土木结构用复合材料的耐久性.pdf

Durability of composites for civil structural applications i Related titles Corrosion of reinforcement in concrete Monitoring, prevention and rehabilitation techniques EFC 38 ISBN 978-1-84569-210-0 Corrosion of metal within reinforced concrete is one of the most important problems facing the construction industry. Key research on this topic is summarised in this latest volume of 24 chapters from the prestigious European Federation of Corrosion. The book begins by reviewing findings from various experiments designed to test the corrosion rate of metals induced by a range of factors. Later chapters discuss techniques for monitoring and testing for corrosion. Important s of prevention, including inhibitors and protective coatings are uated. The book concludes with the discussion of electrochemical s for protection and rehabilitation procedures for susceptible structures. Composites ing technologies ISBN 978-1-84569-033-5 When ing composite materials with textiles there is always a degree of error when draping a fabric over the mould and adding the resin. The fabric can de or shift in the mould before the resin is added or whilst it is being poured in. Such problems can cause weaknesses in the composite leading to failure or even rendering the composite useless. In order to counteract this it is necessary to be able to model the draping of different textiles to fully understand the issues that may arise and how to prevent them from occurring in the future. Composites ing technologies brings together the research of leading experts in the area to give a comprehensive understanding of modelling and simulation within composites ing and design. Durability of concrete and cement composites ISBN 978-1-85573-940-6 Concrete and other cement-based composites are by far the most widely used man- made construction materials in the world. However, major problems of infrastructure deterioration have been caused by unanticipated premature degradation of these materials. This book provides an up-to-date review of several of the main s of degradation, examining what is known about their causes and control. Trends in modelling and prediction of service-life are also examined. Details of these and other Woodhead Publishing materials books, as well as materials books from Maney Publishing, can be obtained by ∑visiting ∑contacting Customer Services e-mail saleswoodhead-; fax 44 0 1223 893694; tel. 44 0 1223 891358 ext. 130; address Woodhead Publishing Ltd, Abington Hall, Abington, Cambridge CB21 6AH, England Maney currently publishes 16 peer-reviewed materials science and engineering journals. For further ination visit www.maney.co.uk/journals. ii Durability of composites for civil structural applications Edited by Vistasp M. Karbhari Woodhead Publishing and Maney Publishing on behalf of The Institute of Materials, Minerals and C. SIKORSKY, California Department of Transportation, USA 13.1Introduction284 13.2Defects in composite materials286 13.3Defects occurring during rehabilitation289 13.4Effect of defects299 13.5Use of non-destructive uation/non-destructive testing302 13.6Future trends321 13.7References322 14Structural health monitoring and field uation of composite durability324 A. A. MUFTI, University of Manitoba, Canada; and L. A. Bisby, Queen’s University, Canada Contentsix 14.1Introduction324 14.2The need for structural health monitoring326 14.3Civionics328 14.4Field applications and service-life determination331 14.5Future trends350 14.6Sources of further ination and advice351 14.7References351 Index355 x Contributor contact details * main contact Editor and Chapters 1, 2 and 4 author; Chapters 3 and 13 co-author Professor Vistasp M. Karbhari University of California San Diego Department of Structural Engineering Jacobs School of Engineering University of California, San Diego 9500 Gilman Drive MC 0085 La Jolla CA 92093-0085 USA E-mail vkarbhariucsd.edu Chapter 3 C. Helbling and V. M. Karbhari* University of California San Diego Department of Structural Engineering Jacobs School of Engineering University of California, San Diego 9500 Gilman Drive MC 0085 La Jolla CA 92093-0085 USA E-mail vkarbhariucsd.edu Chapter 5 J. W. Chin National Institute of Standards and Technology NIST Materials and Construction Research Division Polymeric Materials Group 100 Bureau Drive, Stop 8615 Building 226, Room B350 Gaithersburg MD 20899 USA E-mail joannie.chinnist.gov Chapter 6 A. P. Mouritz Sir Lawrence Wackett Centre for Aerospace Design Technology School of Aerospace, Mechanical and Manufacturing Engineering Royal Melbourne Institute of Technology GPO Box 2476V Melbourne Victoria 3001 Australia E-mail adrian.mouritzrmit.edu.au xi Contributor contact detailsxii Chapter 7 A. Zhou* Assistant Professor Department of Engineering Technology William States Lee College of Engineering University of North Carolina at Charlotte 9201 University City Boulevard Charlotte, NC 28223-0001 USA E-mail azhou3uncc.edu N. Post, R. Pingry, J. Cain, J. J. Lesko and S. W. Case 120D Patton Hall, MC-0219 Department of Engineering Science and Mechanics Virginia Polytechnic Institute and State University Blacksburg VA 24061-0219 USA Chapter 8 L. S. Lee Louisiana Tech University College of Engineering and Science Bogard Hall 248 600 West Arizona Ruston LA 71272 USA E-mail lukeleelatech.edu Chapter 9 A. P. Mouritz Sir Lawrence Wackett Centre for Aerospace Design Technology School of Aerospace, Mechanical and Manufacturing Engineering Royal Melbourne Institute of Technology GPO Box 2476V Melbourne Victoria 3001 Australia E-mail adrian.mouritzrmit.edu.au Chapter 10 L. C. Hollaway School of Engineering University of Surrey Guildford Surrey GU2 7XH UK E-mail l.hollawaysurrey.ac.uk Chapter 11 B. Benmokrane*, M. Robert and T. Youssef NSERC Research in Innovative FRP Composite Materials for Infrastructure Department of Civil Engineering University of Sherbrooke Sherbrooke Quebec J1K 2R1 Canada E-mail Brahim.BenmokraneUSherbrooke.ca Contributor contact detailsxiii Chapter 12 J. J. Myers Associate Professor UMR-UTC Interim Director Architectural Engineering Program Coordinator University of Missouri-Rolla 325 Butler Carlton Hall 1870 Miner Circle Rolla MO 65409-0030 USA E-mail jmyersumr.edu Chapter 13 H. Kaiser and V. M. Karbhari* University of California San Diego Department of Structural Engineering Jacobs School of Engineering University of California, San Diego 9500 Gilman Drive MC 0085 La Jolla CA 92093-0085 USA E-mail vkarbhariucsd.edu C. Sikorsky California Department of Transportation Engineering Services Center 1801 30th Street MS 9 Sacramento CA 95816 USA Chapter 14 A. A. Mufti* ISIS Canada Research Network Agricultural and Civil Engineering Building University of Manitoba A250 – 96 Dafoe Road Winnipeg Manitoba R3T 2N2 Canada E-mail muftiacc.umanitoba.ca L. A. Bisby Department of Civil Engineering 99 University Avenue, Ellis Hall Queen’s University Kingston Ontario K7L 3N6 Canada E-mail bisbycivil.queensu.ca xiv 1 1.1Introduction The infrastructure of constructed facilities for the transportation and housing of people, goods and services, which was largely expanded in the period between 1950 and the early 1970s, is now reaching a critical age with increasing signs of deterioration and reduced functionality. Deficiencies in the existing bridge inventory, for example, range from those related to wear, environmental deterioration and aging of structural components, to increased traffic demands and changing patterns; and from insufficient detailing at the time of construction/original design, to the use of substandard materials in initial construction, to inadequate maintenance and rehabilitation measures taken through the life of the structure. These deficiencies are not limited to bridge and other transportation-related structures alone, but are endemic to the built environment, ranging from residential housing and industrial/commercial structures to pipelines used for the distribution of water and sewage. This deterioration and the inability to provide the required services have a tremendous impact on society in terms of socio-economic losses resulting from delays, accidents and irregularity in supply. Conventional materials such as steel, concrete and wood have a number of advantages, not least of which is the relatively low cost of materials and construction. However, it is clear that conventional materials and technologies, although suitable in many cases and with a history of good applicability, lack longevity in some cases, and in others are susceptible to rapid deterioration, emphasizing the need for better grades of these materials or newer technologies to supplement those used conventionally. It should also be noted that in a number of cases design alternatives are constrained by the current limitations of the materials used, e.g. the length of the clear span of a bridge due to weight constraints, or the size of a column due to restrictions on design and minimum dimensions needed. Similarly, the use of conventional materials is often either not possible in cases of retrofit, or may be deemed ineffective in terms of functionality. In other cases, constraints such as dead load restrict 1 Introduction the use of composites in civil structural applications V. M. K A R B H A R I, University of California San Diego, USA Durability of composites for civil structural applications2 the widening of current structures or the carriage of higher amounts of traffic over existing lifelines. In all such and other cases, there is a critical need for the use of new and emerging materials and technologies, with the end goal of facilitating functionality and efficiency. 1.2Application in civil infrastructure Since the beginning of mankind, the human race has attempted to create new materials with enhanced properties for the construction of structural systems. The use of combinations of materials to provide both ease of use and enhanced perance – as in the application of straw reinforcement in mud by the ancient Israelites 800 BC, or in the combination of different orientations of veneer to plywood – has a long history. The concept of combining materials to create a new system having some of the advantages of each of the constituents can be seen in reinforced concrete. The use of fiber-reinforced polymer FRP composites takes this one step further enabling the synergistic combination of reinforcing fibers, with appropriate fillers/additives, in a polymeric resin matrix. The fibrous reinforcement carries load in predetermined directions indicated by fiber orientation and the polymer acts as a medium to transfer stresses between adjoining fibers through adhesion, and also provides toughness and protection for the material. The combination of the matrix phase with the fiber reinforcement thus creates a new material that is conceptually analogous to steel rebar-reinforced concrete although the reinforcing fractions vary considerably i.e. reinforced concrete in general rarely contains more than 5 reinforcement, whereas in FRP composites the reinforcing volume fraction can range from 25 to 70 depending on the process used; the matrix has both tensile and compression capabilities unlike cement which is strong only in compression and, unlike concrete, polymeric resins used in the civil infrastructure area impart a high degree of toughness and damage tolerance as well. These materials provide the designer with a wide palette of materials choices to fit the specific requirements of the structure and show immense potential for adding to the current palette of materials being used in civil infrastructure. The attractiveness of FRP composites as construction materials derives from a set of advantages that include high specific stiffness and specific strength characteristics; low weight, corrosion resistance and potentially high durability; the mechanical properties can be tailored using characteristics of anisotropic materials; the ability to have low conductivity and to act as an insulator in the case of glass fiber-reinforced composites, and to be electromagnetically transparent. In addition the wide variety of manufacturing processes available enables these materials to be fabricated both in the field under highly uncontrolled environments such as in the case of wet layup used in external strengthening applications and to very precise dimensional Introduction3 tolerances under highly controlled factory conditions such as in the case of autoclave-cured composites. The ease of application of FRP composites makes them extremely attractive for use in civil infrastructure applications, especially in cases where dead weight, space or time restrictions exist. Although FRP composites can have strength levels significantly higher than those of steel, and can be ed of constituents such as carbon fibers that have moduli equal to, or greater than, the modulus of steel, it is important to note that the limit of use is often dictated by strain limitations. FRP composites in general behave in a linear elastic fashion to failure, without any significant yielding or plastic deation- induced ductility as seen in steel or reinforced concrete. In addition, it should be noted that unlike reinforcing steel, some fibers, such as carbon fibers, are anisotropic, having different properties in the longitudinal i.e. along the length of the fiber and transverse directions. For example, although the tensile modulus for T300 carbon fibers in the longitudinal direction is 230 GPa, in the transverse direction it is only about 40 GPa, a fact that must be considered when designing with fibers or fabrics that have to con to tight radii and corners. In the case of aramid fibers, the fiber structure itself tends to fibrillate on the compression side, again emphasizing the need for special consideration in design. This anisotropy is also apparent in relation to the different coefficients of thermal expansion in the longitudinal and transverse directions. 1.3Durability FRP composites are increasingly being used in civil infrastructure in a range of applications such as reinforcing rods and tendons; wraps for seismic retrofit of columns; externally bonded reinforcement for strengthening of walls, beams and slabs; composite bridge decks; and even hybrid FRP composite in combination with conventional materials and all-composite structural systems. Since FRP composites are still relatively unknown to the practicing civil engineer and infrastructure systems planner, there are heightened concerns related to the overall durability of these materials, especially as related to their capacity for sustained perance under harsh and changing environmental conditions under load. Although FRP composites have been successfully used in the industrial, automot