Engineering Structures 248 (2021) 113212 Available online 9 October 2021 0141-0296/© 2021 Published by Elsevier Ltd. Infuence of the fexural and shear reinforcement in the concrete cone resistance of headed bars Mauricio Ferreira b, * , Manoel Pereira Filho a , Nataniel Lima a , Marcos Oliveira a a University of Brasilia, Brasilia, Brazil b Federal University of Para, Belem, Brazil A R T I C L E INFO Keywords: Concrete cone failure Cast-in anchors Headed bars Concrete cracking Supplementary reinforcement ABSTRACT This paper presents the experimental response and resistance of sixteen axial tensile tests on headed deformed bars embedded in reinforced concrete members, used as cast-in anchors, under concrete cone failure. Nine of these tests investigated the infuence of the fexural reinforcement ratio, which affects the concrete cracking state in the vicinity of the anchor. The other seven tests measured the shear reinforcement contribution, adjusted to work as supplementary reinforcement, distributed in the tests in different amounts and arrangements. Furthermore, design and theoretical methods were used to discuss the authors’ experimental results compared to other literature results. The fexural reinforcement ratio signifcantly infuenced the concrete cone resistance, as it controls the crack width. Well-detailed stirrups, placed following the design codes’ spacing limitations for supplementary reinforcement, can substantially increase the concrete cone resistance. The assumptions under- lying the design methods are conservative, which is justifed by the simplicity of their equations, but more ac- curate calculation methods are required. 1. Introduction Headed deformed bars are often used as cast-in anchors to transfer forces between structural members. Their use simplifes structural de- tailing and boosts the construction process and economy. They are widely used to connect different structural members, such as in base- column and beam-column connections, among other applications. When headed deformed bars are submitted to tensile loading, the following failure modes described by both fb Model Code 2010 [1] and ACI 318 [2] can be observed: steel failure (see Fig. 1a); concrete cone failure or concrete breakout (see Fig. 1b); concrete splitting (see Fig. 1c); and edge failure or side-face blow-out (see Fig. 1d). The switching from one to another failure mode depends on the embedment length, the side cover, the bearing area of the head, the thickness of the concrete structural member, and other variables, as discussed in detail by Gil- Martín and Hern´ andez-Montes [3]Signifcant scientifc efforts were carried to investigate the performance of cast-in anchors failing due to concrete cone failure (see [4,7–9]), accounting for the infuence of concrete cracking degree (see [9–12]). The main conclusion is that for crack widths varying between 0.3 mm and 0.5 mm, mean strength reduction factors of 0.70 can be applied to the resistance of anchors embedded in uncracked concrete. ACI 318 [2] and EN 1992-4 [6] as- sume a strength reduction factor of 0.8 and 0.7 applied to the resistance for uncracked concrete situations, respectively. These recommendations are based on experimental tests on cast-in anchors embedded on thick concrete members, most of them without surface reinforcement and with induced cracks, which widths ranged from 0.3 mm to 0.5 mm. These tests are representative of some design cases, like for base-column connections. However, design situations where headed deformed bars are embedded in structural members with signifcant amounts of fexural and shear rebars deserve more attention (see [13,14] as reference). Tensile tests on headed bars embedded in thick concrete members led to the conclusion that the surface reinforcement does not affect the concrete cone failure load (see Eligehausen et al., [12]). Nevertheless, Nilsson et al. [15] showed that the surface reinforcement could improve the load-carrying capacity of anchor bolts as a function of their amount and positioning. Furthermore, for reinforced concrete structures under service load, the maximum crack width allowed varies from 0.2 to 0.4 mm. Thus, unless the anchor’s position coincides with a particular structural member’s most tensioned zone, it is likely that its load- carrying capacity will vary between cracked and uncracked resistances. * Corresponding author. E-mail address: mpina@ufpa.br (M. Ferreira). Contents lists available at ScienceDirect Engineering Structures journal homepage: www.elsevier.com/locate/engstruct https://doi.org/10.1016/j.engstruct.2021.113212 Received 14 October 2020; Received in revised form 13 August 2021; Accepted 12 September 2021