Este trabalho tem por objetivo a proposição de um conjunto de medidas visando trazer um incremento na produtividade do serviço de concretagem em Estruturas Reticuladas de Concreto Armado (ERCA). Inicialmente o trabalho baseou-se em um amplo levantamento sobre o tema produtividade da mão-de-obra no serviço de concretagem e sobre métodos de obtenção e avaliação de opiniões de pessoas. Procedeu-se, através da realização de entrevistas e por meio de estudo de campo ao levantamento de fatores intervenientes na produtividade do serviço concretagem. A análise dos fatores apontados nas duas abordagens subsidiou a elaboração de uma proposição de ações que potencialmente levariam a melhorias nos indicadores de produtividade da concretagem; um questionário Delphi serve ao propósito de escolher, dentro do conjunto de propostas, aquelas com maior expectativa quanto à relação custo-benefício com priorização de ações mais viáveis de serem implementadas. / This research had as an objective the proposition of a group of measures that can be used to improve labor productivity in buildings structures concrete placement. At first this work raised data on the subject of labor productivity in concrete placement and on the method of obtaining and evaluating persons\' opinions. By means of interview and field camp study, information could be raised about factors involved in concrete placement. Those factors\' analysis provided the elaboration of a proposition of actions that would help on the improvement of the labor productivity indexes in concrete placement; with the Delphi questionnaire the best propositions amongst all could be chosen in the aspect of cost-benefit and viability.

Para melhor aproveitamento da resistência do concreto, utiliza-se concreto de maior resistência à compressão em pilares e concreto de resistência inferior em vigas e lajes. Considerando o método construtivo adotado tradicionalmente no Brasil, a região do pilar que cruza o nível do pavimento é moldada com a utilização do mesmo material que é lançado no pavimento. Essa mistura de materiais no mesmo pilar gera dúvida em relação ao seu dimensionamento. Dado que essa região está confinada pelo pavimento pode-se considerar, no caso em que uma laje lisa circunda o pilar, dentro de determinados limites, que esse pilar se comportará como tendo resistência uniforme. Este trabalho levantou pesquisas anteriores e normas vigentes com o objetivo de saber o que já foi estudado e quais são as recomendações atuais para a situação em que se tem laje apoiada sobre vigas e não uma laje lisa, isto é, uma situação menos confinada. Com base nessa pesquisa, formularam-se modelos a serem ensaiados em escala reduzida no laboratório e modelos de elementos finitos com a finalidade de aprofundar o estudo dessa situação. / Aiming the better use of the concrete strength a high-performance concrete is use in columns and a less resistant concrete in slabs and beams. Considering the constructive method adopted in Brazil, the region of the column that crosses the floor is executed using the same material that is used at the pavement. When used in columns, it is blended with a less resistant concrete in the floors, which is not considered during the column design. Is it possible that this less resistant concrete can confine the column to the point that its strength turns out to be the same of the rest of the members? This paper has studied earlier researches and up-to-date standards with the goal of know what have been studied and the actual recommendations for situations that the floor has beams and slabs instead of only slabs, in other words, a less confined region. Based in this research was formulated models to be tested in the laboratory and models in Finite Element Models to studie further the stresses.

An experiment was conducted to evaluate the durability, toughness, and strength of Synthetic Fiber Reinforced Concrete after being immersed in five separate environments for one year at FAU SeaTech. The specimens were molded and reinforced with two-inch Polypropylene/Polyethylene Fibers in a concrete aggregate matrix and were cut into identical sizes. Some of these environments had accelerated parameters meant to increase degradation to simulate longevity and imitate harsh environments or seawater conditions. The environments consisted of: a high humidity locker (ideal conditions), submerged in the Intracoastal Waterway (FAU barge), seawater immersion, a wet and dry seawater immersion simulating a splash/tidal zone, and another in low pH seawater. The latter three were in an elevated temperature room (87-95°F) which produced more degradative properties. The specimens were monitored and the environments were controlled. The specimens were then evaluated using the IDT test method using force to initiate first-cracking and post-cracking behaviors. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

An experimental study was conducted on the strength and toughness characteristics of concrete made from recycled aggregate, cement and fly ash reinforced with reclaimed high density polyethylene plastic (HDPE) fibers. The objectives of the investigation were: (1) to evaluate the performance of a sustainable concrete containing up to 90% recycled materials; (2) to determine the variation of strength and toughness with a Fiber Factor incorporating length, width and amount of HDPE fibers; (3) to identify the best performing mix design based on tensile strength and toughness and (4) to provide some guidelines for the use of this sustainable composite in Civil Engineering construction. The results showed that the HDPE fiber reinforcements did not improve the compressive strength of the mixture. However, HDPE fibers improved the ductility and toughness which may be beneficial for structural and pavement applications. / by Roody Numa. / Thesis (M.S.C.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

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

In the United States design for fire safety follows a prescriptive code-based approach. Building codes detail the types of construction materials, assemblies, and fire suppression systems that are required for various building types. This prescriptive method has prevented structural engineers from exposure to performance-based design approaches for fire safety. The motivation for this thesis was to increase the awareness of the structural engineering field to the concepts behind structural design for fire safety. Extensive research has been published on the performance of structural steel in fire conditions, and simplified design tools already exist to describe its behavior. Such tools do not exist for reinforced concrete structures. Research on concrete has been more focused on material properties rather than structural performance. This thesis presents a simplified design tool which assesses the fire performance of reinforced concrete. An Excel-based spreadsheet application was developed for thermal analysis of concrete slabs. It accounts for different aggregate types, slab thicknesses, and fire exposures. Several analyses were performed with the spreadsheet application to examine the affect slab thickness and aggregate types have on the fire performance of concrete slabs in standard and natural fires. The results were compared with published test data and finite element software simulations to benchmark the accuracy of the proposed tool. Furthermore, methods for the design of reinforced concrete slabs in fire conditions are presented.

Digitized by Kansas Correctional Industries / Department: Civil Engineering.

Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1963. / MIT Institute Arcives copy has the appropriate accompanying leaves of plates after each title; MIT Rotch Library copy has them all lumped-together at the end. / Three individual titles bound together with a collective title and an introduction. Compiled, with an introduction, by Prof. Eduardo F. Catalano. / Preface: By presenting the three individual theses with a common analysis of material pertinent to the design of each thesis it is hoped that a more rich and extensive result has been attained. / Brunken, Alan Wayne. A multistory precast concrete office building (1963) -- Henney, Thomas. A precast concrete high-rise office building (1963) -- Westbury, Rodney Ames. A multi-story precast concrete office building (1963). / M.Arch.

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.

Self-Compacting Concrete (SCC) is a material which under its own self-weight flows to form and fill any shape, attains full compaction, without external energy input, to create a dense homogenous mass (based on Holton, 2003; The Concrete Society and BRE, 2005; Damtoft et al, 2008). It is, in respect to the history of concrete, a relatively new development, with its first UK application occurring in the late 1990s. Since then a significant amount of research has sought to understand its physical and structural properties, but there is a lack of a knowledge base on its practical application and performance in construction projects. Where it does exist, such research lacks robust and transparent data, particularly relating to the claimed attributes of the material (such as better surface finish, faster construction and lower overall costs). Using a combination of qualitative and quantitative research methods, this research investigates the construction practices employed when pouring SCC and presents new data on its practical applications. Interviews with a range of building contractors, ranging from multinationals to small UK businesses (SMEs), show that current perceptions of SCC limit its use to specific applications because practitioners see SCC as just another type of concrete . A critical examination of these attitudes led to the identification of three distinct scenarios for the use of SCC: 1. Reactive selection: in which a particular attribute of SCC provokes its use to solve a particular problem, often as a last minute substitution for conventional concrete the most common scenario. 2. Strategic change: in which the material is chosen on the basis of a balanced assessment of all its benefits and on the understanding that such benefits can only be attained if the contractor appreciates that there may be implications for the construction process a rarely experienced scenario. 3. Specification: in which there is complete acceptance of SCC as a method, not just as a material; a significant amount of early project involvement with knowledge holders, such as contractors and material suppliers, optimises the construction process. A rigorous work measurement study of live construction projects has made it possible to quantify the as-built costs of SCC for selected UK residential slab and multi-storey flat slab applications and compare this with the equivalent conventional concrete slab construction. On-site use of self-compacting concrete vi The results indicate that SCC can reduce construction times of structural topping layers of residential slabs by up to 73%, and has shown that SCC can also match, if not reduce, total as-built concrete placement costs in multi-storey applications. This new data will enable contractors, designers and specifiers to better understand the practical implications of using SCC for on-site applications, thereby leading to more potential instances of its early and planned specification, hence resulting in more of its full benefits being realised.