A FINITE-ELEMENT MODEL FOR THE NONLINEAR-ANALYSIS OF REINFORCED NAD PRESTRESSED MASONRY WALLS

A materially nonlinear layered finite element model is proposed for th e analysis of reinforced and/or prestressed masonry wall panels under monotonic loadings in the plane and/or out of the plane, capable of ev aluating both the serviceability load and the ultimate load. An orthot ropic incrementally linear relationship and equivalent uniaxial concep t are used to represent the behaviour of masonry under biaxial stresse s while a uniaxial bilinear elasto-plastic model with hardening is emp loyed for rebar and the so-called 'power-formula' is adopted to descri be the stress-strain relationship of prestressing steel. After crackin g, the smeared coaxial rotating crack model is adopted and tension sti ffening, reduction in compressive strength and stiffness after crackin g, and strain softening in compression are accounted for. The modified Newton-Raphson iteration method is employed to ensure convergency of non linear solution. The proposed finite element model has been tested by a comparison with experimental data available in literature, both for reinforced and prestressed wall panels. The analysis of results sh ow good agreement between the values obtained by the proposed model an d those obtained experimentally.