## 1 Introduction  
In concrete structures, post-installed fastening techniques consist of using a steel rod to transfer external loads to hardened concrete via the contact between the two materials, which can be a mechanism of friction, mechanical interlock, bond or a combination of them [1]. Since they allow flexibility for the design of new concrete structures and the strengthening of existing ones, their use has increased in recent years. Among them, bonded anchors are a widely used technique, which consists of installing the steel rod in a drilled hole in hardened concrete and bonding it to the surrounding concrete with an adhesive mortar. The short-term and long-term behavior of bonded anchors has been the focus of several investigations [2; 3; 4; 5; 6], where it has been highlighted that this behavior is affected by different parameters such as installation conditions (drilling condition, hole cleaning, etc.) and in-service conditions (loading type, moisture, temperature, etc.). Moreover, the load-bearing capacity is directly dependent on the properties of the bonding material, which can be organic (with epoxy, polyester or vinylester), inorganic (ceentitious, etc.) or a mixture of them [2,6]. When a bonded anchor located far from the edges of the concrete element and the neighboring anchors is loaded in tension, the three most frequent failure modes at ambient temperature are the pull-out failure, the concrete cone failure and the combined concrete cone and pull-out failure [5]. The pull-out failure corresponds to the debonding of the anchor over the whole embedment depth, which can occur at the concrete-mortar interface or at the mortar-steel interface. In general, the strength of this bond is specified for a given mortar after approval tests. The concrete cone failure is characterized by the extraction of a cone-shaped portion of concrete having its apex at the embedded end of the anchor, due to circumferential stresses. At ambient temperature, the slope of the failure surface is about 35\({}^{\circ}\) with respect to the horizontal plane [7], and the failure through an unstable crack propagation occurs when the cone-shaped crack that initiated at the embedded end reaches a critical length of about 45% of the slant height of the entire cone after a stable crack propagation phase [8]. Because fire represents one of the most severe environmental conditions to which structures may be subjected, the behavior of fasteners at high temperature is an important aspect of building design. In fact, they could experience a significant reduction in load capacity under fire, which must be taken into account for the holistic fire safety concept. Different investigations have been conducted around the qualification and design of fasteners under fire conditions. This problem often requires important efforts, as highlighted recently in a detailed discussion of the evaluation process to determine the fire resistance of anchor channels [9]. For post-installed anchors and rebars, a recent review presents the status of the regulations, as well as the underlying background [10]. Regarding bonded anchors, since the available bonding materials are mainly sensitive to temperature increases, the pull-out failure tends to be the most probable failure mode under high-temperature conditions. Different investigations have been devoted to the analysis of this resistance to pull-out failure at high temperature, in uncracked and cracked concrete [11, 12, 13, 14, 15, 16, 17, 18]. However, the evolution of manufacturing technology has recently enabled the improvement of the fire resistance of adhesive mortars. Additionally, it is known that the mechanical strength of concrete can be substantially reduced with fire exposure [19]. Consequently, the probability to observe a concrete-related failure mode at high temperature, e.g., during an event of fire, is increased. For anchors in general, the concrete-related failure modes under fire conditions for both tension and shear loadings are not widely documented but are gaining interest.