Investigating the seismic response of URM walls with irregular opening layout through different modeling approaches

TThe façade and internal walls of unreinforced masonry (URM) buildings often present an irregular opening layout, due to architectural reasons or modifications to the structure, which make the expected seismic damage pattern less predictable a priori. Therefore, the discretization of the walls in structural components is not standardized, conversely to cases with a regular opening layout for which the available modeling methods are corroborated by seismic damage surveys reporting recurrent failure patterns. The structural component discretization is a relevant step for the code-conforming seismic assessment, typically based on comparing the internal forces and drifts of each component to strength criteria and drift thresholds. Therefore, the lack of well-established approaches can significantly influence the assessment. The issue is even more evident when the structural components must be identified a priori in the modeling stage, namely for equivalent frame models. The applicability of available methods for discretization of URM walls with irregular opening layout has been already investigated in literature, but a conclusive judgment requires further studies. In this context, this paper presents an overview of the preliminary results addressing the numerical modeling of this type of walls within the framework of the DPC-ReLUIS 2022-2024 project (Subtask 10.3), funded by the Italian Department of Civil Protection. The Subtask aims to propose consensus-based recommendations for researchers and practitioners which can contribute to harmonize the use of different modeling approaches. Seven research groups are involved in the research, adopting different modeling approaches and computer codes, but similar assumptions and the same analysis method (pushover) are used. The benchmark URM structure illustrated in the paper is a two-story wall from which four configurations with increasing irregularity of opening layout were derived. The results of four modeling approached are presented. Three of them reproduce the mechanical response of masonry at the material scale by means of FE models implemented in OpenSees, DIANA and Abaqus software, while the remaining approach describes the mechanical response of masonry at the macro-element scale in 3DMacro software. Results were compared in terms of capacity curves, predicted failure mechanisms and evolution of internal forces in piers. The adoption of consistent assumptions among the different approaches led to an overall agreement of predictions at both wall and pier scales, particularly in terms of damage pattern with higher concentration of damage at the ground story. Despite that, differences on the pushover curves have been highlighted. They are mainly due to some deviations of the internal forces in squat piers deriving from a complex load flow in these elements.DPC - Dipartimento della Protezione Civile, Presidenza del Consiglio dei Ministri(LA/P/0112/2020

Internal carotid artery rupture caused by carotid shunt insertion

Introduction: Shunting is a well-accepted method of maintaining cerebral perfusion during carotid endarterectomy (CEA). Nonetheless, shunt insertion may lead to complications including arterial dissection, embolization, and thrombosis. We present a complication of shunt insertion consisting of arterial wall rupture, not reported previously. Presentation of case: A 78-year-old woman underwent CEA combined with coronary artery bypass grafting (CABG). At the time of shunt insertion an arterial rupture at the distal tip of the shunt was detected and was repaired via a small saphenous vein patch. Eversion CEA and subsequent CABG completed the procedure whose postoperative course was uneventful. Discussion: Shunting during combined CEA-CABG may be advisable to assure cerebral protection from possible hypoperfusion due to potential hemodynamic instability of patients with severe coronary artery disease. Awareness and prompt management of possible shunt-related complications, including the newly reported one, may contribute to limiting their harmful effect. Conclusion: Arterial wall rupture is a possible, previously not reported, shunt-related complication to be aware of when performing CEA

Study on the efficacy of surgery of the superficial venous system and of compression therapy at early stages of chronic venous disease for the prevention of chronic venous ulceration

The mainstay of treatment of chronic venous ulceration (CVU), as also suggested by current treatment guidelines for chronic venous disease (CVD), is represented by surgery and compression therapy for which there is strong evidence of their role in clinically relevant improvement in wound healing and also in the reduction of CVU recurrence, but no information is available as to whether or not these treatments provide effective protection from the onset of CVU. In our study, we have followed, for a median time of 13 years, a total of 3947 patients with CVD at classes C2-C3 of CEAP classification, treated with our treatment protocol (surgery and compression therapy) in order to track the natural history of these patients with regards to CVU development. We identified four groups of patients: 2354 patients (59·64%) (Group A) fully adherent to protocols; 848 patients (21·48%) (Group B) fully adherent to surgery and non-compliant to compression therapy; 432 patients (10·95%) (Group C) fully adherent to compression therapy and non-compliant to surgery; and 313 patients (7·93%) (Group D) non-compliant to either treatments. Regardless of compliance to treatments, the ulcer development rates were very similar between groups (range: 3·23-4.79%), with no statistical significance (P = 0·1522). Currents treatments used in the early stages of CVD appear to have no effects to progression to CVU. Additional longitudinal studies are required to confirm these findings