Experimental study of bond–slip in RC structural elements with plain bars

Melo, José; Rossetto, Tiziana; Varum, Humberto

doi:10.1617/s11527-014-0320-9

Cited by 45 publications

(20 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Since adhesion is found to cause 60% of the bond strength of smooth bars [ 40 ], it would only be about 10% for ribbed bars (assuming the bar geometry does not change the concrete-steel adhesion). Experimental research shows bond strengths for smooth rebars of between 1.5 and 2.5 MPa [ 41 , 42 ], which globally corresponds with the results of [ 39 ].…”

Section: Cable Reinforcementsupporting

confidence: 77%

“…Since the 1970s, the use of smooth bars has been discontinued in Europe in favour of ribbed bars because of their far superior bond properties caused by the much higher dilatancy resistance. The bond resistance of ribbed bars is found to be approximately 6.6 times as high as for smooth bars [ 39 ]. This, naturally, also influences the proportion between adhesive and dilatancy resistance.…”

Section: Cable Reinforcementmentioning

confidence: 99%

See 1 more Smart Citation

Experimental Exploration of Metal Cable as Reinforcement in 3D Printed Concrete

et al. 2017

View full text Add to dashboard Cite

The Material Deposition Method (MDM) is enjoying increasing attention as an additive method to create concrete mortar structures characterised by a high degree of form-freedom, a lack of geometrical repetition, and automated construction. Several small-scale structures have been realised around the world, or are under preparation. However, the nature of this construction method is unsuitable for conventional reinforcement methods to achieve ductile failure behaviour. Sometimes, this is solved by combining printing with conventional casting and reinforcing techniques. This study, however, explores an alternative strategy, namely to directly entrain a metal cable in the concrete filament during printing to serve as reinforcement. A device is introduced to apply the reinforcement. Several options for online reinforcement media are compared for printability. Considerations specific to the manufacturing process are discussed. Subsequently, pull-out tests on cast and printed specimens provide an initial characterisation of bond behaviour. Bending tests furthermore show the potential of this reinforcement method. The bond stress of cables in printed concrete was comparable to values reported for smooth rebar but lower than that of the same cables in cast concrete. The scatter in experimental results was high. When sufficient bond length is available, ductile failure behaviour for tension parallel to the filament direction can be achieved, even though cable slip occurs. Further improvements to the process should pave the way to achieve better post-crack resistance, as the concept in itself is feasible.

show abstract

Section: Cable Reinforcementsupporting

confidence: 77%

Section: Cable Reinforcementmentioning

confidence: 99%

Experimental Exploration of Metal Cable as Reinforcement in 3D Printed Concrete

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Bond was very sensitive to surface roughness and peaked at a very low slip, typically of 0.01 mm or less, suggesting resistance was almost entirely attributable to adhesion and that the friction component active at higher slips was absent. Melo et al 11 proposed a bond-slip relationship based on loaded end slips. Hot rolled bars were used "as delivered" with mill scale largely intact.…”

Section: Local Bond-slip Modelsmentioning

confidence: 99%

Local bond–slip model for plain surface reinforcement

Cairns

2020

Structural Concrete

View full text Add to dashboard Cite

Nowadays virtually all-concrete construction uses reinforcement with deformations rolled or indented on the bar surface to improve bond between bar and concrete, but many older structures built with plain surface bars remain in service. The increasing need for assessment of existing construction means there is a continuing need for information on their performance. Research into plain surface bars essentially ceased when ribbed bars became established, and plain bars have consequently been bypassed in developments in understanding and modeling of bond since 1960. The profession's ability to numerically model behavior of concrete structures has expanded dramatically since plain surface reinforcement was discontinued. The option of numerically modeling may be particularly important for assessment of existing structures with noncompliant details. Although the fib Model Code 2010 includes a local bond-slip model for plain surface bars, information on the derivation of the model and supporting evidence of its validation are not available. The current paper analyses data on bond-slip behavior of plain surface bars and demonstrates shortcomings in the fib model. An improved model is proposed and verified against test data from an independent source. K E Y W O R D S anchorage, assessment, bond slip, local bond, plain bars 1 | INTRODUCTION Code committees have responded to the increasing requirement to verify capacity of existing structures by developing codes oriented toward assessment as well as new design. The American Concrete Institute (ACI) first published its Code Requirements for Evaluation, Repair, and Rehabilitation of Concrete Buildings in 2013. 1 The version of EN1992 currently under development will include content on assessment, as will the fib Model Code

show abstract

“…Numerous empirical and simplified relationships are provided in the literature to estimate the bond strength of non-corroded plain bars embedded in concrete, often as a result of a large number of pull-out tests [33][34][35][36]. Verderame et al [34] estimated the maximum bond strength to 31% of the square root of the concrete cylindrical compressive strength, in megapascal.…”

Section: Average Bond Strength In the Unyielded Zonementioning

confidence: 99%

“…Verderame et al [34] estimated the maximum bond strength to 31% of the square root of the concrete cylindrical compressive strength, in megapascal. Melo et al [35] and Feldman and Bartlett [36] agreed on the dependence of the bond strength on the concrete compressive strength, but considered also the yield stress of steel (Melo et al) and the surface roughness and the development length (Feldman and Barlett). All the experimental results presented in these works had less than 3 MPa of maximum bond strength.…”

Section: Average Bond Strength In the Unyielded Zonementioning

confidence: 99%

Anchorage of naturally corroded, plain reinforcement bars in flexural members

et al. 2020

View full text Add to dashboard Cite

Reinforced concrete structures are often damaged by corrosion, which affects the interaction between reinforcement bars and concrete. Earlier studies mostly applied artificial corrosion to test the bond between deformed bars and concrete. However, there is a lack of knowledge on the effects of natural corrosion on plain bars. In this paper, 20 beams with naturally corroded plain bars and varying amount of damage were taken from an 80-year-old bridge and tested in three-point bending. All but three of the specimens anchored the yield force of the bars after the opening of one or two major bending cracks. At large deflections, the load-carrying mechanism changed from beam to arch action. Eventually, end-slip of the reinforcement bars was observed. The bars were extracted, cleaned, three-dimensionally scanned, and tested in tension. The average bond strength in the unyielded zone was found to be equal to 7.39 MPa, with a standard deviation of 3.33 MPa. The casting position was identified as an important factor: when uncorroded, bottom-cast bars had a higher bond strength than that of top-cast bars. However, they were more prone to splitting cracks and, consequently, loss of bond strength for small corrosion levels. Topcast bars had increasing bond strength with increasing corrosion levels, owing to the absence of external cracks. These differences were likely related to a denser concrete surrounding the bottom-cast bars. The remaining bond capacity in the yielded zones was evaluated to be approximately 1.0 MPa.

show abstract

Experimental study of bond–slip in RC structural elements with plain bars

Cited by 45 publications

References 5 publications

Experimental Exploration of Metal Cable as Reinforcement in 3D Printed Concrete

Experimental Exploration of Metal Cable as Reinforcement in 3D Printed Concrete

Local bond–slip model for plain surface reinforcement

Anchorage of naturally corroded, plain reinforcement bars in flexural members

Contact Info

Product

Resources

About