External bonded shear reinforcement for T‐section beams

Etman, Emad

doi:10.1002/suco.201000005

Cited by 6 publications

(5 citation statements)

References 11 publications

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“…Numerous researchers have already investigated and proven the efficiency and usefulness of applying CFRP sheets to strengthen existing RC structures in shear (see e.g., References ). If the cross section of a structure allows for it, the full wrapping with CFRP sheets is the easiest way to ensure maximum effectiveness and strength gain.…”

Section: Applied Strengthening Techniquesmentioning

confidence: 99%

Developing optimized strengthening systems for shear‐deficient concrete members

Randl

Harsányi

2017

Structural Concrete

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Austrian Federal Railways ÖBB, Austrian motorway operator ASFINAG Strengthening methods for shear-deficient bridges were developed and tested in cooperation with the HILTI Corporation and SIKA Austria. In order to identify the strengthening effect in shear, a number of 12 T-shaped RC-beams with a length of 5.38 m were designed. In the experimental campaign two different types of strengthening systems were applied and subjected to shear loading until failure. The successful use of a modern digital image correlation system provided the basis for an in-depth analysis of failure mode and crack pattern as well as shear degradation at each load stage. Finally, the applicability of existing shear design models with consideration of the strengthening elements analogously to cast-in shear reinforcement was evaluated.anchorage, carbon fiber, FRP, postinstalled, shear, shear test, strengthening, undercut anchor 1 | INTRODUCTION Subsequent strengthening of existing structures has gained in importance over the last decades due to the decreasing number of new structures and the ever-growing number of existing ones. The ongoing increase in traffic loads, continuous updating of design codes, and also paradigm shifts lead to the fact that a number of existing bridge structures do not fulfill the required safety level concerning the shearbearing capacity as required by codes of practice such as Eurocode 2. 1 Meanwhile, there exist refined methods for the verification of the shear load-bearing capacity 2-7 , developed from more consistent mechanical models. MC2010 8 provides advanced design approaches allowing for a better utilization of the real structural resistance. Nevertheless, the need for sound technical solutions in the subsequent shear strengthening of existing reinforced concrete (RC) structures is constantly increasing.While the flexural strengthening of RC members has become a routine task, the retrofitting of shear-deficient members is still a challenging issue for the following reasons:• Local shear retrofitting requires the introduction of forces over very short distances. In comparison, flexural strengthening is oriented in the longitudinal direction of a structural member and usually applied over larger sections. Therefore, adequate stiffness and proper anchorage solutions are needed when strengthening in shear. • The strengthening system must be reliably activated without the necessity of large additional live loads or deformations of the structure. • Currently, there are no harmonized recommendations for RC shear design itself available; therefore, the rather complex design of shear strengthening is even more disputable.A few established methods to strengthen RC structures in shear already exist (see e.g., overview in Reference 9). Selected popular methods for shear strengthening are discussed and compared on the basis of experimental investigations in Reference 10. With respect to the affected sections of a structure and the impact on the overall structural behavior, such strengthening solutions can generally be...

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Section: Applied Strengthening Techniquesmentioning

confidence: 99%

Developing optimized strengthening systems for shear‐deficient concrete members

Randl

Harsányi

2017

Structural Concrete

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“…The use of fiber-reinforced polymer sheets is a well-studied area of research for RC T-beams and, in particular, many experimental campaigns have been carried out for monotonic loading, e.g., [11,12]. Etman [13] showed that strengthening RC T-beams in the shear zone using carbon-fiber-reinforced polymer (CFRP) enhanced the shear capacity of existing RC beams, which showed that the use of the CFRP sheet reflected higher specimen stiffness, compared to steel. Another experimental study [14] was designed to assess the effects of increased steel shear reinforcement, changes in shear span-to-depth ratios, as well as the effect of different retrofit layouts and materials (the use of fiber-reinforced polymer and textile-reinforced mortars), where the experimental results were used to calibrate a detailed nonlinear finite element analysis to further complete the parametric study, and it was found that the parameters of interest do influence the retrofit effectiveness.…”

Section: Introductionmentioning

confidence: 99%

Flange Contribution to the Shear Strength of RC T-Beams with Flange in Compression

et al. 2022

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As is well known, in the current design codes, the shear strength of beams is calculated based on the modified truss theory, which does not consider the effects of the flange area of T-beams. The main objective of this paper was to gain a better understanding and enhance the experimental database of the shear behavior of RC T-beams and illustrate the contribution of the flange to the shear capacity of T-beams. To accomplish this aim, a specially designed experimental program was executed, and its test results were analyzed. The main investigated variables were flange dimensions (thickness and width) and its reinforcement (longitudinal and/or vertical). Nineteen simply supported beam specimens were tested to failure under a load configuration made of two concentrated loads. Eighteen specimens had T-shaped cross-sections, while one specimen had a rectangular cross-section for comparison purposes. The items monitored during testing included the development of diagonal cracks, concrete strains, reinforcement strains, maximum loads, and deflections. Test results showed a notable increase in the shear strength of T-beams compared to rectangular beams with the same web size. For the range of variables investigated, increasing the flange thickness-to-beam depth ratio (ρt) from 0.3 to 0.5 increased the shear capacity by up to 54%. In addition, increasing the flange width-to-web width ratio (ρb) from 3 to 5 increased the shear capacity by up to 19%. It was also shown that the results of three-dimensional finite element (FE) analyses using ANSYS compared reasonably well with the test results for all specimens. Finally, based on the test and FE results, a simplified method that accounts for the contribution of the flange to shear capacity was proposed.

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“…There are many reasons why the existing reinforced concrete (RC) beams frequently require retrofitting. The primary reasons stem from the increase in loading conditions, manufacturing defects, changes in intended usage, or design code requirements and progress in the deterioration mechanisms due to aging of the structure . Uncertainty related to material degradation and some design parameters can dramatically affect the mechanical behavior and expected failure modes over the lifetime of strengthened structures .…”

Section: Introductionmentioning

confidence: 99%

“…The primary reasons stem from the increase in loading conditions, manufacturing defects, changes in intended usage, or design code requirements and progress in the deterioration mechanisms due to aging of the structure. [1][2][3] Uncertainty related to material degradation and some design parameters can dramatically affect the mechanical behavior and expected failure modes over the lifetime of strengthened structures. 4 A key factor in the robustness of strengthening design is comprehensive consideration of the possible failure modes and the durability of materials subjected to harsh environmental conditions.…”

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confidence: 99%

Life cycle reliability assessment of reinforced concrete beams shear‐strengthened with carbon fiber reinforced polymer strips in accordance with fib bulletin 14

Taki

Firouzi

Mohammadzadeh

2018

Structural Concrete

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The results of time‐variant reliability analysis of shear‐strengthened reinforced concrete (RC) beams with externally bonded fiber‐reinforced polymer (FRP) are presented with an emphasis on the effects of environmental harshness and effective design parameters. The effects of chloride‐induced pitting corrosion and FRP degradation are considered using Monte Carlo simulation to assess the influence of environmental deterioration on the fib 2001 limit states instead of applying design reduction factors. For the defined worked example, the proposed method specifies the remaining lifetime of the strengthened beam by considering a reasonable value for the target reliability index. With regard to the reliability index profiles, it is shown that chloride‐induced pitting corrosion has a greater effect on the shear capacity of strengthened beams than the degradation of the FRP. It was found that the FRP reinforcement ratio has a considerable effect on the governing failure mode; hence, it is important to calibrate the proposed safety verifications of fib bulletin 14 using sufficient experimental data for the relevant random variables in a reliability‐based context.

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External bonded shear reinforcement for T‐section beams

Cited by 6 publications

References 11 publications

Developing optimized strengthening systems for shear‐deficient concrete members

Developing optimized strengthening systems for shear‐deficient concrete members

Flange Contribution to the Shear Strength of RC T-Beams with Flange in Compression

Life cycle reliability assessment of reinforced concrete beams shear‐strengthened with carbon fiber reinforced polymer strips in accordance with fib bulletin 14

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