Concrete Beams Strengthened with Externally Bonded FRP Plates

Abstract:As an alternative to externally bonded FRP reinforcement, near-surface mounted (NSM) FRP reinforcement can be used to effectively improve the flexural performance of RC beams. In such FRP-strengthened RC beams, end cover separation failure is one of the common failure modes. This failure mode involves the detachment of the NSM FRP reinforcement together with the concrete cover along the level of the steel tension reinforcement. This paper presents a new analytical strength model for end cover separation failure in RC beams strengthened in flexure with NSM FRP strips (i.e. rectangular FRP bars with a sectional height-to-thickness ratio not less than 5), which was formulated on the basis of extensive numerical results from a parametric study undertaken using an efficient finite element approach. The proposed strength model consists of an approximate analytical equation for the debonding strain of the FRP reinforcement at the critical cracked section and a conventional section analysis to relate this debonding strain to the moment acting on the same section (i.e. the debonding strain). Once the debonding strain is known, the load level at end cover separation of an FRP-strengthened RC beam can be easily determined for a given load distribution. Predictions from the proposed strength model are compared with those of two existing strength models of the same type and available test results, which shows that the proposed strength model is in close agreement with test results and is far more accurate than the existing strength models.

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“…[13][14][15] and several analytical strength models for this failure mode have been established [e.g. [16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Strength model for end cover separation failure in RC beams strengthened with near-surface mounted (NSM) FRP strips

Teng

Zhang

Chen

2016

Engineering Structures

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“…Fiber reinforced composites create average impact to temperatures when the thermal source involved. Form [1][2] as the temperature increases, the impact strength of the composites decrease steadily [6][7][8]. The bagasse fiber has been reinforced with polyester resin in addition to its mechanical properties were distinguished.…”

Section: Frp On Polyester Resinmentioning

confidence: 99%

Computational analysis of frp composite under different temperature gradient

Gunasekar

Manigandan

2017

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract.Composite material strength depends on the stiffness of fiber and the resin which is used for reinforcement. The strength of the laminate can be increased by applying good manufacturing practices. The strength is directly depending on the property of resin. The property of the any compound subjected to changed when they exposed to the temperature. This paper investigates the strength of laminate when they subjected to different temperature gradient of resin while manufacturing. The resin is preheated before adding hardener with them. These types of laminate reinforced with resin at different levels of temperature 20c, 40c, and 60c. These different temperature resin are used for reinforcement and the specimen tested. The comparative results are made to find how the stiffness of laminate changes with respect to the thermal property of resin. The results are helpful to obtain high strength laminate. IntroductionRecent years, quick advance in construction materials skill have enabled civil engineers to attain impressive gains in the economy and safety. The earliest FRP materials used glass fibers rooted in polymeric resins that were made available at World War II. The combination of high-strength, stiffness structural fibers with low cost and lightweight. The environmentally challenging polymers resulted in composite materials with mechanical properties and durability superior than metals. Fiber materials such as boron, carbon, and aramid, were used in space exploration and air due to its higher strength, higher stiffness, and lower density. Stable cross-sectioned FRP composite are produced for use in the construction industry for building bridge and other superstructures. Recent research on pultruded FRP shapes is very high.

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“…In fact, a large number of experimental studies reported premature failures by debonding rather than concrete crushing or FRP rupture. For this reason, considerable research effort has been expended on understanding the underlying factors that cause FRP debonding, to develop models for predicting debonding, and to propose design guidelines to minimize the risk of its occurrence under design loading conditions [2,8,9,10].…”

Section: Introductionmentioning

confidence: 99%

Statistical analysis of existing models for flexural strengthening of concrete bridge beams using FRP sheets

Ceci

Casas

Ghosn

2012

Construction and Building Materials

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This paper performs a statistical analysis of previously proposed models for resisting the debonding of FRP sheets used in strengthening reinforced and prestressed concrete beams. End debonding and intermediate crack-induced debonding modes of failure are studied for beams in flexure. Two different databases are assembled from published experimental debonding tests on concrete beams of different span lengths. The first database contains the results of four point bending tests performed to study the behavior of the FRP-concrete bond at the end of the FRP sheet. The second database which includes four point bending tests, three point bending tests and one point loading tests, has been created to examine intermediate crack-induced debonding. These two databases are significantly larger than those used in developing any of the existing debonding strength models and provide a solid basis for assessing the performance of such models. A regression analysis reviews the relationship between the experimentally measured loads that caused debonding to the model predicted values as well as the bias and the variability in the prediction models. This regression analysis allows for drawing conclusions on the most appropriate and accurate models, from a statistical point of view, that may be used in a follow up reliability-based calibration of partial safety factors. The applicability of such information for the development of design specifications for strengthening of deteriorated concrete bridges is highlighted. This will be implemented in a forthcoming companion paper.

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Concrete Beams Strengthened with Externally Bonded FRP Plates

Cited by 305 publications

References 20 publications

Strength model for end cover separation failure in RC beams strengthened with near-surface mounted (NSM) FRP strips

Strength model for end cover separation failure in RC beams strengthened with near-surface mounted (NSM) FRP strips

Computational analysis of frp composite under different temperature gradient

Statistical analysis of existing models for flexural strengthening of concrete bridge beams using FRP sheets

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