Fatigue Performance Of Rc Beams Strengthened With Near Surface Mounted Cfrp Composites
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Fatigue Performance Of Rc Beams Strengthened With Near Surface Mounted Cfrp Composites
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Author : Tamer Ghaith Mousa Eljufout
language : en
Publisher:
Release Date : 2019
Fatigue Performance Of Rc Beams Strengthened With Near Surface Mounted Cfrp Composites written by Tamer Ghaith Mousa Eljufout and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with Carbon fiber-reinforced plastics categories.
Bridges have a fundamental role in improving the effectiveness of highways and providing an expedient and express traffic system. Over time, Reinforced Concrete (RC) bridges degrade due to gradually increased traffic loads and environmental deteriorations. Subsequently, service loads might cause higher stresses in concrete and steel reinforcement than stresses considered in the design stage. This affects the structural performance of RC beams and leads to sudden fatigue failure. As such, there is an essential need for rehabilitation to avoid hazards and tragedies. Carbon Fiber Reinforced Polymer (CFRP) composites are becoming widely used to strengthen RC bridges. Near Surface Mounted (NSM) technique has proven its advantages over other applied strengthening techniques. This study investigates several factors associated with the fatigue performance of RC beams strengthened with NSM CFRP reinforcement, such as: the effect of strengthening techniques on the fatigue limit of RC beams; the influence of loading history on the fatigue behavior of rehabilitated RC beams; the development of deflections, stiffness degradation, and energy dissipation of strengthened RC beams under different loading patterns; and the viability of an accelerated fatigue approach for developing a fatigue stress-life predication model of RC beams. Analytical, experimental, and numerical analyses were performed to achieve the study’s objectives. Empirical fatigue stress-life prediction models for non-strengthened and strengthened RC beams were developed based on least-squares regressions of eighty experimental data points obtained from the literature. The proposed models have a satisfactory precision for design purposes. The experimental program in this study includes eleven cast-in-place RC beams with dimensions of 152.4 × 152.4 × 1,521 mm. Specimens were tested under four-point bending configuration to simulate long-span RC beams. Monotonic tests were performed to determine the flexural static capacity, ductility index, and cracking patterns of non-strengthened and strengthened RC beams. The effect of CFRP strengthening techniques on the fatigue limit of RC beams was examined using Locati method. A non-strengthened RC beam, a RC beam strengthened with NSM CFRP reinforcement, and a RC beam strengthened with Externally Bonded (EB) CFRP sheet were tested under a step-like constant amplitude cyclic loading to failure. Accordingly, CFRP strengthening techniques increase the fatigue limit of RC beams and improve their fatigue responses. Strengthened RC beams showed less stiffness degradation and energy dissipation when compared to non-strengthened RC beams. NSM CFRP technique demonstrated a better flexural static strength and fatigue life than EB CFRP technique. Six RC beams were tested to investigate the influence of loading history on the fatigue behavior of rehabilitated RC beams. Two of the six RC beams were strengthened with NSM CFRP reinforcement and tested as a reference under constant amplitude cyclic load. To simulate the condition of service traffic loading, the other four RC beams were cyclically pre-loaded then rehabilitated with NSM CFRP reinforcement. These specimens were tested under the same loading conditions of the reference specimens. The rehabilitated pre-fatigued RC beams had stiffness degradation and failure modes similar to the reference specimens. The pre-fatigue induced an under-stressing effect that extends the fatigue life of the rehabilitated RC beams. Moreover, the post-fatigue monotonic behavior of the rehabilitated RC beams showed an increase in the elastic modulus and a decrease in ductility within the flexural static capacity. Finally, numerical analyses were performed to predict the fatigue responses of RC beams strengthened with NSM CFRP reinforcement, and to check the viability of an accelerated fatigue approach for developing a fatigue stress-life predication model. The accelerated fatigue loading has a higher rate of damage accumulation than the standard testing approach. The developed model fits the upper 95% prediction band of RC beams tested under constant amplitude cyclic loading.
Fatigue Behavior And Modeling Of Reinforced Concrete Structures Using Nsm Frp Composites
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Author : Cheng Chen
language : en
Publisher:
Release Date : 2016
Fatigue Behavior And Modeling Of Reinforced Concrete Structures Using Nsm Frp Composites written by Cheng Chen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Near-surface mounted (NSM) method using Fiber Reinforced Polymer (FRP) composites proves to be promising in structural strengthening and rehabilitation of deficient reinforced concrete (RC) and prestressed concrete members. However, the fatigue behavior of strengthened members is still not well understood and needs extensive research before practical design guidelines are established. The objective of this research is to experimentally and analytically assess the fatigue performance and predict the fatigue life of NSM CFRP strengthened RC beams. In particular, it aims to: (1) experimentally evaluate the bond performance of the NSM CFRP reinforcement-epoxy interface and its degradation; (2) propose an analytical model to predict the bond performance; (3) evaluate the test results of the flexural performance of the NSM CFRP strengthened RC beams subject to fatigue loadings; and (4) develop models to predict the corresponding flexural performance and fatigue life of the strengthened concrete members. Thirty-six NSM strengthened concrete block specimens were fabricated and then subject to various fatigue loadings. Direct pull-out test was conducted on each specimen to obtain the bond characteristics and performance. Variables considered in this study include: cycles of fatigue loadings and types of NSM reinforcements. The result shows that specimens using NSM rods had higher bond strength at the epoxy-NSM interface than that at the concrete-epoxy interface, resulting in the governing failure due to breakage of epoxy and concrete. Specimens using NSM strips, on the other hand, failed mainly due to debonding (at the epoxy-NSM interface). Moreover, fatigue loading tended to shift the FRP strain and the local bond stress distribution from the loaded end towards the free end in NSM-strengthened specimens. The local bond stress-slip relationship under fatigue followed a hardening-softening behavior for both types of NSM reinforcement. Fatigue loading generally decreased the bond strength while the corresponding slip remained almost unchanged. A theoretical solution to this bond characteristics under fatigue loading is derived to predict the debonded length progression and fatigue behavior of the bond related variables (e.g. distribution of bond stress, slip, and tensile stress of the NSM reinforcement) for concrete blocks strengthened by NSM CFRP reinforcement. Twenty RC beams strengthened with NSM FRP were constructed in 2 batches, one strengthened by NSM rods and the other by NSM strips. Sixteen NSM strengthened specimens were subject to different levels of fatigue loading until failure, while four strengthened specimens were tested under monotonic loadings. Typical elastic-plastic behavior was observed in monotonic test, yielding of specimen occurred when the tensile strain of steel rebar reached around 0.2%. Most fatigue specimens failed by rebar rupture and small group of specimens failed by debonding between NSM and concrete. However, unstable crack propagation was also observed to occur with rebar rupture in certain specimens, especially specimens with lower fatigue load and longer fatigue life. The crack and deflection progression could be generally divided into three distinct stages: (1) initial stage with decelerating increase; (2) steady stage with increase of constant and small rate; (3) final unstable stage of accelerating increase, and the second stage occupied most of fatigue life. An analytical solution to the flexural response of the RC beams strengthened with NSM CFRP reinforcement is derived, using a trilinear bond-slip relation for the CFRP-epoxy interface and the previously derived theoretical solution to bond characteristics. As the analytical model provides solution to flexural response, an independent fatigue life prediction model is also developed for reinforced concrete beams strengthened with NSM FRP rods under flexural fatigue loading. The model is based on the fracture-mechanics approach using cohesive model and capable of predicting fatigue life due to rebar rupture, where the effect of cohesive stresses due to aggregate, steel rebar, NSM FRP reinforcement is approximated by specific cohesion laws.In conclusion, this dissertation presents thorough and detailed research to experimentally and analytically investigate the flexural behavior of NSM FRP beams, including the strain of FRP, rebar and concrete, deflection, and crack progression, etc. Moreover, approaches to address the fatigue life prediction is also proposed and verified by experimental results.
Monotonic And Fatigue Flexural Behaviour Of Rc Beams Strengthened With Prestressed Nsm Cfrp Rods
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Author : Moataz Assad Badawi
language : en
Publisher:
Release Date : 2007
Monotonic And Fatigue Flexural Behaviour Of Rc Beams Strengthened With Prestressed Nsm Cfrp Rods written by Moataz Assad Badawi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
10th International Conference On Frp Composites In Civil Engineering
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Author : Alper Ilki
language : en
Publisher: Springer Nature
Release Date : 2021-11-26
10th International Conference On Frp Composites In Civil Engineering written by Alper Ilki and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-11-26 with Technology & Engineering categories.
This volume highlights the latest advances, innovations, and applications in the field of FRP composites and structures, as presented by leading international researchers and engineers at the 10th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering (CICE), held in Istanbul, Turkey on December 8-10, 2021. It covers a diverse range of topics such as All FRP structures; Bond and interfacial stresses; Concrete-filled FRP tubular members; Concrete structures reinforced or pre-stressed with FRP; Confinement; Design issues/guidelines; Durability and long-term performance; Fire, impact and blast loading; FRP as internal reinforcement; Hybrid structures of FRP and other materials; Materials and products; Seismic retrofit of structures; Strengthening of concrete, steel, masonry and timber structures; and Testing. The contributions, which were selected by means of a rigorous international peer-review process, present a wealth of exciting ideas that will open novel research directions and foster multidisciplinary collaboration among different specialists.
Static And Fatigue Performance Of Reinforced Concrete Beams Retrofitted With External Cfrp Composites
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Author : Yongtao Dong
language : en
Publisher:
Release Date : 2003
Static And Fatigue Performance Of Reinforced Concrete Beams Retrofitted With External Cfrp Composites written by Yongtao Dong and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Concrete beams categories.
Monotonic And Fatigue Performance Of Rc Beams Strengthened With Externally Post Tensioned Cfrp Tendons
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Author : Ahmed El Refai
language : en
Publisher:
Release Date : 2007
Monotonic And Fatigue Performance Of Rc Beams Strengthened With Externally Post Tensioned Cfrp Tendons written by Ahmed El Refai and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
Fatigue Performance Of Rc Beams Strengthened Using Prestressed Nsm Cfrp
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Author : Fadi Oudah
language : en
Publisher:
Release Date : 2012
Fatigue Performance Of Rc Beams Strengthened Using Prestressed Nsm Cfrp written by Fadi Oudah and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
Externally Bonded Frp Reinforcement For Rc Structures
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Author : fib Fédération internationale du béton
language : en
Publisher: fib Fédération internationale du béton
Release Date : 2001-01-01
Externally Bonded Frp Reinforcement For Rc Structures written by fib Fédération internationale du béton and has been published by fib Fédération internationale du béton this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001-01-01 with Technology & Engineering categories.
In December 1996, the then CEB established a Task Group with the main objective to elaborate design guidelines for the use of FRP reinforcement in accordance with the design format of the CEB-FIP Model Code and Eurocode2. With the merger of CEB and FIP into fib in 1998, this Task Group became fib TG 9.3 FRP Reinforcement for concrete structures in Commission 9 Reinforcing and Prestressing Materials and Systems. The Task Group consists of about 60 members, representing most European universities, research institutes and industrial companies working in the field of advanced composite reinforcement for concrete structures, as well as corresponding members from Canada, Japan and USA. Meetings are held twice a year and on the research level its work is supported by the EU TMR (European Union Training and Mobility of Researchers) Network "ConFibreCrete”. The work of fib TG 9.3 is performed by five working parties (WP): Material Testing and Characterization (MT&C) Reinforced Concrete (RC) Prestressed Concrete (PC) Externally Bonded Reinforcement (EBR) Marketing and Applications (M&A) This technical report constitutes the work conducted as of to date by the EBR party. This bulletin gives detailed design guidelines on the use of FRP EBR, the practical execution and the quality control, based on the current expertise and state-of-the-art knowledge of the task group members. It is regarded as a progress report since it is not the aim of this report to cover all aspects of RC strengthening with composites. Instead, it focuses on those aspects that form the majority of the design problems. several of the topics presented are subject of ongoing research and development, and the details of some modelling approaches may be subject to future revisions. as knowledge in this field is advancing rapidly, the work of the EBR WP will continue. Inspite of this limit in scope, considerable effort has been made to present a bulletin that is today’s state-of-art in the area of strengthening of concrete structures by means of externally bonded FRP reinforcement.
Guide For The Design And Construction Of Concrete Reinforced With Fiber Reinforced Polymer Bars
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Author : ACI Committee 440
language : en
Publisher:
Release Date : 2003
Guide For The Design And Construction Of Concrete Reinforced With Fiber Reinforced Polymer Bars written by ACI Committee 440 and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Fiber-reinforced concrete categories.
Proceedings Of The 6th International Conference On Smart Monitoring Assessment And Rehabilitation Of Civil Structures
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Author : Xiang-Lin Gu
language : en
Publisher: Springer Nature
Release Date : 2024-02-27
Proceedings Of The 6th International Conference On Smart Monitoring Assessment And Rehabilitation Of Civil Structures written by Xiang-Lin Gu and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024-02-27 with Technology & Engineering categories.
This book is a compilation of selected papers from the 6th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures (SMAR 2022). The work focuses on the state-of-the-practice and recent advances in testing and monitoring technology, in structural modeling and assessment methods, and in the application of advanced materials for structural rehabilitation. The contents make valuable contributions to international professors, research scientists, professional engineers, postdoctoral fellows and postgraduate students.