Retrofitting of Reinforced Concrete Beams with CARDIFRC

2014

J. Struct. Eng.

The addition of an external layer of reinforced ultrahigh performance fiber-reinforced concrete (R-UHPFRC) on top of reinforced concrete (RC) floor slabs and bridge decks is an emerging technique for strengthening RC structures. As an additional reinforcement, a layer of R-UHPFRC significantly increases the maximum resistance and deformation capacity of RC elements, thus creating a composite element that herein is referred to as RU-RC elements. This paper presents an elastic-plastic fictitious RU-RC composite hinge model for the damage caused by flexural and flexure-shear cracks in the RC element of the composite members. The model accounts for the nonlinear interaction of the two elements due to intermediate-crack-induced debonding (ICD) zone in the near-interface concrete. The model determines the force-deflection response and force in the RU-RC composite tension chord. Furthermore, the contribution of the R-UHPFRC element and the shear resistance envelope of the member are calculated. Comparison with available experimental results shows that the model can accurately predict the member response, resistance and failure mode. A simplified formulation for the shear resistance of the composite members is proposed. The models in this paper are needed for the design of the structural behavior of RC beams strengthened with R-UHPFRC.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analytical Model for Predicting Response and Flexure-Shear Resistance of Composite Beams Combining Reinforced Ultrahigh Performance Fiber-Reinforced Concrete and Reinforced Concrete

Noshiravani¹,

2014

J. Struct. Eng.

“…1a), the R-UHPFRC layer can be either cast in place or glued as prefabricated elements to the surface of an RC member [1,6]. Casting is done over a rough surface of concrete where the bond is provided by the chemical adherence of the new cement to the old concrete surface and the roughness of the interface.…”

Section: Introductionmentioning

confidence: 99%

“…Dowels or stirrups are not required to connect the two layers. Researchers have independently shown that debonding only begin after the strain-hardening phase and as the steel rebars begin to yield [1,5].…”

Section: Introductionmentioning

confidence: 99%

“…Similar to RC beams, the opening and full development of a flexuralshear crack in the RC element of an RU-RC beam leads to the local flexure-shear collapse of the composite member [1,16]. When subjected to high shear forces, RU-RC members are susceptible to intermediate-crack-induced debonding (ICD) that softens the connection between the two elements [17].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Rotation capacity and stress redistribution ability of R-UHPFRC–RC composite continuous beams: an experimental investigation

Noshiravani

2013

Mater Struct

The results of tests on two continuous composite beams combining a reinforced concrete (RC) beam with a layer of reinforced ultra-high performance fiber reinforced concrete (R-UHPFRC) are presented. The R-UHPFRC element acts both as a tensile membrane and a flexural element. The tests show the element's contribution to the member capacity by allowing the redistribution of the internal forces. The continuous beams are placed on two intermediate supports; the shear span-depth ratios and stirrup content are chosen to provoke two successive formations of local flexure-shear collapse mechanisms, forming a plastic hinge at each support. With the formation of the first support hinge, the stresses redistribute. As the applied actuator displacement increases, the member continues to resist the increasing force up to the formation of a second support hinge that causes the member to collapse. The member deflection and resistance at collapse were respectively 4.5 and 1.3 times greater than the corresponding values at the formation of the first hinge. The response demonstrates the redundancy in RC beams with additional R-UHPFRC reinforcement, which can be used for designing structures against progressive collapse.

Stahl‐UHFB – Stahlbeton Verbundbauweise zur Verstärkung von bestehenden Stahlbetonbauteilen mit Ultra‐Hochleistungs‐Faserbeton (UHFB)

Beton und Stahlbetonbau

Denarié

2013

EinleitungStrengthening of existing reinforced concrete elements using Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) An original concept is presented for the strengthening of concrete structures. The main idea is to use Ultra-High Performance Fibre Reinforced Concrete (UHPFRC) complemented with steel reinforcing bars to strengthen those zones of the structure that are exposed to severe environmental influences and high mechanical loading. This concept combines efficiently protection and resistance properties of UHPFRC and significantly improves the structural performance of the rehabilitated concrete structure in terms of durability. Properties of UHPFRC are outlined and the essential theoretical background of structural behavior of R-UHPFRC -RC composite elements is given. This novel technology has been validated by means of field applications.Bild 1 Grundkonfiguration für die Verstärkung von Stahlbeton mit UHFB Basic configuration for the strengthening of reinforced concrete using UHPFRC