Scale effects in prestressed concrete structures: Maximum reinforcement percentage to avoid brittle crushing

Carpinteri, Alberto; Accornero, Federico; Cafarelli, Renato

doi:10.1016/j.engstruct.2022.113911

Cited by 9 publications

(4 citation statements)

References 24 publications

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“…In this context, it is interesting to recall that previous analyses of RC rectangular cross‐sections 24,48,49,61 provided a scale effect on the minimum reinforcement percentage proportional to h −0.15 , and a scale effect on the maximum reinforcement percentage proportional to h −0.25 , thus defining an effective range in which structures can develop a safe ductile behavior at ULS (Figure 13). Current Standards, such as Model Code, 29 BS 81110, 62 AS 3600, 63 and ACI, 57 completely disregard the size‐scale effects on these two reinforcement percentages leading to a wrong assessment of the rotation capacity of real structures 64 .…”

Section: Minimum and Maximum Reinforcement Percentages For Rc Beamsmentioning

confidence: 91%

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Size‐scale effects in high‐performance reinforced and prestressed concrete T‐beams

Cafarelli

Accornero

Carpinteri

2023

Structural Concrete

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Reinforced concrete (RC) and prestressed concrete (PC) structural elements need to be designed in order to guarantee large plastic deformations, avoiding any loss in their load bearing capacity. In this framework, the rotation capacity of RC and PC beams has been demonstrated to be a function of concrete mechanical properties, reinforcement characteristics, and of the structural size. On the other hand, Theory of Plasticity as well as the International Standards completely disregard size‐scale effects and ductile‐to‐brittle transitions, leading to an overlook of the strain‐softening behavior of the concrete matrix and of the rotation capacity of RC beams. On the other hand, the Cohesive/Overlapping Crack Model is able to evaluate concrete cracking in tension and concrete crushing in compression, as well as snap‐back and snap‐through unstable phenomena, steel yielding and/or slippage. This Nonlinear Fracture Mechanics model predicts a reduction in the moment versus rotation plastic plateau by increasing the beam depth and/or the reinforcement percentage. The numerical investigations carried out on reinforced and prestressed high‐performance concrete beams having rectangular or T‐shaped cross‐sections highlight the size‐scale effects on plastic rotation capacity that allow to formulate new scale‐dependent upper and lower limits of reinforcement percentage to guarantee a stable and ductile postpeak behavior of reinforced concrete structures.

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Section: Minimum and Maximum Reinforcement Percentages For Rc Beamsmentioning

confidence: 91%

“…13 . In this context, it is interesting to recall that previous analyses of RC rectangular cross-sections 24,48,49,61 provided a scale effect on the minimum reinforcement percentage proportional to h À0. 15 , and a scale effect on the maximum reinforcement percentage proportional to h À0.…”

Section: Minimum and Maximum Reinforcement Percentages For Rc Beamsmentioning

confidence: 94%

Size‐scale effects in high‐performance reinforced and prestressed concrete T‐beams

Cafarelli

Accornero

Carpinteri

2023

Structural Concrete

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“…In order to overcome these evident shortcomings, several parametric analyses are performed in the following by means of the cohesive/overlapping crack model (COCM). [18][19][20][21][22]…”

Section: Introductionmentioning

confidence: 99%

“…From a fracture mechanics point of view, considering that no plastic plateau can be envisaged in the stress–strain behavior of GFRP bars, current AASHTO, ACI, and FIB codes offer an unsafe approach that considers only structural brittleness instead of ductility, which, on the contrary, is a crucial characteristic for a correct structural design. In order to overcome these evident shortcomings, several parametric analyses are performed in the following by means of the cohesive/overlapping crack model (COCM) 18–22 …”

Section: Introductionmentioning

confidence: 99%

Scale effects in GFRP‐bar reinforced concrete beams

Accornero

Cafarelli

Carpinteri

et al. 2023

Structural Concrete

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Glass fiber‐reinforced polymer (GFRP)‐reinforced concrete (RC) can be defined as a cementitious material in which the reinforcing secondary phase consists in corrosion‐resistant GFRP rebars. For this next‐generation structural material, experimental flexural tests highlight how the postcracking response is strongly affected by the amount of GFRP area together with the structural size‐scale. In this work, the cohesive/overlapping crack model (COCM) is adopted to describe the transition between cracking and crushing failures occurring in GFRP‐RC beams by increasing the beam depth, the reinforcement percentage, and/or the concrete compression strength. Within this nonlinear fracture mechanics model, the tensile and compression ultimate behaviors of the concrete matrix are modeled through two different process zones that advance independently one of another. Moreover, this model is able to investigate local mechanical instabilities occurring in the structural behavior of GFRP‐RC beams: tensile snap back and snap‐through, which are due to concrete cracking and reinforcement bridging action, and the compression snap‐back generated by the unstable growth of the crushing zone. In this context, the application of the COCM highlights that the ductility, which is represented by the plastic rotation capacity of the GFRP‐RC beam only when the reinforcement can slip, decreases as reinforcement percentage and/or beam depth increase. In this way, rational and quantitative definitions of hyperstrength and brittle compression crushing behaviors can be provided as a GFRP percentage depending on the beam depth.

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