1,258 research outputs found
FAILURE MODE CONTROL OF X-BRACED FRAMES UNDER SEISMIC ACTIONS
No full textIn this article, a new method for designing concentrically braced steel frames is presented. The aim of the proposed method is the design of concentrically braced steel frames able to guarantee, under seismic horizontal forces, a collapse mechanism of global type. This result is of great importance in the seismic design of structures, because local failure modes give rise to a worsening of the energy dissipation capacity of structures and, therefore, to an higher probability of failure during severe earthquakes. With reference to the examined structural typology, the global mechanism is characterized by the yielding of bracing diagonals of all the stories.
The proposed method is rigorously based on “capacity design” which requires that non dissipative zones have to be designed to withstand the internal actions coming from the seismic design
horizontal forces and the vertical loads acting in the seismic load combination, while non dissipative zones have to be designed considering the maximum internal actions that dissipative zones,
yielded and strain-hardened, are able to transmit [Mazzolani and Piluso, 1996]. The new design issue covered by the proposed design procedure is the need to account for the contributions of
the compressed diagonals in deriving the design axial force of non dissipative members (beams and columns).
The seismic inelastic response of a sample structure is investigated by means of nonlinear dynamic analyses, which have been carried out by means of the PC-ANSR [Maison, 1992] program, where the cyclic behavior of brace elements has been accurately modeled by means of the Georgescu model [Georgescu et al., 1991].
The results of dynamic inelastic analyses carried out with reference to the braced frame designed according to the proposed procedure are compared with those obtained with reference to the same structural scheme designed according to Eurocode 8 [CEN, 2000; CEN, 2003]. In particular, it is pointed out that the application of Eurocode 8 design criteria leads to premature buckling of columns, so that the proposal of a new design approach is fully justified
Introduzione [a La banca mista prima e dopo la crisi]
No full textIntroduzione al numero monografico della rivista "Archivi e imprese" dedicato alla banca mista in Italia dopo la crisi dei primi anni trenta
Mercati settoriali e squilibri regionali nella formazione di un sistema bancario in Italia (1860-1936)
No full textRegole, istituzioni, mercati: modelli e innovazioni istituzionali a Milano dalla Restaurazione all'Unità
No full textLa piazza milanese, nonostante ruolo e dimensioni di rilievo conseguiti durante la Restaurazione, non fu in grado di pervenire a forme di articolazione istituzionale e funzionale prima dell’Unità. L’assenza di una banca di emissione lombarda non dipese, quanto meno sino alla fine degli anni quaranta dell’Ottocento, solo dai veti politici viennesi ma anche da resistenze interne ai ceti mercantili milanesi. La comunità degli affari milanese, restia a impegnarsi in progetti di modernizzazione finanziaria dopo la tormentata esperienza dell’età napoleonica, temeva una gestione «politica» della circolazione monetaria affidata a una banca di emissione, vale a dire un governo della moneta largamente subordinate alle esigenze espansive della finanza pubblica dell’Impero. L’area lombarda, impermeabile alla circolazione cartacea della Banca Nazionale Austriaca, dovette così fare assegnamento su fattori di compensazione delle rigidità deriva-te nell’offerta di mezzi di pagamento: forme di cooperazione orizzontale all’interno della categoria; ricorso alle reti internazionali dei corrispondenti; assunzione di comportamenti improntati a cautela. In tale contesto - in mancanza di una banca di emissione - dalla fine degli anni quaranta i negozianti e i banchieri milanesi optarono per alcune innovazioni di natura essenzialmente adattativa: un’estensione progressiva delle operazioni della Cassa di risparmio di Milano; l’introduzione di operazioni e pratiche di piazza volte ad attenuare i forti vincoli alla regolazione della liquidità. L’originalità della traiettoria evolutiva della piazza milanese viene ricondotta ai fattori politico-istituzionali, alle pratiche operative dei banchieri e alla cultura economica dei soggetti implicati nei processi di innovazione e resistenza all’innovazione. A compensazione di tali lacune istituzionali la piazza fu regolata dagli operatori non secondo un sistema di norme positivamente codificate quanto piuttosto secondo un insieme di norme informali ampiamente condivise dalla business community: le norme informali della piazza di Milano, in parte, erano connesse ai meccanismi di fiducia e solidarietà necessari a garantire la continuità degli affari e, in altra parte, erano connesse a specifici rapporti di fiducia e solidarietà, innervati sulle relazioni etnico-religiose di particolari gruppi di minoranze (dagli israeliti ai protestanti) . In un complesso quadro regolativo - condizionato dalle autorità di governo (ma con ciò non definito, se non per via negativa, dagli organi della statualità) - i banchieri e i negozianti milanesi attuarono strategie adat-tative al fine di assicurare un discreto grado di stabilità e crescita al di fuori, tuttavia, dei principi e degli strumenti regolativi dell’offerta di moneta e credito in quei decenni in via di affermazione nelle aree europee con le quali la Lombardia aveva intensi rapporti di scambio
Italy: Building on a Long Insurance Heritage
No full textThis chapter provides a long-run analysis on the evolution of the Italian insurance market considering insurance industry dynamics as well. The fall of the Italian economy from its central position in the sixteenth century resulted in its relegation from the areas of strongest economic growth in Europe and is probably at the heart of the decline in importance of Italy’s financial intermediaries. This contrasted strongly with the innovative capacity of both the Italian insurance and credit markets during their period of primacy in the late Middle Ages and the early Renaissance. By contrast, from the mid-seventeenth century, innovative institutions and instruments were stimulated in countries with strong economic demand and growing financial needs, such as the Netherlands and, particularly following the Industrial Revolution, Great Britain. The relative fall in Italian per capita income— stagnant in the seventeenth century and in slight decline in the eighteenth century — was accompanied by modest growth in trade, which limited the spread of insurance contracts. In the early decades of the nineteenth century, insurance companies began to be established in various cities that triggered a slow and gradual convergence of the Italian insurance market with the more dynamic French, German, and Austrian markets. Nevertheless, over the long term, the Italian insurance market has displayed three distinctive elements: (1) lower per capita income than countries that were its major commercial partners and a concomitant lower take-up of insurance instruments, off set by a persistently high rate of savings; (2) a legislative system that was not conducive to insurance activity, which in some periods saw the adoption of stringent regulations restricting foreign companies; and (3) the considerable direct state intervention since the eve of the First World War, intended to boost demand for insurance and social security cover. The insurance market was thus aff ected by these constraints on growth and by the policies adopted to off set them, which played a part in determining, for example, the low level of growth in supplementary social security instruments in the last fi ft een years, despite a decrease in state provision of pension cover
La «capitale finanziaria» e la rete regionale: il sistema finanziario lombardo tra mercato e istituzioni
No full textThe Regional Financial System: Institutional Varieties and Complementarity (1861-1914)
No full textThis chapter discusses the evolution of Lombardy’s financial structure as a regional component of the emerging national system and its region-specific trajectories, profoundly influenced by some pre-Unitarian features such as the absence of a bank of issue. The contribution highlights some evolutionary patterns: Lombardy took advantage of its international connections by attracting foreign capital; the major German-style universal banks established in Milan in the 1890s fostered the development of the stock market; thus, Milan became Italy’s main financial centre before WWI by harmonising all the components of the regional banking system, while small local banks, widely spread in the provinces, supported industrial districts and small manufacturing firms (also, and quite often, through insider lending practices). Milan achieved its primacy by combining the greatest financial institutions (namely, Banca Commerciale Italiana and Credito Italiano) with many private bankers in Milan, the largest Italian savings bank, and a number of small- or medium-sized banks operating in the provinces. This combination stresses the relevance of two main features of the evolutionary process of the regional financial system: as such, in the longer term, the system was characterised by institutional varieties and complementarity of its components
Interactive Plastic Local Buckling of Box-shaped Aluminium Members under Uniform Compression
No full textA theoretical approach for predicting the ultimate resistance of aluminium alloy members subjected to local buckling under uniform compression is presented focusing the attention on box sections. Starting from the J2 deformation theory of plasticity, the theory of plastic buckling of plates is presented including, as an original contribution, also the variability of the Poisson's ratio depending on the stress levels. The differential equation of the plates at the onset of buckling is developed and the corresponding solution is provided. Starting from the obtained closed-form solution, the interactive buckling either in the elastic or in the plastic range is analysed. The interaction between the plate elements constituting the member section is explicitly accounted for using a completely theoretical approach where the evaluation of the critical stress leading to local buckling in the plastic range is derived as the value corresponding to the existence of a non-trivial solution for which the determinant of the matrix of the equation system is equal to zero. The accuracy of the plastic buckling theory is pointed out by comparing the buckling resistance obtained by the theoretical approach with the values of the ultimate resistance provided by stub column tests. Finally, some advances concerning the use of the effective thickness approach, currently adopted by Eurocode 9, are also proposed and herein presented for the first time and compared with test results
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