Flexural Strengthening of RC Beams with Cement-Based Composites
01 Oct 2011-Journal of Composites for Construction (American Society of Civil Engineers)-Vol. 15, Iss: 5, pp 707-720
TL;DR: In this article, the effectiveness of fiber-reinforced cementitious matrix (FRCM) materials for the strengthening of reinforced concrete (RC) beams is experimentally investigated.
Abstract: In this paper, the effectiveness of fiber-reinforced cementitious matrix (FRCM) materials for the strengthening of reinforced concrete (RC) beams is experimentally investigated. Bending tests on RC beams strengthened with different FRCM materials, made out of (1) carbon fiber nets; and (2) poliparafenilenbenzobisoxazole (PBO) fiber nets embedded in cement-based matrix, are performed. For case (2), different net shapes, cementitious matrices, and a number of net layers were considered. Depending on the type of fibers and matrix, different flexural debonding failure modes are identified. The fiber strain at debonding is evaluated by comparing the experimental results with those obtained with two different theoretical models. The results obtained in this study confirm the effectiveness of FRCM materials for the strengthening of RC structures and encourage further experimental and theoretical work on the topic. A better understanding of the debonding phenomenon is crucial for an optimal design of the strength...
Citations
More filters
TL;DR: In this article, the effectiveness of externally bonded strengthening for reinforced concrete (RC) elements strongly depends on the bond between the strengthening material and the concrete and on the mechanical properties of the concrete cover.
Abstract: The effectiveness of externally bonded strengthening for reinforced concrete (RC) elements strongly depends on the bond between the strengthening material and the concrete and on the mechanical properties of the concrete cover In this paper the bond between fiber reinforced cementitious matrix (FRCM) materials made out of a poliparafenilenbenzobisoxazole (PBO) net embedded in a cement based matrix and the concrete is experimentally analyzed Experimental results of double shear tests involving different bond lengths and fibers cross sections are presented The results allow to estimate the effective anchorage length and evidence that the debonding occurs at the fibers/matrix interface after a considerable fibers/matrix slip They also confirms the effectiveness of the FRCM materials as external reinforcements for concrete The obtained experimental results can be used to calibrate a local bond-slip relation to be used in the design of the external reinforcement
252 citations
Cites background or result from "Flexural Strengthening of RC Beams ..."
...A similar type of debonding has been also observed in [17] in the case of flexural tests on RC beams strengthened with PBO-FRCM materials and in [30] in the case of single face shear tests....
[...]
...Indeed in the case of the FRP materials the debonding surface is, in the most cases, placed within the concrete, while in the case of the FRCM materials different debonding mechanisms, also involving the fibers/matrix interface, are observed [8,17]....
[...]
...In the case of the FRCM materials in most of the performed experimental analyses [9,12,13,15–17] the failure of the RC strengthened members was caused or initiated by the loss of the strengthening action consequent to the debonding of the FRCM material....
[...]
...This last observation qualitatively agrees with the experimental results of beams strengthened for flexure with PBO-FRCM materials presented in [17], in which the fibers debonding strain decreases less than proportionally to 1= ffiffiffi n p with the increase of the number of layers n....
[...]
...Experimental results relative to strengthening materials similar to those considered in this paper can be found in [1,15–17] for the case of flexural strengthening of concrete beams....
[...]
TL;DR: The results of single-lap shear tests, conducted on specimens with fiber reinforced cementitious matrix (FRCM) composite strips bonded to concrete blocks, are presented in this paper.
214 citations
Cites background from "Flexural Strengthening of RC Beams ..."
...The limited available literature [1–23] reports that FRCM composites can be used effectively for strengthening and rehabilitation of RC structures....
[...]
TL;DR: In this paper, the carbon-firm reinforced cementitious matrix (FRCM) materials made out of a carbon net embedded in a cement-based matrix and the masonry is experimentally and analytically investigated.
Abstract: Historical masonry constructions often need to be strengthened and upgraded to satisfy current seismic code requirements. Recently many interventions have been done bonding composite materials to the surface of existing masonry elements. The effectiveness of these interventions strongly depends on the bond between the strengthening material and the masonry and on the mechanical properties of the masonry substrate. In this paper the bond between fiber reinforced cementitious matrix (FRCM) materials made out of a Carbon net embedded in a cement based matrix and the masonry is experimentally and analytically investigated. Experimental results of double shear tests involving different bond lengths are presented. The results evidence that the debonding occurs at the fibers/matrix interface after a considerable fibers/matrix slip. They also confirms the effectiveness of the Carbon-FRCM materials as external reinforcements for masonry structures. The obtained experimental results are used to calibrate a local bond-slip relation that is essential in the modeling of the structural behavior of masonry elements strengthened with Carbon-FRCM.
202 citations
TL;DR: In this paper, the bond between fiber reinforced cementitious matrix (FRCM) materials made out of a poliparafenilenbenzobisoxazole (PBO) net embedded in a cement based matrix and the concrete is analyzed with reference to the approach generally adopted for the fiber reinforced polymers (FRP) materials, which is based on the local bond-slip relation between the strengthening fibers and the supporting concrete.
Abstract: Existing reinforced concrete (RC) structures often need to be repaired, strengthened and upgraded to satisfy current code requirements. In recent years many interventions have been done bonding composite materials to the surface of existing RC elements. The structural effectiveness of these interventions strongly depends on the bond between the strengthening material and the concrete and on the mechanical properties of the concrete cover. In this paper the bond between fiber reinforced cementitious matrix (FRCM) materials made out of a poliparafenilenbenzobisoxazole (PBO) net embedded in a cement based matrix and the concrete is analytically analyzed with reference to the approach generally adopted for the fiber reinforced polymers (FRP) materials, which is based on the local bond-slip relation between the strengthening fibers and the supporting concrete. A local bond-slip relation is calibrated on the base of the results of an experimental investigation previously performed by the authors. The bond-slip relation is essential in the modeling of the structural behavior of RC elements strengthened with PBO-FRCM, in that it allows to calculate the force that can be transferred to the concrete, the effective anchorage length, the concrete cracks distance and opening.
188 citations
TL;DR: In this paper, a procedure that combines the results of direct tensile and shear bond tests to provide engineering design parameters for externally bonded FRCM reinforcements is proposed, which is suitable for standard product qualification and material assurance purposes.
Abstract: Fibre Reinforced Cementitious Matrix (FRCM) composites are now widely used for repair and retrofitting existing structures. Guidelines for product qualification are needed to characterize the strengthening systems before they are made available in the market and installed. The paper proposes a procedure that combines the results of direct tensile and shear bond tests to provide engineering design parameters for externally bonded FRCM reinforcements. Due to the possible occurrence of different failure modes, the procedure provides results on the base of the weakest mechanism that takes place. Thanks to its simplicity, the proposed method is suitable for standard product qualification and material assurance purposes. In order to investigate its feasibility, the qualification procedure is applied to different reinforcements comprising basalt, carbon, glass, and steel textiles, bonded with either cement or lime mortars to clay bricks and tuff units.
165 citations
References
More filters
01 Jan 2002
TL;DR: The Emerging Technology Series as mentioned in this paper is a series of information and recommendations based on available test data, technical reports, limited experience with field applications, and the opinions of committee members, with a focus on the development and appropriate use of new and emerging technologies.
Abstract: *Co-chairs of the subcommittee that prepared this document. Note: The committee acknowledges the contribution of associate member Paul Kelley. ACI encourages the development and appropriate use of new and emerging technologies through the publication of the Emerging Technology Series. This series presents information and recommendations based on available test data, technical reports, limited experience with field applications, and the opinions of committee members. The presented information and recommendations, and their basis, may be less fully developed and tested than those for more mature technologies. This report identifies areas in which information is believed to be less fully developed, and describes research needs. The professional using this document should understand the limitations of this document and exercise judgment as to the appropriate application of this emerging technology.
2,963 citations
Book•
01 Jan 1993
Abstract: Inevitably, reading is one of the requirements to be undergone. To improve the performance and quality, someone needs to have something new every day. It will suggest you to have more inspirations, then. However, the needs of inspirations will make you searching for some sources. Even from the other people experience, internet, and many books. Books and internet are the recommended media to help you improving your quality and performance.
1,578 citations
TL;DR: The application of textile reinforced mortar (TRM) as a means of increasing the shear resistance of reinforced concrete members is investigated in this article, where it is concluded that textile-mortar jacketing provides substantial gain in shear resilience; this gain is higher as the number of layers increases and is sufficient to transform shear type failure to flexural failure.
Abstract: The application of textile reinforced mortar (TRM) as a means of increasing the shear resistance of reinforced concrete members is investigated in this study. TRM may be considered as an alternative to fiber reinforced polymers (FRP), providing solutions to many of the problems associated with application of the latter without compromising much the performance of strengthened members. Based on the experimental response of reinforced concrete members strengthened in shear it is concluded that textile-mortar jacketing provides substantial gain in shear resistance; this gain is higher as the number of layers increases and, depending on the number of layers, is sufficient to transform shear-type failure to flexural failure. TRM jackets were provided in this study either by conventional wrapping of fabrics or by helically applied strips. Both systems resulted in excellent results in terms of increasing the shear resistance. However, compared with their resin-impregnated counterparts, mortar-impregnated textiles may result in reduced effectiveness. Modelling of reinforced concrete members strengthened in shear with TRM jackets instead of FRP ones is presented by the authors as a rather straightforward procedure by the proper introduction of experimentally derived jacket effectiveness coefficients. From the limited results obtained in this study it is believed that TRM jacketing is an extremely promising solution for increasing the shear resistance of reinforced concrete members.
322 citations
TL;DR: In this article, the application of textile-reinforced mortars (TRMs) as a means of increasing the axial capacity of concrete through confinement is investigated experimentally in this study.
Abstract: The application of textile-reinforced mortars (TRMs) as a means of increasing the axial capacity of concrete through confinement is investigated experimentally in this study. TRM may be thought of as an alternative to fiber-reinforced polymers (FRPs), addressing many of the problems associated with application of the latter without compromising performance by a significant degree. Based on the response of confined cylinders and short rectangular columns, it is concluded that textile-mortar jacketing provides a substantial gain in compressive strength and deformability; this gain is higher as the number of confining layers increases and depends on the tensile strength of the mortar. Compared with their resin-impregnated counterparts, mortar-impregnated textiles may result in reduced effectiveness. This reduction was more pronounced in cylindrical specimens but rather insignificant in rectangular ones. Favorable confinement characteristics on rectangular columns were also obtained by using helically applied unbonded strips with end anchorages-an interesting concept that deserves further investigation. Modeling of concrete confined with jackets other than resin-impregnated ones is presented by the authors as a rather straightforward procedure through the proper introduction of experimentally derived jacket effectiveness coefficients. From the results obtained in this study, it is believed that TRM jacketing is an extremely promising solution for the confinement of reinforced concrete.
302 citations