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Concrete In Australia : March 2013
28 Concrete in Australia Vol 39 No 1 2 by the differences in the compressive and tensile strengths measured before and after the tests. e ultimate tensile capacities measured in all experiments are summarised in Table 3. ese have been converted in the same table in terms of Working Load Limits (WLL) based on the following expression 2: LSF k x WLL s (1) where φ is a reduction factor, x denotes the mean value of the test results (here taken as the actual test measurement of each sample), ks is the sampling factor and LSF limit state factor. e WLL values provided in Table 3 were calculated based on the minimum value of 2.5 for ks(LSF)/φ, as recommended in Clause 2.4.2 of AS3850 2 for lifting inserts. Samples with anchor CA05240 reached, on average, higher ultimate loads. Very similar ultimate capacities were measured for samples utilising the same anchors while prepared with different steel arrangements, ie REO1 and REO2. It is worth pointing out that the two sets of samples, ie those prepared with REO1 and those with REO2, were conducted at different concrete strengths, the strength of samples with REO1 being 20% higher in average on day 1 than that of specimens with REO2 (Table 2). Views of the panel conditions after the tests are presented in Figures 8 and 9. e crack patterns observed after the tests had a typical V-shaped form. e angle of the failure cracks measured for most of the specimens was around 55-65° (measured from the axis of the anchor). For the samples prepared with SJH anchors, an additional V-shaped crack developed near the panel edge at the anchor location (Figures 8e, 9e and 9f ). e wide crack patterns illustrated in Figures 8 and 9 highlight how the design of the test set-up effectively represented the loading condition of real lifting operations, allowing the cracks to develop freely, without influence from loads induced in the concrete by the method of test. is might have not been the case, for example, if the load had been applied through a self-resisting frame reacting against the panels edges on either side of the anchor as reported in previous tests 16, 19, 20. In such cases, loads induced in the concrete by the test method might not be representative of the real lifting situation leading to different results and crack patterns. Further experimental work will be carried out by the authors to investigate the influence of the test set-ups on the measured response. In this context, the testing procedure proposed in this paper represents a suitable alternative standard method for the evaluation of the performance of anchors when subjected to tension. 6.0 CONCLUSION is paper describes an experimental study investigating the behaviour of anchors used for edge-lifting when subjected to tension. As part of this work, 12 precast concrete samples were prepared and tested using three different types of anchors. e panels were 150 mm thick. e various steps involved in the sample preparation and loading procedure used in the experiments have been presented. e experiments highlighted that, at such an early age of the concrete, companion samples tested later in the day were able to reach higher capacities because of the considerable increase in concrete strength that had taken place during the testing period. All measured ultimate tensile capacities were reported together with equivalent Working Load Limits. Samples with anchor CA05240 reached, on average, higher ultimate loads. A V-shaped cracking pattern layout was observed in most of the tests with cracks developing at angles of around 55-65° measured from the axis of the anchor. ACKNOWLEDGEMENT is research was supported under Australian Research Council s Linkage Projects funding scheme (project number LP110100008) and by Unicon Systems. e experimental work was carried out in the JW Roderick Materials and Structures Testing Laboratory of the School of Civil Engineering at the University of Sydney. e assistance of the laboratory staff is also acknowledged. REFERENCES 1. Department of Education, Employment and Workplace Relations, Commonwealth of Australia, "National code of practice for precast, tilt-up and concrete elements in building construction -- February 2008", Australian Safety and Compensation Council, Australian Government, 2008. 2. Standards Australia, "AS 3850-2003 Tilt-up concrete construction", Standards Australia, 2003. 3. NPCAA and CIA, "Precast concrete handbook", National Precast Concrete Association Australia and Concrete Institute of Australia, 2002. 4. Fuchs, W., Eligehausen, R., Breen, J. E., "Concrete Capacity Design (CCD) Approach for Fastening to Concrete", ACI Structural Journal, 92(1), 1995, pp 73-94. 5. Eligehausen, R., Balogh, T., "Behaviour of Fasteners Loaded in Tension in Cracked Reinforced Concrete", ACI Structural Journal, 92(3), 1995, pp 365-379. 6. Cannon, R. W., "Straight Talk About Anchorage to Concrete-Part I", ACI Structural Journal, 92(5), 1995, pp 581-586. 7. Cannon, R. W., "Straight Talk About Anchorage to Concrete-Part II", ACI Structural Journal, 92(6), 1995, pp 724-734. 8. American Concrete Institute, "State of the Art Report on Anchorage to Concrete (ACI 355-1R)", ACI Committee 355, 1991, Michigan. 9. American Concrete Institute, "Wedge type expansion anchor Performance in Tension (SP135-5)", ACI Committee 355, 1987, pp 89-106. 10. Vintzeleou, E., Eligehausen, R., "Behaviour of fasteners under monotonic or cyclic shear displacements", SP 130-7. American Concrete Institute Committee 355, Anchors in Concrete -- Design and Behaviour, 1991, pp 181-204. 11. Amman. "Static and Dynamic Long-term Behaviour of Anchors", ACI SP 130-8, 1991. 12. Elfgren, B., Cederwall, G., "Anchor Bolts in Reinforced Concrete Foundations", ACI SP 103-3, 1987. 13. Elfgren, L., Ohlsson, U., Gylltoft, K., "Anchor bolts