Effects of post-fracture repeated impacts and short-term temperature gradients on monolithic glass elements bonded by safety films

Weathering and operational conditions, as known, have significant impact on typical constituent materials which are used for many construction applications. Among others, structural glass solutions can suffer for these effects in terms of major modification of material properties of interlayers, bonds, connections, gaskets and polymeric components in general. In this paper, the attention is given to the effects of repeated low-amplitude impacts and short-term temperature gradients for the characterization of load-bearing capacity in monolithic glass elements retrofitted by safety films. Especially for existing glass systems which are made of monolithic glass with limited strength and resistance capacity against ordinary and accidental mechanical loads, safety films are commercially available for retrofit interventions. They are primarily expected to keep together glass fragments in case of breakage, and thus minimize possible injuries. Besides, after first fracture, the so obtained glass-film composite elements have uncertain residual mechanical capacity against ordinary loads, given that it mostly depends on thin films composed of Polyethylene terephthalate (PET)-layers and pressure sensitive adhesives (PSAs). To this aim, a set of experiments (for a total of 950 configurations) is carried out in laboratory conditions (30 °C) on small-scale samples of fractured annealed monolithic glass elements bonded by commercial safety films, under repeated low-amplitude impacts / vibrations (S1-TR series), or additionally subjected to preliminary short-term thermal gradients (S2-TC1 series cooled at +5 °C and S3-TC2 series at −20 °C). Localized impacts are quantified in acceleration peaks in the range of 2 ÷ 14 m/s2 and rotations at supports in the order of 15 ÷ 20°. The interpretation of dynamic experimental results is carried out in terms of post-fracture vibration frequency (based on classical operational modal analysis techniques) and used, with the support of simplified analytical models or Finite Element (FE) numerical simulations, to characterize the response of cracked glass-film samples. Most importantly, the vibration frequency decrease is used to quantify their residual load-bearing capacity under unfavourable conditions, and to quantify the post-critical benefit of thin bonding safety films under unfavourable conditions

Influence of structural irregularity on the q-behaviour factor of light-frame timber buildings by means of incremental dynamic analysis

This paper investigates the role of sheathing-to-framing connection ductility in the evaluation of the structural q-behaviour factor for Light-Frame Timber (LFT) buildings, by means of Incremental Dynamic Analyses (IDA). This approach allows to consider nonlinear cyclic behaviour of the walls, which cannot be taken into account with the static approaches used in most of the available literature on LFT buildings. To this aim, Finite Element wall models, preliminary calibrated towards a cyclic full-scale experimental test, are built to study six case-study buildings, both regular and non-regular, with 2, 3 or 4 storeys, which were designed according to Eurocode and Capacity Design provisions. Parametric analyses are performed by varying the displacement-ductility of the panel. Finally, numerical results are discussed in terms of q-behaviour factor, and its sensitivity to structural irregularities, with respect to existing code provisions for timber buildings

Effect of Spring-Mass-Damper Pedestrian Models on the Performance of Low-Frequency or Lightweight Glazed Floors

Funding Information: This research activity has been carried out at Department of Civil Engineering and Architecture of University of Trieste, and financially supported in the framework of “ComBioDyn” Microgrants 2022 project. Publisher Copyright: © 2023 by the authors.For structural design purposes, human-induced loads on pedestrian systems can be described by several simplified (i.e., deterministic equivalent-force models) or more complex computational approaches. Among others, the Spring-Mass-Damper (SMD), Single Degree of Freedom (SDOF) model has been elaborated by several researchers to describe single pedestrians (or groups) in the form of equivalent body mass m, spring stiffness k and damping coefficient c. For all these literature SMD formulations, it is proved that the biodynamic features of walking pedestrians can be realistically reproduced, with high computational efficiency for vibration serviceability assessment of those pedestrian systems mostly sensitive to human-induced loads (i.e., with vibration frequency f1 1/130th) or low- (1/4th) mass ratio, compared to the occupant. Normal walking scenarios with frequency in the range fp = 1.5–2 Hz are taken into account for a total of 100 dynamic simulations. The quantitative comparison of typical structural performance indicators for vibration serviceability assessment (i.e., acceleration peak, RMS, CREST) shows significant sensitivity to input SMD assumptions. Most importantly, the sensitivity of structural behaviours is observed for low-frequency systems, as expected, but also for low-mass structures, which (as in the case of glazed floor solutions) can be characterized by the use of lightweight modular units with relatively high vibration frequency. As such, major attention can be required for their vibrational analysis and assessment.publishersversionpublishe

Numerical simulation of the flexural behaviour of composite glass-GFRP beams using smeared crack models

This paper presents a numerical study about the flexural behaviour of rectangular composite glass-GFRP beams, comprising annealed glass and GFRP pultruded profiles bonded with two different adhesives: (soft) polyurethane and (stiff) epoxy. The main objectives of this study were: (i) to fully characterize the non-linear behaviour of glass using the smeared crack approach; and (ii) to assess the applicability of different options to simulate adhesively bonded glass-GFRP joints. An extensive parametric study was developed to evaluate the influence of five parameters on the glass post-cracking non-linear behaviour: (i) glass fracture energy, Gf, (ii) crack band width, h, (iii) glass tensile strength, fg,t, (iv) shape of the tension-softening diagram, and (v) shear retention factor, β. The wide range of the joints’ shear stiffness was simulated by either (i) assuming a perfect bond between glass and GFRP (i.e., neglecting the presence of the adhesive), or (ii) explicitly considering the adhesive, by means of using (ii.1) plane stress elements, or (ii.2) interface elements. For the beams analysed in this paper, the following material model for glass provided a good agreement with experimental results: Gf in the range of 3 to 300 N/m, h equal to the square root of the finite element area, fg,t = 50 MPa, linear softening diagram and β according to a power law. It was also shown that the hypothesis of perfect bond at the GFRP-glass interfaces allows for an accurate simulation of joints with high levels of interaction (epoxy), while calibrated interface elements are needed for joints with low level of interaction (polyurethane).The authors wish to acknowledge FCT, ICIST/CERIS and ISISE for funding the research, and companies SIKA, Guardian and ALTO for supplying the adhesives, the glass panes and the GFRP pultruded profiles used in the experiments. The first author also wishes to thank FCT for the financial support through his PhD scholarship SFRH/BD/80234/2011

Multidisciplinary Approach of Proactive Preservation of the Religions Complex in Old Cairo - Part 1: Geoscience Aspects

Old Cairo is a unique site in the world because of its historical, cultural, and religious values. Old Cairo, a UNESCO World Heritage site, represents a rich tapestry of history and culture. Its significance lies in its role as a center of Coptic and Islamic civilizations and its preservation of numerous historical monuments. Today, the conservation of cultural heritage demands a proactive approach that integrates a robust multidisciplinary strategy. This approach must consider the unique characteristics of the heritage itself and the extensive research and efforts devoted to various scientific fields and avenues. As a case study, the focus is on the Religions Complex, the target of the “Particular Relevance” bilateral Italy–Egypt “CoReng” project. The historic Religions Complex in Old Cairo, a UNESCO World Heritage site, faces significant seismic hazards, threatening its irreplaceable Coptic and Islamic heritage. This research contribution focuses on reviewing and assessing aspects of geological and seismic hazards. This assessment serves as a crucial foundation for future vulnerability analyses and the development of effective retrofitting strategies for the Complex’s historic structures. The current work identifies critical vulnerabilities related to sub-surface geology and geotechnical conditions, various deterioration driving forces, rising groundwater levels, and earthquake ground shaking of the complex site to mitigate these risks and ensure the long-term preservation of this invaluable cultural heritage. In addition, attention is given to missing/weak characterization aspects and the proposal of possible future solutions and research developments

Vibration issues in timber structures: A state-of-the-art review

The increasing use of timber structures worldwide has brought attention to the challenges posed by their lightweight nature, making them more prone to vibrations than more massive structures. Consequently, significant research efforts have been dedicated to understanding and mitigating vibrations in timber structures, while scientific committees strive to establish suitable design regulations. This study aims to classify and identify the main research themes related to timber structure vibrations and highlight future research needs and directions. A bibliometricbased selection process briefly introduces each research topic, presenting the latest findings and proposals for vibration design in timber structures. The paper emphasizes the key outcomes and significant contributions to understanding and addressing vibration issues in timber structures. These findings serve as valuable guidance for researchers, designers, and regulatory bodies involved in designing and assessing timber structures subjected to vibrations

Age dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi

Over the course of its history, the Milky Way has ingested multiple smaller satellite galaxies1. Although these accreted stellar populations can be forensically identified as kinematically distinct structures within the Galaxy, it is difficult in general to date precisely the age at which any one merger occurred. Recent results have revealed a population of stars that were accreted via the collision of a dwarf galaxy, called Gaia–Enceladus1, leading to substantial pollution of the chemical and dynamical properties of the Milky Way. Here we identify the very bright, naked-eye star ν Indi as an indicator of the age of the early in situ population of the Galaxy. We combine asteroseismic, spectroscopic, astrometric and kinematic observations to show that this metal-poor, alpha-element-rich star was an indigenous member of the halo, and we measure its age to be 11.0 ± 0.7 (stat) ± 0.8 (sys) billion years. The star bears hallmarks consistent with having been kinematically heated by the Gaia–Enceladus collision. Its age implies that the earliest the merger could have begun was 11.6 and 13.2 billion years ago, at 68% and 95% confidence, respectively. Computations based on hierarchical cosmological models slightly reduce the above limits

Eucalyptus urograndis stem proteome is responsive to short-term cold stress

Eucalyptus urograndis is a hybrid eucalyptus of major economic importance to the Brazilian pulp and paper industry. Although widely used in forest nurseries around the country, little is known about the biochemical changes imposed by environmental stress in this species. In this study, we evaluated the changes in the stem proteome after short-term stimulation by exposure to low temperature. Using two-dimensional gel electrophoresis coupled to high-resolution mass spectrometry-based protein identification, 12 proteins were found to be differentially regulated and successfully identified after stringent database searches against a protein database from a closely related species (Eucalyptus grandis). The identification of these proteins indicated that the E. urograndis stem proteome responded quickly to low temperature, mostly by down-regulating specific proteins involved in energy metabolism, protein synthesis and signaling. The results of this study represent the first step in understanding the molecular and biochemical responses of E. urograndis to thermal stress.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, BrazilDepartamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista “Júlio de Mesquita Filho”, Jaboticabal, SP, BrazilFAPESP: 2011/11650-0FAPESP: 2011/51949-5FAPESP: 2013/06370-4FAPESP: 2013/06352-6FAPESP: 2011/23582-

Comprehensive genetic dissection of wood properties in a widely-grown tropical tree: Eucalyptus

Background: Eucalyptus is an important genus in industrial plantations throughout the world and is grown for use as timber, pulp, paper and charcoal. Several breeding programmes have been launched worldwide to concomitantly improve growth performance and wood properties (WPs). In this study, an interspecific cross between Eucalyptus urophylla and E. grandis was used to identify major genomic regions (Quantitative Trait Loci, QTL) controlling the variability of WPs. Results: Linkage maps were generated for both parent species. A total of 117 QTLs were detected for a series of wood and end-use related traits, including chemical, technological, physical, mechanical and anatomical properties. The QTLs were mainly clustered into five linkage groups. In terms of distribution of QTL effects, our result agrees with the typical L-shape reported in most QTL studies, i.e. most WP QTLs had limited effects and only a few (13) had major effects (phenotypic variance explained > 15%). The co-locations of QTLs for different WPs as well as QTLs and candidate genes are discussed in terms of phenotypic correlations between traits, and of the function of the candidate genes. The major wood property QTL harbours a gene encoding a Cinnamoyl CoA reductase (CCR), a structural enzyme of the monolignol-specific biosynthesis pathway. Conclusions: Given the number of traits analysed, this study provides a comprehensive understanding of the genetic architecture of wood properties in this Eucalyptus full-sib pedigree. At the dawn of Eucalyptus genome sequence, it will provide a framework to identify the nature of genes underlying these important quantitative traits. (Résumé d'auteur