Evaluation of Sustained Load Behavior of Bonded Anchors— Evaluation Testing vs. Long-Term Results

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Title: Evaluation of Sustained Load Behavior of Bonded Anchors— Evaluation Testing vs. Long-Term Results

Author(s): Hannes A. Spieth

Publication: Special Publication

Volume: 283

Issue:

Appears on pages(s): 1-12

Keywords: bonded anchor, sustained load, Findley

Date: 3/1/2012

Abstract:
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.