at 3%, and calcium chloride curing accelerators at 3% and 5%. The results of the axial compression tests indicated the potential use of waste for three species combined with calcium chloride curing accelerator treatment at 5%. Wood-cement particleboards were made with waste of the species Cedrela odorata L. (Cedar), Vochysia maximum Ducke (Quaruba), Hymenaea courbaril L. (Jatoba) and a mixture of them. The test results of the physical and mechanical properties of the particleboards showed that all had adequate characteristics for the purpose, and the Cedar species particleboards presented the best performance.
Acesso aberto (Open Access)
Comportamento de blocos cerâmicos estruturais produzidos a partir da mistura de lama vermelha e argila
(2011-12) MACÊDO, Alcebíades Negrão; COSTA, Diogo Henrique Pereira e; TRINDADE, Sandro Roberto dos Santos
The use of new techniques for waste reuse has become increasingly important in construction, especially when it deals with the use of waste from other industries and reduction on the consumption of natural materials. The purpose of this study was to evaluate the use of red mud (LV) waste, alumina metallurgical residue, on the production of structural ceramic blocks. The production of the blocks was carried out at a ceramic industry, using a mixture of 60% of red mud and 40% of clay. After the production of blocks, tests were conducted according to technical standards, such as water absorption and simple axial compression. From the analysis of the results, the conclusion was made that that structural blocks, made from the mixture of clay and LV, complied the standard parameters related to the rate of water absorption and compressive strength, and that the strength of theses blocks was significantly higher than those made from 100% clay.
Acesso aberto (Open Access)
Concretes with red mud coarse aggregates
(2012-06) OLIVEIRA, Dênio Ramam Carvalho de; ROSSI, Carlos Rodrigo Costa
Red mud (RM) is a mineral waste, residue of the Bayer process used to obtain alumina from bauxite. While the exploration of rolled pebble damages the environment and is much more controlled by the government, the huge RM disposal areas do not stop increasing and polluting soil, rivers and groundwater sources in Amazon. In this work, the material mixtures used to produce coarse aggregates presented up to 80% of RM, 30% of metakaolin and 30% of active silica as recycled waste. Several tests were carried out to determine the aggregates physical properties and to evaluate the mechanical performance of the concretes with the new aggregates, including hydraulic abrasion strength, and the results were compared to the reference ones, i.e. rolled pebble concretes. Additionally, the sintering process neutralizes any toxic substance as occur in some RM products like tiles and bricks, and these results have encouraged an industrial or semi-industrial production of RM aggregates for concretes.
Acesso aberto (Open Access)
Contribuição ao estudo de lajes lisas unidirecionais de concreto armado com pilares retangulares ao puncionamento
(2007-12) FERREIRA, Maurício de Pina; OLIVEIRA, Dênio Ramam Carvalho de
Analysis of recommendations to predict the ultimate punching resistance of flat slabs according to the actual Brazilian code, NBR 6118:2003, which does not consider the effects of the internal columns' rectangularity, and its previous version, NBR 6118:1980, are presented. In rectangular cross sections, the shear stress polarization rate is crescent. Thus, the slab failure mode changes, since the punching failure takes place at the column's ends, without compromizing the larger sides, as recommended by the new version of the code. This behavior tends to reduce the ultimate punching resistance of flat slabs when the normative estimates are compared. In addition to the results from the two codes, are presented a numerical analysis by the Finite Element Method and a proposal to improve the ductility of flat slabs based on the minimal dimensions for rectangular columns. The results showed that the NBR 6118:2003 estimates can be improved.
Acesso aberto (Open Access)
Controle Fuzzy aplicado à melhoria da estabilidade dinâmica em sistemas elétricos de potência
(2005-06) BARRA JUNIOR, Walter; BARREIROS, José Augusto Lima; COSTA JÚNIOR, Carlos Tavares da; FERREIRA, André Maurício Damasceno
This work presents a fuzzy control strategy which can be applied to improve the dynamic stability of electric power systems. The gains of fuzzy controller are smoothly adjusted by using interpolation among the gains of a set of previously designed local controllers, according to the current plant operating condition. In this way, the parameters of the fuzzy controller are automatically adjusted on-line, in order to cope with changes in the power system operating conditions. The performance of the fuzzy strategy was assessed by simulation studies, using a nonlinear machine infinite bus bar dynamic model. The results show that it is possible to improve the power system dynamic performance under time-variable operating conditions.in english. Please notice that the abstract in english comes first.
Acesso aberto (Open Access)
Efeitos do tipo, tamanho e teor de agregado graúdo no módulo de deformação do concreto de alta resistência
(2011) POMPEU NETO, Bernardo Borges; OLIVEIRA, Dênio Ramam Carvalho de; RAMOS, Danielle
Concrete, material with heterogeneous and complex composition, is the main structural material applied in the construction industry. From the structural point of view its main property is the mechanical strength. The behavior of concrete based on conceptual studies of granular resistance can lead to a safer structural design and better use of the material. This paper presents the results of a study conducted to evaluate the effects of type, size and content of coarse aggregates on the modulus of deformation of high strength concretes. The concrete mixture studied contains basalt or granite aggregates with maximum dimensions of 9.5 mm and 19.0 mm and water/cement ratio of 0.35. The deformation modulus of the material was determined using the linear length of Load-CMOD curve (displacement of the crack mouth opening) from three point bending tests performed using a middle span cracked beam, following the propositions made by the RILEM 89-FMT technical committee.
Acesso aberto (Open Access)
Experimental analysis of the efficiency of steel fibers on shear strength of beams
(Associação Brasileira de Ciências Mecânicas, 2016-07) GOMES, Lana Daniele dos Santos; OLIVEIRA, Dênio Ramam Carvalho de; MORAES NETO, Bernardo Nunes de; MEDEIROS, Adelson Bezerra de; MACÊDO, Alcebíades Negrão
The efficiency of steel fibers for shear strength of reinforced concrete beams is assessed. Four beams were evaluated: control consisted of one beam without any steel fibers and three beams with reinforced concrete with steel fibers. All beams were reinforced for shear strength by a minimum reinforcement rate. The influence of fiber content added to concrete, at 0.5%, 0.8% and 1.0%, and the possibility of partial or total replacement of conventional shear reinforcement (stirrups) by steel fibers were evaluated. Results showed a significant increase in ductility and stiffness of the beams with steel fibers and, consequently, changes in the failure mode were observed, of shear (control beam) to flexure behavior (beams with steel fibers).
Acesso aberto (Open Access)
Extração de oleoresina de Cúrcuma (Curcuma longa l) com CO2 supercrítico
(1997-12) CHASSAGNEZ MÉNDEZ, Angel Luis; CORRÊA, Nádia Cristina Fernandes; MEIRELES, Maria Angela de Almeida
Turmeric (Curcuma longa L) is one of the most used source of natural color in the food industry. Curcuminoids can be obtained from the roots of this plant. These pigments impact a yellow color and they might be able to substitute synthetic dyes. Turmeric oleoresin extraction experiments have been carried out with supercritical CO2 to investigate the influences of the pretreatment of the rhizomes on oleoresin. The extractions were conducted at the Department of Chemical Engineering of the Federal University of Pará (Universidade Federal do Pará). Turmeric was dried at 70ºC and 105ºC. Extractions have been carried out at pressures of 200, 250 and 300 bar and a temperature of 45ºC. Results shown the total yield and the content of curcumin present in the oleoresin. Amount of oleoresin extracted from the material dried at 70ºC was larger while most of the curcuminoids remained in the solid material.
Acesso aberto (Open Access)
Fatigue lifetime of a RC bridge along the Carajás railroad
(Universidade Federal do Pará, 2012-10) SANTOS, Régis Rivo Ferreira dos; OLIVEIRA, Dênio Ramam Carvalho de
The aim of this paper is to present and discuss the results obtained with a methodology used to characterize the concrete and to evaluate the structural safety against fatigue of the reinforced concrete bridge number 50A located in the Carajás railroad. An “in situ” inspection was carried out in order to assess the evolution of damage in structural elements, with reference to information available in existing projects, calculation memory and reporting of previous inspections. Extractions of concrete testimonies, alkalinity tests, sclerometry, pacometry and laboratory tests were also performed to characterize the materials mechanically and estimate the structural behavior of the bridge under higher future loads.
Acesso aberto (Open Access)
Global stability analysis of reinforced concrete buildings using the γ z coefficient
(Universidade Federal do Pará, 2017-10) VIEIRA, Vitor Vinicius dos Santos; RODRIGUES JÚNIOR, Sandoval José; VELOSO, Luís Augusto Conte Mendes
Global stability analysis is becoming increasingly important in the design of reinforced concrete buildings, especially in the slender ones, due its sensitivity to lateral displacement. The loss of stability is usually associated with the intensity of the second order effects and, in that sense, the gamma-z (γz) coefficient is an important evaluation parameter for this problem. This work aims to verify the γz efficiency as a global stability parameter based on the buckling load factors of the structures and their respective critical buckling modes. To this purpose, a comparative analysis is performed in several idealized structures, from which an approximate equation for calculating the critical load factor based on the γzcoefficient is obtained. This equation was verified by numerical analysis of Finite Elements Method models of real reinforced concrete buildings. It was concluded that the proposed equation presents satisfying results within a certain range of γz.
Acesso aberto (Open Access)
Influence of the cable´s layout on the shearing resistance of prestressed concrete beams
(Universidade Federal do Pará, 2016-10) SOUZA JUNIOR, Orivaldo de Azevedo; OLIVEIRA, Dênio Ramam Carvalho de
Little information on experimental investigations regarding the influence of the prestressing forces in the shear resistance of prestressed beams is found in the technical literature. Thus, it was experimentally evaluated the shear resistance of six post-tensioned prestressed concrete beams with cross section of (150 x 450) mm2, total length of 2400 mm and concrete’s compressive resistance of 30 MPa, with the variables of this work being the layout of the prestressing cable, straight or parabolic, and the stirrups geometric rate. Verticals displacement, steel and concrete’s strains and a comparison of the experimental loads with the estimates of ACI 318, EUROCODE 2 and NBR 6118: 2014 codes are presented and discussed. The results showed that the cable’s parabolic layout increased the beams’ shear resistance in up to 16% when compared to beams with straight cables.
Acesso aberto (Open Access)
Influence of the column rectangularity index and of the boundary conditions in the punching resistance of slab-column connections
(Universidade Federal do Pará, 2015-06) PAIVA, Odilson da Silva de; FERREIRA, Maurício de Pina; OLIVEIRA, Dênio Ramam Carvalho de; LIMA NETO, Aarão Ferreira; TEIXEIRA, Marcelo Rassy
Experimental evidence indicates that both the column rectangularity index and the boundary conditions of the connection may affect the ultimate punching resistance. This paper presents general aspects of these topics and, through the analysis of experimental results of tests on 131 slabs, evaluates the accuracy and suitability of recommendations presented by ABNT NBR 6118, Eurocode 2, ACI 318 and fib Model Code 2010. Experimental results showed that the security level of normative estimates trend to reduce as the column rectangularity increases, and in some cases, the punching resistance was overestimated. Finally, adjustments are suggested in equations presented by NBR 6118 and MC2010 in order to eliminate this trend of unsafe results.
Acesso aberto (Open Access)
Lajes lisas nervuradas bidirecionais com furos
(Universidade Federal do Pará, 2014-08) MATEUS, Gustavo Menezes; AGUIAR, Amaury José Oliveira de; FERREIRA, Maurício de Pina; OLIVEIRA, Dênio Ramam Carvalho de
The position of pipes and hoses for several installations still deserves special attention from designers mainly when the failure mode can be modified due to changes in behavior. This work compares experimental results of six two-way reinforced concrete ribbed flat slabs with rectangular holes close to the column and without shear reinforcement with the estimates obtained from codes ACI 318 and NBR 6118 equations. All slabs were casted and tested in the Civil Engineering Laboratory of UFPA and had dimensions of 1.800 mm x 1.800 mm x 150 mm and were submitted to central loading applied through 120 mm side square steel plates simulating the columns. EPS was used as inert material and the ribs were spaced 250 mm with 130 mm height and 75 mm average wide. The results showed that the codes’ shear equations estimates agree when the ribs are considered as beam and also for punching shear, but trend to be safer when the slabs present two shafts.
Acesso aberto (Open Access)
Lajes lisas nervuradas de concreto armado ao cisalhamento
(Universidade Federal do Pará, 2011-10) SOUZA, Shirley do Socorro Melo de; OLIVEIRA, Dênio Ramam Carvalho de
The structural systems with waffle flat slabs are the most used in Brazil when the main requirement is flexible "layouts" and long spans with reasonable economy. However, few studies have been developed in Brazil regarding the behavior of these slabs when the flexural resistance is satisfactory and the shear in the ribs and punching resistances become competitive. This work shows the experimental analysis of 8 two-way reinforced concrete waffle flat slabs under centered load. The dimensions of the slabs were the same and equal to 1800 mm x 1800 mm x 140 mm. The ribs were 80 mm (height) by 50 mm (width) and the compressive concrete strength was approximately 40 MPa. The experimental results were compared to those estimated by the Brazilian code NBR 6118:2003. It was verified that the resistance of the ribs is not satisfactorily estimated by the code, which excessively underestimates the results for ribs with and without shear reinforcement.
Acesso aberto (Open Access)
Monitoramento de pilares em edifícios altos de concreto armado
(Universidade Federal do Pará, 2010-06) NAHUM, Kelly Ataide Rodrigues; OLIVEIRA, Dênio Ramam Carvalho de
The structural behavior simulated by computer programs can be very different from reality, once the adapted loading distribution (regular) is far from the real one, and this disparity becomes more significant in high buildings because of vertical and horizontal actions which contribute to the global effects of second order for columns, making accuracy in the calculation of great importance for the stability of the overall structure. In this work are presented loads for a high building simulated using the commercial software CAD/TQS and the loads from the monitoring of 7 columns that received 3 extra bars along their height in two levels before concreting. In the steel bars were set electric strain gages to measure the strains. The data acquisition was performed through 1 module “Spider” that gets and stores the read- ings. The measurements were executed in periods previously chosen until the end of the structure building, including upper reservoir. The computation loads for the columns were satisfactory when compared to the loads from the strains and characteristic mechanical properties of the materials.