*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.

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Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures

This updated, definitive reference book on concrete technology covers the fundamentals and detailed information on freshly mixed and hardened concrete for Canada The properties of concrete as needed in concrete construction are presented, including strength and durability All concrete ingredients are reviewed for their optimal use in designing and proportioning concrete mixtures Applicable standards from the American Society for Testing and Materials, Canadian Standards Association and American Concrete Institute are referred to extensively Individual chapters address: (1) fundamentals of concrete; (2) Portland, blended and other hydraulic cements; (3) fly ash, slag, silica fume and natural pozzolans; (4) mixing water; (5) aggregates for concrete; (6) admixtures for concrete; (7) fibers; (8) air-entrained concrete; (9) designing and proportioning normal concrete mixtures; (10) batching, mixing, transporting and handling concrete; (11) placing and finishing concrete; (12) curing concrete; (13) hot weather concreting; (14) cold-weather concreting; (15) volume changes of concrete; (16) control tests for concrete; (17) high-performance concrete; and (18) special types of concrete

Design and Control of Concrete Mixtures

Modeling of strength of high-performance concrete using artificial neural networks

External bonding of steel plates has been used to strengthen deficient reinforced-concrete structures since the 1960s. In recent years, fiber-reinforced polymer (FRP) plates have been increasingly used to replace steel plates due to their superior properties. A key issue in the design of an effective retrofitting solution using externally bonded plates is the end anchorage strength. This paper first presents a review of current anchorage strength models for both FRP-to-concrete and steel-to-concrete bonded joints under shear. These models are then assessed with experimental data collected from the literature, revealing the deficiencies of all existing models. Finally, a new simple and rational model is proposed based on an existing fracture mechanics analysis and experimental observations. This new model not only matches experimental observations of bond strength closely, but also correctly predicts the effective bond length. The new model is thus suitable for practical application in the design of FRP-to-concrete as well as steel-to-concrete bonded joints.

Anchorage strength models for FRP and steel plates bonded to concrete

Bond-slip models for FRP sheets/plates bonded to concrete

The authors conducted an experimental and theoretical comparison between flexural behaviors of concrete beams reinforced with fiber reinforced plastic (FRP) reinforcing bars and identical conventionally reinforced ones. Comparisons were made in relation to cracking behavior, load-carrying capacities and modes of failure, load-deflection response, flexural rigidity, and strain distribution. The results revealed that perfect bond exists between FRP reinforcing bars and the surrounding concrete. Also, American Concrete Institute (ACI) Code formulas for predicting deflection response, cracking-ultimate moments, and cracked-effective moments of inertia can easily be adapted for modeling the flexural behavior of concrete beams reinforced with FRP reinforcing bars if appropriate modifications are made.

Flexural response of concrete beams reinforced with FRP reinforcing bars

This paper presents a comprehensive design approach for reinforced concrete flexural beams and unidirectional slabs strengthened with externally bonded fiber-reinforced-plastic (FRP) plates. The ap...

Strengthening of reinforced concrete beams with externally bonded fiber-reinforced-plastic plates: design guidelines for shear and flexure

The dynamic amplification factor (DAF) is an important parameter in the design of highway bridges and yet no worldwide consensus has been reached so far as to its value. Some disagreement exists be...

Bridge dynamics and dynamic amplification factors — a review of analytical and experimental findings

This paper focuses on shear strengthening of reinforced concrete (RC) beams with externally bonded fiber-reinforced polymer (FRP) composites. Its aims are to synthesize findings of the research studies conducted to date, and to examine and analyze the parameters that have the greatest influence on the shear behavior of RC members strengthened with externally bonded FRP. Over 100 tests were considered in the synthesis. Several conclusions were drawn from this work and are discussed. It was found that the parameters related to the properties of the FRP and to those of the shear steel reinforcement are not the only ones having an influence on the shear behavior of RC members strengthened with externally bonded FRP. The shear span ratio a/d, longitudinal steel reinforcement ratio, and geometry of the member also have influence on the shear behavior of these members and deserve further investigation. An experimental parametric study with close variable control is recommended.

Shear strengthening reinforced concrete beams with fiber-reinforced polymer: assessment of influencing parameters and required research

This paper presents results of an experimental investigation on the response of reinforced concrete beams strengthened in shear using externally applied epoxy-bonded unidirectional carbon-fiber plastic side strips. Three series of 1,300-mm-long reinforced concrete (RC) beams are considered: (1) a series of beams having full strength in shear; (2) a series of beams underreinforced in shear; and (3) a series of beams strengthened in shear. Side strips placed either perpendicularly or diagonally to a beam’s longitudinal axis provided the external shear reinforcement. The beams were instrumented and tested under four-point load conditions. Results show the feasibility of using epoxy-bonded strips to restore or increase the load-carrying capacity in shear of RC beams while substantially reducing shear cracking. RC beams strengthened by diagonal side strips outperformed those strengthened with vertical side strips. However, under extreme loading conditions concrete may be torn off at anchorage zone where high concentration of tensile normal stresses is present.

Omar Chaallal

Papers

Flexural response of concrete beams reinforced with FRP reinforcing bars

Strengthening of reinforced concrete beams with externally bonded fiber-reinforced-plastic plates: design guidelines for shear and flexure

Bridge dynamics and dynamic amplification factors — a review of analytical and experimental findings

Shear strengthening reinforced concrete beams with fiber-reinforced polymer: assessment of influencing parameters and required research

Shear strengthening of rc beams by externally bonded side cfrp strips