Masonry walls made of stones/bricks joined by mortar with poor mechanical properties, resulting in very irregular structures, are very common in ancient buildings. In this case, piers and spandrels ultimate strength is not always well predicted by simplified formulas suggested by codes of practice, which typically are tailored to regular textures. In this framework, a two-step numerical model for the pushover analysis of in-plane loaded masonry walls constituted by the irregular assemblage of stones/bricks is proposed. In Step I, ultimate bending moment-shear force strength domains of structural elements are derived by means of a heterogeneous upper bound FE limit analysis and the results are stored in a database. In Step II, a frame model of entire walls is assembled, where piers and spandrels are modeled as elasto-plastic Timoshenko beams. At each analysis step, the internal forces of each structural element are compared to the failure loads stored in the database created in Step I. If the capacity is exceeded, suitable plastic hinges are introduced at the end of the structural elements. Furthermore, the resistance of the element is set to zero when a limit drift is exceeded. With the numerical tool developed, a real scale masonry wall arranged in irregular texture is analyzed in the inelastic range under increasing static loads. Results are compared with those obtained by a very expensive plane-stress non linear heterogeneous FEM model and with those obtained by a standard frame approach available in the market stock.

Simple model for pushover analysis of masonry walls with irregular texture

MILANI, GABRIELE;
2011-01-01

Abstract

Masonry walls made of stones/bricks joined by mortar with poor mechanical properties, resulting in very irregular structures, are very common in ancient buildings. In this case, piers and spandrels ultimate strength is not always well predicted by simplified formulas suggested by codes of practice, which typically are tailored to regular textures. In this framework, a two-step numerical model for the pushover analysis of in-plane loaded masonry walls constituted by the irregular assemblage of stones/bricks is proposed. In Step I, ultimate bending moment-shear force strength domains of structural elements are derived by means of a heterogeneous upper bound FE limit analysis and the results are stored in a database. In Step II, a frame model of entire walls is assembled, where piers and spandrels are modeled as elasto-plastic Timoshenko beams. At each analysis step, the internal forces of each structural element are compared to the failure loads stored in the database created in Step I. If the capacity is exceeded, suitable plastic hinges are introduced at the end of the structural elements. Furthermore, the resistance of the element is set to zero when a limit drift is exceeded. With the numerical tool developed, a real scale masonry wall arranged in irregular texture is analyzed in the inelastic range under increasing static loads. Results are compared with those obtained by a very expensive plane-stress non linear heterogeneous FEM model and with those obtained by a standard frame approach available in the market stock.
2011
Irregular masonry; Limit analysis; Equivalent frame approach; FE method
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/613102
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