1,721,052 research outputs found
Design and assessment of steel structures in seismic areas: Outcomes of the last italian conference of steel structures
No full textThe influence of geometry, loads and steel grade for the development of a specific collapse type of MR-Frames
No full textThe work is devoted to the analysis of the influence of geometry, loads and steel grade for the development of a specific collapse type of steel Moment Resisting Frames (MRFs). In order to provide the results, the Theory of Plastic Mechanism Control (TPMC) has been applied to a large number of steel frames with different geometrical configurations and different loads and steel grades. TPMC is based on the extension of kinematic theorem of plastic collapse to the concept of mechanism equilibrium curve that allows accounting for second order effects that are very relevant especially in MRFs. This wide parametric analysis has been carried out on more than 100000 cases pointing out that for ordinary and regular MRFs type-1 mechanism is the one controlling the failure mode. In these last case, a simplified application of the Theory of Plastic Mechanism Control can be used
PERFORMANCE BASED DESIGN OF MR-FRAMES BY TPMC AND ENERGY APPROACH
No full textThe work herein presented is devoted to the development of a design procedure based on the combination of the Theory of Plastic Mechanism Control (TPMC) with the energy approach to satisfy both the performance requirements corresponding to different levels of the seismic intensity measure and the target plastic mechanism.
To this scope, with reference to MR-Frames, the seismic design forces are directly derived by means of the energy balance equation. The earthquake input energy is evaluated according to the well-known Housner formulation. The maximum energy that the structure is able to absorb in elastic range is estimated by means of the Akiyama approach. As a result, the energy to be dissipated by means of hysteresis is obtained as the difference between the seismic input energy and the maximum stored elastic energy. The energy to be dissipated is related to the plastic collapse mechanism by means of the classical work equation by assuming an appropriate distribution of the seismic horizontal forces. The internal work is, therefore, strictly related, on one hand, to the collapse mechanism typology and, on the other hand, to the cumulated plastic rotation demand expected for a given level of the seismic intensity measure. As a result, the seismic design horizontal forces are derived as a function of the seismic intensity measure, i.e. the spectral acceleration value, and of the plastic rotation capacity.
Regarding the beam dimensioning, two cases can be identified. The first case corresponds to beams whose size is governed by gravity loads. The second case corresponds to beams, parallel to the direction of the corrugation of the deck slab, whose size is governed by the seismic load combination. In this second case, the beams are preliminarily designed by assuming a distribution of their size according to the storey shear distribution and by imposing the prevention of storey mechanism at first storey. As a result, a system of two equations are derived where the unknowns are the plastic moment of beams at top storey and the plastic moment of columns at first storey. Finally, at all the other storeys, the column sections are designed by means of TPMC.
The seismic performance of MR-Frames designed according to the above procedure are compared with those of frames designed according to codified rules by means of both push-over analysis and dynamic non-linear analyses
Metodologie per la valutazione della risposta dinamica di gallerie paramassi: il caso studio della Galleria San Liberatore sulla A3
No full textDrones for survey in the field of restoration: a multidisciplinary approach to the preservation of cultural heritage
No full textTheory of plastic mechanism control for eccentrically braced frames with inverted y-scheme
No full textSeismic response of EB-frames with inverted Y-scheme: TPMC versus eurocode provisions
No full textThe Theory of Plastic Mechanism Control (TPMC) has been recently extended to the case of Eccentrically Braced Frames (EBFs) with inverted Y-scheme, i.e. EBFs with vertical links. In this paper a further validation of the design procedure, based on TPMC, is provided by means of Incremental Dynamic Analyses (IDA) pointing out the fulfilment of the design goal, i.e. the development of a pattern of yielding consistent with the collapse mechanism of global type where all the links are yielded and all the beams are yielded at their ends while all the columns and the diagonal braces remain in elastic range with the only exception of the base sections of first storey columns. In particular, a study case is designed according to both TPMC and Eurocode 8 provisions and the corresponding seismic performances are investigated by both push-over and IDA analyses.
The results show the different performances obtained in terms of pattern of yielding, maximum interstorey drift, link plastic rotation demand and sharing of the seismic base shear between the moment-resisting part and the bracing part of the structural system. The seismic performance improvement obtained by means of TPMC, compared to Eurocode 8 provisions, is pointed out
Theory of Plastic Mechanism Control for MRF-EBF dual systems: Closed form solution
No full textIn this paper, the closed form solution of the Theory of Plastic Mechanism Control (TPMC) is extended to the case of Moment Resisting Frames-Eccentrically Braced Frames (MRF-EBF) dual systems. As it is known, Eurocode 8 does not provide any specific design criterion regarding such structural typology, so that practitioners commonly carry out the design process by combining the design rules suggested for simple MRFs and EBFs. Therefore, the aim of this work is to provide a complete and exhaustive design procedure for MRF-EBF dual systems, considering all the brace configurations commonly adopted and with the goal of assuring the development of a collapse mechanism of global type. The design procedure to assure this ambitious design goal is based on TPMC whose aim is to derive the column sections required to assure the desired collapse mechanism starting from the knowledge of the dissipative zones. In order to point out the accuracy of the proposed design approach and the differences between itself and Eurocode 8, a number of MRF-EBF dual systems have been designed and their performances have been evaluated by means of push-over analyses
Modelling of floor joists contribution to the lateral stiffness of RC buildings designed for gravity loads
No full textThe work herein presented is aimed to the estimation of the contribution of floor joists acting as an "equivalent beam" in RC buildings designed for gravity loads where the deck has often no beams in the direction parallel to the warping of the floor joists. Regarding this issue a simplified theoretical model has been preliminarily developed. This model accounts for the ratio between the torsional stiffness of transverse beams supporting the floor joists and the flexural stiffness of the floor joists. The relation obtained has been applied to compute the number of collaborating joists defining the equivalent beam for a sample of single-story and multi-storey buildings with different geometrical characteristics. Successively, by means of a wide comparison between the lateral stiffness of a structural model based on the "equivalent beam" and the 3D structural model including all the joists, a correction factor is proposed to improve the accuracy of the formulation based on the simplified theoretical model
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