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Shear behaviour of RC-UHPFRC composite beams without transverse reinforcement
Highlights Shear tests on RC beams strengthened with UHPFRC layer. Studied variables: reinforcement ratio in the existing RC substrate, reinforcement ratio in the UHPFRC layer, size effect. Significant strengthening ratios were achieved and the failure mode of the strengthened beams is significantly less brittle than that of the reference beams. The shear force at the instant of sudden critical shear crack propagation is well predicted using a composite failure criterion based on the critical shear theory and accounting for the UHPFRC layer. The model based on the upper bound theorem of limit analysis provides safe estimates of the shear strength of the smaller specimens representative of typical building or bridge slabs.
Abstract Strengthening existing reinforced concrete (RC) beams and slabs using a thin layer of ultra-high performance fibre reinforced cementitious composites (UHPFRC), plain (U) or reinforced (RU) with ordinary steel bars, has been shown to be a very effective way of increasing the flexural capacity in hogging moment regions. However, as the increase in the flexural strength can be very significant, the shear strength of the composite RC-RU or RC-U elements may govern the capacity of the strengthened element and must be conveniently assessed to provide suitable design recommendations. In this regard, the available experimental evidence concerning the shear strength of beams (or one-way shear strength for slabs) is relatively limited. In this work, the results of an experimental campaign are presented where the influence of important parameters was systematically evaluated, namely the reinforcement ratios in the original RC beam and the new UHPFRC layer, the size effect, the thickness of the UHPFRC layer and the sign of the being moment - hogging or sagging - changing the state of stress in the UHPFRC layer from tensile to compressive. The structural behaviour is discussed, and an analytical approach for calculating the shear strength is evaluated.
Shear behaviour of RC-UHPFRC composite beams without transverse reinforcement
Highlights Shear tests on RC beams strengthened with UHPFRC layer. Studied variables: reinforcement ratio in the existing RC substrate, reinforcement ratio in the UHPFRC layer, size effect. Significant strengthening ratios were achieved and the failure mode of the strengthened beams is significantly less brittle than that of the reference beams. The shear force at the instant of sudden critical shear crack propagation is well predicted using a composite failure criterion based on the critical shear theory and accounting for the UHPFRC layer. The model based on the upper bound theorem of limit analysis provides safe estimates of the shear strength of the smaller specimens representative of typical building or bridge slabs.
Abstract Strengthening existing reinforced concrete (RC) beams and slabs using a thin layer of ultra-high performance fibre reinforced cementitious composites (UHPFRC), plain (U) or reinforced (RU) with ordinary steel bars, has been shown to be a very effective way of increasing the flexural capacity in hogging moment regions. However, as the increase in the flexural strength can be very significant, the shear strength of the composite RC-RU or RC-U elements may govern the capacity of the strengthened element and must be conveniently assessed to provide suitable design recommendations. In this regard, the available experimental evidence concerning the shear strength of beams (or one-way shear strength for slabs) is relatively limited. In this work, the results of an experimental campaign are presented where the influence of important parameters was systematically evaluated, namely the reinforcement ratios in the original RC beam and the new UHPFRC layer, the size effect, the thickness of the UHPFRC layer and the sign of the being moment - hogging or sagging - changing the state of stress in the UHPFRC layer from tensile to compressive. The structural behaviour is discussed, and an analytical approach for calculating the shear strength is evaluated.
Shear behaviour of RC-UHPFRC composite beams without transverse reinforcement
Sine, Aurélio (author) / Pimentel, Mário (author) / Nunes, Sandra (author) / Dimande, Américo (author)
Engineering Structures ; 257
2022-02-20
Article (Journal)
Electronic Resource
English
Shear strength of UHPFRC I-shaped beams without stirrups
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SHEAR BEHAVIOR OF BEAMS WITHOUT TRANSVERSE REINFORCEMENT
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Shear Strength of UHPFRC Beams Without Stirrups: Fracture Mechanics Approach
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