Precast Concrete

Mounir Khalil El Debs

After 17 years the work receives a reinvigorated and expanded edition. It brings the last update of the main Brazilian standard on the subject, the NBR-9062 – Design and execution of precast concrete structures. In addition to the technical update, new issues, such as those related to sustainability, have gained importance during the period.

 

If industrialization of construction and rationalization of the execution of concrete structures had great momentum in the 60s and 70s, they also led, on the other hand, to a criticized architectural sameness. As a result, a “new precast concrete” emerges, allowing greater flexibility and architectural renovation.

 

The potential of precast concrete is little explored in Brazil, despite the intensive process of urbanization of the population and densification of cities. This work seeks to motivate readers to its application, breaking a vicious circle: one does not build because does not have technological input (knowledge, experience, equipment and auxiliary devices) and one does not have technological input because one does not build.

 

With more than 400 pages, the book is divided into 4 parts and 13 chapters, ranging from the basics of precast concrete and applications in buildings, bridges and other civil constructions to the elements of specialized production. In the last part, annexes are presented, which, among other subjects, include numerical examples.

 

This book is intended for students and professionals in civil engineering and architecture, with an emphasis on the design of structures formed by precast elements.

Original title
Concreto pré-moldado
ISBN
978-85-7975-279-7
eISBN
978-85-7975-280-3
Pages
456
Year of publication
2017
Edition
2nd

About the authors

Mounir Khalil El Debs

Mounir Khalil El Debs is a civil engineer graduated from the University of São Paulo at São Carlos School of Engineering (1972). He holds a Master’s degree in Structural Engineering (1976) and a PhD in Engineering – Structures Area (1984) from the same university. He is a “livre-docente” professor (1991) and a full professor (2006 to 2014) at the Department of Structural Engineering of the São Carlos School of Engineering – EESC/USP. He is currently a senior lecturer at the Department of Structural Engineering at EESC/USP.

Preface

This is the second, revised and expanded edition of this book, whose first edition was published by the São Carlos School of Engineering at University of São Paulo, through the so-called Reenge Project, in 2000.
It was intended to publish a new edition after ten years of its launch, reviewing issues that were out of date due to the research developed, such as calculating the socket base connections, and incorporating or reinforcing aspects that were gaining importance, such as issues related to sustainability. However, due to several factors, professional and personal, only now, after 17 years, this new edition is being finalized. On the other hand, the timing is convenient, since it is possible to take into account the last update of the main Brazilian rule on the subject, NBR 9062 – Design and execution of precast concrete structures, of the Brazilian Association of Technical Standards.
The term “precast concrete” refers to the use of precast concrete elements, in other words, concrete elements molded out of their final position of use, in construction.
The use of precast concrete has two guidelines. One points to the industrialization of construction, the other to the rationalization of the execution of concrete structures. In this book, precast concrete was treated in the context of these two guidelines.
Although precast concrete followed the evolution of concrete technology from the late 19th century to the beginning of World War II, its development is generally related to the great impetus in the quarter-century after World War II.
Nowadays there is no longer the euphoria of that period, but the precast concrete has still advanced, with what may be called a new precast concrete. With this new philosophy, customized solutions are sought in order to escape the criticized architectural designs of precast concrete constructions in the past decades, and greater design and production flexibility.
Despite advances since the first edition of the book, precast concrete could be more explored in Brazil. The main reasons that have been attributed to it being underutilized are: the tax system, which penalizes the use of precast elements from factories; economic instability, which makes planning and investment difficult in the long term; the conservatism of agents and procedures involved in construction; the little knowledge of alternatives in concrete precast; limited supply of equipment; and the low commercial availability of auxiliary devices to make connections and handle elements. The first two reasons are macroeconomic ones. The rest of them are cultural or consequence of the former ones.
This conjunction of factors fuels a vicious circle, largely responsible for the non-exploitation of the potentiality of precast concrete, which is that one does not built because there are no technological inputs (knowledge, experience, equipment and auxiliary devices) and one does not have technological inputs because it is not built. With this book, the intention is to contribute to minimize the effects of this circle, by providing structured technical knowledge to professionals in the field of construction.
In this work, the aim is to motivate readers to apply the precast concrete, while also alerting to the inherent difficulties of the process. In fact, these difficulties cause the precast concrete to be faced with the “feet on the ground”. But, on the other hand, one must have the “eye on the future” because, although there may be unfavorable conditions, one cannot fail to keep in mind that, as the country’s technological and social development increases, the chances of using precast concrete increase.
This book is aimed at students and professionals of Civil Engineering, with emphasis on the design of structures formed by precast elements. Also Architecture students and architects can make use of the majority of the material presented.
The book was born from class notes of a precast concrete discipline of the Department of Structural Engineering of São Carlos School of Engineering at University of São Paulo. It was tried to approach most of the subjects related to the precast concrete, but, due to this origin, there were intensification only in subjects related to the structural project.
One of the goals of this book is to motivate readers to study precast concrete. Due to this objective, bibliographical references are provided, in quantity and quality, to facilitate the work of readers interested in deepening knowledge on topics of interest. It was also tried to present, besides the usual constructive alternatives, other little used, in order to sweep the existing possibilities, since it is believed that the knowledge of the various alternatives and their characteristics is important for the choice of more appropriate solutions depending on the circumstances of each work, as well as for the design of innovative alternatives.
Another objective of this edition is to incorporate the research developed with the postgraduate program, under the guidance of the author, in order to provide the main results for the professionals involved. This is done throughout the main text and concentrated in Annexes D and F.
In addition, this edition of the book also presents results from the three editions of the National Meeting of Research-Project-Production in Precast Concrete, held in 2005, 2009 and 2013 at São Carlos School of Engineering at University of São Paulo, under the coordination of the author. These meetings aimed to promote integration between the academic sector and the productive sector, which is very important for both sectors. On the one hand, the productive sector is aware of research in the academic sector. On the other hand, the academic sector is aware of the needs of the productive sector. As a result, the research generated by the academic sector would be in better conditions to be transferred to the productive sector, with a great benefit for the national or regional industry, according to each case.
In this book, it is considered that the reader has basic knowledge of reinforced and prestressed concrete and structural analysis, which are treated in Civil Engineering courses. As this knowledge is much less common in the prestressed concrete than in the reinforced concrete, an annex with an introduction to the subject was included in this edition (Annex F).
Most of the precast concrete applications presented in this book were made in the United States and Europe, which remained in the first edition. In this second edition were included several examples of applications in Brazil, the result of the aforementioned meetings and the fact that was more publicity after the first edition. In this sense, it is worth mentioning the publications of the Brazilian Association of Industrialized Concrete Construction, in particular the magazine Industrialize in concrete.
It should be noted that the information on the products presented here serve as a reference, since the values change according to the market, and in addition, a part of the information comes from foreign references. Therefore, it is recommended to consult the manufacturers for updated information of the products available in the national or international market, if it is the case.
The author also wishes to clarify and justify the following aspects: a) in the symbols used, it was sought to follow NBR 6118 – Concrete Structures Project: procedure, which made it necessary to make adjustments in relation to the symbols used in NBR 9062 – Project and execution of precast concrete structures; b) in the location of bibliographical references, at the end of the book, it may be necessary, in the case of publication by entity, to first consult the acronym in the list of symbols and acronyms; c) although it was tried to use the most recent versions of the norms and codes, in some cases it was not possible to use the last version, so, in certain situations, in the bibliographical references, a notice of the existence of a more recent version has been placed, but of course, due to the dynamics of the updates, it is recommended to the reader to verify the possible existence of more recent versions; and d) the term deformation is used in this book both to designate the change of the geometric configuration of a structure or structural element, according to the etymological meaning of the word, and to designate the relation between tension and modulus of elasticity, which has been commonly used in the large most of the publications, and for the latter, if necessary, the specific complement.
The book is divided into three parts. In the first part, comprising the introduction and the first five chapters, the fundamentals of precast concrete are presented, in which general and specific indications for the design are given, especially in relation to the connections between the elements. In the second part, Chapters 6 to 12, applications in buildings, bridges and other civil constructions are included. In the third part, with four chapters, the elements of specialized production are addressed. What is being referred to here as specialized production elements are precast elements that are often used in civil construction, easily available on the market, in some cases even found for prompt delivery. The types of said elements are: precast beams for slabs, alveolar panels for slabs and walls, concrete circular tubes, staves (rectangular section galleries), stakes, posts, crossties and barriers. At the end of the book, the annexes are presented, which, among other subjects, include numerical examples.

São Carlos, February 2017
Mounir Khalil El Debs