Post-installed anchoring technology with mechanical anchor and adhesive anchor systems has found widespread use in concrete construction due to their numerous fields of applications, flexibility for fastening solutions, and advantages in productivity. Continuous improvement and advancement in post-installed fastening technology has yielded different products with certain areas of application and differing installation procedures. Therefore, in many cases, a post-installed anchor seems to be the perfect choice. However, as it is for cast-in anchors, the use of post-installed anchors requires in-depth knowledge in fastening technology for all people involved. These include the designers, who select the anchors for the correct load transfer from the attachment to the load-bearing structure, as well as the installers, who have to ensure that the anchors are installed correctly on the construction site. Lack of knowledge in the field of post-installed fastening technology is inevitably increasing the probability of misuse and misinstallations. In the recent past, discussions on the reliable use of post-installed anchors arose due to misinstalled mechanical anchors in the nuclear power plant in Biblis, Germany, or the fatal collapse of the Boston I-90 Tunnel ceiling panel that was suspended with the use of such anchors. To counteract and avoid these situations, a survey1 was performed in 2007 in Germany, Italy and Croatia on the installation of adhesive anchors on-site was performed as a first step in studying the issue. Based on the results of this investigation a field research project was started in 2009 in the United States to identify the situation on construction sites with regard to adhesive anchor installation in practice. The project was intended to benefit the construction industry by forming a basis for the development of easy to install adhesive-bonded anchors, and to improve the installation instructions for actual and future anchors, as well as to get information on the necessity and content of adhesive anchor installation training programs. This paper gives an overview on the findings on 23 sites in five locations in the United States and conclusions.

This CD-ROM contains 18 papers that were presented at sessions sponsored jointly by Committee 355 & 503 at the ACI 2010 Spring Convention in Chicago, IL. The objective of the papers is to provide a reference document and give a better understanding of the performance, capability, and reliability of adhesive anchors installed in concrete. The papers present the design, installation, qualification, and inspection requirements. Other papers discuss the characteristics of sustained load behavior and other specific anchor installation and qualification considerations. Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-283CD

Adhering carbon fiber (CF) sheets onto RC piers is one of the effective seismic strengthening methods. When the pier has an irregular shape such as I-shaped cross section, CF sheets cannot be adhered continuously around the pier. In such cases, the edge of the CF sheets have to be fixed with steel angles and anchor bolts in conventional fixing method. Therefore, an alternative fixing method using CF-anchors consisted of bundles of CF strands and fan shaped was developed and practically applied. One end of the CF-anchor spreaded like a fan was adhered to the CF sheet and other end is embedded in a hole drilled in the concrete member and fixed with injected epoxy resin. Applying this CF-anchor for the reinforcement of the concrete piers, it is necessary to design the adhesive load of the adhered part and the pull-out load of the embedded CF-anchor corresponding to the amount of the CF sheets. This paper describes the design of CF-anchors based on the experimental results for the adhesive load of the adhered part and the pull-out load of the embedded CF-anchor.

Adhesive-bonded anchors are increasingly adopted as structural fasteners for connections to hardened concrete. Due to their reliance on chemical bond, the tensile capacity of adhesive anchors is uniquely dependant on a number of factors [1]. These factors include the geometric parameters of the anchorage system, installation conditions, and adhesive bond strength which is manufacture dependent. Due to the complexity of these factors and their interaction in contributing to the tensile capacity of adhesive concrete anchors, it has proved to be difficult to evaluate their tensile strength. The design guidelines of anchorages using cast-in-place and post-installed mechanical anchors is discussed in ACI 318-08, Appendix D [2]. While, bonded anchors are used extensively in practice, they have not yet been incorporated into the design provisions of ACI 318-08 [3]. The worldwide database containing 2,878 tests of the anchors’ tensile capacity was provided to the authors by Dr. Ronald A. Cook, of ACI Committee 355 on Anchorage to Concrete. The aim of this study is to estimate the tensile strength of concrete adhesive anchors in uncracked concrete using artificial neural networks (ANNs) subject to bond failure and the effect of different parameters on it. As a result of this study, the ANN model will be able to capture the complex relationship between the adhesive bond stress and geometric parameters that compose the anchorage system.

Bonded anchors are frequently used for connections between structural or non-structural elements to concrete members. These connections are loaded by long-term and short-term loads respectively. The evaluation of the long-term behavior in the current approval guidelines in the U.S. and Europe is established by sustained load tests having a minimum duration of 1,000 hours in the U.S. and 2,000 hours in Europe. The results of these tests are extrapolated to approximately 450,000 hours (50 years) for tests at standard temperature and to roughly 90,000 hours (10 years) for tests at elevated temperature. The extrapolation technique and the evaluation criteria are developed to allow for an evaluation on the safe side. The paper presents results of tests on anchors installed using a proprietary adhesive anchor system that were subjected to sustained loads for up to approximately 21,000 hours (2.4 years). In these tests not only the time of testing but also the load level were beyond the requirements of the current approval guidelines. Based on these results the current evaluation method is analyzed and the conservatism associated with several aspects of the testing and evaluation methods is discussed.