On the mechanics of “false vaults”: new analytical and computational approaches

The aim of this paper is to present new analytical and computational approaches for assessing the structural safety of “false vaults” structures like Trulli, and more generally for corbelled structures. In particular, the proposed procedure is capable of taking into account the three-dimensional behavior of such complex masonry structures

Optimal model through identified frequencies of a masonry building structure with wooden floors

The paper presents the analysis of an important historical building: the Saint James Theater in the city of Corfù (Greece) actually used as the Municipality House. The building, located in the center of the city, is made of carves stones and is characterized by a stocky shape and by the presence of wooden floors. The study deals with the structural identification of such structure through the analysis of its ambient vibrations recorded by means of accelerometers with high accuracy. A full dynamic testing was developed using ambient vibrations to identify the main modal parameters and to make a non-destructive characterization of this building. The results of these dynamic tests are compared with the modal analysis of a complex finite element (FE) simulation of the structure. This analysis may present several problems and uncertainties for this stocky building. Due to the presence of wooden floors, the local modes can be highly excited and, as a consequence, the evaluation of the structural modal parameters presents some difficulties.This work was supported in part by the European Territorial Cooperation Programme “Greece-Italy 2007-2013”, under grants of the project Structural Monitoring of ARTistic and historical BUILding Testimonies (S.M.ART:BUIL.T.)

Simple model for predicting the vibration transmission of a squat masonry tower by base forced vibrations

This paper presents the analysis of the dynamic performances of a simple model related to a squat masonry tower situated in the Swabian Castle of Trani (Italy). The main objective of this paper is to introduce a novel strategy based on a simple model validated by experimental data for defining the influence of the excitation frequency on the structural damping dynamic transmission. To this aim, first, the accelerations have been acquired simultaneously in 23 points of the tower at different levels, both due to environmental vibrations and due to a series of sinusoidal forced vibrations applied at the base by using an electro‐hydraulic shaker device specifically designed for the tests. Four different excitation frequencies have been then selected for exciting the structure. An operational modal analysis has been carried out by the environmental recordings and with the different forcing loads obtaining a very good correlation of the identified frequencies in all the cases. Then a digital filtering process has been applied over all the recorded signals to evaluate the specific contribution for each frequency generated by the shaking device at each level of the tower. Increments of damping ratio have been detected with these forced vibrations at the base. Finally, a simple frame numerical model has been developed to reproduce the dynamic amplification at the most significant locations of the tower. It has been updated not only to have the same main frequencies and modal shapes but also to get a similar response under forced vibrations at the base. A good correlation has been obtained between the model and the real structure for the base forced vibrations at different excitation frequencies in order to correctly predict the dynamic behaviour of the structure.Authors acknowledge the Italian project PRIN 2015: “Mitigating the impacts of natural hazards on cultural heritage sites, structures and artefacts” and the Spanish project BIA2015‐69952‐R

Model Updating Based on the Dynamic Identification of a Baroque Bell Tower

The sanctuary of Santa Maria di Loreto (Mola di Bari, Italy) was built in in the sixteen century and it is constituted by a church with a simple hut façade characterized by a fine calcareous rose window and on its left side a high bell tower with heavy bells. In the present study, a non-destructive dynamic identification of the modal characteristics of the structure has been carried out by firstly organising an experimental setup of environmental measurements with several accelerometers placed on different levels of the bell tower. Secondly, the data acquired by the accelerometers have been elaborated by using modern statistic techniques of operational modal analysis (OMA). Finally, these results have been used for calibrating a complete finite element (FE) model of the bell tower structure that may permit to obtain important information about the state of integrity of the medieval structure. This calibrated model was developed to obtain a preliminary evaluation of the seismic vulnerability of the bell tower by performing a nonlinear static analysis

Measuring the modal parameters of a cultural heritage tower by using strong-motion signals

This paper presents the dynamic experimental campaign carried out on a stocky masonry clock tower situated in the Swabian Castle of Trani (Italy). The main objective of this paper is, after estimating the main frequencies and vibration modes of the considered structure, defining the transmission of vibrations along the height of the tower by varying the forced frequency at the base. At this aim, short acceleration records have been acquired simultaneously in 20 points of the tower at different levels, due to a series of sinusoidal forced vibrations applied at the base by using a pneumatic shaker device specifically designed for the tests. The proposed procedure permits to extract for each monitored point the amplitude of the sinusoidal component related to the excitation frequency and the phase shift due to the structure damping. The results of the proposed procedure are compared with the results of a classical operational modal analysis in environmental conditions in order to demonstrate that the short forced tests permit to classify the typology of the structural mode shapes.This work was supported by Structural Monitoring of ARTistic and historical BUILding Testimonies - (S.M.ART. BUIL.T.) Project of the European Territorial Cooperation Programme Greece-Italy 2007-2013 and by PRIN-MIUR 2010 research project entitled “Dynamics, Stability and Control of Flexible Structures”

Long-term physical impairments in survivors of COVID-19-associated ARDS compared with classic ARDS: A two-center study

Purpose: This work aimed to compare physical impairment in survivors of classic ARDS compared with COVID-19-associated ARDS (CARDS) survivors. Material and methods: This is a prospective observational cohort study on 248 patients with CARDS and compared them with a historical cohort of 48 patients with classic ARDS. Physical performance was evaluated at 6 and 12 months after ICU discharge, using the Medical Research Council Scale (MRCss), 6-min walk test (6MWT), handgrip dynamometry (HGD), and fatigue severity score (FSS). We also assessed activities of daily living (ADLs) using the Barthel index. Results: At 6 months, patients with classic ARDS had lower HGD (estimated difference [ED]: 11.71 kg, p < 0.001; ED 31.9% of predicted value, p < 0.001), 6MWT distance (ED: 89.11 m, p < 0.001; ED 12.96% of predicted value, p = 0.032), and more frequent significant fatigue (OR 0.35, p = 0.046). At 12 months, patients with classic ARDS had lower HGD (ED: 9.08 kg, p = 0.0014; ED 25.9% of predicted value, p < 0.001) and no difference in terms of 6MWT and fatigue. At 12 months, patients with classic ARDS improved their MRCss (ED 2.50, p = 0.006) and HGD (ED: 4.13 kg, p = 0.002; ED 9.45% of predicted value, p = 0.005), while those with CARDS did not. Most patients in both groups regained independence in ADLs at 6 months. COVID-19 diagnosis was a significant independent predictor of better HGD (p < 0.0001) and 6MWT performance (p = 0.001), and lower prevalence of fatigue (p = 0.018). Conclusions: Both classic ARDS and CARDS survivors experienced long-term impairments in physical functioning, confirming that post-intensive care syndrome remains a major legacy of critical illness. Surprisingly, however, persisting disability was more common in survivors of classic ARDS than in CARDS survivors. In fact, muscle strength measured with HGD was reduced in survivors of classic ARDS compared to CARDS patients at both 6 and 12 months. The 6MWT was reduced and fatigue was more common in classic ARDS compared to CARDS at 6 months but differences were no longer significant at 12 months. Most patients in both groups regained independent function in ADLs at 6 months

Surgical repair of muscle laceration: biomechanical properties at 6 years follow-up

Muscle injuries are challenging problems for surgeons. Muscle trauma is commonly treated conservatively with excellent outcome results while surgical repair is advocated for larger tears/lacerations, where the optimal goal is restore of function. Repair of muscle belly lacerations is technically demanding because the sutures pull out and the likelihood of clinical failure is high. Different suture techniques have been described but still the best suture is debated. We show a case of a pure vastus medialis muscle laceration surgically repaired at 6 years of follow-u

Surgical repair of muscle laceration: biomechanical properties at 6 years follow-up

Muscle injuries are challenging problems for surgeons. Muscle trauma is commonly treated conservatively with excellent outcome results while surgical repair is advocated for larger tears/lacerations, where the optimal goal is restore of function. Repair of muscle belly lacerations is technically demanding because the sutures pull out and the likelihood of clinical failure is high. Different suture techniques have been described but still the best suture is debated. We show a case of a pure vastus medialis muscle laceration surgically repaired at 6 years of follow-u