A Design-Oriented Stress-Strain Constitutive Model for Clay-Brick Masonry Columns Confined by FRP

Abstract:

Experimental tests proved that the external confinement of masonry columns through Fiber-Reinforced Polymers (FRP) induces increment of axial strength and ductility. Contrary to FRP-confined concrete, for which reliable unified theoretical stress-strain models are available in literature or included in the codes, to develop easy-to-use constitutive models valid for whatever type masonry represents a difficult challenge. In fact, several parameters influence the axial stress-strain response of confined masonry, such as the relative mortar-to-stones strength, masonry texture, deformation capacity of materials, type of reinforcement ad its arrangement. In this paper, a design-oriented stress-strain model devoted to describe the compressive behavior of FRP-confined clay-brick masonry columns is presented. The main scope of the research consists of providing an easy-to-use predictive model, applicable both in the research field and design practice. The stress-strain response of the confined masonry has been idealized in a parabola-rectangular behavior described by Lam and Teng’s equations - originally developed for FRP-confined concrete - adapted to masonry elements. The equations are ruled by the mechanical properties of confined and unconfined masonry, those of composite material and by a parameter that takes into account the dispersion of the experimental data (i.e., variability of materials properties, different stone arrangements and masonry textures). The entire stress-strain behavior has been calibrated by means of the least-squares optimization criterion, based on a sufficient number of experimental results available in the literature. Comparisons between experimental and theoretical stress-strain curves show good accordance of the results. The design-oriented model is able to capture the experimental response of the confined masonry, in terms of initial elastic stiffness, ductility ad maximum confinement pressure.

• Periodical: Key Engineering Materials (Volume 916)
• Pages: 147-154
• DOI: https://doi.org/10.4028/p-653xvs
• Online since: April 2022
• Authors: Antonio Sandoli*, Gian Piero Lignola, Bruno Calderoni, Andrea Prota
• Keywords: Constitutive Behavior, Design-Oriented Model, FRP-Confined Masonry, Stress-Strain

References

[1] A. Sandoli, C. Musella, G. P. Lignola, B. Calderoni, A. Prota, Spandrels panels in masonry buildings: effectiveness of the diagonal strut model within the equivalent frame model, Structures 27 (2020) 879-893.

DOI: 10.1016/j.istruc.2020.07.001

[2] T. D. Krevaikas, T. C. Triantafillou, Masonry confinement with fiber-reinforced polymers, J. Comp. Constr. 9 (2005) 128-35.

DOI: 10.1061/(asce)1090-0268(2005)9:2(128)

[3] M. Corradi, A. Grazini, A. Borri, Confinement of brick masonry columns with CFRP materials, Comp. Sci. Technol. 67 (2007) 1772-1783.

DOI: 10.1016/j.compscitech.2006.11.002

[4] M.A. Aiello, F. Micelli, L. Valente, FRP confinement of square masonry columns, J. Comp. Contr. 13(5) (2003) 148-158.

DOI: 10.1061/(asce)1090-0268(2009)13:2(148)

[5] M. Di Ludovico, C. D'Ambra, A. Prota, G. Manfredi, FRP confinement of tuff and clay brick columns: experimental study and assessment of analytical models, J. Comp. Constr. 14(5) (2010) 128583-596.

DOI: 10.1061/(asce)cc.1943-5614.0000113

[6] C. Faella, E. Martinelli, S. Paciello, G. Camorani, M.A. Aiello, F. Micelli, E. Nigro, Masonry columns confined by composite materials: experimental investigation, Comp. Part B 42 (2011), 692-704.

DOI: 10.1016/j.compositesb.2011.02.001

[7] F. Micelli, M. Di Ludovico, A. Balsamo, G. Manfredi, Mechanical behavior of FRP-confined masonry by testing of full-scale columns, Mater. Struct. 47 (2014) 2081-2100.

DOI: 10.1617/s11527-014-0357-9

[8] A. Sandoli, B. Ferracuti, B. Calderoni, FRP-confined tuff masonry columns: regular and irregular stone arrangement, Comp Part B. 162 (2019) 621-630.

DOI: 10.1016/j.compositesb.2019.01.015

[9] J. Thamboo, T. Zahra, M. Asad, Monotonic and cyclic compression characteristics of CFRP confined masonry columns, Comp. Struct. 272 (2021) 114257.

DOI: 10.1016/j.compstruct.2021.114257

[10] G.P. Lignola, R. Angiuli, A. Prota, M.A. Aiello, FRP confinement of masonry: analytical modeling, Mat. Struct. 47 (2014) 2101-2115.

DOI: 10.1617/s11527-014-0323-6

[11] G. Minafò, J. D'Anna, C. Cucchiara, A. Monaco, L. La Mendola, Analytical stress-strain law for FRP confined masonry in compression: literature review and design provisions, Comp. Part B 115 (2017) 160-169.

DOI: 10.1016/j.compositesb.2016.10.019

[12] G. Campione, N. Miraglia, Strength and strain capacities of concrete compression members reinforced with FRP. Cem. & Conc. Comp 25 (2003) 31-41.

DOI: 10.1016/s0958-9465(01)00048-8

[13] M.R. Spoelstra, G. Monti, FRP-confined concrete model, J. Comp. Contr. 3 (1999) 143-150.

[14] L. Lam, J.G. Teng, Design-oriented stress-strain model for FRP-confined concrete, Constr. Build. Mat 17(2003) 471-489.

DOI: 10.1016/s0950-0618(03)00045-x

[15] A. Sandoli, B. Calderoni, Constitutive stress-strain law for FRP-confined tuff masonry, Mat. Struct. 53:57 (2020).

DOI: 10.1617/s11527-020-01491-y

[16] EN 1996-1-1. Eurocode 6: design of masonry structures. Part 1-1: general rules for reinforced and unreinforced masonry structures.

DOI: 10.3403/30092858

[17] G. Ramaglia, G.P. Lignola, F. Fabbrocino, A. Prota, Multi-parameters mechanical modeling to derive a confinement model for masonry columns, Contr. Build. Mat. 214 (2019) 303-317.

DOI: 10.1016/j.conbuildmat.2019.04.111

[18] CNR-DT R1, Guide for the design and construction of externally bonded FRP systems for strengthening existing structures, Italian Council of Research (CNR), Rome, 2013, Italy.