Out-of-plane seismic response and modelling of unreinforced masonry infill walls

Past and recent earthquakes showed that the seismic performance of buildings is strongly influenced by the presence and contribution of unreinforced masonry (URM) infills, which are usually considered as non-structural elements. Such enclosures are used – especially in Mediterranean countries – to provide buildings with thermic, visual and acoustic insulation. On one hand, URM infills can stand significant lateral loads and, so, they contribute to the lateral strength capacity of structures. In addition, they are provided with a high in-plane stiffness. For this reason, the assessment of a construction modelled as bare frame can yield to a significant underestimation of its lateral strength and stiffness. On the other hand, it is well-known that the high force demand that URM enclosures attract and then transfer to the confining elements can yield to unexpected failures of structural members designed without accounting for infills’ presence. For example, Reinforced Concrete (RC) columns (and beams, potentially) not designed addressing seismic and capacity design provisions sometimes exhibit brittle failures during strong earthquakes due to the so-called “frame-infill interaction”, i.e., due to the shear forces transferred by infills and not considered in the design. Moreover, the absence of infills at a certain storey of a building (typically, the first) produces a non-negligible stiffness variation of the structure lateral stiffness along its height, leading, in this way, to potential peaks of inelastic demand at that storey yielding to a sidesway collapse due to a soft-storey mechanism. In addition, infills’ damaging due to IP actions and their repair or refurbishment produces most of the financial losses consequent to earthquakes. In other words, neglecting infills’ presence and their contribution to the seismic response of structures can be both conservative and unconservative. For these reasons, the interest in the characterization of the seismic response of URM infills has significantly grown in the engineering and research community in the last decades. It should be noted that these bi-dimensional non-structural elements are subjected to the seismic action both in the in-plane (IP) and in the out-of-plane (OOP) direction. The expulsion or overturning from the confining frame due to OOP actions of URM infills is potentially highly detrimental for human life safety and amplifies the economic losses consequent to earthquakes. The OOP collapse of URM infills is promoted by the damage due to IP actions, which can reduce their OOP strength, stiffness and displacement capacity. This phenomenon is called IP/OOP interaction. This PhD thesis is dedicated to the characterization and modelling of the OOP behaviour of URM infills and to the study of the effects of the IP/OOP interaction both at the level of the single (non-structural) component and at the level of the infilled structure seismic performance. Chapter I is dedicated to the existing literature concerning this issue and investigating the definition of the OOP strength, stiffness and displacement capacity of URM infills. In addition, existing formulation for the prediction and reproduction of the IP/OOP interaction effects are addressed. Finally, existing URM infills’ modelling strategies accounting for their OOP behaviour and for the IP/OOP interaction effects are described in detail. Chapter II constitute the second part of the previous literature recall, as it is dedicated to a detailed description of the experimental tests carried out in the past to investigate the OOP behaviour of URM infills and the IP/OOP interaction effects. It is observed that the experimental database allowing evaluating the effectiveness and robustness of literature formulations and models described in Chapter I is extremely poor. For this reason, a comprehensive and extended experimental program has been carried out at the Department of Structures for Engineering and Architecture of University of Naples Federico II. The experimental program main aim is the characterization of the effects of the panel height-to-thickness slenderness ratio, of the boundary conditions at edges and of the IP/OOP interaction on the OOP strength, stiffness and displacement capacity of URM infills. A total of fifteen tests has been carried out to enrich the available experimental database. Chapter III is dedicated to a detailed description of the experimental program and of its results. In Chapter IV, the experimental database collected in Chapter II and III is analysed and discussed, in order to compare the prediction of literature formulations and models aimed at assessing the OOP response of URM infills and/or its significant parameters, such as the force at first macro-cracking and at maximum, as well as their secant stiffness at the first macro-cracking and at maximum and the displacement capacity/ductility. The predicting capacity of the available IP/OOP interaction models is assessed, too. This comparison is aimed at evaluating the effectiveness of the available models for the prediction of the OOP response of both IP-undamaged and IP-damaged URM infills. Based on the results of this comparison, original and mechanical based proposals are described for a robust and effective modelling of URM infills’ OOP response. In addition, empirical formulation for the prediction of the IP/OOP interaction are proposed. With Chapter IV, the characterization of the OOP behaviour of the single panel, which is the first part of this thesis, is completed. Chapter V is dedicated to a simple state-of-the-art concerning the current provisions given by international technical codes and standards for the assessment of URM infills safety with respect to OOP seismic demands. More specifically, demand and capacity models provided by codes are described and discussed. This is preliminary to the assessment of the seismic performance of RC buildings accounting for the OOP response of infills and for the IP/OOP interaction effects, which is the second part of this thesis. To this aim, a set of sixteen case-study buildings has been designed according to Eurocodes’ provisions. The case-study buildings are described and commented in detail in Chapter VI. The case-study buildings are different for the number of storeys, which is equal to 2, 4, 6 or 8, and for the design peak ground acceleration (PGA) at Life Safety Limit State. In Chapter VII, the case-study buildings described in the previous section are used to assess the PGA at the first OOP collapse of different infill layouts in a non-linear static framework by using both a simplified “Designer (code-based) Approach” and a refined “Reference Approach”. Only the least accounts, in evaluating the OOP force demand and capacity of infills, for the structural nonlinearity as well as for the IP/OOP interaction effects. The dependence of such the PGA capacity with respect to the first OOP collapse on the number of storeys and on the design PGA is discussed. In addition, the PGA at the first OOP collapse is compared with the design PGA of the case-study buildings as well as to the PGA corresponding to their conventional structural collapse. It is shown that weak infills in mid- and high-rise buildings can collapse for OOP actions and due to the IP/OOP interaction effects at PGA demand lower than the PGA at structural collapse or even than the design PGA. In addition, simplified criteria to evaluate, based on infills geometric and mechanical properties, if the OOP safety check is necessary or not are presented. In Chapter VIII, the seismic performance of the case-study buildings accounting and not accounting for the IP/OOP interaction effects on URM infills is assessed by means of non-linear incremental dynamic analysis. Also in this case, the overall capacity of buildings with respect to the first OOP collapse is investigated. In addition, the OOP behaviour factor and effective stiffness of URM infills accounting for the IP/OOP interaction effects is evaluated. Such values can be used for a simplified OOP safety check of URM infills in a linear elastic framework. In the appendix section, some theoretical considerations and experimental data supporting the discussions above proposed are reported in detail

EMPIRICAL UNREINFORCED MASONRY INFILL MACRO-MODEL ACCOUNTING FOR IN-PLANE/OUT-OF-PLANE INTERACTION

Unreinforced Masonry (URM) infills are widely used in Reinforced Concrete (RC) structures in Mediterranean countries. URM infills are subjected to the seismic action in their plane, i.e. in the In Plane (IP) direction, and in the Out Of Plane (OOP) direction. The IP displacement demand reduce the OOP capacity and vice-versa: this phenomenon is called IP-OOP interaction. A large number of studies has been carried out on the IP behaviour of infills, while their OOP response and the IP-OOP interaction have been less investigated. In this paper, a review of code and literature provisions concerning URM infills OOP behaviour is presented together with a review of the experimental tests carried out to investigate the infills OOP response and the effects of the IP-OOP interaction. An experimental database is collected to assess the effectiveness of literature and code provisions and to propose new empirical formulations both for predicting infills OOP strength, stiffness and displacement capacity and for modelling the effects of IP displacement demand on the OOP behavior and vice versa. A state of art on infills OOP behaviour and IP-OOP interaction modelling is presented. Most of these distributed-plasticity models are not based on experimental evidences and do not allow taking into account the IP and OOP stiffness degradation due to OOP and IP actions, respectively. A lumped-plasticity macro-model based on the proposed empirical formulations and conceived to represent the IP and the OOP behavior taking into account the mutual interaction effects is defined. Part of the proposed modelling strategy is a routine that removes the whole infill panel from the structural model in case of its IP or OOP collapse. The proposed model is used for an example application showing the effects of taking into account or neglecting the IP-OOP interaction phenomena during structural analyses

Experimental investigation on the influence of the aspect ratio on the in-plane/out-of-plane interaction for masonry infills in RC frames

Abstract The analysis of the behaviour of masonry infills under out-of-plane (OOP) and in-plane (IP) loading is paramount to correctly assess the seismic performance of reinforced concrete (RC) frames. A very important issue about this topic is certainly the IP/OOP interaction, namely the analysis of how the IP damage, which affects infills during earthquakes, can influence their OOP behaviour (and vice-versa). Some studies about this topic were developed in the last years; nevertheless, only a dozen of tests currently exists in the literature to experimentally explore this key issue. This work first presents an experimental campaign carried out on square infill walls in RC frames to investigate about the OOP behaviour of the masonry infills, and about the IP/OOP interaction. On the whole, four specimens have been tested under OOP monotonic loading. Three of them have been first damaged under cyclic IP actions, with different extent; the remaining one, used as a reference, was tested under OOP loading only. The experimental campaign is described in detail in terms of specimens' characteristics, material properties, adopted setup and instrumentation layout. The experimental results are analysed in terms of IP and OOP force-displacement responses, vertical arch strength contribution evolutions, and damage state evolutions, and compared with prediction proposals from the literature. Then, the influence of the infill aspect ratio (width (w)-to-height (h) ratio) on the IP/OOP interaction is investigated by means of the comparison between data presented herein (collected on infills with w/h = 1) and a companion experimental campaign previously performed on nominally identical infills except that for the aspect ratio of the specimens (in that case, higher than the unit). It has been observed that under given IP drift levels, square infills presented lower IP damage levels with respect to rectangular infills (with w/h > 1), thus generally producing a less pronounced detrimental effect of the IP imposed drift on the OOP strength. Nevertheless, none of the predictions from literature takes into account the role of the aspect ratio on the IP/OOP interaction, generally resulting in conservative predictions, to be improved in future works

Simulated microgravity promotes the formation of tridimensional cultures and stimulates pluripotency and a glycolytic metabolism in human hepatic and biliary tree stem/progenitor cells

Many pivotal biological cell processes are affected by gravity. The aim of our study was to evaluate biological and functional effects, differentiation potential and exo-metabolome profile of simulated microgravity (SMG) on human hepatic cell line (HepG2) and human biliary tree stem/progenitor cells (hBTSCs). Both hBTSCs and HepG2 were cultured in a weightless and protected environment SGM produced by the Rotary Cell Culture System (Synthecon) and control condition in normal gravity (NG). Self-replication and differentiation toward mature cells were determined by culturing hBTSCs in Kubota's Medium (KM) and in hormonally defined medium (HDM) tailored for hepatocyte differentiation. The effects on the expression and cell exo-metabolome profiles of SMG versus NG cultures were analyzed. SMG promotes tridimensional (3D) cultures of hBTSCs and HepG2. Significative increase of stemness gene expression (p < 0.05) has been observed in hBTSCs cultured in SMG when compared to NG condition. At the same time, the expression of hepatocyte lineage markers in hBTSCs differentiated by HDM was significantly lower (p < 0.05) in SMG compared to NG, demonstrating an impaired capability of hBTSCs to differentiate in vitro toward mature hepatocytes when cultured in SMG condition. Furthermore, in HepG2 cells the SMG caused a lower (p < 0.05 vs controls) transcription of CYP3A4, a marker of late-stage (i.e. Zone 3) hepatocytes. Exo-metabolome NMR-analysis showed that both cell cultures consumed a higher amount of glucose and lower glutamate in SMG respect to NG (p < 0.05). Moreover, hBTSCs media cultures resulted richer of released fermentation (lactate, acetate) and ketogenesis products (B-hydroxybutyrate) in SGM (p < 0.05) than NG. While, HepG2 cells showed higher consumption of amino acids and release of ketoacids (3-Methyl-2-oxovalerate, 2-oxo-4-methyl-valerate) and formiate with respect to normogravity condition (p < 0.05). Based on our results, SMG could be helpful for developing hBTSCs-derived liver devices. In conclusion, SMG favored the formation of hBTSCs and HepG2 3D cultures and the maintenance of stemness contrasting cell differentiation; these effects being associated with stimulation of glycolytic metabolism. Interestingly, the impact of SMG on stem cell biology should be taken into consideration for workers involved in space medicine programs

Biochemical and computational studies of the interaction between a glucosamine derivative, NAPA, and the IKKα kinase

The glucosamine derivative 2-(N-Acetyl)-L-phenylalanylamido-2-deoxy-β-D-glucose (NAPA), was shown to inhibit the kinase activity of IKKα, one of the two catalytic subunits of IKK complex, decreasing the inflammatory status in osteoarthritis chondrocytes. In the present work we have investigated the inhibition mechanism of IKKα by NAPA by combining computational simulations, in vitro assays and Mass Spectrometry (MS) technique. The kinase in vitro assay was conducted using a recombinant IKKα and IKKtide, a 20 amino acid peptide substrate derived from IkBα kinase protein and containing the serine residues Ser32 and Ser36. Phosphorylated peptide production was measured by Ultra Performance Liquid Chromatography coupled with Mass Spectrometry (UPLC-MS), and the atomic interaction between IKKα and NAPA has been studied by molecular docking and Molecular Dynamics (MD) approaches. Here we report that NAPA was able to inhibit the IKKα kinase activity with an IC50 of 0.5 mM, to decrease the Km value from 0.337 mM to 0.402 mM and the Vmax from 0.0257 mM·min-1 to 0.0076 mM·min-1. The computational analyses indicate the region between the KD, ULD and SDD domains of IKKα as the optimal binding site explored by NAPA. Biochemical data indicate that there is a non-significant difference between Km and Ki whereas there is a statistically significant difference between the two Vmax values. This evidence, combined with computational results, consistently indicates that the inhibition is non-competitive, and that the NAPA binding site is different than that of ATP or IKKtide

On the estimation of landslide intensity, hazard and density via data-driven models

Maps that attempt to predict landslide occurrences have essentially stayed the same since 1972. In fact, most of the geo-scientific efforts have been dedicated to improve the landslide prediction ability with models that have largely increased their complexity but still have addressed the same binary classification task. In other words, even though the tools have certainly changed and improved in 50 years, the geomorphological community addressed and still mostly addresses landslide prediction via data-driven solutions by estimating whether a given slope is potentially stable or unstable. This concept corresponds to the landslide susceptibility, a paradigm that neglects how many landslides may trigger within a given slope, how large these landslides may be and what proportion of the given slope they may disrupt. The landslide intensity concept summarized how threatening a landslide or a population of landslide in a study area may be. Recently, landslide intensity has been spatially modeled as a function of how many landslides may occur per mapping unit, something, which has later been shown to closely correlate to the planimetric extent of landslides per mapping unit. In this work, we take this observation a step further, as we use the relation between landslide count and planimetric extent to generate maps that predict the aggregated size of landslides per slope, and the proportion of the slope they may affect. Our findings suggest that it may be time for the geoscientific community as a whole, to expand the research efforts beyond the use of susceptibility assessment, in favor of more informative analytical schemes. In fact, our results show that landslide susceptibility can be also reliably estimated (AUC of 0.92 and 0.91 for the goodness-of-fit and prediction skill, respectively) as part of a Log-Gaussian Cox Process model, from which the intensity expressed as count per unit (Pearson correlation coefficient of 0.91 and 0.90 for the goodness-of-fit and prediction skill, respectively) can also be derived and then converted into how large a landslide or several coalescing ones may become, once they trigger and propagate downhill. This chain of landslide intensity, hazard and density may lead to substantially improve decision-making processes related to landslide risk

Contact-force monitoring increases accuracy of right ventricular voltage mapping avoiding "false scar" detection in patients with no evidence of structural heart disease

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Loss of p53 activates thyroid hormone via type 2 deiodinase and enhances DNA damage

: The Thyroid Hormone (TH) activating enzyme, type 2 Deiodinase (D2), is functionally required to elevate the TH concentration during cancer progression to advanced stages. However, the mechanisms regulating D2 expression in cancer still remain poorly understood. Here, we show that the cell stress sensor and tumor suppressor p53 silences D2 expression, thereby lowering the intracellular THs availability. Conversely, even partial loss of p53 elevates D2/TH resulting in stimulation and increased fitness of tumor cells by boosting a significant transcriptional program leading to modulation of genes involved in DNA damage and repair and redox signaling. In vivo genetic deletion of D2 significantly reduces cancer progression and suggests that targeting THs may represent a general tool reducing invasiveness in p53-mutated neoplasms

Minimally invasive vs. open segmental resection of the splenic flexure for cancer: a nationwide study of the Italian Society of Surgical Oncology-Colorectal Cancer Network (SICO-CNN)

Background Evidence on the efficacy of minimally invasive (MI) segmental resection of splenic flexure cancer (SFC) is not available, mostly due to the rarity of this tumor. This study aimed to determine the survival outcomes of MI and open treatment, and to investigate whether MI is noninferior to open procedure regarding short-term outcomes. Methods This nationwide retrospective cohort study included all consecutive SFC segmental resections performed in 30 referral centers between 2006 and 2016. The primary endpoint assessing efficacy was the overall survival (OS). The secondary endpoints included cancer-specific mortality (CSM), recurrence rate (RR), short-term clinical outcomes (a composite of Clavien-Dindo &gt; 2 complications and 30-day mortality), and pathological outcomes (a composite of lymph nodes removed &gt;= 12, and proximal and distal free resection margins length &gt;= 5 cm). For these composites, a 6% noninferiority margin was chosen based on clinical relevance estimate. Results A total of 606 patients underwent either an open (208, 34.3%) or a MI (398, 65.7%) SFC segmental resection. At univariable analysis, OS and CSM were improved in the MI group (log-rank test p = 0.004 and Gray's tests p = 0.004, respectively), while recurrences were comparable (Gray's tests p = 0.434). Cox multivariable analysis did not support that OS and CSM were better in the MI group (p = 0.109 and p = 0.163, respectively). Successful pathological outcome, observed in 53.2% of open and 58.3% of MI resections, supported noninferiority (difference 5.1%; 1-sided 95%CI - 4.7% to infinity). Successful short-term clinical outcome was documented in 93.3% of Open and 93.0% of MI procedures, and supported noninferiority as well (difference - 0.3%; 1-sided 95%CI - 5.0% to infinity). Conclusions Among patients with SFC, the minimally invasive approach met the criterion for noninferiority for postoperative complications and pathological outcomes, and was found to provide results of OS, CSM, and RR comparable to those of open resection