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O presente estudo tem como objetivo central analisar os motivos do declínio da cooperação para o desenvolvimento entre o Brasil e a Alemanha e as suas perspectivas num contexto de integração regional.

O objetivo deste artigo é analisar a evolução de um regime hemisférico de segurança tendo em vista duas questões fundamentais: o impacto do Mercosul no equilíbrio geopolítico continental e o papel do Brasil como ator-chave na conformação deste arranjo hemisférico de segurança. Nossa hipótese é de que, tanto na dimensão regional, quanto global, o Brasil tem atuado no sentido de contrabalançar a hegemonia norte-americana, reforçando a correlação entre o status de potência regional e o cálculo de opções internacionais.

Abstract The purpose of this work is the development and implementation of a numerical procedure for the design of reinforced concrete columns (RC) and composite columns with fully concrete encased steel I-section (SC). For this purpose, a computer program was developed to determine the load capacity of these columns, applying the General Method adopted by ABNT NBR 6118:2014. The program is based on an iterative process from integration of the curvatures along the column, obtained by determining the moment-curvature relationship of the cross section by the Newton-Raphson method. Several experimental and numerical results are compared to the program's to demonstrate the accuracy of the procedure.

Abstract This paper presents recommendations for security check of precast beams in transitory phases, compare results of parametric analyzes with national and international code recommendations and confront the formulations used for the calculation of critical load of lateral instability. In transport and lifting phases, precast beams are susceptible to loss lateral stability because the established supports provides little restriction to the element rotate on its principal axis and move laterally. To recommend limits of slenderness, parametric analysis are performed using formulations based on bifurcacional instability, including eigenvalue problems with the finite element method. The results show that the safety limits for I beams and rectangular beams are different. For the analyzed cases and with reference to beam slenderness equation used by fib Model Code [13], the limit determined for rectangular beams would be 85 and for I beams 53, which could be taken as 50, as recommended by the code. Within the analyzed cases of I beams, only the fib Model Code [13] recommendation attend the slenderness limit for transitory phases.

Abstract The modeling of reinforced concrete structures has taken advantage of the increasing progress on Computational Mechanics, in such way that complex phenomena, such as cracking and crushing, creep, reinforcement yielding, steel-concrete bond loss, can be modeled in a reasonable realistic way, using the proper set of numerical and computational resources. Among several options, the ones based on the Finite Element Method (FEM) allow complex analysis simulations of reinforced concrete structures, including the interaction of different nonlinear effects. This paper deals with the nonlinear finite element analysis of the bond-slip between reinforcing steel and concrete, taking into account an experimental study previously performed. The FEM analysis presented uses a combination of resources where the material behavior of concrete is described by the Microplane Constitutive Model, and an embedded reinforcement model is used to represent steel inside the concrete and take into account the effect of bond-slip. The FEM models were created using the INSANE (INteractive Structural ANalysis Environment) computational system, open source software that has a set of FEM tools for nonlinear analysis of reinforced concrete structures. The correlations between numerical-experimentals results and several parameters validate the proposed combination of resources and identifies the significance of various effects on the response.

Resumo Os recentes aumentos dos registros de abalos sísmicos no Brasil impulsionaram a publicação da NBR 15421:2006 [1] - Projeto de Estruturas Resistentes a Sismos - na qual são definidas as cargas sísmicas a serem consideradas no projeto em função da capacidade de dissipação de energia no regime inelástico das estruturas e da sismicidade do território brasileiro. Algumas edificações construídas antes da publicação dessa norma não foram projetadas para resistir a ações sísmicas aumentando a sua fragilidade e vulnerabilidade para terremotos de qualquer intensidade. Observa-se ainda que alguns desses edifícios foram projetados e construídos com distribuições irregulares de massa, rigidez ou resistência ao longo da sua altura que podem levar a um desempenho sísmico inadequado. Assim, torna-se essencial para os engenheiros e projetistas uma melhor compreensão dos efeitos dos abalos sísmicos no comportamento sísmico de edificações, especialmente aquelas com diversas irregularidades. Por simplicidade, utiliza-se neste trabalho o termo "estruturas irregulares" para referenciar estruturas como as descritas. Nesse sentido, o objetivo deste trabalho é avaliar o comportamento sísmico de uma estrutura de concreto armado de oito pavimentos e com diversas irregularidades introduzidas na planta da mesma, a fim de verificar a influência dessas irregularidades na perda da capacidade de resistir cargas laterais e dissipação de energia, as quais são calculadas utilizando o método dinâmico espectral e uma análise pushover, procedimentos descritos nas normas NBR15421:2006 [1] e na norma americana FEMA 356 [2]. Do mesmo modo, calcula-se o desempenho sísmico dos modelos usando o método do espectro de capacidade definido na norma ATC-40 [3]. Todos os resultados são comparados com os obtidos para uma estrutura totalmente regular chamada de caso base ou de referência, com o intuito de visualizar as diversas mudanças provocadas pelas irregularidades. O estudo proposto é realizado de forma numérica e as simulações são feitas no programa CSI ETABS(r) Nonlinear v9.5 [4]. Os resultados mostram que a capacidade da estrutura dependerá da plasticidade de seus elementos para não colapsar e do detalhamento adequado para garantir o bom funcionamento do sistema resistente.

Resumo Atualmente, com o avanço da tecnologia de corte e solda, perfis de aço com aberturas sequenciais na forma circular, denominados perfis celulares, vêm sendo bastante utilizadas como vigas de edificações. A ABNT NBR 8800:2008 e as normas estrangeiras não abordam vigas de aço e vigas mistas de aço e concreto com perfil celular, o que contribui para que o seu uso seja limitado. Foi desenvolvido e aferido um programa computacional para o dimensionamento de vigas mistas de aço e concreto com perfil celular biapoiadas de acordo com duas metodologias distintas da literatura. Um estudo paramétrico abordando vigas mistas com perfis celulares obtidos de dois perfis I de aço laminados comerciais foi realizado. Nesse estudo, a influência dos parâmetros geométricos do perfil celular e do comprimento do vão da viga na resistência e na forma de colapso foi analisada. Foi possível concluir que em muitas situações o uso de vigas mistas com perfil celular é vantajoso em relação às vigas mistas de alma cheia.

This article presents the study of reinforced concrete columns strengthened using a partial jacket consisting of a 35mm self-compacting concrete layer added to its most compressed face and tested in combined compression and uniaxial bending until rupture. Wedge bolt connectors were used to increase bond at the interface between the two concrete layers of different ages. Seven 2000 mm long columns were tested. Two columns were cast monolithically and named PO (original column) e PR (reference column). The other five columns were strengthened using a new 35 mm thick self-compacting concrete layer attached to the column face subjected to highest compressive stresses. Column PO had a 120mm by 250 mm rectangular cross section and other columns had a 155 mm by 250mm cross section after the strengthening procedure. Results show that the ultimate resistance of the strengthened columns was more than three times the ultimate resistance of the original column PO, indicating the effectiveness of the strengthening procedure. Detachment of the new concrete layer with concrete crushing and steel yielding occurred in the strengthened columns.

This study presents an analytical model for evaluation of the reinforced beams under simple bending based on recommendations of the Brazilian Concrete Code (NBR-6118) and a study published by the International Federation of Concrete (fib). In this paper are considered two different section types, rectangular and "T" sections and the beam´s deformation are analyzed considering the moment-curvature diagram taking into consideration the limits of deformation of materials. The results obtained by both Codes are confronted each other, showing great similarity. Additionally, destructive tests of reinforced beams have been made in the laboratory and were compared to results obtained by the analytical model, showing excellent performance of the proposed model. The objective of this publication is to present the analytical model. Analysis comparing the field results and the analytical model were presented in another publication mentioned in this study.

When added to concrete in appropriate content, silica fume may provide an increase in the mechanical strength of the material due to its high pozzolanic reactivity. In addition to the chemical contribution, physical changes can also be observed in concretes with silica fume due to an improvement in the particle packing of the paste. This is a result of their small size spherical particles, which fill the voids between the larger cement grains. However, it is necessary to properly establish the cement replacement content by silica fume, because at high amounts, which exceed the volume of voids between the cement particles, silica fume can promote the loosening of these particles. Thus, instead of filling the voids and increasing the packing density, the addition of silica fume will increase the volume of voids, decreasing the solid concentration. Consequently, this will impair the properties of the concrete. The objective of this paper is to use a particle packing analytical model, the CPM (Compressible Packing Model), to verify the maximum packing density of cement and silica fume, which could be associated with the silica fume optimum content in pastes. The ideal content of silica fume in pastes, mortars and concretes is usually experimentally determined. However, a theoretical study to contrast experimental data may help understanding the behaviour of silica fume in mixes. Theoretical results show maximum amounts of silica fume in the order of 18 to 20% of the cement weight, which is high considering recommendations on literature of 15%. Nevertheless, the packing model does not consider the effect of silica fume high specific surface on the agglomeration of particles or water demand. Hence, the packing density predicted by this model cannot be used as the single parameter in determining the optimum amount of silica fume in pastes.

Several cases of alkali-silica reaction involving granitic aggregates have been diagnosed in damaged concrete structures in Portugal. Nonetheless, this kind of rock is usually regarded as slow/late reactive or even non-reactive to alkalis. Granitic rocks are widely exploited in Northern and Central Portugal, representing almost half of the produced aggregates in this country. Project IMPROVE rose from the need to accurately diagnose the potential reactivity of granites to alkalis. The study involved about forty granites collected from different regions in Portugal, from which the results of eight samples are being presented in this paper. The tests carried out include the petrographic analyses of the aggregates and mortar and concrete expansion tests. It was concluded that the content of microcrystalline quartz correlates better with the results of AAR-4.1 than with the other expansion tests.

The expansion of urban areas under constant changes in the hydrological cycle directly affects the drainage of rainwater. The problems of urban drainage become major engineering problems to be solved in order to avoid negative consequences for local populations. Another urban problem is the excessive production of construction and demolition waste (CDW), in which , even with a increasingly policy of waste management , have been an end up being thrown in inappropriate disposal sites. Alternatively aiming to a minimization of the problems presented, we propose the study of permeable concrete using recycled concrete aggregate. In this study, there were evaluated the performance of concrete by means of permeability, consistency, strength, and interface conditions of the materials . Satisfactory relationships of resistance/permeability of concrete with recycled aggregate in relation to the concrete with natural aggregates was obtained, showing their best potential.

The ongoing process of industrialization of construction sites encourages the use of new building systems that conflict with traditional techniques associated with the risks of incompatibilities and continuance of control fixed ideas with a significant variability. A practical example is the cement mortar for plastering, commonly used as a corrective factor for facade flatness failures caused by the inaccuracy of the plumb line, rudimentary method used in geometric control of concrete structures and facade of mapping during the execution of the work, favoring the accumulation of errors that reflect the mortar thickness, increasing consumption, losses and defects. Alternatively for improvement, this study analyzed through a case study, the innovative application of 3D laser scanning technology consolidated on the facade of a building to map the surface flatness of the façade and, in an unprecedented manner, to quantify the volume of mortar. The results showed the feasibility of the technique as a solution to accurately identify the critical areas of the facade on the peripheral concrete structure and masonry and calculate, based on the volumes, the financial impact associated with mortar overthicknesses in critical areas compared with the reductions thickness after treatment of these areas.

The use of carbon fiber reinforced polymer (CFRP) has been widely used for the reinforcement of concrete structures due to its practicality and versatility in application, low weight, high tensile strength and corrosion resistance. Some construction companies use CFRP in flexural strengthening of reinforced concrete beams, but without anchor systems. Therefore, the aim of this study is analyze, through an experimental program, the structural behavior of reinforced concrete beams flexural strengthened by CFRP without anchor fibers, varying steel reinforcement and the amount of carbon fibers reinforcement layers. Thus, two groups of reinforced concrete beams were produced with the same geometric feature but with different steel reinforcement. Each group had five beams: one that is not reinforced with CFRP (reference) and other reinforced with two, three, four and five layers of carbon fibers. Beams were designed using a computational routine developed in MAPLE software and subsequently tested in 4-point points flexural test up to collapse. Experimental tests have confirmed the effectiveness of the reinforcement, ratifying that beams collapse at higher loads and lower deformation as the amount of fibers in the reinforcing layers increased. However, the increase in the number of layers did not provide a significant increase in the performance of strengthened beams, indicating that it was not possible to take full advantage of strengthening applied due to the occurrence of premature failure mode in the strengthened beams for pullout of the cover that could have been avoided through the use of a suitable anchoring system for CFRP.

ABSTRACT This work deals with numerical modeling of the mechanical behavior of steel-fiber-reinforced concrete beams using a constitutive model based on damage mechanics. Initially, the formulation of the damage model is presented. The concrete is assumed to be an initial elastic isotropic medium presenting anisotropy, permanent strains, and bimodularity induced by damage evolution. In order to take into account the contribution of the steel fiber to the mechanical behavior of the media, a homogenization procedure is employed. Finally, numerical analyses of steel-fiber-reinforced concrete beams submitted to bending loading are performed in order to show the good performance of the model and its potential.

ABSTRACT In this moment in which civil engineering is undergoing a phase where structural projects have been developed with structural systems composed of different and complex elements, some methods and criteria are used for the purpose of evaluating important aspects with regard to global and local stability. Among them, it is necessary to mention the parameters of instability a and ?z. In this sense, this work has the objective to present the basic concepts of the instability parameters a and ?z in accordance with what is clearly defined in the Brazilian standard ABNT NBR 6118; to present the results of simulations of models in the Brazilian structural software TQS varying the stress of compression in the columns in order to relate these values with the stability parameters.

ABSTRACT The number of buildings higher than 30 floors has shown remarkable growth; many of them are supported on foundations of hollow circular piles. This increasing of height of constructions causes an increment of the shear stresses that are transmitted to their foundations, however these elements are more shear critical due to the hollow core. Most of the existing codes are based on shear models for rectangular sections, and guidelines for assessment of shear strength of members with hollow circular cross sections are practically non-existent. This study evaluates, on a comparative basis, the shear strength of elements with hollow circular cross sections, obtained from experimental tests, with values computed using the Canadian Code (CSA A23.3) and using a proposed simple procedure based on the Brazilian standard (NBR 6118).

ABSTRACT The mixing process of fiber-containing cementitious suspensions is a crucial factor to obtaining a good dispersion of fibers and guarantee adequate mechanical performance of the hardened products. The addition of fibers into the suspension causes reduction of the fluidity of the system due to factors inherent to the fibers, the matrix and their interaction. During mixing, these interactions make dispersion and homogenization processes more difficult due to the formation of fibers - particles agglomerates. Conventional techniques to assess workability of mortars are inadequate to evaluate the rheological behavior of fiber-reinforced systems, in which parameters like viscosity and yield stress are not completely taken into account. Therefore, this work employs rotational rheometry to evaluate the influence of fiber and water addition sequences on mixing and rheological behavior of mortars containing Polyvinyl Alcohol (PVA) fibers. Constant test parameters were: mixing time of 317s; impeller velocity 126.5 rpm; water flow 128g/s. A constant mix design was used with a water content of 16%wt, and a 0.2%vol of fibers were added to the reference composition. Four mixing sequences were studied: S1 and S2 are based on the addition of fibers at different stages of the mixing process; while in S3 and S4 not only the fibers are added at different stages, but also the water addition is performed in two steps (25% first and 75% latter).Results showed that it is possible to optimize the mixing step of fiber-containing systems by changing the moment of fiber addition into the mixture. The introduction of fibers after mixing the dry mortar with water, when it already had achieved its fluidity point, demanded a lower mixing effort and produced a more flowable material.

ABSTRACT The construction system of prestressed flat slabs has been gaining market in Brazil, since it eliminates the use of beams, allows you to perform structures under coluns by area and reduces the cycle of concrete slabs. Thus the analysis of global stability of buildings, takes into account the effects of 2nd order, and these additional effects to the structure obtained from the deformation thereof, calculated by the iterative method P-Delta. The Brazilian ABNT NBR 6118: 2014 [2] assesses the overall stability of reinforced concrete structures through practical parameters, which are the parameter a (Alpha) and gz (Gamma z) coefficient. In this research we seek to study the global stability of slender buildings consist of flat slabs, with slenderness (ratio of the smaller width with the height of the building) approximately one to six, from the modeling of a building with prestressed slabs nonadherent and waffle slabs. To model will use the commercial software CAD / TQS.

ABSTRACT Four continuously reinforced concrete pavement (CRCP) sections were built at the University of São Paulo campus in order to analyze the pavement performance in a tropical environment. The sections short length coupled with particular project aspects made the experimental CRCP cracking be different from the traditional CRCP one. After three years of construction, a series of nondestructive testing were performed - Falling Weight Deflectometer (FWD) loadings - to verify and to parameterize the pavement structural condition based on two main properties: the elasticity modulus of concrete (E) and the modulus of subgrade reaction (k). These properties estimation was obtained through the matching process between real and EverFE simulated basins with the load at the slab center, between two consecutive cracks. The backcalculation results show that the lack of anchorage at the sections end decreases the E and k values and that the longitudinal reinforcement percentage provides additional stiffness to the pavement. Additionally, FWD loadings tangential to the cracks allowed the load transfer efficiency (LTE) estimation determination across cracks. The LTE resulted in values above 90 % for all cracks.