Reliability Estimation of the Compressive Concrete Strength Based on Non-Destructive Tests

The uncertainty in the concrete compressive strength is one of the most challenging issues in safety checking of existing reinforced concrete (RC) buildings. The concrete compressive strength used in the assessment can highly influence the vulnerability results and thus the retrofit strategies. The need to use less expensive and less invasive in situ measurements such as the non-destructive tests should be balanced with a careful check of their structural reliability. The compressive concrete strength is characterized herein based on a large database of both in situ destructive and non-destructive results measured on the same structural members. The data are obtained from existing RC buildings mainly located in the Campania region, Southern Italy. Probabilistic linear and multilinear regression models are developed for calculating the compressive concrete strength based on non-destructive tests. Furthermore, the implementation of the concrete strength based on ultrasonic test results are investigated together with the relative measurement error through a fully probabilistic workflow. Accordingly, the relative weights of non-destructive data for calculating concrete compressive strength are estimated and compared with those recommended by the Italian national code. The results demonstrate that the effective weights of the non-destructive data are very close to the code-based recommendation

Earthquake induced floor accelerations on a high-rise building: Scale model tests on a shaking table

The paper discusses results of shaking table tests on an in-scale high-rise building model. The purpose was to calibrate a dynamic numerical model for multi-hazard analyses to investigate the effects of floor acceleration. Accelerations, because of vibration of non-structural elements, affect both the comfort and safety of people. The research investigates the acceleration effects of both seismic and wind forces on an aeroelastic in-scale model of a multi-story building. The paper discusses the first phase of experiments and gives results of floor accelerations induced by several different base seismic impulses. Structural analyses were first performed on the full-scale prototype to take soil-structure interaction into account. Subsequently the scale model was designed through aeroelastic scale laws. Shaking table experiments were then carried out under different base accelerations. The response of the model and, in particular, amplification of effects from base to top are discussed

Damage assessment in single-nave churches and analysis of the most recurring mechanisms after the 2016–2017 central Italy earthquakes

Assessment of churches based on empirical data at a territorial scale is a suitable tool to have an overview of the seismic behaviour of this peculiar structural typology and to evaluate their current state of vulnerability. Fragility and vulnerability curves are also aimed to perform the analysis of different seismic scenarios. The paper presents a detailed typological analysis of 633 single-nave churches, as a selected subset of the database previously examined by the authors, with the aim of evaluating more in detail the influence of some parameters, such as masonry typology, church dimensions and presence of the bell tower, on the vulnerability of the overall church. Then, specific analyses are carried out to assess the influence played by single mechanisms on the definition of the overall damage index, with the focus of providing qualitative evaluations and explicit vulnerability and fragility curves related to the most recurring and significant collapse mechanisms. This is an original contribution of the paper in the field of the vulnerability assessment of churches, since nowadays little information is available in the literature about the damage levels related to specific mechanisms, while most attention is still focused on global damage

Proposal of A Probabilistic Model for Multi-Hazard Risk Assessment of Structures in Seismic Zones Subjected To Blast for the Limit State of Collapse,” Structural Safety

a b s t r a c t It is desirable to verify the structural performance based on a multi-hazard approach, taking into account the critical actions the structure in question could be subjected to during its lifetime. This study presents a proposal for a probabilistic model for multi-hazard risk associated with the limit state of collapse for a reinforced concrete (RC) structure subjected to blast threats in the presence of seismic risk. The annual risk of structural collapse is calculated taking into account both the collapse caused by an earthquake event and the blast-induced progressive collapse. The blast fragility is calculated using a simulation procedure for generating possible blast configurations, and verifying the structural stability under gravity loading of the damaged structure, using a kinematic plastic limit analysis. As a case study, the blast and seismic fragilities of a generic four-storey RC building located in seismic zone are calculated and implemented in the framework of a multi-hazard procedure, leading to the evaluation of the annual risk of collapse

Axial Compression Tests on Rubble Stone Masonry Reproducing Opus Incertum of Ancient Pompeii

In order to investigate the mechanical behaviour of the typical ancient rubble stone masonry type at the archaeological Pompeii site, an experimental program was carried out on masonry panels realized with the aim of reproducing the ancient technique opus incertum. Three panels (1.20m x 1.20m x 0.45m) were realized by using original rock units from ruins emerged in the excavation works at Regio V at the site and pozzolanic lime-based mortar realized according to the traditional technique. The first phase of the experimental program involved the accurate reproduction of Pompeii-like masonry panels and the execution of sonic pulse velocity tests to be compared with those carried out on original structures at the site. Thus, three in-situ diagonal compression tests were carried out to derive masonry shear strength and relevant correlation with sonic velocities. The last phase of the experimental program focuses on laboratory axial compression tests on five specimens extracted from the three panels analyzed in the first phase and is herein described in detail. The results of axial compression tests on two of such specimens in terms of axial compression strength and elastic modulus as well as the analysis of the crack pattern and failure mode is herein presented and discussed

Understanding the mechanisms of lung mechanical stress

Physical forces affect both the function and phenotype of cells in the lung. Bronchial, alveolar, and other parenchymal cells, as well as fibroblasts and macrophages, are normally subjected to a variety of passive and active mechanical forces associated with lung inflation and vascular perfusion as a result of the dynamic nature of lung function. These forces include changes in stress (force per unit area) or strain (any forced change in length in relation to the initial length) and shear stress (the stress component parallel to a given surface). The responses of cells to mechanical forces are the result of the cell's ability to sense and transduce these stimuli into intracellular signaling pathways able to communicate the information to its interior. This review will focus on the modulation of intracellular pathways by lung mechanical forces and the intercellular signaling. A better understanding of the mechanisms by which lung cells transduce physical forces into biochemical and biological signals is of key importance for identifying targets for the treatment and prevention of physical force-related disorders

GIS integration of DInSAR measurements, geological investigation and historical surveys for the structural monitoring of buildings and infrastructures. An application to the Valco San Paolo urban area of Rome

Structural health monitoring is a crucial issue in areas with different hazard sources, such as Italy. Among non-invasive monitoring techniques, remote sensing provides useful information in supporting the management process and safety evaluations, reducing the impact of disturbances on the functionality of construction systems. The ground displacement time-series based on the analysis of Differential Interferometric Synthetic Aperture Radar (DInSAR) measurements, as well as the information about the geology of the area and the geometry of the construction under monitoring, provides useful data for the built environment's structural assessment. This paper focuses on the structural monitoring and damage assessment of constructions based on the GIS integration of DInSAR measurements, geological investigation, historical surveys and 3D modeling. The methodology is applied to the residential area of Valco San Paolo in the city of Rome (Italy). Once the geological interpretation has confirmed the results of the DInSAR measurements, a quick damage assessment that considers all the possible conditions of the pre-existing damage at the time zero of the monitoring is shown for a damaged manufact in the area. The presented results highlight how the strategy to correlate the DInSAR-monitored ground settlements with the damage scales allows potentially to monitor continuous construction systems

Structural Determinants of the Dictyostatin Chemotype for Tubulin Binding Affinity and Antitumor Activity Against Taxane- and Epothilone-Resistant Cancer Cells

A combined biochemical, structural, and cell biology characterization of dictyostatin is described, which enables an improved understanding of the structural determinants responsible for the high-affinity binding of this anticancer agent to the taxane site in microtubules (MTs). The study reveals that this macrolide is highly optimized for MT binding and that only a few of the structural modifications featured in a library of synthetic analogues resulted in small gains in binding affinity. The high efficiency of the dictyostatin chemotype in overcoming various kinds of clinically relevant resistance mechanisms highlights its potential for therapeutic development for the treatment of drug-resistant tumors. A structural explanation is advanced to account for the synergy observed between dictyostatin and taxanes on the basis of their differential effects on the MT lattice. The X-ray crystal structure of a tubulin−dictyostatin complex and additional molecular modeling have allowed the rationalization of the structure−activity relationships for a set of synthetic dictyostatin analogues, including the highly active hybrid 12 with discodermolide. Altogether, the work reported here is anticipated to facilitate the improved design and synthesis of more efficacious dictyostatin analogues and hybrids with other MT-stabilizing agents.We thank Peter T. Northcote for peloruside A, W.-S. Fang for Flutax-2, K. H. Altmann for epothilone D, Dr. Paraskevi Giannakakou (Weill Cornell Medical Center, New York) for the 1A9, PTX10, PTX22, and A8 cell lines, and Prof. Richard Ludueñ a (University of Texas) for the HeLa βIII-transfected cells. We thank Matadero INCOVA (Segovia) for the calf brains for tubulin purification. This work was supported in part by grants BIO2013-42984-R (J.F.D.) and SAF2012-39760-C02-02 (F.G.) from Ministerio de Economia y Competitividad, grant S2010/ ́ BMD-2457 BIPEDD2 from Comunidad Autonoma de Madrid ́ (F.G. and J.F.D.), and the Swiss National Science Foundation grants 310030B_138659 and 31003A_166608 (M.O.S.). The authors acknowledge networking contribution by the COST Action CM1407 “Challenging organic syntheses inspired by naturefrom natural products chemistry to drug discovery” and the COST action CM1470. I.P. thanks the EPSRC and AstraZeneca for funding, Dr. John Leonard (AstraZeneca) for useful discussions, Dr. Stuart Mickel (Novartis) for the provision of chemicals, and the EPSRC UK National Mass Spectrometry Facility at Swansea University for mass spectra

Silica encapsulation of ZnO nanoparticles reduces their toxicity for cumulus cell-oocyte-complex expansion

Background Metal oxide nanoparticles (NPs) are increasingly used in many industrial and biomedical applications, hence their impact on occupational and public health has become a concern. In recent years, interest on the effect that exposure to NPs may exert on human reproduction has grown, however data are still scant. In the present work, we investigated whether different metal oxide NPs interfere with mouse cumulus cell-oocyte complex (COC) expansion. Methods Mouse COCs from pre-ovulatory follicles were cultured in vitro in the presence of various concentrations of two types of TiO2 NPs (JRC NM-103 and NM-104) and four types of ZnO NPs (JRC NM-110, NM-111, and in-house prepared uncoated and SiO2-coated NPs) and the organization of a muco-elastic extracellular matrix by cumulus cells during the process named cumulus expansion was investigated. Results We show that COC expansion was not affected by the presence of both types of TiO2 NPs at all tested doses, while ZnO NM-110 and NM-111 induced strong toxicity and inhibited COCs expansion at relatively low concentration. Medium conditioned by these NPs showed lower toxicity, suggesting that, beside ion release, inhibition of COC expansion also depends on NPs per se. To further elucidate this, we compared COC expansion in the presence of uncoated or SiO2-coated NPs. Differently from the uncoated NPs, SiO2-coated NPs underwent slower dissolution, were not internalized by the cells, and showed an overall lower toxicity. Gene expression analysis demonstrated that ZnO NPs, but not SiO2-coated ZnO NPs, affected the expression of genes fundamental for COC expansion. Dosimetry analysis revealed that the delivered-to-cell mass fractions for both NPs was very low. Conclusions Altogether, these results suggest that chemical composition, dissolution, and cell internalization are all responsible for the adverse effects of the tested NPs and support the importance of a tailored, safer-by-design production of NPs to reduce toxicity