Ilaria Senaldi

Following an earthquake, it is vital to quickly evaluate the safety of the impacted areas. Damage detection systems, powered by computer vision and deep learning, can assist experts in this endeavor. However, the lack of extensive, labeled datasets poses a challenge to the development of these systems. In this study, we introduce a technique for generating semi-synthetic images to be used as data augmentation during the training of a damage detection system. We specifically aim to generate images of cracks, which are a prevalent and indicative form of damage. The central concept is to employ parametric meta-annotations to guide the process of generating cracks on 3D models of real-word structures. The governing parameters of these meta-annotations can be adjusted iteratively to yield images that are optimally suited for improving detectors' performance. Comparative evaluations demonstrated that a crack detection system trained with a combination of real and semi-synthetic images outperforms a system trained on real images alone.

City centres of Europe are often composed of unreinforced masonry structural aggregates, whose seismic response is challenging to predict. To advance the state of the art on the seismic response of these aggregates, the Adjacent Interacting Masonry Structures (AIMS) subproject from Horizon 2020 project Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe (SERA) provides shake-table test data of a two-unit, double-leaf stone masonry aggregate subjected to two horizontal components of dynamic excitation. A blind prediction was organized with participants from academia and industry to test modelling approaches and assumptions and to learn about the extent of uncertainty in modelling for such masonry aggregates. The participants were provided with the full set of material and geometrical data, construction details and original seismic input and asked to predict prior to the test the expected seismic response in terms of damage mechanisms, base-shear forces, and roof displacements. The modelling approaches used differ significantly in the level of detail and the modelling assumptions. This paper provides an overview of the adopted modelling approaches and their subsequent predictions. It further discusses the range of assumptions made when modelling masonry walls, floors and connections, and aims at discovering how the common solutions regarding modelling masonry in general, and masonry aggregates in particular, affect the results. The results are evaluated both in terms of damage mechanisms, base shear forces, displacements and interface openings in both directions, and then compared with the experimental results. The modelling approaches featuring Discrete Element Method (DEM) led to the best predictions in terms of displacements, while a submission using rigid block limit analysis led to the best prediction in terms of damage mechanisms. Large coefficients of variation of predicted displacements and general underestimation of displacements in comparison with experimental results, except for DEM models, highlight the need for further consensus building on suitable modelling assumptions for such masonry aggregates.

This paper presents an experimental and numerical study on different retrofit solutions for stone masonry buildings with timber diaphragms in earthquake-prone regions, aiming at enhancing wall-to-diaphragm connections, diaphragms’ stiffness, and masonry properties. The experimental results of incremental dynamic shake-table tests on three full-scale two-story buildings, complemented by material and component characterization tests, are initially summarized. The first building specimen was unstrengthened. The second one was retrofitted at the floor and roof levels with improved wall-to-diaphragm connections and a moderate increase in diaphragm stiffness. Connections were also improved in the third specimen together with a significant enhancement of diaphragm stiffness. The calibration of two numerical models, versus the experimental response of the retrofitted building specimens, is then presented. The models were further modified and reanalyzed to assess the effects of masonry mechanical upgrades, which could be achieved in practice through deep joint repointing or various types of jacketing. These solutions were simulated by applying correction coefficients to the masonry mechanical properties, as suggested by the Italian building code. The effectiveness of the experimentally implemented and numerically simulated interventions are discussed in terms of strength enhancement and failure modes.

The University of Pavia owns an extensive real estate portfolio, largely consisting of historic buildings still hosting teaching and research activities. This implies a continuous challenge in keeping them efficient, sustainable and completely usable. Indeed, these heritage buildings, alongside an undeniable charm, bring with them deficiencies regarding safety, accessibility, energy efficiency, etc. This work presents an interdisciplinary strategy addressing the issues involved in the management of the multiple needs of conservation and use, complying with modern standards. The legal requirement of a seismic safety assessment was the occasion to launch a comprehensive review of the state of the University building heritage, considering together the different aspects involved, in a perspective of economic sustainability, combining preservation needs and valorisation. The steps of this strategy included a preliminary screening of all the buildings, by simple methods and tools. The aim was to gather homogeneous and comparable information, useful to identify critical structures and/or repeated issues, to allocate resources for deeper analyses and implementation. The case study of San Felice Palace, which presents emblematic features and deficiencies, is illustrated in more detail, with complete seismic safety and accessibility analyses leading to proposals of enhancement interventions.

A unidirectional shake-table test was performed on the half-scale prototype of a natural stone masonry building aggregate, to investigate the seismic performance of this type of historical construction and to assess the effectiveness of two retrofit solutions. The specimen represented a building aggregate with two adjacent three-storey units, connected along one side as if they were built at different times. Double-leaf stone masonry with undressed blocks and river pebbles was used for the walls. Timber floors constituted flexible diaphragms in their planes. Roofs with different timber truss configurations and heights covered the two units. Improved wall-to-diaphragm connections and tie rods were pre-installed, although initially not fastened, on the prototype. Both retrofit systems were activated after significant damage was reached testing the unstrengthened specimen. This paper describes the seismic behaviour of the prototype, focusing on the effects of the retrofit interventions on damage mechanism evolution, lateral displacement demand, hysteretic response, and dynamic properties degradation.