Experimental Tests on FRP Shear Retrofitted RC Beams

Nuti, Camillo; Santini, Silvia; Sguerri, Lorena

doi:10.1007/978-3-642-17487-2_167

“…Often, as described by Lavorato et al [8], the shear strength of reinforced concrete beams reveals insufficient transversal steel reinforcement, mainly due to design or construction defects or increased design load requirements. In this context, the three-point bending test is used to evaluate the structural capacity of beams without and with retrofitting solutions, for example by carbon fiber reinforced polymer (CFRP) reinforcements, as shown by Lavorato et al [42] and Nuti et al [9].…”

Section: Three-point Bending Testmentioning

confidence: 99%

“…This school was located in Tuscany and demolished in 2003 for a structural safety deficiency. Four portions of columns and one beam were transported to the Proof Testing and Research in Structures and Materials (PRiSMa) Laboratory of Roma Tre University, where the authors had already described similar experiences in the field of diagnosis on existing reinforced concrete elements [8][9][10]. It is to be noted that in the above-mentioned research, as well as in the school building presented, the specimens are real RC elements removed from an existing building.…”

Section: Introductionmentioning

confidence: 99%

The Structural Diagnosis of Existing RC Buildings: The Role of Nondestructive Tests in the Case of Low Concrete Strength

Santini

¹

,

Forte

²

,

Sguerri

³

2020

Infrastructures

Self Cite

3

0

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In the structural safety assessment process of existing structures, knowledge of the mechanical properties of the materials is key. Different experimental activities carried out on materials extracted from existing reinforced concrete buildings show a high strength variability, especially concrete. In the past, the lack of standardized quality control for materials and workmanship caused nonuniform and homogeneous properties within the same structure. The most accurate and reliable experimental technique consists of performing direct tests on the materials, but these are considerably expensive and invasive. In this paper, alternative indirect methods that estimate material properties by correlating different physical measures were proved to reduce invasive inspections on existing buildings and infrastructures, especially in built heritage. A complete experimental activity concerning destructive and nondestructive tests was conducted on elements (four portions of a column and a beam portion) removed from an Italian school building built in 1940. Destructive and nondestructive methods were compared and appropriate correlation laws developed to predict the main mechanical properties of the studied material. Reliable correlations were identified considering the pull-out test, Sonic–Rebound (SonReb) combined method and ultrasonic pulse velocities (UPVs). The latter were mapped by tomography, which highlighted the compression properties of concrete in the different structural sections.

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“…Specimen contribution to beam shear strength at support B, where the C-FRP reinforcement was anchored in a zone with negative bending moment. Some details about the tests are reported in Nuti et al (2010Nuti et al ( , 2014. The simply supported beam with cantilever is an isostatic load scheme, and therefore, internal forces, bending moment, and shear depend on the position and intensity of the external applied loads only, as shown in Fig.…”

Section: Tests: Set Up For Loadings and Applied Load Historiesmentioning

confidence: 99%

Nonlinear finite element dynamic analysis of squat shear wall with openings

Gopalarathnam

¹

,

Kumar

²

2013

Int J Adv Struct Eng

2

0

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The shear strength of reinforced concrete beams extracted from existing buildings often reveals insufficient transversal steel reinforcement, mainly due to design or construction defects or increased design load requirements. FRP wrapping is one of the best solutions to improve beam shear strength as the retrofitting intervention is fast and the cost is modest. Design codes provide clear indication about the retrofitting design of simply supported beams, while the case of a beam with negative moments at the end is not considered, although this is in the case of a beam in a framed structure. One of the main uncertainties lies in the effectiveness of the FRP U sheet anchorage behavior in the area of negative bending moments with cracked concrete. This may limit the shear strength of the retrofitted beam. In this study, two beams extracted from an existing building constructed in the 1930s in Rome and retrofitted by carbon fiber-reinforced polymer (C-FRP) U strips placed at beam ends, where also negative bending moments were present, and have been evaluated with experimental tests at the laboratory of the Department of Architecture of Roma Tre University. Beam steel and concrete characteristics were evaluated by means of different tests. The experimental results are discussed considering the final results in terms of maximum shear resistance in the presence of negative bending moments. Load deflections at different points along the beam, shear-C-FRP deformation along the reinforcement strips and the damage state for different load levels, are presented. The importance of avoiding possible fragile mechanisms in the sections retrofitted with FRP is clearly shown.

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Experimental tests on existing RC beams strengthened in flexure and retrofitted for shear by C-FRP in presence of negative moments

Lavorato

¹

,

Bergami

²

,

Fiorentino

³

et al. 2018

Int J Adv Struct Eng

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The shear strength of reinforced concrete beams extracted from existing buildings often reveals insufficient transversal steel reinforcement, mainly due to design or construction defects or increased design load requirements. FRP wrapping is one of the best solutions to improve beam shear strength as the retrofitting intervention is fast and the cost is modest. Design codes provide clear indication about the retrofitting design of simply supported beams, while the case of a beam with negative moments at the end is not considered, although this is in the case of a beam in a framed structure. One of the main uncertainties lies in the effectiveness of the FRP U sheet anchorage behavior in the area of negative bending moments with cracked concrete. This may limit the shear strength of the retrofitted beam. In this study, two beams extracted from an existing building constructed in the 1930s in Rome and retrofitted by carbon fiber-reinforced polymer (C-FRP) U strips placed at beam ends, where also negative bending moments were present, and have been evaluated with experimental tests at the laboratory of the Department of Architecture of Roma Tre University. Beam steel and concrete characteristics were evaluated by means of different tests. The experimental results are discussed considering the final results in terms of maximum shear resistance in the presence of negative bending moments. Load deflections at different points along the beam, shear-C-FRP deformation along the reinforcement strips and the damage state for different load levels, are presented. The importance of avoiding possible fragile mechanisms in the sections retrofitted with FRP is clearly shown.

show abstract

Experimental Tests on FRP Shear Retrofitted RC Beams

Cited by 3 publications

References 2 publications

The Structural Diagnosis of Existing RC Buildings: The Role of Nondestructive Tests in the Case of Low Concrete Strength

The Structural Diagnosis of Existing RC Buildings: The Role of Nondestructive Tests in the Case of Low Concrete Strength

Nonlinear finite element dynamic analysis of squat shear wall with openings

Experimental tests on existing RC beams strengthened in flexure and retrofitted for shear by C-FRP in presence of negative moments

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