Shear Strengthening Of Reinforced Concrete Beams With Bi Directional Carbon Fiber Reinforced Polymer Cfrp Strips And Cfrp Anchors
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Shear Strengthening Of Reinforced Concrete Beams With Bi Directional Carbon Fiber Reinforced Polymer Cfrp Strips And Cfrp Anchors
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Author : Nawaf Khaled Alotaibi
language : en
Publisher:
Release Date : 2014
Shear Strengthening Of Reinforced Concrete Beams With Bi Directional Carbon Fiber Reinforced Polymer Cfrp Strips And Cfrp Anchors written by Nawaf Khaled Alotaibi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
The use of externally bounded Carbon Fiber Reinforced Polymer (CFRP) for strengthening existing RC structures has shown promising results. Although CFRP materials have high tensile strength, the ability to utilize that strength is limited by debonding of the CFRP laminates from the concrete surface. In order to prevent or delay debonding, CFRP anchors were used to provide an alternative means of transferring forces from CFRP strips to the concrete. Previous tests on prestressed I-girders strengthened with uni-directional and bi-directional CFRP strips showed that bi-directional CFRP application resulted in significant shear strength gain in comparison to a uni-directional application. The objective of this thesis is to evaluate the behavior of reinforced concrete beams strengthened in shear with bi-directional CFRP strips and CFRP anchors so that the findings from the previous work can be understood and implemented. Four 24 in. deep T-beams were fabricated at the Phil M. Ferguson Structural Engineering Laboratory at The University of Texas at Austin. Eight tests were conducted on these specimens to examine the effect of the bi-directional layout of CFRP on the shear strength. Specimens with 14-in. web width were selected as a part of the experimental program to allow for direct comparison with test results from the previous project. Additional beams with a web width of 8 in. were included to evaluate thinner webs similar to those in the I-girders. Test results indicate a significant increase in shear strength due to the bi-directional application of CFRP strips with CFRP anchors installed on beams with a shear span-to-depth ratio (a/d) of 3. Substantial shear strength gain up to 62% was achieved in beams with 14-in. webs. and up to 43% for beams with 8-in. webs. However, negligible shear strength gain was observed in beams with a/d of 1.5 (deep beams). Experimental test results demonstrate an interaction between the contribution of concrete, transverse steel and CFRP to the shear resistance of a reinforced concrete beam. The findings of this research contribute to a better understanding of the shear behavior of reinforced concrete members strengthened with externally bonded CFRP applied bi-directionally. Experimental results from this research project provide data needed in the field of CFRP shear strengthening since limited data are available on large-scale tests.
Performance Of Concrete Panels Strengthened Using Carbon Fiber Reinforced Polymers Cfrp
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Author : Chang Hyuk Kim
language : en
Publisher:
Release Date : 2014
Performance Of Concrete Panels Strengthened Using Carbon Fiber Reinforced Polymers Cfrp written by Chang Hyuk Kim and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Many bridges are handling heavier loads than those expected at design, making it increasingly necessary to strengthen existing members or conduct repairs on damaged structural members. Carbon Fiber Reinforced Polymer (CFRP) materials have been broadly used to repair and strengthen reinforced concrete structures. Using CFRP materials as the strengthening material is an excellent solution because of their mechanical properties. CFRP has properties of high strength, corrosion resistance, and light weight. CFRP materials are being widely used for shear and flexural strengthening. Most studies have focused on uni-directional layout of CFRP strips in high shear regions of beams. Recent shear tests on full-scale I-girders have shown that the use of bi-directional CFRP layouts with CFRP anchors led to much higher shear strength increases than when using uni-directional layouts. The objective of the study is to determine the mechanism that governs shear strengthening of bridge girders using bi-directional CFRP and, in doing so, demonstrate the feasibility of using bi-directional CFRP for shear strengthening of large bridge I- and U-beams. Small-scale panel tests have been conducted to investigate parameters that influence the shear strength provided by bi-directional CFRP layouts. Panels were tested under compressive forces to simulate the compression struts that develop in the webs of I-beams. The applied loads generated bottle-shaped compressive struts. CFRP anchors were used to prevent early failure due to CFRP strip delamination from the panel surface. The panels, while not fully reproducing the boundary condition of girder webs, were tested ahead of full-scale girders to investigate a wide range of parameters in a cost-effective manner. The variables considered include the amount of CFRP and steel reinforcement, the inclination of CFRP fibers, and the layout and spacing of CFRP strips. The panel tests provide qualitative comparisons between the influence of the various parameters. The relative strength contributions of CFRP strips, steel stirrups, and concrete were evaluated.
Shear Behavior Of Reinforced Concrete Bridge Pile Cap Girders Strengthened With Carbon Fiber Reinforced Polymer Cfrp Strips And Cfrp Anchors
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Author : William Asad Shekarchi
language : en
Publisher:
Release Date : 2016
Shear Behavior Of Reinforced Concrete Bridge Pile Cap Girders Strengthened With Carbon Fiber Reinforced Polymer Cfrp Strips And Cfrp Anchors written by William Asad Shekarchi 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.
Externally bonded CFRP strips are ideal for rehabilitating existing members due to their high tensile strength-to-weight ratio, relatively low cost, formability, and expedited installation times. However, without proper anchorage, CFRP strips debond from the concrete surface before the strength of the CFRP can be mobilized. Consequently, CFRP spike anchors are used to delay debonding and develop the fracture strength of the CFRP strips. Previous research conducted on large-scale T-beams have shown that uni-directional (vertical) and bi-directional (vertical and horizontal) applications of CFRP strips and anchors increased the cracking load and ultimate shear capacity of members with transverse steel reinforcement, thin webs, and span-to-depth ratios above three (i.e., sectional behavior). However, the ability of the CFRP to strengthen wide-webbed members remained unknown. The objective of this research was to investigate the feasibility of strengthening wide-webbed reinforced concrete pile cap girders in shear using CFRP strips and CFRP anchors and to develop comprehensive design and detailing recommendations for CFRP shear strengthening. An experimental test program, consisting of nine tests, was created to investigate: 1) the effects of loading conditions, 2) retrofitting uncracked and cracked sections, 3) placing anchors in tension zones, and 4) uni- and bi-directional CFRP layouts on the shear performance of 32-in. deep by 32-in. wide reinforced concrete pile cap girders. The test results indicated that the uni-directional CFRP layouts were able to increase the shear capacity by as much as 56% while the bi-directional layouts increased the cracking shear load by as much as 22%. Anchored CFRP layouts were found to be as efficient as fully wrapped layouts despite anchors being placed in tension zones. Moreover, at the onset of the loss of shear strength, the measured lower bound average CFRP fracture strain was 0.007, which is significantly larger than the permitted effective strain in current ACI 440.2R-08 design guidelines (i.e., 0.004).
Rehabilitation Of Concrete Structures With Fiber Reinforced Polymer
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Author : Riadh Al-Mahaidi
language : en
Publisher: Butterworth-Heinemann
Release Date : 2018-11-12
Rehabilitation Of Concrete Structures With Fiber Reinforced Polymer written by Riadh Al-Mahaidi and has been published by Butterworth-Heinemann this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-11-12 with Technology & Engineering categories.
Rehabilitation of Concrete Structures with Fiber Reinforced Polymer is a complete guide to the use of FRP in flexural, shear and axial strengthening of concrete structures. Through worked design examples, the authors guide readers through the details of usage, including anchorage systems, different materials and methods of repairing concrete structures using these techniques. Topics include the usage of FRP in concrete structure repair, concrete structural deterioration and rehabilitation, methods of structural rehabilitation and strengthening, a review of the design basis for FRP systems, including strengthening limits, fire endurance, and environmental considerations. In addition, readers will find sections on the strengthening of members under flexural stress, including failure modes, design procedures, examples and anchorage detailing, and sections on shear and torsion stress, axial strengthening, the installation of FRP systems, and strengthening against extreme loads, such as earthquakes and fire, amongst other important topics. Presents worked design examples covering flexural, shear, and axial strengthening Includes complete coverage of FRP in Concrete Repair Explores the most recent guidelines (ACI440.2, 2017; AS5100.8, 2017 and Concrete society technical report no. 55, 2012)
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.
Shear Strengthening Of Reinforced Concrete Beams With Carbon Fiber Reinforced Polymer Cfrp And Improved Anchor Details
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Author : Kevin Timothy Quinn
language : en
Publisher:
Release Date : 2009
Shear Strengthening Of Reinforced Concrete Beams With Carbon Fiber Reinforced Polymer Cfrp And Improved Anchor Details written by Kevin Timothy Quinn and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
Fifteen tests were conducted to evaluate the shear performance of beams with carbon fiber reinforced polymer (CFRP) laminates and CFRP anchors. The specimens consisted of 24-in. deep T-beams. The specimens were strengthened in shear with CFRP laminates that were anchored using several different CFRP end anchorage details. Load was applied to the reinforced concrete members at three different shear span-to-depth ratios. Observations of the behavior and data from the tests were used to evaluate the performance of the CFRP laminates and CFRP anchors. Overall, a 30-40% increase in shear strength was observed when anchored CFRP laminates were installed on members loaded at a shear span-to-depth ratio greater than two. The CFRP strengthening system performed well when properly detailed CFRP anchors were installed. Design recommendations regarding the installation of the CFRP anchors were developed. The CFRP anchorage detail developed in this study provided additional CFRP material in critical locations to reinforce the anchor and prevent premature failures from occurring due to anchor rupture. Theoretical calculations predicting the shear strength of the retrofitted concrete members were carried out and compared to the measured strengths of the members. Based on this analysis, a design equation was developed that produced conservative results for all of the specimens tested.
Shear Strengthening Of Reinforced Concrete Beams With Carbon Fiber Reinforced Polymer Cfrp Under Fatigue And Sustained Loading Applications
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Author : Christopher Neil Satrom
language : en
Publisher:
Release Date : 2011
Shear Strengthening Of Reinforced Concrete Beams With Carbon Fiber Reinforced Polymer Cfrp Under Fatigue And Sustained Loading Applications written by Christopher Neil Satrom and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Four specimens were tested to evaluate the shear performance of beams with carbon fiber reinforced polymer (CFRP) laminates and CFRP anchors under fatigue and sustained loading applications. The specimens consisted of 24-in. deep T-beams that were constructed and tested at Phil M. Ferguson Structural Engineering Laboratory at the University of Texas at Austin. The specimens were strengthened in shear with CFRP laminates anchored with CFRP anchors. One end of each specimen was strengthened using bonded CFRP laminates while the other end was strengthened using unbonded CFRP laminates. Two specimens were used for fatigue testing and two were used for sustained load testing. For each set of tests, one specimen was strengthened using CFRP laminates prior to cracking and one specimen was strengthened using CFRP laminates following the initial cracking of the specimen. The CFRP laminates showed no signs of deteriorations in strength during fatigue testing, with only small increases in strain occurring in the CFRP laminates during testing. After fatigue loading was completed, the specimens were monotonically loaded to failure. The failure loads were 5 to 15% lower than beams that were not subjected to fatigue loading. Sustained load tests were subjected to a constant midpoint load based on service load requirements for a period of 217 days. CFRP laminates performed well during sustained loading. CFRP strains increased slightly throughout testing, but no signs of deterioration were observed. For both types of tests, specimens strengthened using bonded CFRP laminates demonstrated an increased stiffness resulting in smaller crack widths and lower strains in the internal steel. These benefits were not as great in specimens strengthened after the initial cracking of the specimen.
Shear Behavior Of Reinforced Concrete T Beams Strengthened With Carbon Fiber Reinforced Polymer Cfrp Sheets And Cfrp Anchors
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Author : Yun Gon Kim
language : en
Publisher:
Release Date : 2011
Shear Behavior Of Reinforced Concrete T Beams Strengthened With Carbon Fiber Reinforced Polymer Cfrp Sheets And Cfrp Anchors written by Yun Gon Kim and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
The objective of this research is the evaluation of shear behavior of full-scale reinforced concrete T-beams strengthened with carbon fiber reinforced polymer (CFRP) sheets and CFRP anchors. Although the CRFP material has high tensile strength, premature failure due to debonding CFRP sheets prevents utilizing that strength. The use of CFRP anchors prevents this failure, so the CFRP sheets are able to reach ultimate strain. The current shear design is based on plasticity, which assumes that all steel (ductile material) stirrups, across the critical section yield at ultimate. However the strain in the CFRP (brittle material), is essential to estimate the shear contribution of CFRP. To evaluate the validity of CFRP strengthening for shear, 24 tests were conducted with several parameters including shear-span-to-depth ratio, depth of beams, different transverse reinforcement ratios, and the layout of CFRP strips. In addition, a simple shear behavior model was developed to explain the differences between ductile and brittle material. From test observation, the use of CFRP anchors resulted in U-wrap application to perform like continuous wrapping which implies that a CFRP strip reached rupture strain because the anchors prevented debonding failure. However, all FRP strips did not rupture simultaneously because the strain distribution across a critical crack was not uniform. The average strain across the critical crack was about 0.005. Therefore a conservative value of effective strain (0.004) was selected for design purposes. In addition, when a beam is strengthened with CFRP, interactions between the contributions of the CFRP, steel or concrete must be taken into account. Factors ka, ks, and kf were introduced in the proposed shear design equations. Factor ka reflects the change in the material contributions as the shear span to depth ratio (a/d ratio) changes in deep beams. Factors ks and kf account for the change in steel or CFRP shear contribution due to the change in the critical crack angle as well as the interactions between the steel and FRP transverse reinforcement. As the amount of either steel or FRP material increase, the efficiency of the other material decreases.
Shear Strengthening Of Reinforced And Prestressed Concrete Beams Using Carbon Fiber Reinforced Polymer Cfrp Sheets And Anchors
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Author : Yungon Kim
language : en
Publisher:
Release Date : 2012
Shear Strengthening Of Reinforced And Prestressed Concrete Beams Using Carbon Fiber Reinforced Polymer Cfrp Sheets And Anchors written by Yungon Kim and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Carbon fiber-reinforced plastics categories.
The ability to quickly apply carbon fiber reinforced polymer (CFRP) materials with a minimum of disruption to the use of a structure and with virtually no change in the geometry or weight of the element makes CFRP a viable and attractive material for strengthening existing elements. However, without adequate anchorage of CFRP sheets to the concrete surface, premature failures by debonding of the CFRP from the concrete significantly limit the capacity of CFRP strengthening systems. The objective of the study was to demonstrate the feasibility of using anchored CFRP for shear strengthening of large bridge girders or supporting elements. An extensive experimental program was undertaken on several full-scale T-beams and I girders to achieve project objectives. CFRP anchors used in the study performed well and were able to develop the full capacity of CFRP sheets thereby precluding debonding failures. Studied anchored CFRP systems were thus able to generate significant shear strength gains of up to 50 percent of the unstrengthened beam capacity. Experimental results, installation procedures for CFRP sheets and anchors, specifications for fabrication and installation of CFRP anchors, and anchored CFRP shear design guidelines are presented.
Shear Strengthening Of Reinforced Concrete Beams Using Externally Bonded Bi Directional Carbon Fibre Reinforced Polymer
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Author : J. Jayaprakash
language : en
Publisher:
Release Date : 2006
Shear Strengthening Of Reinforced Concrete Beams Using Externally Bonded Bi Directional Carbon Fibre Reinforced Polymer written by J. Jayaprakash and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Concrete beams categories.