Fiber-reinforced polymer (FRP) is a common term used by the civil engineering community for high-strength composites. Composites have been used by the space and aerospace communities for over six decades and the use of composites by the civil engineering community spans about three decades.
In the composite system, the strength and the stiffness are primarily derived from fibers, and the matrix binds the fibers together to form structural and nonstructural components. Composites are known for their high specific strength, high stiffness, and corrosion resistance.
Repair and retrofit are still the predominant areas where FRPs are used in the civil engineering community. The field is relatively young and, therefore, there is considerable ongoing research in this area. American Concrete Institute Technical Committee 440 documents are excellent sources for the latest information.
The primary purpose of this book is to introduce the reader to the basic concepts of repairing and retrofitting reinforced and prestressed concrete structural elements using FRP. Basic material properties, fabrication techniques, design concepts for strengthening in bending, shear, and confinement, and field evaluation techniques are presented.
The book is geared toward advanced undergraduate and graduate students, professional engineers, field engineers, and user agencies such as various departments of transportation. A number of flowcharts and design examples are provided to facilitate easy and thorough understanding. Since this is a very active research field, some of the latest techniques such as near-surface mounting (NSM) techniques are not covered in this book.
Rather, the aim is to provide the fundamentals and basic information. The chapters in the book are arranged using the sequences followed in textbooks on reinforced concrete. Chapter 1 provides the introduction, brief state of history, typical field applications, and references to obtain the latest information.
In Chapter 2, the properties of common types and forms of fiber reinforcement materials and resins are presented. Brief descriptions of the four basic types of hybrids are also discussed.
Chapter 3 deals with the methods to prepare laminate samples, including resin mixing, hand lay-up technique, vacuum bagging, curing methods, density determination, and laminate cutting.
Chapter 4 provides the basic information on the properties of fibers and matrices used for the composite, behavior of beams and columns strengthened with the composites, design philosophies, and recent advances.
The most popular uses are for (i) strengthening of reinforced and prestressed concrete beams for flexure, (ii) shear strengthening of reinforced and prestressed concrete beams, (iii) column wrapping to improve the ductility for earthquake-type loading, (iv) strengthening of unreinforced masonry walls for inplane and out-of-plane loading, (v) strengthening for improved blast resistance, and (vi) repair of chimney or similar one-of-a-kind structures.
Chapter 5 deals with the procedures to analyze the reinforced concrete and strengthened beams and to estimate the required extra reinforcement. Even though excellent books are available for reinforced concrete design, the flexural behavior of beams is explained briefly to provide continuity in the thought process, especially in the area of tensile force-transfer from extra reinforcement to the beam.
Chapter 6 deals with the procedures to analyze prestressed concrete and strengthened beams and to estimate the required extra reinforcement. Beams with both bonded and unbonded tendons are covered. Here again, the flexural behavior of beams is explained briefly to provide continuity in the thought process, especially in the area of tensile forcetransfer from extra reinforcement to the beam.
Chapter 7 presents the design procedures for shear strengthening of beams. It also presents a summary of the provisions used for reinforced and prestressed concrete, the schemes used for composite general guidelines, stress and strain limits, design procedures, and examples.
As in the case of other chapters, the reader is referred to texts on reinforced concrete for detailed discussions on mechanisms and provisions. Chapter 8 encompasses repair and retrofitting of columns. Here, the primary contribution of FRP is for confinement of concrete and the resulting improved ductility of columns.
The most common retrofits are aimed at improving the earthquake resistance of columns. Chapter 9 provides a method for efficiently and accurately assessing, in situ, the structural adequacy of reinforced and prestressed concrete building components.
The guidelines allow the engineer to determine whether a specific portion of a structure has the necessary capacity to adequately resist a given loading condition. These guidelines establish a protocol for full-scale, in situ load testing including planning, executing, and evaluating a testing program, which will assist the engineer in implementing an efficient load test.
We would like to inform the readers that the tables and figures may not be exactly the same as those presented in the sources cited; modifications were made to improve clarity. Some of the illustrations have been taken from original reports, but the references cited were typically published papers.
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