STRUCTURAL FIRE SAFETY OF EXISTING STEEL BUILDINGS, Possible general approach and application to the case of the intumescent coatings

The fire safety of the existing structures is very important from the socio-economic point of view and has high social impact for civil, industrial, and commercial buildings. The verification of the minimum fire resistance of civil structures is done through some regulations, drafted to ensure occupant and rescue teams safety as well as a limited structural damage. These national fire rules are not always easily applicable to existing buildings. The purpose of this paper is to provide guidance about the structural analysis of existing buildings exposed to fire, with particular reference to steel buildings protected with intumescent coatings

EXPERIMENTAL INVESTIGATION AND NUMERICAL SIMULATIONS ON STEEL ELEMENTS PROTECTED WITH INTUMESCENT COATING

Intumescent coatings (IC) have long been used as effective methods for longterm passive fire protection for buildings. However, much is still unknown about these coatings. IC react under the influence of fire and swell to many times their original thickness, producing an insulating char that protects the substrate from the effects of the fire (damage or excessive deformation). Its role is also to provide a smooth, aesthetically pleasing finish, which is durable and easy to maintain. In the current international framework for designing of structures in case of fire, the performance based approach is provided (Fire Safety Engineering,FSE). The performance based approach consists of detailed analysis of the fire,considering natural fire curves, which combine more sophisticated calculation(advanced methods) for structural models. In order to perform rigorous and realistic analyses on structures protected with IC, thermal properties of IC should be known. Nevertheless, the thermal characterization of these systems is not available. Hence, experimental tests at high temperature should be performed. The aim of this work is to provide a thermal characterization of reactive protective (IC), which can be used in advanced calculations. This aspect is important to predict the behaviour of IC , to optimize the experimental tests and to increase reliability. Moreover the thermal characterization of IC is useful to design an intervention of IC fire protection with performance-based approach and not only with prescriptive-based approach. So, in order to investigate the different fire phenomena that can affect the IC performance and their behaviour under different fire conditions, two sets of experiments representing different types of heating exposure were conducted for different water based IC. In the first set of experiments, in furnace, steel plates were exposed to ISO834 and Smouldering fire curves with different initial heating rates. The steel specimens were steel plates with three different section factors protected by 500 μm, 1000 μm, 1500 μm and 2000 μm of dry film thickness (dIC) of IC. In the second set of experiments, steel plate samples protected by 3 different IC and by two different dICs (1000 μm, 1500 μm) were tested in a cone calorimeter. The steel specimens were expose to different heat fluxes: 50 and 30 kW/m2. Moreover, the IC performance was quantitatively assessed according to two different parameters: the thermal conductivity based on the Eurocode formula for insulated steel sections and the IC swelling (directly measured during the test using the digital image correlation technique). The results underlined that many IC characteristics, such as the IC expansion and the equivalent thermal conductivity, are dependent on the section factor and on dIC; these two parameters depend also on the type of heating (e.g. furnace and cone calorimeter). However, other aspects like the paint activation temperature or the temperature at which the minimum value of thermal conductivity is reached, are intrinsic characteristics and they seems to be independent of the fire conditions. One of the main goals of this work was to find a thermal conductivity law of the IC, based on a series of experimental data, which can also be applied to cases of real structures, in order to model them. In particular, starting from the typical development of the IC equivalent conductivity, calculated according the Eurocode formula, a standard segmented multivariate linear regression analysis was applied to the data gathered in the previous phase at significant temperatures, depending on the two factors that have been seen to have a greater influence on IC behavior: the section factor and initial thickness of IC. In order to validate the calibrated regression laws of the equivalent IC conductivity, several real scale tests were also simulated. In particular, starting from experimental data (on the same IC tested in small scale), that are easily accessible by the current state-of-the-art testing procedures, several section of different type and protected with different IC thickness were modeled: hollow circular section, H shape sections and I shape section were considered. In all the cases the numerical/analytical results are in good agreement with the experimental temperatures

Seismic and Fire Assessment and Upgrading Process for Historical Buildings: The Case Study of Palazzo Colonna in Caggiano

The assessment and retrofit of existing masonry structures with historical and cultural value in highly seismic zones are challenging issues in earthquake engineering. In fact, the historic and recent earthquakes have shown the problem of the seismic vulnerability of existing masonry constructions. A historical masonry palace located in Caggiano (Salerno, Italy) is used herein as a case study, showing the vulnerability assessment and the seismic upgrading process. The case study building has a masonry structural type at the first two floors while there is a third floor realized in reinforced concrete and a fourth floor realized with a wood structure. The building was characterized by a remarkable seismic vulnerability and needed seismic upgrading operations. After the vulnerability assessment process, some design suggestions are proposed for the seismic upgrading of the building. The structure before and after the upgrading operations has been checked through nonlinear static and dynamic analyses. Then, coherently with the "Sismabonus" approach, the attribution of the seismic risk class, performed through numerical analyses, is founded on two parameters, namely, the expected annual mean losses (PAM), related to economic factors, and the Life Safety Index (IS-V), related to the structure seismic safety. Finally, the overcoming of the different classes of risk is shown and compared with the amount of the retrofit operations, their costs, and the impact on the existing space. Moreover, fire assessment has been investigated. In fact, in many cases, the buildings such as the case study structure are intended for public activities such as museums, so specific fire requirements, like fire resistance, are necessary. This topic became relevant especially if the structure is equipped with particular structural retrofit interventions which can be altered and modified in case of a fire. The paper presents the results of advanced thermomechanical analyses on the historical masonry palace under investigation. Since the case study building has a masonry structural type at the first two floors while there is a third floor realized in reinforced concrete, the fire analyses were conducted on the third and fourth floors, which may be more vulnerable to fire

The discovery space of ELT-ANDES. Stars and stellar populations

The ArmazoNes high Dispersion Echelle Spectrograph (ANDES) is the optical and near-infrared high-resolution echelle spectrograph envisioned for the European Extremely Large Telescope (ELT). We present a selection of science cases, supported by new calculations and simulations, where ANDES could enable major advances in the fields of stars and stellar populations. We focus on three key areas, including the physics of stellar atmospheres, structure, and evolution; stars of the Milky Way, Local Group, and beyond; and the star-planet connection. The key features of ANDES are its wide wavelength coverage at high spectral resolution and its access to the large collecting area of the ELT. These features position ANDES to address the most compelling and potentially transformative science questions in stellar astrophysics of the decades ahead, including questions which cannot be anticipated today.Comment: 46 pages, 8 figures; submitted to Experimental Astronomy on behalf of the ANDES Science Tea

A roadmap for amphibious drilling at the Campi Flegrei caldera: insights from a MagellanPlus workshop

Large calderas are among the Earth's major volcanic features. They are associated with large magma reservoirs and elevated geothermal gradients. Caldera-forming eruptions result from the withdrawal and collapse of the magma chambers and produce large-volume pyroclastic deposits and later-stage deformation related to post-caldera resurgence and volcanism. Unrest episodes are not always followed by an eruption; however, every eruption is preceded by unrest. The Campi Flegrei caldera (CFc), located along the eastern Tyrrhenian coastline in southern Italy, is close to the densely populated area of Naples. It is one of the most dangerous volcanoes on Earth and represents a key example of an active, resurgent caldera. It has been traditionally interpreted as a nested caldera formed by collapses during the 100–200 km3 Campanian Ignimbrite (CI) eruption at ∼39 ka and the 40 km3 eruption of the Neapolitan Yellow Tuff (NYT) at ∼15 ka. Recent studies have suggested that the CI may instead have been fed by a fissure eruption from the Campanian Plain, north of Campi Flegrei. A MagellanPlus workshop was held in Naples, Italy, on 25–28 February 2017 to explore the potential of the CFc as target for an amphibious drilling project within the International Ocean Discovery Program (IODP) and the International Continental Drilling Program (ICDP). It was agreed that Campi Flegrei is an ideal site to investigate the mechanisms of caldera formation and associated post-caldera dynamics and to analyze the still poorly understood interplay between hydrothermal and magmatic processes. A coordinated onshore–offshore drilling strategy has been developed to reconstruct the structure and evolution of Campi Flegrei and to investigate volcanic precursors by examining (a) the succession of volcanic and hydrothermal products and related processes, (b) the inner structure of the caldera resurgence, (c) the physical, chemical, and biological characteristics of the hydrothermal system and offshore sediments, and (d) the geological expression of the phreatic and hydromagmatic eruptions, hydrothermal degassing, sedimentary structures, and other records of these phenomena. The deployment of a multiparametric in situ monitoring system at depth will enable near-real-time tracking of changes in the magma reservoir and hydrothermal system

Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires

The production of tt‾ , W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓν , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of $t\overline{t}$, $W+b\overline{b}$ and $W+c\overline{c}$ is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 $\pm$ 0.02 \mbox{fb}^{-1}. The $W$ bosons are reconstructed in the decays $W\rightarrow\ell\nu$, where $\ell$ denotes muon or electron, while the $b$ and $c$ quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions

Multidifferential study of identified charged hadron distributions in ZZ-tagged jets in proton-proton collisions at s=\sqrt{s}=13 TeV

Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a $Z$ boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20 $< p_{\textrm{T}} < 100$ GeV and in the pseudorapidity range $2.5 < \eta < 4$. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb$^{-1}$. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb public pages

Study of the B−→Λc+Λˉc−K−B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-} decay

The decay $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ is studied in proton-proton collisions at a center-of-mass energy of $\sqrt{s}=13$ TeV using data corresponding to an integrated luminosity of 5 $\mathrm{fb}^{-1}$ collected by the LHCb experiment. In the $\Lambda_{c}^+ K^{-}$ system, the $\Xi_{c}(2930)^{0}$ state observed at the BaBar and Belle experiments is resolved into two narrower states, $\Xi_{c}(2923)^{0}$ and $\Xi_{c}(2939)^{0}$, whose masses and widths are measured to be $$m(\Xi_{c}(2923)^{0}) = 2924.5 \pm 0.4 \pm 1.1 \,\mathrm{MeV}, \\ m(\Xi_{c}(2939)^{0}) = 2938.5 \pm 0.9 \pm 2.3 \,\mathrm{MeV}, \\ \Gamma(\Xi_{c}(2923)^{0}) = \phantom{000}4.8 \pm 0.9 \pm 1.5 \,\mathrm{MeV},\\ \Gamma(\Xi_{c}(2939)^{0}) = \phantom{00}11.0 \pm 1.9 \pm 7.5 \,\mathrm{MeV},$$ where the first uncertainties are statistical and the second systematic. The results are consistent with a previous LHCb measurement using a prompt $\Lambda_{c}^{+} K^{-}$ sample. Evidence of a new $\Xi_{c}(2880)^{0}$ state is found with a local significance of $3.8\,\sigma$, whose mass and width are measured to be $2881.8 \pm 3.1 \pm 8.5\,\mathrm{MeV}$ and $12.4 \pm 5.3 \pm 5.8 \,\mathrm{MeV}$, respectively. In addition, evidence of a new decay mode $\Xi_{c}(2790)^{0} \to \Lambda_{c}^{+} K^{-}$ is found with a significance of $3.7\,\sigma$. The relative branching fraction of $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ with respect to the $B^{-} \to D^{+} D^{-} K^{-}$ decay is measured to be $2.36 \pm 0.11 \pm 0.22 \pm 0.25$, where the first uncertainty is statistical, the second systematic and the third originates from the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb public pages