SEISMIC RELIABILITY-BASED DESIGN OF STRUCTURES EQUIPPED WITH DFPS

This work deals with seismic reliability-based design (SRBD) for softening and hardening structures equipped with double friction pendulum system (DFPS) isolators. The isolated system is represented by means of an equivalent 3dof model having a softening/hardening post-yield slope for the superstructure and velocity-dependent rules for the two surfaces of the DFP devices. The yielding characteristics of the superstructures are defined in compli-ance with the seismic hazard of L’Aquila site (Italy) and with NTC18 assuming ordinary characteristics. Considering several natural seismic records and the relevant random varia-bles, incremental dynamic analyses are carried out for assessing the seismic fragility and the seismic reliability of these systems. Finally, seismic reliability-based design (SRBD) curves for these systems are proposed

Seismic reliability-based design of softening structures equipped with double sliding devices

This study deals with seismic reliability-based design (SRBD) relationships in terms of beha-vior factors and displacement demands for softening structures equipped with double friction pendulum system (DFPS) bearings. An equivalent 3dof system having a softening post-yield slope is adopted to describe the superstructure behavior, whereas velocity-dependent laws are assumed to model the responses of the two surfaces of the DFPS. The yielding characte-ristics of the superstructures are defined for increasing behavior factors in compliance with the seismic hazard of L’Aquila site (Italy) and with NTC18 assuming a lifetime of 50 years. Considering several natural seismic records and building properties under the hypothesis of modelling the friction coefficients of the two surfaces of the DFPS as random variables, in-cremental dynamic analyses are performed to evaluate the seismic fragility and the seismic reliability of these systems. Finally, seismic reliability is assessed and seismic reliability-based design (SRBD) curves for the two surfaces of the double sliding devices are described

L'impiego dei dispositivi viscosi e viscoelastici nella progettazione sismica di sistemi strutturali

2010 - 2011Le tecniche di controllo passivo della risposta dinamica dei sistemi strutturali sono generalmente impiegate nell'ambito di metodologie di miglioramento o adeguamento sismico di strutture esistenti. Nella totalità dei casi, la struttura e il sistema di controllo sono dunque progettati separatamente e solo successivamente integrati seguendo logiche e principi di natura prestazionale. Un esempio per tutti è il caso del "Millennium Bridge" la cui funzionalità è stata ripristinata solo grazie all'impiego di dissipatori viscosi per ridurre i fenomeni di risonanza... [a cura dell'autore]X n.s

Logica laurentiana. Studio sui libri II e III della dialettica di Lorenzo Valla

2015 - 2016My PhD thesis is concerned with logic developed by Lorenzo Valla in the second and third book of the Dialectica, his main philosophical work. Valla’s logic, by himself named «logica laurentiana», aim to reform aristotelian and medieval logic introducing a series of principles borrowed by rhetoric and grammar. The purpose of my thesis is to show the deep influence of this principles on the aristotelian paradigm, at least on moments that Valla is concerned with. Far from separate rhetoric from logic, or the oratorical point of view from the philosophical/logical point of view, Valla intends to give birth to a new course of logic through a refoundation of old method. In light of that, it must be reviewed another exegetical topos widespread among Dialectica’s scholars: the reduction of dialectic to rhetoric. Valla mantains the autonomy (but not the indipendence) of dialectic from rhetoric, and he grants to the first a separate space from second because the obiect of these two artes is different. [edited by Author]XXIX n.s

A Comprehensive Model of Customer Trust in Two Retail Stores

Purpose – The purpose of this paper is to develop and test a comprehensive model of customer trust in a retail service setting. Three levels of the customer‐to‐store relationship are simultaneously taken into account: customer to sales associates, customer to store branded products, and customer to the store itself. Design/methodology/approach – Using partial least square (PLS) on a sample of 393 customers of an Italian supermarket retailer, a model linking customer trust (in the store, in store branded products and in sales associates) to overall perceived value and store loyalty intentions and behaviors is tested. Subsequently an expanded model to determine the influence of managerially controlled antecedent variables (salespeople\u27s trustworthiness, store environment, store assortment, and communications) is estimated on the various trust levels. Findings – Trust in the salesperson and trust in store branded products have positive effects on overall store trust. Store trust, in turn, increases perceived value and loyalty intentions. Looking at the drivers of the three levels of customer trust, salesperson trustworthiness positively affects only trust in the salesperson. Store environment has a positive impact only on overall trust in the store. Store communication fosters all three levels of customer trust, while store assortment increases both overall trust and trust in store branded products. Practical implications – Findings of the study suggest an alternative perspective to the dominant strategies in grocery retailing services. To foster store patronage, retailers have typically invested in price cuts, promotions and loyalty schemes. Store managers may rather use sales associates, the store environment, store assortment, store branded products, and communication to foster customer trust and increase customer loyalty. Managing store brands with the goal to build trust, as opposed to increase immediate profit margins, may call for a completely different approach to private labels. Similarly, the potential relevance of interpersonal trust may suggest retailers to devote more resources to selection, recruitment and training of sales associates, and may stimulate changes in evaluation criteria, incentive schemes and reward systems. Originality/value – The study aims at filling two important gaps in the literature: the scarcity of comprehensive store patronage models and the lack of exploration of the operational means of improving customer trust in retail services

Optimal sliding friction coefficient for isolated bridges in different soil conditions

The work evaluates the optimal properties of friction pendulum system (FPS) bearings for the seismic protection of bridge piers under earthquake excitations having different frequency characteristics representative of different soil conditions in order to reduce the seismic vulne-rability of infrastructures. A two-degree-of-freedom model is adopted to describe, respective-ly, the response of the infinitely rigid deck isolated by the FPS devices and the elastic behavior of the pier. By means of a non-dimensional formulation of the motion equations, a wide parametric analysis for several structural parameters is carried out. Seismic excitations, modelled as time-modulated filtered Gaussian white noise random processes having different intensities and frequency contents, are considered. Specifically, the filter parameters, which control the frequency contents, are properly calibrated to reproduce stiff, medium and soft soil conditions, respectively. Finally, the optimum values of the sliding friction coefficient able to minimize the pier displacements with respect to the ground are derived as a function of the structural properties, of the seismic input intensity and of the soil condition

SEISMIC PERFORMANCE OF BRIDGES ISOLATED WITH DCFP DEVICES

The paper analyzes the influence of double concave friction pendulum (DCFP) isolator properties on the seismic performance of isolated bridges. The behavior of these systems is analyzed by employing an eight-degree-of-freedom model accounting for the first five vibra-tional modes of the pier and the presence of a rigid abutment, whereas the DCFP isolator behaviour is described combining two single FPSs in series. The uncertainty in the seismic input is taken into account by considering a set of natural records with different character-istics. The variation of the statistics of the response parameters relevant to the seismic per-formance is investigated through an extensive parametric study carried out for different sys-tem properties

The Rhythms of the Night: increase in online night activity and emotional resilience during the Spring 2020 Covid-19 lockdown

Context. The lockdown orders established in multiple countries in response to the Covid-19 pandemics are arguably one of the most widespread and deepest shock experienced by societies in recent years. Studying their impact trough the lens of social media offers an unprecedented opportunity to understand the susceptibility and the resilience of human activity patterns to large-scale exogenous shocks. Firstly, we investigate the changes that this upheaval has caused in online activity in terms of time spent online, themes and emotion shared on the platforms, and rhythms of content consumption. Secondly, we examine the resilience of certain platform characteristics, such as the daily rhythms of emotion expression. Data. Two independent datasets about the French cyberspace: a fine-grained temporal record of almost 100 thousand YouTube videos and a collection of 8 million Tweets between February 17 and April 14, 2020. Findings. In both datasets we observe a reshaping of the circadian rhythms with an increase of night activity during the lockdown. The analysis of the videos and tweets published during lockdown shows a general decrease in emotional contents and a shift from themes like work and money to themes like death and safety. However, the daily patterns of emotions remain mostly unchanged, thereby suggesting that emotional cycles are resilient to exogenous shocks.Comment: Under revie

MODEL UNCERTAINTIES IN NLFEAS OF RC SYSTEMS UNDER CYCLIC LOADS

This work is focused on the resistance model uncertainties in non-linear finite element anal-yses (NLFEAs) for reinforced concrete structures under cyclic loading conditions. In detail, different walls experimentally tested are numerically reproduced by means of appropriate plane stress finite elements (FE) structural models within different assumptions and numeri-cal codes. After that, the values of the global resistances computed through numerical simu-lations are compared to the experimental outcomes to evaluate the influence of the different assumptions on the mechanical behaviour of reinforced concrete members subjected to cy-clic loads