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![-(a) Tension softening behavior; (b) Compression hardening behavior; [4]](profile/Bledian-Nela/publication/334415705/figure/fig2/AS:779849199263754@1562941946954/a-Tension-softening-behavior-b-Compression-hardening-behavior-4.png)
Source publication
Masonry presents a heterogeneous material and therefore many challenges. Since there are many bond techniques for masonry constructions, their behavior is not the same. Major differences can be observed from different bond configurations of units in masonry constructions. The experimental determination of mechanical properties of all possibilities...
Contexts in source publication
Context 1
... results presented a very similar behavior for the axial compression test, diagonal tension test and bed joint shear test. The CDP model assumes that the two main failure mechanisms are the tensile cracking and the compressive crushing of the material (Figure 2). ...
Context 2
... damage parameter in compression has values ranging from 0 (no degradation) up to 1 (full degradation). In Abaqus the inelastic strain is automatically converted to plastic strain (í µí¼ c pl ) with the relationship presented in equation (3), which can also be followed in Figure 2 (b). Index "c" refers to compression. ...
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Citations
... Traction-separation behaviour relates to the normal and shear separations across the interfaces before the initiation of damage. The mortar thickness is assumed to be 20 mm [25,44,45]. This interface property is assigned as an interaction surface between the two consecutive bricks as a surface-to-surface contact interaction. ...
... The shear tractions are directly related to the cohesion parameter (c) for zero confining stress or the initial shear strength. The stiffness and damage parameters for the cohesive model parameters are summarised in Table 3 [25]. The separation between two brick units was taken as crack width in the finite element analyses. ...
... Cohesive behaviour of joint ([25]. ...
The effects of deep excavations on existing brick masonry walls have been extensively investigated, but the influence of twin excavations on brick masonry wall is seldom reported in the literature. In this study, a 3D numerical parametric analysis using an advanced hypoplastic soil model was carried out to investigate the response of an existing isolated brick masonry wall due to twin excavations with different construction sequences in dry sand. Three different numerical simulations were conducted. In first case, twin excavations (which were perpendicular to the brick masonry wall) were simulated one after the other. In second case, the first excavation was parallel and the second excavation was perpendicular to the brick masonry wall. In third case, analysis was performed with the change of construction sequence of twin excavations in which the first excavation and the second excavation were carried out perpendicular and parallel to the brick masonry wall, respectively. The computed results revealed that the maximum settlement after twin excavation in the second case is 37% larger than that in third case. The twin excavations (perpendicular to the masonry wall) resulted in the hogging deformation profile causing the cracks at the top of the wall.
... Traction-separation behaviour relates to the normal and shear separations across the interfaces before the initiation of damage. The mortar thickness is assumed to be 20 mm (Nela & Grajçevci, 2019). This interface property is assigned as an interaction surface between the two consecutive bricks as a surface-to-surface contact interaction. ...
... The shear tractions are directly related to the cohesion parameter (c) for zero confining stress or also known as the initial shear strength. The stiffness and damage parameters for the cohesive model parameters are summarised in Table 3 (Nela & Grajçevci, 2019). The separation between two brick units was taken as crack width in the finite element analyses. ...
The effects of tunnel construction on existing brick masonry walls have been extensively investigated, but the influence of deep excavation-induced stress relief is seldom reported in the literature. This paper presents a three-dimensional study to investigate damaging effects on a brick masonry wall (constructed parallel to the diaphragm wall) due to deep excavation at different depths. In addition, the effects of the wall orientation (i.e., orthogonal to the diaphragm wall), wall locations with respect to the deep excavation, and sand density were examined. The hypoplastic sand model was used to capture soil behaviour. The brick masonry wall was modelled with a micro-modelling technique. The traction-separation behaviour of cohesive elements was employed to model the mortar joints. It was found that the maximum settlement was induced at the mid-part of the wall parallel to the diaphragm wall. The induced settlement resulted in developed cracks in the wall. In the orthogonal case, the wall was bended downward, behaving like a cantilever beam. Negligible footing settlements were observed when the wall was located at a distance exceeding 0.48He (excavation depth) from the diaphragm wall. By increasing the relative density from 30% to 90%, the induced footing settlement decreased by up to 72%.
... The linear elastic properties of the surface which include the stiffness components in the traction-separation stiffness matrix are computed according to Equations (11) and (12). The mortar thickness is assumed to be 20 mm (Nela & Grajçevci, 2019). This interface property is assigned as an interaction surface between the two consecutive bricks as a surface-to-surface contact interaction. ...
... The shear tractions are directly related to the cohesion parameter (c) for zero confining stress or also known as the initial shear strength. The stiffness and damage parameters for the cohesive model parameters are summarised in Table 3 (Nela & Grajçevci, 2019). ...
Basement excavation inevitably causes stress changes in the ground leading to soil movements which may affect the serviceability of adjacent structures specially in case of masonry building. Because soil stiffness degrades with induced stress release during excavation, it is vital to investigate the masonry façade responses to an adjacent excavation. This paper presents three-dimensional numerical parametric study to investigate damaging effects on an existing brick masonry façade due to an adjacent basement excavation. The orientation of the façade is perpendicular to the basement. An advanced hypoplastic (sand) model with small-strain stiffness is adopted. The model parameters are calibrated against centrifuge test results in sand reported in literature. Effects of excavation depths, wall locations with respect to excavation, sand density and applied loads on the wall are examined. The computed results revealed that differential settlement (with maximum settlement closest to the excavation) was induced in the wall due to excavation-induced stress relief. Consequently, cracks were developed in the façade during excavation. By increasing the relative density from 30% to 90%, the excavation-induced footing settlement decreases by up to 72%. The different loads applied on the top of the façade have significant effects on the responses of the wall due to excavation.
