1,721,032 research outputs found
Simplified analytical Moment-Curvature relationship for hollow circular RC cross-sections
No full textThe seismic vulnerability analysis of multi-span bridges can be based on the response of the piers, provided that deck, bearings and foundations remain elastic. The lateral response of an RC bridge pier can be affected by different mechanisms (i.e., flexure, shear, lap-splice or buckling of the longitudinal reinforcement bars, second order effects). In the literature, simplified formulations are available for mechanisms different from the flexure. On the other hand, the flexural response is usually calculated with a numerically-based Moment-Curvature diagram of the base section and equivalent plastic hinge length. The goal of this paper is to propose a simplified analytical solution to obtain the Moment-Curvature relationship for hollow circular RC sections. This based on calibrated polynomials, fitted against a database comprising 720 numerical Moment-Curvature analyses. The section capacity curve is defined through the position of 6 characteristic points and they are based on four input parameters: void ratio of the hollow section, axial force ratio, longitudinal reinforcement ratio, transversal reinforcement ratio. A case study RC bridge pier is assessed with the proposed solution and the results are compared to a refined numerical FEM analysis, showing good match
Seismic vulnerability of r.c. circular bridge columns
No full textThe seismic response of highway viaducts with bearing-supported superstructures and characterized by structural
regularity, essentially depends on the behaviour of its piers. Therefore, the vulnerability analysis of the most
exposed column often coincides with that of the whole structure. This paper is focused on a simplified procedure
that furnishes the expected damage vs ground acceleration for homogeneous families of piers, characterized by
same design and site parameters. The procedure preliminarily analyzes different forms of column failures
(flexural failure for inadequate confinement of the plastic hinge zone; flexural strength degradation in sections
with lap-spliced reinforcement; shear failure; buckling of reinforcements). Subsequently, on the basis of a
comparative analysis, the most probable condition of collapse is determined. The algorithm utilizes an
approximated closed-form approach, properly obtained, in terms of longitudinal reinforcement, transverse
confining steel, and base axial compression
Rotational ductility of R.C. beams: a parametric analysis
No full textThe evaluation of plastic rotation capacity in reinforced concrete beams is essential to prevent brittle failures. In order to facilitate practical applications, the methods usually adopted in International Codes (see EC2, MC90 or DIN), provide approximate functions θpl vs (x/d)u,conv in which the following principal parameters appear: (i) ultimate concrete strength; (ii) ductility characteristics of the reinforcement steel; (iii) shear slenderness.
Indeed, more accurate formulations have highlighted, especially for slender beams, a fundamental importance of additional variables.
Hence, it is here proposed a mechanical model through the use of dimensionless expressions able to examine in a more accurate way the effects of the bending rupture for rectangular sections. The analytical approach allows to perform simple parametric analyses and evaluate the significancy of mechanical characteristics that are usually neglected in other formulations.
The following simplifications are made: (i) after the first cracking, the contribution of the concrete in the tension region is neglected; (ii) tension-stiffening effects are disregarded.
The parameters included in the model are: a) material constitutive laws; b) mechanical tensile reinforcement ratio; c) compressive-tensile reinforcement ratio; d) characteristics of the plastic part in the idealised moment-curvature relationship
Una formulazione approssimata del comportamento elasto-viscoso di strutture non omogenee ad inerzia e schema statico variabile nel tempo
No full textInteraction domains for buckling of isolated R.C. columns
No full textInteractions domains for buckling of isolated r.c. columns represent an efficient and versatile instrument for the evaluation of the resistance at ULS and allow also the optimisation of structural geometry and section reinforcement.
The paper presents the above mentioned domains for rectangular symmetrically reinforced columns and provides a detailed analysis of the load-carrying capacity for various classes of concrete and reinforcement steel. Domains have been obtained according to the model-column method, taking into account the uncertainties both in geometry and in the position of axial loads. The effects related to creep phenomena are ignored.
In order to facilitate the practical utilization, the generic domain has been approximated by a two-branch curve, parabolic and elliptic. The first-one is related to axially-dominated rupture, the second one to flexural crisis. This approximation leads to simple closed-form expressions, particularly suitable for engineering preliminary design
Il comportamento elasto-viscoso di travi non omogenee a sezione variabile e vincoli posticipati
No full text
08/09 Laboratorio 3 di Progettazione Architettonica
No full textAnnuario dell'attività didattica svolta presso il Politecnico di Bari nell'a.a. 2008-2009, nel Laboratorio di Progettazione architettonica III. Tema d'anno: rapporto tra spazio e struttura in un edificio museale
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