Title:
Experimental Efficiency of FRP Bars as Injected Anchors for Masonry Structures
Author(s):
Francesca Ceroni, Alberto Balsamo, Marco Di Ludovico
Publication:
Symposium Paper
Volume:
360
Issue:
Appears on pages(s):
383-394
Keywords:
masonry, out-of-plane mechanisms, injected anchors, FRP bars, bond behavior.
DOI:
10.14359/51740637
Date:
3/1/2024
Abstract:
Masonry structures are very sensitive to out-of-plane mechanisms under horizontal actions. A common traditional technique to avoid or mitigate the activation of these mechanisms is represented by injected anchors made of steel bars aimed to improve the connections between orthogonal masonry walls or between floors and masonry walls. The bars are usually embedded in the masonry by means of cement-based grout in holes realized inside the elements to be connected. Recently, an increased interest has developed in the scientific community about the use of Fibre Reinforced Plastic (FRP) bars as alternative to the steel ones for injected anchors, mainly because of their high tensile strength and inertia to corrosion, which can give them high durability, in addition to the use of high-performance grouts.
The paper reports the results of experimental pull-out tests realized by the Authors on several types of FRP bars used as injected anchors in small masonry specimens made of yellow tuff blocks. A hydraulic lime and pozzolana-based grout is used to fix the bars in holes realized in the masonry specimens along an embedded length of 250 mm. The set-up is realized in order to apply pure tension to the bars and shear stresses along the bar-grout and the grout-masonry interfaces. The results are analysed in terms of maximum pull-out forces, failure modes and force-displacement relations in order to evidence the global performance of each tested system, especially in relation with the diameter and the surface treatment of the bars.
Some comparisons with literature formulation for predicting the pull-out force are developed too.
Related References:
1. ACI 318-11, Building code requirements for structural concrete (ACI 318-11) and commentary, 2011.
2. Arifpovic F., Nielsen M.P. (2006). Strength of anchors in masonry. Department of Civil Engineering, Technical University of Denmark, Rapport BYG DTU No. R-134, ISSN 1601-2917, ISBN 87-7877-205-2, 2006.
3. CEB, Comité Euro-International du Béton, Fastenings to concrete and masonry structures. State-of-the-art report, Thomas Telford, London, 1994.
4. Ceroni F., Prota A. (2009), Case study: Seismic upgrade of a masonry bell tower by GFRP ties, ASCE Journal of Composite for Construction, 13 (3): 188-197.
5. Ceroni F., Di Ludovico M. (2020). Traditional and innovative systems for injected anchors in masonry elements: experimental behaviour and theoretical formulations, Construction and Building Materials, 254, art. no. 119178.
6. Ceroni F., Darban H., Luciano R. (2020). Analysis of bond behavior of injected anchors in masonry elements by means of Finite Element Modeling, Composites Structures, 241, art. no. 112099.
7. EN 1926:2007, Natural stone test methods - Determination of uniaxial compressive strength.
8. EN 14580:2005, Natural stone test methods - Determination of static elastic modulus.
9. EN 12372:2022, Natural stone test methods - Determination of flexural strength under concentrated load.
10. EN 1015-11:2007, Methods of test for mortar for masonry – Part 11: Determination of flexural and compressive strength of hardened mortar.
11. Eurocode 6: Design of masonry structures - Part 1-1: General rules for reinforced and unreinforced masonry structures) Comité Européen de Normalisation, Bruxelles, Belgium.”
12. fib Bulletin 58, Design of anchorages in concrete: guide to good practice, fib, Special Activity Group 4, Fastenings to structural concrete and masonry structures, 978-2-88394-098-7, 2011.
13. Gigla B., Wenzel F. (2000). Design recommendations for injection anchors as supplementary reinforcement of historic masonry, in: Proc. 12th Int. Brick/ Block Masonry Conf., Madrid, Spain, 2000, pp. 691–706.
14. Maione A., Casapulla C., Di Ludovico M., Prota A., Ceroni F. (2023). Limit analysis and design-oriented approach for Out-of-plane loaded masonry walls strengthened by grouted anchors, Engineering Structures, Vol. 285, 15 June 2023, 115991, doi.org/10.1016/j.engstruct.2023.115991.
15. Moreira S., Ramos L.F., Oliveira D.V., Lourenço P.B. (2014). Experimental behavior of masonry wall-to-timber elements connections strengthened with injection anchors, Eng. Struct. 81 (2014) 98–109.
16. MSJC, Masonry Standard Joint Committee’s, Building Code requirements for masonry structures, (TMS 402-13/ACI, 530-13/ASCE), 2013, 125–128.
17. Muñoz R, Lourenço PB. (2019). Mechanical Behaviour of Metal Anchors in Historic Brick Masonry: An Experimental Approach. In: Aguilar R, editor. Struct. Anal. Hist. Constr., vol. 18, 2019, p. 788–98. doi: 10.1007/978-3-319-99441-3_85
18. Paganoni S., D. D’Ayala D. (2014). Testing and design procedure for corner connections of masonry heritage buildings strengthened by metallic grouted anchors, Eng. Struct. 70 (2014) 278–293.
19. Panizza M., Girardello P., Garbin E., Valluzzi M.R., Cardani G., Dalla Benetta M., Casadei p. (2015). On-site pullout tests of steel anchor spikes applied to brickwork masonry, Key Eng. Mater. 624 (2015) 266–274.