**Nomenclature**

FEA is determined defining a discontinuity surface between two brick units along the thickness of the mortar. The maximum tensile strain can be found as 0.061. Load-displacement

As shown in **Figure 24**, the analysis is terminated upon reaching the maximum tensile strain at a horizontal drift of 13.00 mm. Experimental value is approximately as 12.40 mm. The effect of tensile deformations grows up along the toe of the wall under increasing lateral load and

This chapter deals with the implementation of the plasticity theory to URM and FRP-strengthened masonry walls under compression and shear by considering the constitutive behavior of masonry units, mortar, and FRP composite material separately. A DP-type yield criterion is also employed relating the cohesion and the internal friction angle of both unit and mortar to their uniaxial compressive strength by extending the previous approach to the FRP-strengthened masonry walls. For this purpose, a large parametric study is performed in order to explain the mechanical properties of unit and mortar with only a single parameter, that is, their uniaxial compressive strength [24]. In order to evaluate the accuracy of the proposed approach, the analytical results are compared with the experimental results of both unreinforced and strengthened masonry

walls tested in two different experimental studies. Following conclusions are drawn:

ness of the mortar. It is possible to calculate the maximum strain *ε1*

**1.** The analytical approach previously recommended for masonry columns for the cohesion and internal friction angle have been updated and extended to the analysis of FRPstrengthened URM walls. The behavior of URM as well as the FRP-confined masonry walls simulated by means of the proposed approach considering these analytical relations is

**2.** Elasto-plastic analyses need an ending-point definition to terminate NLFEA when the stress-strain curve has an ideal plastic plateau. For the case of URM wall, the end point is determined defining the discontinuity surface between two clay units along the thick-

thickness by two block heights plus the mortar thickness. FEA should be interrupted when the ultimate tensile strain at the wall reaches this value. For the case of strengthened walls with FRP, FEA can be interrupted when the ultimate tensile strain reaches the rupture

tested and damaged ones, and the employment of FRP strips which confines only to one side of the wall partially, the use of the maximum tensile strain criterion of masonry seems

**3.** Cohesion and internal friction values of the masonry units are expressed in terms of hydrostatic pressure at the failure and their uniaxial compressive strength. The relations of masonry constituents are recommend are valid for ξ/fmu < 0.58. The dependency of the material parameters of the frictional materials on the hydrostatic pressure is then reflected

*/EFRP*. For the analyses of both the strengthened walls which are previously

by dividing the mortar

curve obtained from NLFEA and experimental data is given in **Figure 23**.

the critical tensile strain is observed at the toe of the wall (**Figure 24**).

**4. Conclusions**

20 New Trends in Structural Engineering

consistent with the test results.

strain, *εrup = f*

*t*

much more reasonable.

into the analysis directly.

