Numerical Evaluation of Unreinforced Masonry Brick Walls Retrofitted by Polypropylene Straps Subjected to Lateral Loading

Document Type : Research Article


1 Department of Civil Engineering, K. N. Toosi University of Technology, Tehran, Iran

2 University of Southern Queensland, Centre for Future Materials, Toowoomba, Australia


This study investigated the two half-scale (1:2) unreinforced masonry walls, sharing identical dimensions, geometry, and construction characteristics, which were subjected to simultaneous lateral and vertical constant loading. While the first specimen represented an unreinforced masonry wall, the second specimen underwent a transformative retrofitting process involving the incorporation of vertical, horizontal, and oblique Polypropylene straps. To further optimize the retrofit, the minimum area of the wall was reinforced using shotcrete mortar with weak cement. The retrofitting material was defined by introducing Polypropylene straps and shotcrete mortar into the first model, and a comprehensive evaluation of the reference model was conducted. The pushover analysis, conducted through monotonic loading simulations, effectively replicated the essential behaviors observed in the primary experimental specimens. Remarkably, the experimental results exhibited striking agreement with the numerical outcomes derived from the employment of ABAQUS finite element software. Notably, these results unveiled the efficacy of the retrofitting technique, highlighting a remarkable enhancement in the ultimate lateral displacement by 140% and an impressive 71% increase in loading capacity. Furthermore, the retrofitting process induced a notable shift in the failure mode from diagonal tension and shear cracks to a more desirable flexural rocking mechanism, reinforcing the structural integrity of the masonry walls.


Main Subjects

[1] Shabdin, M., Nader KA Attari, and M. Zargaran. "Shaking table study on the seismic performance of an Iranian traditional Un-Reinforced Masonry (URM) building." In Structures, Elsevier, (27) (2020) 424-439.
[2] Vemuri, Jayaprakash, Syed Ehteshamuddin, and Subramaniam Kolluru. "Numerical simulation of soft brick unreinforced masonry walls subjected to lateral loads." Cogent Engineering, 5(1) (2018) 1551503.
[3] Ahari, Gholamreza ZAMANI, and Kentaro Yamaguchi. "A proposal of the most suitable retrofitting methods for URM structures in Iran. An extensive review of recent techniques." Journal of Habitat Engineering, (2) (2010) 105-114.
[4] Tomazevic, Miha. Earthquake-resistant design of masonry buildings. Vol. 1. World Scientific, 1999.
[5] Darbhanzi, A., M. S. Marefat, and M. Khanmohammadi. "Investigation of in-plane seismic retrofit of unreinforced masonry walls by means of vertical steel ties." Construction and Building Materials, (52) (2014) 122-129.
[6] Haach, Vladimir G., Graça Vasconcelos, and Paulo B. Lourenço. "Parametrical study of masonry walls subjected to in-plane loading through numerical modeling." Engineering Structures, 33(4) (2011) 1377-1389.
[7] Petrovčič, Simon, and Vojko Kilar. "Seismic failure mode interaction for the equivalent frame modeling of unreinforced masonry structures." Engineering structures, (54) (2013) 9-22.
[8] Padalu, Pravin Kumar Venkat Rao, Yogendra Singh, and Sreekanta Das. "Cyclic two-way out-of-plane testing of unreinforced masonry walls retrofitted using composite materials." Construction and Building Materials, (238) (2020) 117784.
[9] Mahmood, Hamid, A. P. Russell, and J. M. Ingham. "Laboratory testing of unreinforced masonry walls retrofitted with glass FRP sheets." In Proceedings of the 14th International Brick/Block Masonry Conference, Sydney, Australia, (1720) (2008).
[10] Deng, Mingke, and Shuo Yang. "Cyclic testing of unreinforced masonry walls retrofitted with engineered cementitious composites." Construction and Building Materials, (177) (2018) 395-408.
[11] Chuang, Shih-Wei, Y. Zhuge, T. Y. Wong, and L. Peters. "Seismic Retrofitting of Unreinforced Masonry Walls by Frp Strip." PhD diss., New Zealand Society for Earthquake Engineering, (2003).
[12] Mustafaraj, Enea, and Yavuz Yardim. "Retrofitting damaged unreinforced masonry using external shear strengthening techniques." Journal of Building Engineering, (26) (2019) 100913.
[13] Dutta, Sekhar Chandra, Parthasarathi Mukhopadhyay, and Kundan Goswami. "Augmenting strength of collapsed unreinforced masonry junctions: Principal damage feature of walls damaged by moderate indian earthquakes." Natural Hazards Review, 14(4) (2013) 281-285.
[14] Ebrahimzadeh, Shahrad, and Kourosh Nasrollahzadeh. "Experimental study on performance of repaired and strengthened unreinforced masonry walls using polypropylene bands." Scientia Iranica (2022).
[15] Farahani, Emadoddin Majdabadi, Mohammad Yekrangnia, Masoud Rezaie, and Rita Bento. "Seismic behavior of masonry walls retrofitted by centercore technique: A numerical study." Construction and Building Materials, 267 (2021) 120382.
[16] Vera, Mónica Y. Oña, Giovanni Metelli, Joaquim AO Barros, and Giovanni Plizzari. "New openings in unreinforced masonry walls under in-plane loads: a numerical and experimental study." International Journal of Masonry Research and Innovation, 6(2) (2021) 166-195.
[17] Abdulla, Kurdo F., Lee S. Cunningham, and Martin Gillie. "Simulating masonry wall behavior using a simplified micro-model approach." Engineering Structures, (151) (2017) 349-365.
[18] Su, Zhiming, Wenzhong Zheng, Ying Wang, and Xiaomeng Hou. "Seismic Vulnerability Analysis of Masonry Structures Built with Disassembled Brick Wall Sections." Buildings, 12(11) (2022) 1831.
[19] Lubliner, Jacob, Javier Oliver, Sand Oller, and EJIJos Onate. "A plastic-damage model for concrete." International Journal of solids and structures, 25(3) (1989) 299-326.
[20] Bolhassani, Mohammad, Ahmad A. Hamid, Alan CW Lau, and Franklin Moon. "Simplified micro modeling of partially grouted masonry assemblages." Construction and Building Materials, (83) (2015) 159-173.
[21] Demir, Aydin, Hakan Ozturk, Kemal Edip, Marta Stojmanovska, A. Bogdanovic, and E. Seismology. "Effect of viscosity parameter on the numerical simulation of reinforced concrete deep beam behavior." The Online Journal of Science and Technology, 8(3) (2018) 50-56.
[22] Hsu, L. S., and C-TT Hsu. "Complete stress—strain behavior of high-strength concrete under compression." Magazine of concrete research, 46(169) (1994) 301-312.
[23] Deng, Mingke, and Shuo Yang. "Experimental and numerical evaluation of confined masonry walls retrofitted with engineered cementitious composites." Engineering Structures, (207) (2020) 110249.
[24] Genikomsou, Aikaterini S., and Maria Anna Polak. "Finite element analysis of punching shear of concrete slabs using damaged plasticity model in ABAQUS." Engineering structures, (98) (2015) 38-48.
[25] Zeng, Bowen, Yong Li, and Carlos Cruz Noguez. "Modeling and parameter importance investigation for simulating in-plane and out-of-plane behaviors of un-reinforced masonry walls." Engineering Structures (248) (2021) 113233.