Brick masonry, properties

Table 9.42 Properties of wood, steel, concrete, brick masonry, aluminum, cast iron, and plate glass...

Regarding the modeling of the infill panels, the great number of influencing factors, such as dimension and anisotropy of the bricks, joint width and arrangement of bed and head joints, material properties of both brick and mortar, and quality of workmanship, make the simulation of plain brick masonry extremely difficult. The level of complexity of the analytical model depends on whether masoiuy is considered as one-, two-, or three-phase material, where the three phases are comprised of the units, mortar, and unit-mortar interface. 

The analytical determination of the gravity load distribution between the frame and the infill wall requires several considerations. First, a part of the gravity loads may be applied onto the RC columns before the construction of the infill walls because these walls could be constructed after the frame has been completed. Second, long-term effects such as concrete and masonry creep, concrete shrinkage, and brick masonry expansion with time due to water absorption can significantly affect the gravity load distribution. While refined finite element models with viscoelastic material properties can be employed for the determination of the gravity load distribution, the increased computational burden of such analyses may not necessarily produce results of increased accuracy due to lack of experimental data to allow the cahbration of multiaxial viscoelastic constitutive models. 

In conclusion, (a) deep rejointing may be efficient in case of brick masonries, 300 mm thick at maximum, and (b) provided that the technique is applied with due care and using adequate materials, (c) in case of stone masonries, it is not advisable to apply deep rejointing both because it is not expected to contribute to the improvement of the mechanical properties of masonry and because it is a quite expensive technique (mainly in workmanship). Even if applied to stone masoiuies, deep rejointing is considered as a repair technique, reinstating the initial mechanical properties of masonry. 

The properties that make granite an attractive chemically resistant masonry are its naturally low permeability, thermal expansion (in generally the same range as that of "acid-brick"), high strength and the insolubility of its component minerals in dilute HCI and H2SO4. Hydrofluoric acid is the only acid in which quartz, feldspar and mica, the major constituents of most industrial granites, are easily soluble. Contact with HF must therefore be avoided. 

Table 3.5 Material properties for brick and stone masonry and soil/rock ...

In the case of masonry pieces, the density takes as its value at ambient temperature [2,7]. Some authors point out that the most significant property in the material to characterize the behavior to the fire of the masonry is the density (rather than the type of brick) [ 27]. 

Nevertheless, the mechanical behavior of the different types of masonry has generally a common feature a very low tensile strength. This property is so important that it has determined the shape of ancient constructions. The difficulties in performing advanced testing of ancient structures are quite large due to the innumerable variations of masonry, the variability of the masonry itself in a specific structure, and the impossibility of reproducing it all in a specimen. Therefore, most of the advanced experimental research carried out in the last decade has concentrated in brick/block masonry and its relevance for design. The masonry components are detailed in another essay. 

Eco-efiicient masonry bricks and blocks Design, properties and durability... 

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