Experimental Investigation of Steel-Concrete Bond for Thin Reinforcing Bars

Abstract

The steel-concrete bond is a fundamental property in reinforced concrete structures. Although there are several studies on the steelconcrete bond, few of them have evaluated the performance of reinforcing bars with diameters less than 10.0 mm, which includes 5.0, 6.3, and 8.0 mm diameters, which are normally used in reinforced-concrete elements. This study experimentally evaluates the bond between thin steel bars and concrete of 25MPa compression strength. Three types of methods of testing the bond-strength were performed: confined bar test, pull-out test and beam test. It was compared the adequacy of the tests to calculate the conformation coefficient of the bars. The results of the confined bars tests show that this test may be inadequate to determine the surface conformation coefficient of reinforcing bars thinner than 10 mm, especially for notched (CA-60) steel bars. The pull-out test resulted in better results in terms of evaluating the bond behavior. Regarding the specimens for the pull-out tests, a modified model with an anchorage length equal to 10 times the bar diameter is suggested. Therefore, the main contribution of this study, based on the results obtained and the methodology used, is to present a proposal for the evaluation of steel-concrete bond for thin rebars.

Predicting the Bond Strength of thin Steel Rebars in Concrete by Means of Artificial Neural Networks

“…This work required the acquisition of reliable experimental data to determine the bond steel-concrete through computational intelligence. The database chosen was obtained from Carvalho et al [4]. This database presents 89 experimental tests.…”

“…The type of surface geometry of steel bars present in this study is ribbed (type 1) and notched (type 2). The presented data provided by Carvalho et al [4] are consolidated and have a proper distribution for input and output variables. Still, it was necessary to implement the feature scaling technique to adequately standardize the data used.…”

“…This work aimed to present the study of computational intelligence applied to define the bond strength from an original database obtained by Carvalho et al [4]. A machine learning method, known as an artificial neural network, is used to find the maximum applied load.…”

“…Many authors have conducted experimental investigations into the most critical influence parameters upon the bond, and the bond characteristics are usually affected by the bar diameter, the anchorage length of bars, the concrete compressive strength, and the bar surface [2], [3]. As a phenomenon influenced by many variables, it is a challenge to establish how the steel-concrete adhesion can be described in standards used for reinforced concrete design [4].…”

Pullout strength behaviour of self-compacted concrete in aggressive solutions

“…The first has a dimensions of 200×120×120 mm (l× w× h) [14] which was designed for running the pullout test for the concrete blocks reinforced with the steel bar of Ø12.5 mm. Whilst, the second was designed with dimensions of 375×250×250mm (l× w× h) [14] to suit the pullout test for the concrete blocks reinforced with the steel bar of Ø25 mm, as shown in The mixing, casting and curing operations were carried out in accordance with BS EN12390-2 [15]. Cubes samples were also cast to measure the compressive strength and density feature at different ages.…”