Review of experimental cyclic tests on unreinforced and strengthened masonry spandrels and numerical modelling of their cyclic behaviour

A reliable numerical modelling for the cyclic behaviour of unreinforced and strengthened masonry spandrels is herein presented. The proposed numerical model is adapted from Tomazevic-Lutman\u2019s model for masonry piers in shear and it has been validated upon an experimental campaign conducted at Department of Engineering and Architecture of University of Trieste. The tests were conducted on Hshaped full-scale specimens imposing vertical displacements of increasing amplitude on one leg. Four unreinforced masonry specimens arranged with different masonry material (bricks and stones) and lintel supports (wooden lintel, masonry arch) were considered. Each specimen was then reinforced with a different strengthening technique (tensioned bars, steel profiles, CFRP laminates) and re-tested. Analytical relationships were proposed, based on those available in some Codes of Practice, to estimate the maximum shear resistance of URM and RM spandrels. These relationships provide resistance values in good agreement with the experimental results and can be correctly employed to define the cyclic model of the spandrel to be used in the numerical simulation. The cyclic shear-displacement curves obtained through the numerical model are in good agreement with those of the experimental tests and very good assessment of the dissipated energy was obtained

Nonlinear simulation of masonry vaults under earthquake loading

Masonry vaults are present in a large number of historical structures and often used as floor-ing and roofing systems in monumental palaces and religious buildings, typically incorporat-ing no backfill. Many of these structures are located in seismic regions and have been shownto be particularly vulnerable during recent earthquakes, with a need for accurate modelling to avoid future losses. Masonry vaults are often analysed using limit analysis procedures un-der the hypotheses of no-tension material and absence of sliding along the masonry joints.However, this method can be inaccurate for barrel vaults found in buildings, which are typi-cally slender with no backfill. In this case, the masonry tensile strength and the progressive damage propagation play an important role in the nonlinear behaviour and ultimate strength of the vault. In this study, a detailed mesoscale finite element mesoscale approach is used to model slender unreinforced barrel vaults subjected to cyclic quasi-static and dynamic load-ing. According to this approach, 3D solid elements connected by 2D damage-plasticity inter-faces are used to represent the arrangement of bricks and mortar present in the masonry. Theproposed numerical description is first validated against the results from physical tests on a barrel vault under quasi-static cyclic loading. Subsequently, the shear response of a prototype vault is analysed by performing nonlinear simulations under prescribed horizontal displace-ments at the supports, considering also the influence of previous damage induced by earth-quakes with different magnitudes

Colorectal Cancer Stage at Diagnosis Before vs During the COVID-19 Pandemic in Italy

IMPORTANCE Delays in screening programs and the reluctance of patients to seek medical attention because of the outbreak of SARS-CoV-2 could be associated with the risk of more advanced colorectal cancers at diagnosis. OBJECTIVE To evaluate whether the SARS-CoV-2 pandemic was associated with more advanced oncologic stage and change in clinical presentation for patients with colorectal cancer. DESIGN, SETTING, AND PARTICIPANTS This retrospective, multicenter cohort study included all 17 938 adult patients who underwent surgery for colorectal cancer from March 1, 2020, to December 31, 2021 (pandemic period), and from January 1, 2018, to February 29, 2020 (prepandemic period), in 81 participating centers in Italy, including tertiary centers and community hospitals. Follow-up was 30 days from surgery. EXPOSURES Any type of surgical procedure for colorectal cancer, including explorative surgery, palliative procedures, and atypical or segmental resections. MAIN OUTCOMES AND MEASURES The primary outcome was advanced stage of colorectal cancer at diagnosis. Secondary outcomes were distant metastasis, T4 stage, aggressive biology (defined as cancer with at least 1 of the following characteristics: signet ring cells, mucinous tumor, budding, lymphovascular invasion, perineural invasion, and lymphangitis), stenotic lesion, emergency surgery, and palliative surgery. The independent association between the pandemic period and the outcomes was assessed using multivariate random-effects logistic regression, with hospital as the cluster variable. RESULTS A total of 17 938 patients (10 007 men [55.8%]; mean [SD] age, 70.6 [12.2] years) underwent surgery for colorectal cancer: 7796 (43.5%) during the pandemic period and 10 142 (56.5%) during the prepandemic period. Logistic regression indicated that the pandemic period was significantly associated with an increased rate of advanced-stage colorectal cancer (odds ratio [OR], 1.07; 95%CI, 1.01-1.13; P = .03), aggressive biology (OR, 1.32; 95%CI, 1.15-1.53; P < .001), and stenotic lesions (OR, 1.15; 95%CI, 1.01-1.31; P = .03). CONCLUSIONS AND RELEVANCE This cohort study suggests a significant association between the SARS-CoV-2 pandemic and the risk of a more advanced oncologic stage at diagnosis among patients undergoing surgery for colorectal cancer and might indicate a potential reduction of survival for these patients

New Materials For the Rehabilitation of Cultural Heritage

In this lecture some of the most recent intervention techniques for strengthening the cultural heritage constructions are presented and discussed. Many historical buildings are located in seismic active areas so that it is mandatory to define novel techniques that allow to increase the seismic capacity by respecting the requirements of the conservation. In the last decade the interest of composite materials for the restoration and rehabilitation of ancient masonry buildings was continuosly increased. In particular textile strips of carbon or glass fibers were considered to provide aids for the masonry in those zones subjected to tensile stresses. The fibers are embedded in situ in thermosetting resins. Other composite products concern FRP meshes that are used to reinforce a mortar coating applied on both masonry surfaces. Moreover stainless steel thin strips or strands are also used in particular techniques easy to be applied and that do not modify appreciably the actual seismic response of the structure. Different techniques for confining masonry columns so to increase the compression capacity and the ductility are presented. They concern the realization of hoops with FRP strips, with stainless steel thin strips and with stainless steel strands. The last one may be used also for exposed columns (not plastered) because the strands can be hidden with the mortar joint repointing. For increasing the in-plane shear resistance of masonry walls four strengthening techniques are discussed: two uses FRP composites and two uses stainless steel devices. The application of FRP strips on the masonry surface through adequate adhesives provides good in-plane shear performances, even though the lack of confinement may be crucial for multi-leaf masonries. The realization of a mortar coating reinforced with FRP meshes on both masonry surfaces allowed to increase considerably both the shear capacity and the ductility of the wall. Moreover, the transversal connectors provide good confinement to the masonry so that the technique is effective also for multi-leaf masonries. A strengthening method is based on the use of stainless steel thin strips that provide both the needed transversal confinement and the ties necessary to form a truss system for increasing the in-plane shear resistance. Finally a strengthening technique is made with a grid of stainless steel strands (or FRP wires) disposed on both surfaces of the masonry and connected together through steel elements. Good transversal confinement is provided and the shear resisrance is significantly increased. For out-of-plane flexure of the masonry the techniques with good confinement may guarantee good performances, even though further experimental studies are needed to support the theoretical results