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

Adhesive anchors are used worldwide for structural and non-structural connections. Because their structural behavior is influenced by many factors, adhesive anchors must be prequalified. In the US this is done according to ICC-ES AC308 and ACI 355.4-10. Design provisions for bonded anchors are stated in ICC-ES AC308 and the ACI 318-11, Appendix D. Only prequalified adhesive anchor systems are covered by the ACI Standard. In this paper the testing procedure, assessment criteria and design provisions with respect to sustained tension loading are described and – based on test results – the validity of the design provisions is discussed. It is concluded, that adhesive anchors qualified according to ACI 355.4-10 and designed according to the ACI 318-11, Appendix D can safely be used to resist sustained tension loading provided that they are installed properly. The design provisions given in ICC-ES AC308 and ACI 318-11, Appendix D should be applied to all anchors that must resist sustained tension loads and not only to anchors installed overhead.

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.

The best fire protection strategies for structural components are useless if connections lack the necessary fire resistance. Many current European Technical Approvals for anchors in concrete provide details on duration of fire resistance based on EOTA Technical Report 020 – Evaluation of Anchors in Concrete Concerning Resistance to Fire – published in 2004. This report delineates testing, evaluation and design requirements for anchors subject to fire exposure. It addresses post-installed mechanical anchors, adhesive anchors and plastic anchors and includes a simplified design approach that considers all relevant concrete failure modes as well as pull-out failure and the steel resistance. The failure modes relevant for normal service conditions also apply under fire exposure. Nevertheless, as temperatures increase the yield point of steel drops significantly. Stainless steels exhibit superior resistance to elevated temperature over carbon steels; however, in general, the reduction in the steel strength is greater than that associated with concrete breakout or pull-out failure. Thus, in most cases, steel failure is the governing parameter in the design, although concrete failure may control in case of shallow embedment, anchor groups or close to the edge. The simplified design method to determine the steel capacity under fire exposure provided by the EOTA Technical Report 020 and by the pre-standard CEN/TS 1992-4 ‘Design of fastenings for use in concrete’ yields often very conservative results. Therefore the leading brands in fastening technology perform fire tests according to the regime given in TR 020, which result in design values which are sometimes as much as three times as high as the values according to the simplified prediction.

The paper is related to basic understanding of curing and load performance of adhesive anchors with special focus on thermosetting systems cured at low base temperatures. Simulations of non-isothermal curing kinetics, vitrification and softening of the adhesives are compared to results of sustained load tests. Based on models for the reaction kinetics of thermosetting materials – considering the transition from mass to diffusion controlled curing regime – and a relation between glass transition temperature and chemical conversion the “curing-induced” vitrification was simulated for different temperature programs. The temperature programs are based on meteorological data and experimentally determined heating rates of concrete. In the simulations curing times, curing temperatures and heating rates were systematically varied. The simulated “vitrification” and “softening times” are compared to sustained load tests performed under the same conditions. The test results support the assumptions of our model which provide at least a qualitative prediction of the adhesive performance after different thermal or meteorological history. The behavior of thermosetting anchor systems cured at low base temperatures followed by fast heating is explained in terms of the competition between softening and post curing.