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Experimental and FEM‐based analytical studies revealed the following aspects regarding post‐installed adhesive anchors set with epoxy or UHPFRC adhesive. The experimental and FEM results agreed in regard to maximum load, load–displacement curve, crack pattern, failure mode, and the location of failure. The load‐bearing mechanisms were discussed employing a model with a conic surface and an interface layer below it, which revealed the contribution of a conic surface to the maximum load was low, and that of an interface layer was very high. The mechanisms of combined failure with cone‐shaped fracture of concrete and interface slipping were also discussed.

Unlike traditional base materials such as concrete or masonry, there are no guidelines for rock as a base material for post-installed anchors. The varying rock properties (e.g., rock type, discontinuities) and numerous installation parameters (e.g., embedment depth, anchor diameter) leave engineers with limited information on design resistances, leading to an uncertain basis for anchor applications in rock. To identify the key parameters that determine rock as a base material, an evaluation of rock characteristics was conducted, combined with in situ pull-out tests in different key geologies (granite, limestone, mica schist, dolomite, granulite) and discrete element modeling, which has been found to be suitable for investigating the load-bearing behavior of post-installed anchors in rock. Discontinuities were identified as the main factor influencing the load-bearing capacity of post-installed anchors in rock mass. Based on the in situ investigations, assessment methods for rock as a base material were proposed, along with corresponding resistance partial safety factors for design of 2.5, 2.0, and 1.7 for high, medium, and low levels of uncertainty regarding possible inhomogeneities. A limit value R ≥ 36, associated with rebound hammer assessments, was defined for the low degree of uncertainty, showing limitations for schistose rock. This is concluded by a design approach for determining design resistances of shallow fasteners in rock mass.

The paper presents the results of a numerical analysis (FEM) describing the effect of the undercutting head angle on the formation of the rock mass failure zone during the initial stages of failure propagation. The research was carried out in the context of developing a technology for rock extraction by controlled pull-out of undercut anchors installed in the rock mass. The focus was on the initial stage of crack propagation and its trajectory for anchors embedded at an assumed constant depth and a value of the friction coefficient of the rock against the anchor head. It is shown that smaller angles favor smaller stripping angles and an increased radial impact of the head on the rock material (in the plane perpendicular to the head axis), while the impact of heads with larger angles is found to favor larger fracture penetration angles and faster penetration towards the free rock surface.

This study assesses improvements in the head and extension sleeve parts for a post-installed anchor. The sleeve and head details were proposed to enhance the structural performance of the post-installed anchor, and the optimal structural shape was determined through finite element analysis. The analysis results revealed that the anchor's performance was most efficiently improved when the sleeve length was 9.0 mm and the head length was 3.0 mm. In the model with these dimensions applied, the performance improved approximately 1.71 times compared to the existing model, validating the effectiveness of the proposed structural details. The improved pull-out strength test of anchor diameter M12 showed an increase of 1.25 times in normal-strength concrete and 1.28 times in high-strength concrete, with an embedded depth of 50 mm. The improved pull-out strength test of anchor diameter M16 showed that the pull-out strength increased by 1.42 times for normal-strength concrete and about 1.33 times for high-strength concrete. This research proposes a modified equation that reflects changes in the effective embedded depth and diameter. A comparison of the proposed equation with that of European Technical Approval Guideline (ETAG) showed that the correlation coefficient changed from 0.908 to 0.962, and the coefficient of variation changed from 18.9 to 10.4%, meaning that the proposed equation reflected the actual experimental values more accurately.

In the case of fastenings on rock, as a result of the variability, it is quite difficult to make a preliminary assessment of the load-bearing capacity of rock as a base material. This paper therefore investigates which rock parameters next to an anchor position have an influence on the load-bearing capacity. For this purpose, tests are carried out on post-installed anchors in different lithologies in eastern Austria. It can be shown that the joint weathering has an influence on the load-bearing capacity of post-installed anchors and conclusions can be made about joint weathering by means of rebound hammer. Rebound values can therefore also be used to draw conclusions about the rock quality as a base material for post-installed anchors. Nevertheless, a combined optical assessment of the base material is recommended as an adequate method.

The tests described in this paper were aimed at evaluating the tensile capacity of the anchorages connecting an automated pallet warehouse with an existing RC foundation. The warehouse is a new steel structure erected in the place of a previous warehouse collapsed due to the Emilia earthquake, but whose foundation remained undamaged. The investigated fastening consists of 10 post-installed, bonded threaded rods with diameter (d) and embedment depth (hef) of 20 and 500 mm, respectively. Neither anchor arrangement nor embedment depth (hef > 20d) was covered by current standards for fastening design. To reproduce the in-situ actual conditions of the fastening, an unconfined test configuration was used. The maximum loads achieved were more than 3 times greater than the seismic demand for the fastening. The tests highlighted the crucial role played by the reinforcing steel which was present in the foundation. Concrete-related failure mechanisms, such as the combined pullout and concrete cone failure mechanism typical of bonded anchors, were not activated. The observed crack patterns rather suggest the onset of a flexural failure mechanism of the concrete slab. This feature is confirmed by analytical calculations showing that, at the maximum loads achieved in the tests, the top reinforcement was likely to be yielded. In six preliminary unconfined tension tests on single anchors, steel rod failure was achieved, associated with limited cracking of the concrete surface in proximity of the anchor.

This paper presents an experimental program investigating the behavior of single screw anchors embedded in thin concrete membersunder tension loading. Variables included: concrete thickness, concrete compressive strength, anchor diameter, and anchor manufacturer. Anchors were embedded in the full thickness of the concrete member and the effects of back-face \"blowout\" due to drilling were considered. The results show that concrete strength, anchor diameter, and anchor brand have a statistically significant influence on the capacity of anchors embedded in 4 in. (102 mm) thick concrete. However, these factors make no significant difference to the capacity of screw anchors in 2 in. (51 mm) thick concretemembers. Based on the experimental results, a behavioral and design models are proposed. These models use a reduced embedment depth to address the back-face concrete blowout due to drilling. The proposed model results in levels of accuracy and variability that are consistent with other types of anchorage and the associated models. Keywords: drilling in concrete; post-installed anchors; sandwich wall panels; screw anchors; thin concrete members.

In recent years, the growing need for reducing non-structural damage after earthquakes has stimulated a dedicated effort to develop innovative types of fasteners for anchoring non-structural components (NSCs) to reinforced concrete (RC) host-structures. To contribute to such need, and building on previous research, this paper presents the results of a series of uni-directional shake-table tests of simulated NSCs anchored to concrete via: (1) expansion, and (2) chemical anchors; post-installed into: (a) uncracked, and (b) cracked concrete. Considering different construction details, the experimental investigation focused on traditional anchorage systems, alternative solutions comprising mortar filling into the gap clearance, and a low-damage system relying on supplemental damping devices, capable of reducing the acceleration of the NSCs as well as the force of the anchorage during seismic shakings. The experimental tests provided significant evidence on the beneficial effects of a dissipative anchorage protecting both the non-structural component and the anchorage itself, even during strong earthquakes. Moreover, when construction details allow to close the fixture clearance with a mortar filling, this stiffer solution provide an additional reduction of NSCs seismic accelerations and forces. Therefore, suggestions for further improvements of the adopted low-damage solution are also proposed.

This paper presents an experimental program investigating the behavior of single screw and adhesive anchors embedded in thin concrete with full thickness embedment depth subjected to shear load toward the free edge. Variables included: concrete thickness, concrete compressive strength, anchor diameter, anchor type, and edge distance. Anchors were embedded through the full thickness of the concrete member and the effects of back-face blowout due to drilling were considered. Based on the experimental results of 149 tests, it was shown that concrete capacity design (CCD) method underestimates the shear capacity of the anchors. Application of the thickness modification factor from ACI 318-14 overcorrects for the conservatism in the CCD approach and can lead to unconservative calculated capacities. An alternative thickness modification factor is presented which results in more accurate calculations of shear capacity. Finally, a design model is proposed for shear capacity of a single anchor installed in thin uncracked concrete members with full thickness embedment. The design model is based on 5%fractile of the experimental capacities. Keywords: adhesive anchors; concrete breakout; post-installed anchors; screw anchors; shear capacity; shear test; thin concrete members.

This article presents a numerical study on the influence of the anchorage shear hysteresis on the seismic response of nonstructural components (NSC) connected to multi-storey reinforced concrete (RC) buildings, and of the anchorage itself. To cover a variety of different types of shear hysteresis shapes, this contribution considered the experimental results obtained for five types of post-installed anchors. The results were used for calibrating the hysteresis model of the anchorage connecting an ideal NSC with rigid fixture and a 12-storey RC building host-structure. Using a suit of 40 earthquake records and assuming a single NSC at each storey level anchored by a single fastener, a series of non-linear dynamic analyses of the structure-fastener-nonstructural system was carried out. The results showed significant differences in terms of maximum acceleration and force of the NSC and anchorage, respectively, depending on the type of anchor. These seismic demands were sometimes larger than those required by the reviewed code provisions for rigid NSC, but also for the most restrictive code-case for flexible NSC. The results presented different amounts of scatter, mostly related to the size of the annular gap and of the loading stiffness of the anchorage. It is shown that the maximum force achieved by the anchorage is directly related to the peak relative velocity of the NSC within the gap region. It was concluded that the shape of the shear hysteresis of the anchorage highly influences the response of the NSC and the anchor itself and should not be neglected in practice.