Advances of FRP-based smart components and structures

23 - Non-destructive evaluation (NDE) of composites: using fiber optic sensors

The International Institute for FRP in Construction (IIFC) was formed in 2003 with a mission to advance the understanding and application of fiber–reinforced polymer (FRP) composites in civil infrastructure. Since 2005, IIFC has enjoyed a fruitful association with ASCE via co-sponsorship of the Journal of Composites for Construction (JCC). Therefore, it is fitting that this present JCC issue commemorates the 10th anniversary of IIFC. This is the third special IIFC issue published by JCC; the first two issues were in April 2007 (“Recent International Advancements in FRP Research and Application in Construction”) and April 2011 (“In Honor of Professor Urs Meier”). The flagship events of IIFC are undoubtedly its biannual worldwide and Asia-Pacific regional conference series, which are known as FRP Composites in Civil Engineering (CICE) and Asia-Pacific Conference on FRP in Structures (APFIS), respectively. These conferences are held in alternating years at differing locations around the world: CICE in 2001 (Hong Kong), 2004 (Adelaide), 2006 (Miami), 2008 (Zurich), 2010 (Beijing), and 2012 (Rome); and APFIS in 2007 (Hong Kong), 2009 (Seoul), 2012 (Sapporo), and 2013 (Melbourne). CICE 2014 will be held in Vancouver and CICE 2016 in Hong Kong.This special issue of JCC has been timed for release prior to CICE 2014. IIFC also co-sponsors other international conference series and workshops. To better disseminate knowledge to the wider community, IIFC makes the proceedings of most IIFC official and supported events available on its website (http://www.iifc-hq.org) for free download. IIFC publishes a newsletter and all copies are also held on the IIFC website. The newsletter commenced in 1993, and for its first 10 years, was known as FRP International. IIFC also runs several working groups that offer tangible benefits such as educational resources, state-of-the-art reports, conference special sessions, and journal special issues. IIFC recognizes excellence in the form of several awards, namely, IIFC Medal, Distinguished Young Researcher Award, President’s Award, Lifetime Achievement Award, conference best paper awards, and IIFC fellowships. The IIFC website contains lists of all award recipients over the years, in addition to far more information than can be contained in this editorial. IIFC is a dynamic organization that has been positively influenced by numerous individuals over the years. It is governed by an Executive Committee, which is overseen by an Advisory Committee. The Council is populated by up to 40 elected leading figures in the field from around the world, plus members of the Advisory Committee. At present, 21 countries are represented on these three committees and several of these leading figures also serve on the Editorial Board of JCC. This special issue contains 18 invited papers contributed by members of these committees and their collaborators, addressing a diverse range of topics that are representative of the breadth of activity in the field. More specifically, the papers are of an experimental, analytical, and numerical nature and address: • FRP for strengthening concrete; namely, prestressed FRP plates, strips, and rods (two papers), confinement (one paper), FRP patch anchors (one paper), limits to the application of FRP for repair (one paper), near-surface mounted FRP (one paper), cementitious bonding agents (three papers), and large strain capacity FRP (one paper); • FRP for strengthening timber (one paper), steel (one paper), and masonry (one paper) construction materials; and • FRP for new construction; namely, hybrid FRP tendons (one paper), FRP bars (two papers), FRP beams (one paper), and stay-in-place structural forms (one paper). There is plenty of work still to be done in the field. In particular, more systematic and in-depth research is required on the long-term behavior of both FRP structures and FRP strengthened structures to substantiate the common claim that such structures have superior durability over other structures. Innovative combinations of FRP with either traditional construction materials or new materials to produce new structural members and forms will have an important role in designing the next generation of high-performance and sustainable structures. There is no doubt that the conversion of research findings into workable design guidelines and standards for use by design engineers is critical in widening the applications of FRP in civil construction. The contributions of numerous individuals are acknowledged in the preparation of this special issue. The authors of the papers in this issue are thanked for preparing high-quality manuscripts. Professor Charles E. Bakis, Editor-in-Chief of JCC, is thanked for handling the paper review process and ensuring maintenance of the high JCC standard. Professor Bakis is also supported by Ms. Renee Lindenberg and a large team of reviewers; their contributions are all acknowledged. The idea of an IIFC 10th anniversary special issue was positively received by Professor Lawrence C. Bank, IIFC President, and by the members of the Executive Committee following discussions after CICE 2012. For that, they are all thanked for their support. Finally, all members of IIFC, past and present, are thanked for their various contributions over the years, which have enabled IIFC to move into its second decade on a sound and positive footing.

Strengthening concrete using phosphate cement-based fiber-reinforced inorganic composites for improved fire resistance

This introductory book presents procedures for the analysis of signals and the characterization of systems in civil engineering. The two main topics of this book are at the core of several fast-growing areas in civil engineering today, including: non-destructive testing, system identification, image processing, local or remote monitoring, smart structures, dynamic loading, and feedback control systems in transportation and structural engineering. The authors have provided the readers with a Web site dedicated to this book which includes readily downloadable algorithms for numerical examples, other examples and applications, and errata. Complete with end-of-chapter exercises, this book is appropriate as an upper undergraduate/graduate level textbook or as a reference source for the research or practicing engineer.

Fiber-reinforced polymer (FRP) composites have gained increasing recognition and application in the field of civil engineering in recent decades due to their notable mechanical properties and chemical resistance. However, FRP composites may also be affected by harsh environmental conditions (e.g., water, alkaline solutions, saline solutions, elevated temperature) and exhibit mechanical phenomena (e.g., creep rupture, fatigue, shrinkage) that could affect the performance of the FRP reinforced/strengthened concrete (FRP-RSC) elements. This paper presents the current state-of-the-art on the key environmental and mechanical conditions affecting the durability and mechanical properties of the main FRP composites used in reinforced concrete (RC) structures (i.e., Glass/vinyl-ester FRP bars and Carbon/epoxy FRP fabrics for internal and external application, respectively). The most likely sources and their effects on the physical/mechanical properties of FRP composites are highlighted herein. In general, no more than 20% tensile strength was reported in the literature for the different exposures without combined effects. Additionally, some provisions for the serviceability design of FRP-RSC elements (e.g., environmental factors, creep reduction factor) are examined and commented upon to understand the implications of the durability and mechanical properties. Furthermore, the differences in serviceability criteria for FRP and steel RC elements are highlighted. Through familiarity with their behavior and effects on enhancing the long-term performance of RSC elements, it is expected that the results of this study will help in the proper use of FRP materials for concrete structures.

In civil engineering, fiber reinforced polymer (FRP) bars are commonly employed. As an alternative to reinforcement steel due to their numerous advantages, including great weight-to-strength ratio, light weight, ease of handling electromagnetic neutrality, and lack of rust. Furthermore, as production machinery develops and more becomes industrialized, FRP has evolved into a cost-effective and competitive structural material. This work examines flexural presentation of fiber-reinforced polymer (FRP) bars and concrete reinforced (RC) after beams conditioning for 6, 9, and 12 months simulated seawater in a wet-dry environment cycling. The purpose of this study is to introduce advancements in the research on FRP-reinforced concrete structures based on recent research. The bond presentation of FRP bars flexural behaviour, concrete, compression behaviour, and concrete of ductility structures reinforced with FRP bars in the last few years around the world are among the topics covered in this study. steel-FRP composite bars (SFCBs) and Basalt FRP (BFRP) are the two types of FRP bars used. For comparison, steel bars are used. During the conditioning, the beams are subjected to a steady load. There are a full of 24 simple-supported rays that being verified.

A FRP-wrapped Balsa wood bridge deck system is under development in Louisiana, and the bridge long-term performance will be monitored using fiber optic sensors throughout its service. First, the instrumentation plan of the long-term monitoring system of the bridge is introduced in this paper; then a novel moisture monitoring method using FBG sensors is put forward, in which the expansion induced by moisture in the FRP wrapped Balsa wood is measured to indicate its moisture contents. A test on FRP wrapped Balsa wood specimen was conducted in which moisture penetration process was monitored through the proposed method. The feasibility of the proposed method was validated. Aging, varying environmental conditions, corrosion, damage due to vehicular impact, and increased gross vehicle weight result in structural deterioration, which affects the load carrying capacities of existing bridges. A large number of existing bridges in Louisiana are weight-restricted. There is an urgent need to repair and upgrade this state’s bridge system. Applications of new materials such as Fiber Reinforced Polymers (FRP) are new explorations in dealing with the state’s infrastructure problems. In many cases and in other states, FRP decks were used to replace deteriorated steel reinforced concrete decks. This study will develop a FRP-wrapped Balsa wood bridge deck system in Louisiana. The long-term performance of the bridge will then be monitored throughout its service. Taking advantages of the new development in FRP materials and fiber optic sensors, this research project will potentially provide a new approach to enhancing the transportation infrastructure in Louisiana. In addition to the general instrumentation plan, this study will focus on the moisture monitoring techniques. Even though the deck will be vacuum-sealed for outside moisture protection, the long-term moisture in the Balsa wood of the bridge deck will cause wood decay and structure damage, moisture monitoring to the newly developed bridge deck system becomes necessary.

The use of fiber reinforced polymers (FRP) to reinforce reinforced concrete(RC) structure has become one of the main applications of composites in civil engineering. FRP composite is analyzed using the serial/parallel mixing theory, which deduces the composite behavior from the constitutive equations of its components. Numerical procedure of RC beam reinforceed with FRP is studied based on the finite element method. The numerical results accord with the test results. The validity of the proposed procedure is proved comparing numerical and experimental results.

This study focuses on the tensile behavior of fiber-reinforced polymer (FRP) composites in a concrete-based alkaline environment. Because basalt/glass FRP (BFRP/GFRP) composites exhibit relatively poor alkaline resistance compared with carbon FRP (CFRP) composites, a rubber toughening modification method has been proposed to mitigate microcracking and decrease the diffusion of the alkaline solution in the resin matrix. Different proportions of liquid rubber toughening agents were added into the epoxy resin, on the basis of which different FRP composites were made and then subjected to tensile tests after alkaline exposure. Test results indicated that the rubber toughening modification approach can significantly reduce the tensile strength degradation of the BFRP and GFRP composites in the alkaline solution. Moreover, no degradation of the elastic modulus for the FRP composites was observed. The weight gain and microstructure of the FRP composites were also investigated before and after the alkaline exposure to determine the corrosion mechanisms of the FRP composites in the alkaline environment and interpret the mechanical test results.

FRP-strengthened RC slabs anchored with FRP anchors

This paper provides a review of research being conducted at The University of Hong Kong (HKU) on the strengthening of concrete, metallic and timber construction materials with externally bonded fibre-reinforced polymer (FRP) composites. The motivation of such research is to enhance our understanding of the interfacial behaviour between the FRP and the three different substrate materials via FRP-to-concrete, -metal, and-timber joint tests. Of the three substrate materials, concrete has clearly experienced the most research activity to date by the wider research community, followed by that of metal and then that of timber. In order to progress the extensive knowledge base of FRP-to- concrete behaviour, research at HKU is aimed at enhancing the bond strength of the FRP via the addition of anchorage. The anchor of choice is the so called FRP anchor and its effectiveness in anchoring FRP flexural strengthening applied to reinforced concrete (RC) slabs is also presented. For the metal and timber substrate materials, HKU research is more focused at this stage on understanding the influence of key fundamental variables affecting interfacial behaviour such as FRP geometry, surface preparation and substrate material characteristics.

1 - Using fiber-reinforced polymer (FRP) composites in bridge construction and monitoring their performance: an overview

Fiber reinforced polymer ( FRP) rods have a broad application in civil eng ineering field used as a material substiting steelbars. Based on the domestic and abroad research, the durability of the fiber reinforced polymer (FRP) rods undermultifarious environmental conditions is summarized in this paper, and the effect of environments such as temperature, humidity, corrosion from acid, alkaline and salt solutions on durability performance of FRP materials as well as the degradation of the bond characteristics between FRP rods and the interface of concrete caused by the acceleration environment test are mainly discussed. The results indicate that the environmenta lconditionsm entioned above affect FRP rods and bond characteristics between FRP rods and the in terface of concrete.In addition, a relatedmodel predicting the influence on durability of FRP rods in alkaline solutions is given and future study trend on durability of FRP rods is presented

Fiber reinforced polymer (FRP) materials are currently used for strengthening of masonry structures. The behavior of this retrofit technique depends on the bond characteristics of the FRP to the external surface of the structure. A promising method to control the durability of the FRP reinforced structures is to incorporate fiber optical sensors (FOSs) in the composite material during its application or manufacture. The research leads to design of composite systems for the seismic retrofitting of an ancient masonry vault. The reinforcement technique involves the use of composite systems made up by FRP integrated with FOSs. The FOSs are employed as diagnostic tool for structural health monitoring. doi: 10.12783/SHM2015/202

Fiber-reinforced polymer (FRP) composites have emerged as promising next-generation materials for advanced structures in civil engineering. Notwithstanding the recent progress, the unsatisfactory mechanical properties and problematic long-term stability in the alkali environment remain daunting challenges toward their large-scale practicability. In this study, we address such limitations by a dual modification method, in which first ethyl cellulose (EC) is incorporated into the matrix and then the FRP composite is dipped in a dilute poly(dimethylsiloxane) (PDMS) solution. The FRP composite exhibited enhanced flexural strength by 23.4% and increased flexural modulus by 23.5% compared to those of the pristine basalt fiber-reinforced polymer (BFRP). Such an eminent performance is mainly attributed to the bridging effect of EC. As confirmed by the DMA characterization, the incorporation of EC greatly increased the cross-linking density and improved the thermal stability. Additionally, the FRP composite had a stable performance in the alkali environment tests. Tuning the amount of ethyl cellulose was found to have a profound effect on the mechanical performance and aging behavior in the alkali solution. This study establishes a practical approach to fabricating FRP composites with long-term stability in alkali environments.