1,721,064 research outputs found
Assessment of the effectiveness of repair and retrofitting techniques using SCC and CFRP on damaged r.c. bridge piers
No full textSeismic response of repaired bridges by pseudodynamic tests
No full textEight bridge circular pier specimens (1:6 model of the most stressed piers) severely damaged after previous pseudodynamic and cyclic tests until failure, were repaired and/or upgraded by means of epoxy adhesive, stainless steel rebars, self compacting concrete and C-FRP wrapping and tested by pseudodynamic, under the seismic action used for first tests on undamaged specimen. The undamaged pier specimens were representative of tall and squat circular r.c. piers designed according to Eurocode 8 or Italian Code before 1986. In the pseudodynamic test, the repaired and/or retrofitted piers specimens (one column per bridge) are physically tested in the lab, while the rest of the bridge is numerically simulated. Damage states after the previous tests are assessed and description of the repairing and retrofitting of the piers as well as the description of the In-House pseudodynamic apparatus and dedicated software implemented using LabVIEW and MATLAB are given. Finally a comparison between the seismic behavior of the original and the retrofitted bridge piers are shown in terms of seismic response. Tests results are compared to nonlinear analyses using the computer program OpenSees. Results are discussed. © 2010 Taylor & Francis Group, London
Seismic duration effect on damping reduction factor using random vibration theory
No full textDamping Reduction Factor plays a key role in scientific literature and Technical Codes, but till now existing formulations present differences and inconsistences probably because obtained by integration of real recorded events, thus sensible to specific used data. This paper investigates the relation between damping reduction factor and earthquake duration by means of random vibration theory. A stochastic process, that is non-stationary and filtered, is used to model a seismic event. The modulation function is suitably chosen to describe earthquakes characterized by different durations. The stochastic process peak theory allows to calculate damping reduction factor after the definition of the probabilistic response of a simple linear visco-elastic oscillator. The variability with seismic duration for different soil conditions and damping ratios is investigated. The study points out that damping reduction factor is more sensitive to seismic duration in the range of high period and on rigid soil with respect to other conditions. The results show that, if damping ratio or effective duration values are increased, the damping reduction factor value diminishes
Investigating management control system in the new sustainable and digital business environment
No full textIncremental modal pushover analysis (IMPA) for bridges
Full text linkIn recent years, many research activities were undertaken to develop a reliable and practical analysis procedure to identify the safety level of existing structure. There are many literatures available on the seismic evaluation procedures of buildings using nonlinear static analysis (pushover) instead of performing, as in the well known incremental dynamic analysis (IDA), complex non-linear dynamic analysis (RHA). Conversely, only a few studies are available in literature regarding seismic evaluation of existing bridges, although bridges are strategic infrastructures in every country. The aim of this work is to carry out a seismic evaluation case study for an existing RC bridge, with reinforcement affected by corrosion, using nonlinear static (pushover) analysis. The work starts from an efficient pushover proposal named Incremental Modal Pushover Analysis (IMPA). This procedure has been developed for higher modes sensitive structures; bridge are commonly characterized by a very high participating mass ratio for the higher modes and therefore the application of IMPA to bridges appears as a promising procedure. The procedure, together with some results of the application on one case study, are presented herein
Artificial intelligence activities and ethical approaches in leading listed companies in the European Union
No full textThis study explores the information regarding Artificial Intelligence (AI) included by European listed companies in their annual and/or sustainability reports. The study mainly focuses on (1) the development and use of AI systems/projects reported by companies, (2) the extent to which companies disclose ethical principles or guidelines regarding AI and (3) the factors explaining these practices. The study analyses the reports of 200 companies listed in the major indexes of Germany, Sweden, Finland, France, Spain, and Italy, both from qualitative and quantitative perspectives. All reports are analysed, using content analysis methodology, to identify expressions such as ‘artificial intelligence’, ‘machine learning’, ‘deep learning’, and ‘big data’, and then classified accordingly. The study's findings suggest a growing interest in the above-mentioned technologies, although 41.5% of companies do not report any activity in the field of AI. The adoption of ethical approaches to AI is at a very preliminary stage, and<5% of companies report on that issue. The quantitative analysis shows that larger companies, companies in the Technology and Telecommunications industries, and companies based in Southern countries are more likely to disclose information on AI activity. The majority of companies that develop ethical principles are listed in the Northern region and belong to the Technology and Telecommunications industries. The study provides evidence of AI disclosure, a type of non-financial disclosure that has not been explored yet in the literature. Unlike existing studies, we propose a first definition of the topic and a taxonomy that can be used in further research on AI disclosure and can contribute to the development of KPIs in the field. Furthermore, this study provides a theoretical framework integrating some traditional theories, such as Voluntary disclosure theory, Signalling theory, and Legitimacy theory, specifically drawn to interpret AI disclosure practices, which can help with a further in-depth exploration of AI disclosure combining concurrent perspectives. The study's results may serve as a starting point for researchers and companies interested in the topic
A repair and retrofitting intervention to improve plastic dissipation and shear strength of Chinese RC bridges
No full textIn this paper a rapid repair and retrofitting technique for reinforced concrete (rc) Chinese bridges damaged by a strong earthquake, is proposed and tested. This intervention is an upgrade of the one tested with very good results during a previous experimental research on bridges designed according to the old Italian code without proper seismic details. The improvement of the repair operation consists in the use of dissipation systems to substitute the damaged rebar parts at pier base guaranteeing the correct plastic distribution in plastic hinge only. Dissipation systems with different configurations were considered to optimize the intervention. The repaired and retrofitted Italian bridge already studied in the previous research, was designed according to Chinese codes but with insufficient transversal steel reinforcement. Some pier specimens (scale 1:6) of the most stressed pier of this bridge, with and without dissipation systems, were built. A C-FRP wrapping was applied to increase the insufficient shear strength and the ductility in plastic hinge. Cyclic tests were carried out on the scaled specimens at Fuzhou University lab (China) to evaluate the effectiveness of the proposed technique
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