Non-linear Methods for the Assessment of Seismic Vulnerability of Masonry Historical Buildings

Abstract

The evaluation of seismic performance of existing masonry structures is a fundamental issue for the preservation of cultural heritage in general and of historical buildings in particular, even in view of the adoption of suitable policies for risk mitigation. To assess the seismic performance of existing masonry buildings, several refined push-over procedures for non-linear static analysis can be found in literature, mainly based on the equivalent frame approach. However, these procedures are not only very time consuming, but also very sensitive to modelling hypotheses, so that results could vary in a large interval even when users are very skilled. To solve these problems, the authors, aiming to enhance the classical pushover programs for masonry building, especially in terms of easiness of use, simplicity of modelling and computational demand, developed a reliable and sound push-over procedure allowing a quick evaluation of seismic risk index. The so called E-PUSH program, which allows the verification of multi-story masonry buildings according to the most recent structural codes and relies on very simple structural models, has been validated considering several relevant benchmark studies and comparing the results with classical procedures implemented in commercial programs. In the paper, a review of macro-element methods for the seismic assessment of unreinforced masonry buildings is then discussed considering the main hypothesis on masonry modelling, choice of masonry mechanical parameters and failure criteria and evaluating their impact on the estimation of seismic risk index. The results of the comparison will be finally presented and discussed for a relevant case study of a four story masonry building investigated by the authors in the framework of a research program agreement between the Municipality of Florence and the Department of Civil and Industrial Engineering of the University of Pisa.

Parametric HBIM Procedure for the Structural Evaluation of Heritage Masonry Buildings

“…Grasshopper-Archicad Live Connection tool enables the structural model to be analyzed using an appropriate algorithm with visual programming language (VPL). Grasshopper extracts all previously defined structural data, performing the additional user-specified codes required by the linear or nonlinear structural analyses [6][7][8][9][10][11], as well as the assessment of the structural performance under non-seismic and seismic actions. Combination of Archicad and Grasshopper allows for a highly organized and efficient working flow, where the following main phases can be identified:…”

“…Given these concerns, assessing the vulnerability of existing masonry buildings is crucial [6][7][8][9][10][11]. EN1998-3 [12] and also Annex B of the ISO13822 [13] provide general procedures for seismic evaluation and retrofitting of existing structures.…”

“…For the sake of the structural analysis, considering the computational efficiency and the ability to capture the global behavior of the construction, simplified models [9], specifically macro-element models [20], are, in many applications, preferred to more refined local models.…”

“…Starting from the POR method, several programs for the analysis of masonry structures have been developed over the years based on the Equivalent Frame Model. A review of the most common software programs for the analysis of masonry buildings can be found in [9,20]. Among them, an innovative, particularly simple and efficient program called E-PUSH was developed by the authors for linear and non-linear static analysis of multistory 3D masonry buildings under seismic actions [6,7].…”

“…In the E-PUSH software, consisting of routines written and executed in the MATLAB environment [24], input data for the analysis of the investigated buildings are collected in a table, which can be compiled manually or by means of an Excel file, containing the geometric and mechanical properties of masonry walls, and the stresses due to vertical loads. Requiring a limited number of input data and being based on very clear and simple structural models, the E-PUSH program is nearly independent of the users, so that efficient workflows can be developed for the safety assessment of existing masonry buildings [6,7,[9][10][11].…”