One of the major causes of structural repairs worldwide is the corrosion of reinforced concrete structures, such as residential buildings and piers, which are exposed to harsh marine environments. This investigation aims to provide experimental evidence of the fire resistance of corroded high strength reinforced concrete. For this, 14 reinforced concrete beams of three different concrete mix designs (different strengths) were prepared along with concrete cylinders for compression strength testing (ASTM C39). After proper moist curing, all beams were corroded, in two phases, with impressed current, then “crack scored ”for corrosion evaluation, after which half were exposed to fire, also in two phases, following the ASTM E-119-12 time-temperature curve, using a gas kiln. The fire damage was evaluated and compared between phases by using Ultrasonic Pulse Velocity technology. Finally, all specimens were tested for flexural strength by using the third-point loading method (ASTM C78) and the effects of fire on the corroded beams were analyzed according to the level of corrosion. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

Reinforced concrete moment-resisting frames are structural systems that work to resist earthquake ground motions through ductile behavior. Their performance is essential to prevent building collapse and loss of life during a seismic event. Seismic building code provisions outline requirements for three categories of reinforced concrete moment-resisting frames: ordinary moment frames, intermediate moment frames, and special moment frames. Extensive research has been conducted on the performance of special moment-resisting frames for areas of high seismic activity such as California. More research is needed on the performance of intermediate moment frames for areas of moderate seismicity because the current code provisions are based on past observation and experience. Adapting dynamic analysis software and applications developed by the Pacific Earthquake Engineering Research (PEER) Group, a representative concrete intermediate moment frame was designed per code provisions and analyzed for specified ground motions in order to calculate the probability of collapse. A parametric study is used to explore the impact of changes in design characteristics and building code requirements on the seismic response and probability of collapse, namely the effect of additional height and the addition of a strong column-weak beam ratio requirement. The results show that the IMF seismic design provisions in ACI 318-08 provide acceptable seismic performance based on current assessment methodology as gravity design appeared to govern the system. Additional height did not negatively impact seismic performance, while the addition of a strong-column weak-beam ratio did not significantly improve results. It is the goal of this project to add insight into the design provisions for intermediate moment frames and to contribute to the technical base for future criteria.

Digitized by Kansas Correctional Industries

A multiscale approach, coined as the High Order Computational Continua (HC2), has been developed for efficient and accurate analysis and design of reinforced concrete structures. Unlike existing homogenization-like methods, the proposed multiscale approach is capable of handling large representative volume elements (RVE), i.e., the classical assumption of infinitesimally is no longer required, while possessing accuracy of direct numerical simulation (DNS) and the computational efficiency of classical homogenization methods. The multiscale beam and plate elements formulated using the proposed HC2 methodology can be easily incorporated into the existing reinforced concrete design practices. The salient features of the proposed formulation are: (i) the ability to consider large representative volume elements (RVE) characteristic to nonsolid beams,waffle and hollowcore slabs, (ii) versatility stemming from the ease of handling damage, prestressing, creep and shrinkage, and (iii) computational efficiency resulting from model reduction, combined with the damage law rescaling methods that yield simulation results nearly mesh-size independent. The multiscale formulation has been validated against experimental data for rectangular beams, I beams, pretensioned beams, continuous posttension beams, solid slabs, prestressed hollowcore slabs and waffle slabs.

A possibilidade de redução ou até mesmo da eliminação do uso de formas e escoramento, diminuição do tempo e melhoria da qualidade da obra, são alguns aspectos que têm levado à adoção da pré-moldagem em superestruturas de pontes. Recentes estudos relatam que as chamadas pontes integrais - pontes sem juntas - estão tornando-se cada vez mais utilizadas nos Estados Unidos e Canadá, pois minimizam os custos com manutenção e prolongam a vida útil da obra. Procurando associar os benefícios conseguidos com a utilização dos elementos pré-moldados aos da ausência de juntas, apresenta-se neste trabalho um tipo construtivo para pontes de pequenos vãos em pórtico, com utilização de elementos pré-moldados na superestrutura ligados rigidamente à infraestrutura. Um processo aproximado de cálculo é apresentado e, a partir de um exemplo desenvolvido, compara-se esta alternativa com uma construção similar em viga, verificando-se que os custos diretos são basicamente iguais. Através da avaliação dos esforços provenientes do carregamento móvel com a técnica dos elementos finitos, chega-se a momentos fletores até 50% menores que os obtidos pelo método aproximado, resultando assim numa considerável redução dos custos diretos quando se utiliza o sistema estrutural em pórtico. / The possibility of reduction or even the elimination of the use of forms and bearings, reducing the time and improving the qualitity of the work, are some aspects which have led to the use of precasting in bridges superstructure. Recent studies report that the so-called integral bridges, jointless bridges, are becoming more used in the United States of America and in Canada because they reduce the costs of maintenance and prolonge the useful life of the constructions. Trying to associate the benefits which have resulted from the utilization of precast elements to the ones from the absence of joints, it is present in this work a constructive proposal to small span frame bridges using the precast elements in the superstructure strictly connected to the infrastructure. A design process for bending moments is presented. The comparation between the construtive proposal and similar with joint between the superestructure and infrastructure, by using this design process, shows that the direct cost is basically the same. Through the evaluation of the efforts that come from the mobile carrying with the technique of finite elements, it can reach bending moments that are even 50% lower than those gotten from the presented method. In this case, a significative direct cost reduction can gotten with frame structure system.

Desde o seu surgimento, na França, o concreto armado vem evoluindo, com alterações nos materiais constituintes, nas dosagens e nos processos construtivos. Esta evolução tem como consequência uma variação no seu comportamento. Portanto, torna-se necessária a atualização das normas, que são as responsáveis por suas especificações. Com base na evolução do concreto, as normas, como o EC-2/89, CEB/90 e a NB-1, vem sendo substancialmente atualizadas, baseando-se em novos ensaios. Este trabalho aborda alguns aspectos que estão sendo alterados no estudo das deformações que ocorrem no concreto e no aço. Com base na análise de resultados, são feitas algumas considerações que podem contribuir para as modificações da NB-1, ora em desenvolvimento, e para futuros trabalhos sobre os temas abordados. / Since it appears, in France, the reinforced concrete has been developing, with changes in its component materials, in its doses and in its constructive process. This evolution has as result a change of its behavior. So, it makes necessary to bring the standards that are responsible for its specifications up to date. Based on the concrete evolution, the standards, as the EC-2/89, CEB/90 and the NB-1, have been essentially brought up to date based on new tests. This essay broaches some points of view that are being changed in the steel. Based on the result analysis, I do some considerations that can contribute for the modernization of the NB-1, for the time in development, and for future essays about the topics broached.

Thesis. 1978. M.Arch.A.S.--Massachusetts Institute of Technology. Dept. of Architecture. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / by George Szepesi. / M.Arch.A.S.

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / The reinforced concrete structures, when properly designed and performed, have prolonged its life. However, the lack of proper maintenance, acting loads greater than the design ones, pathological manifestations due to aggressive environment and accidents can impair the performance of the structure requiring the need for repair or structural strengthening. The technique of structural strengthening with application of carbon fiber reinforced polymer (CFRP), bonded externally to the reinforced concrete has advantages such as fast execution, which added to the characteristics of the composite as a high modulus of elasticity make wide its use. The aim of this study is to analyze through an experimental program the structural behavior of reinforced concrete beams strengthened in bending with CFRP. The methodology used was the production of three groups of five RC beams each one, with the same dimension of rectangular cross section, for bending test. The first group of beams was called VA. The second and third groups, called VB and VC and had different ratio of reinforcement. In each group of five beams, one beam was not strengthened (reference beam) and the remaining beams were strengthened with two, three, four and five layers of carbon fiber. The experimental results indicate the efficiency of strengthening, noting an increase in stiffness in all strengthened beams. The increase of load capacity was also observed in all groups of beams varying between 9,11% and 16,69%, 55,14% and 86,83%, 89,46% and 126,18%, of the beams of group VA, VB and VC, respectively in relation to the reference beam of each group. Of the carried through study was observed the excellent performance of strengthening in bending with carbon fiber especially in beams with the lowest ratios of reinforcement (group C), besides gathering a lot of information that can be useful for design criteria of the recovered and strengthened structures. / As estruturas de concreto armado, quando convenientemente projetadas e executadas tÃm sua vida Ãtil prolongada, porÃm, a falta de manutenÃÃo adequada, as solicitaÃÃes de cargas superiores Ãs de projeto, as manifestaÃÃes patolÃgicas devido ao meio ambiente agressivo e a ocorrÃncia de acidentes podem comprometer o desempenho da estrutura exigindo a necessidade de uma recuperaÃÃo ou reforÃo estrutural. A tÃcnica de reforÃo estrutural com a aplicaÃÃo de polÃmeros reforÃados com fibra de carbono (PRFC) colados externamente a peÃas de concreto armado apresenta vantagens como a rÃpida execuÃÃo que, somada a caracterÃsticas do compÃsito como alto mÃdulo de elasticidade fazem largo o seu uso. O objetivo desse trabalho à analisar atravÃs de um programa experimental o comportamento estrutural de vigas de concreto armado reforÃadas à flexÃo com PRFC. A metodologia utilizada foi a produÃÃo de trÃs grupos de vigas de concreto armado, com a mesma dimensÃo de seÃÃo transversal retangular para ensaio à flexÃo. O primeiro grupo, denominado grupo VA, foi dimensionado com seÃÃo normalmente armada. O segundo e terceiro grupo de vigas, aqui denominados grupo VB e grupo VC, respectivamente, foram dimensionados com seÃÃo subarmada, com taxas de armaduras distintas. Cada grupo possuÃa cinco vigas, sendo que, uma viga nÃo foi reforÃada (de referÃncia) e as demais vigas foram reforÃadas com duas, trÃs, quatro e cinco camadas de fibra de carbono. Os ensaios experimentais comprovaram a eficiÃncia do reforÃo, constatando-se um aumento de rigidez de todas as vigas reforÃadas. Observou-se tambÃm o aumento da capacidade resistente em todos os grupos de vigas, variando entre 9,11% e 16,69%, 55,14% e 86,83%, 89,46% e 126,18%, das vigas dos grupos VA, VB e VC, respectivamente, em relaÃÃo à viga de referÃncia de cada grupo. O estudo demonstrou o excelente desempenho do reforÃo à flexÃo com fibra de carbono, especialmente nas vigas com menores taxas de armadura (grupo VC), alÃm de reunir uma sÃrie de informaÃÃes que podem ser Ãteis para critÃrios de projeto de estruturas recuperadas e reforÃadas.

Tese de Mestrado Integrado. Mestrado em Engenharia Civil (Construções). Faculdade de Engenharia. Universidade do Porto. 2013

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