In plane seismic response of unreinforced masonry walls: comparison between detailed and equivalent frame models

Abstract eng:
In the last decade, the achievement of performance-based earthquake engineering concepts has led to an increasing use of nonlinear static procedures in evaluation of the seismic performance of masonry buildings. Different strategies of modelling may be pursed to evaluate the response of the structure in terms of both overall strength and ultimate displacement capacity. A first approach consists in describing the structure by very detailed models based on the Finite Element Method: the masonry continuum is discretized in a number of finite elements and suitable non-linear constitutive laws are adopted. A second one consists in idealizing the structure through an “equivalent frame”: each resistant wall is discretized by a set of masonry panels (piers and spandrels) in which the non-linear response is concentrated. The FEM method may provide quite an accurate description of the structure and of its material. However, it presents the drawback of a high computational effort. Moreover, it poses some uncertainties in the verification procedures. As an example, the correlation of the displacement capacity of the structure to predefined limit states, commonly related to the drift evaluated at the scale of the panel, might be ambiguous and may imply repeated average operations performed ex-post. The equivalent frame approach is based on strongly simplifying hypotheses on the geometry and the mechanical behaviour of the masonry structure. Thus, its reliability depends on the consistency between such hypotheses and the structure actually examined. Thus, the equivalent frame idealization in case of walls with non regular opening patterns, the proper prediction of the in-plane load bearing capacity of panels, the interaction between orthogonal walls, may represent very crucial issues. The paper proposes a review of the most critical issues associated to the use of the two modelling approaches. A comparison between the results obtainable from the Finite Element Method (by adopting the non linear constitutive law) and those obtainable by the Equivalent Frame approach (by using the Tremuri program) is performed by considering small masonry building prototype, for which experimental results are available.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket