A Visual Scripting Based Limit Analysis Approach for Predicting Collapse in Masonry Structures

The broad Italian cultural heritage, largely composed of masonry historical constructions, requires preservation, enhancement, and safety assessment. Therefore, ensuring the integrity of this valuable historical asset imposes the need for a precise evaluation of the structural conditions of existing masonry constructions. Understanding the possible collapse mechanisms of historical buildings is crucial to identify critical issues and to guarantee structural safety. These considerations motivate the present paper which proposes a simplified limit analysis numerical approach, implemented within an interactive visual scripting environment. In particular, an optimization algorithm, employing linear programming techniques, is adopted to solve an upper bound limit analysis problem and to determine the load multiplier of the collapse mechanism in masonry structures, modeled as two-dimensional rigid macro-element block systems. The visual scripting approach enables the direct calculation of the collapse load multiplier, while providing immediate visualization of the most probable mechanism corresponding to the critical value of the acting loads capable of inducing collapse. The obtained results are validated and discussed through the analysis of a benchmark case in which a masonry macro-element is subjected to vertical loads N, ranging from 1 to 20 kN, its self-weight W and an horizontal variable load αW applied at the centroid of the block. The corresponding collapse mechanism is characterized by the circumstance that the initial element divides into two blocks with the appearance of an internal horizontal hinge which determines the vertical bending of the two-blocks wall. The associated limit load multiplier α increases with N, while the internal hinge shifts progressively downward. The proposed procedure results intuitive for professional use and is designed to be integrated into open platforms, thus representing a valuable and efficient tool for a rapid and effective understanding of the possible structural crises in historical constructions.