A Brief Overview on Crack Patterns, Repair and Strengthening of Historical Masonry Structures

Abstract

Given that a significant fraction of buildings and architectural heritage in Europe’s historical centers are masonry structures, the selection of proper diagnosis, technological surveys, non-destructive testing, and interpretations of crack and decay patterns is paramount for a risk assessment of possible damage. Identifying the possible crack patterns, discontinuities, and associated brittle failure mechanisms within unreinforced masonry under seismic and gravity actions allows for reliable retrofitting interventions. Traditional and modern materials and strengthening techniques create a wide range of compatible, removable, and sustainable conservation strategies. Steel/timber tie-rods are mainly used to support the horizontal thrust of arches, vaults, and roofs and are particularly suitable for better connecting structural elements, e.g., masonry walls and floors. Composite reinforcing systems using carbon, glass fibers, and thin mortar layers can improve tensile resistance, ultimate strength, and displacement capacity to avoid brittle shear failures. This study overviews masonry structural diagnostics and compares traditional and advanced strengthening techniques of masonry walls, arches, vaults, and columns. Several research results in automatic surface crack detection for unreinforced masonry (URM) walls are presented considering crack detection based on machine learning and deep learning algorithms. In addition, the kinematic and static principles of Limit Analysis within the rigid no-tension model framework are presented. The manuscript sets a practical perspective, providing an inclusive list of papers describing the essential latest research in this field; thus, this paper is useful for researchers and practitioners in masonry structures.

Determining the characteristics of concrete in a historical building under the influence of climatic and biological factors

“…8, 9) showed the presence of an insignificant content of sulfur and sulfur dioxide in the experimental and control samples of concrete. Studies [22,23] also raised the issue of the peculiarities of the restoration of old buildings.…”

Construction and Building Materials: Masonry Structures and Reinforced Concrete Structures

“…The aspects of strengthening were described in the papers [10,13,24]. Tabrizikahou, Hadzima-Nyarko, Kuczma, and Lozančić, in the paper [10], described possible applications of strengthening using Shape Memory Alloys (SMAs) in historic buildings in areas subjected to seismic actions.…”

“…The described tests showed that the accidental eccentricities did not substantially affect the obtained results, and that the more slender the specimen was, the more consistent the results were. The paper [24] was a review work. Latifi, Hadzima-Nyarko, Radu, and Rouhi described the diagnostic potential for masonry structures and compared traditional and advanced techniques of strengthening masonry walls, arches, vaults, and columns.…”

“…The numerical validation of the model of wall connections was proposed only in the paper [21]. Tests on component elements [2,4,5,7,9,11,14,21], and on repairs and strengthening of constructions [10,13,19,24] were conducted for both reinforced concrete and masonry structures.…”

Deep Learning-Based Automated Detection of Cracks in Historical Masonry Structures

“…Transfer learning is applicable to any CNN and FCN (fully convolutional networks) architecture [26]. Deep learning-based automated crack detection systems have been developed for masonry structures [27,28]. These systems utilize deep convolutional neural networks and image-processing techniques to detect cracks on concrete and masonry surfaces [29,30].…”