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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 19 Abstracts search results
March 1, 2012
Ingo Alig, Dirk Lellinger, Frank Bohm, Ralf Neuerburg, and Friedrich Wall
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.
A.M. Said and S.E. Robinson
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 . 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 . While, bonded anchors are used extensively in practice, they have not yet been incorporated into the design provisions of ACI 318-08 . 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.
Todd M. Davis and Ronald A. Cook
ASTM E488 and ASTM E1512 as well as ICC-ES AC308 and ACI 355.4 have extensive testing protocols for the short-term and long-term evaluation of adhesive anchor systems. Currently the sustained load testing procedures establish residual load and displacement criteria on projected displacements from a 1000 hour sustained load test. An anchor is considered approved for sustained load if it meets these pass/fail criteria. In an NCHRP research project conducted at the University of Florida, an AASHTO standard (AASHTO TP 84-10) was developed to evaluate the sustained load performance of adhesive anchor systems based on a stress versus time-to-failure approach common with many testing protocols. Adhesive anchors are loaded to failure at various percentages of the mean static load as determined from static load tests. The resulting stress versus time-to-failure relationship generated from this test method is very useful to an engineer designing with adhesive anchors under sustained load. A subsequent NCHRP research project conducted in partnership at the University of Florida and the University of Stuttgart will utilize this test method to evaluate the long-term performance of adhesive anchor systems under sustained load coupled with various installation and in-service conditions (temperature, moisture, etc).
Editors: Richard E. Wollmershauser and Donald F. Meinheit / Sponsored by: ACI Committee 355 and ACI Committee 503
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.
B. Winkler, Y. Li, and F. Wall
Numerical simulation has become a powerful tool for supporting the development of innovative fastening products. The information on the failure mechanism developing during the load transfer from fasteners to concrete can be obtained and analyzed by simulation, which offers the basic requirement for designing innovative fasteners. During the last 15 years Hilti Corporation has developed a simulation tool based on the finite element method and concrete material models to support the fastener design process. In this paper various simulation examples for typical post-installed anchors, particularly for adhesive anchors, are presented. Numerical simulations are carried out for single anchors and anchor groups consisting of four adhesive anchors loaded in tension. The simulation results are discussed and compared with experimental data. The comparison shows a good agreement.
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