1,720,975 research outputs found
Seismic loss analysis of a non-ductile infilled rc building
No full textMean annual financial losses due to seismic events in Italy are about 2-3 billion euro. For this reason, in recent years increasing attention has been placed on strategies to reduce the seismic risk of the national building stock. In this work, a comparative seismic loss analysis of an infilled R/C building is performed using the FEMA P-58 probabilistic framework and the tool PACT. The objective is to evaluate how the structural modeling and the characterization of structural and nonstructural elements fragility can affect the loss estimation. Fragility and consequence functions for discrete damage states are assumed for structural and non-structural components. A case study prototype typical of Italian pre-1970 R/C infilled buildings is chosen. Nonlinear Incremental Dynamic Analyses (IDA) are performed for three 2D modeling configurations. Financial losses are expressed as median values of repair costs at different hazard levels or in terms of Expected Annual Loss (EAL)
Effetti delle non linearità costitutive dei sistemi di isolamento sismico e metodi semplificati per la valutazione della risposta
No full textNonlinear Seismic Response Analyses of Existing R/C Building and Evaluation of System Components Contribution
No full textA simplified method to predict torsional effects on asymmetric seismic isolated buildings under bi-directional earthquake components
Get PDFThe assessment of maximum displacement demand is a crucial point in the design of seismic
isolating systems, in particular when the non linear behaviour of devices is modeled
through visco-elastic equivalent schemes, as common in the design practice. Several phenomena
influence the maximum demand assessment, among which the torsional and earthquake
directionality effects can be of great impact. International codes use some formulations
which allow to consider torsional effects, while the impact of the other phenomena
is commonly assessed through time-history analyses. In this paper an innovative design
method is developed based on an exact linear elastic formulation with response spectrum,
which keeps in count both torsional and directivity effects considering natural and accidental
eccentricity and by using the CQC3 (Menun and Der Kiureghian in Earthq Spectra
153–163, 1998. https ://doi.org/10.1193/1.15860 25) as directional combination rule. The
method models the seismic action through the response spectra of a set of natural recorded
ground motions, properly oriented along their principal axes to assess the correct ratio
between the horizontal components of spectral accelerations; thus accounting for the sitespecific
earthquake source, without the need to perform time-history analyses. A specific
formalization of the dynamic problem is presented to emphasize the parameters which
more affects the response (e.g. torsional factor, eccentricity, geometrical aspect ratio) and
simplify its interpretation. Results obtained on two case studies are compared with timehistory
analyses to show the effectiveness of the procedure
Graphic dynamic prediction of polarized earthquake incidence response for plan-irregular single story buildings
No full textGraphic dynamic prediction of polarized earthquake incidence response for plan-irregular single story buildings
No full textA graphical dynamic model is presented to predict the directional earthquake response of two-ways plan-asymmetric buildings. The theoretical principles inherent to torsional dynamics and vibrations are investigated and the dynamic directional response is rationally explained based on modal rotational kinematics about modal torsional pivots. Seismic forces and response decomposition are handled through geometric modal torsional trends and the earthquake incidence response envelopes are described through directional modal participation radii and graphic spectrum-based ‘8-shaped’ directional influence circles. The graphic approach provides good predictions of the maximum response and of the critical angle computed through directional combination methods. A nonlinear 3D frame model with eccentric infills is analyzed through linear and nonlinear response history analyses (RHA, NLRHA) changing the earthquake incidence angle. Upon confirmation of weak modal coupling, graphic-dynamic modal torsional trends and directional inelastic response envelopes are used to predict the nonlinear response. Directional incremental dynamic analyses and uncoupled modal response history analyses confirm the prediction of polarization
Evaluation of modelling uncertainties impact in older infilled frame RC structures
No full textThe seismic response of infilled frame reinforced concrete structures is affected by different sources of aleatory and epistemic uncertainties and is particularly sensitive to the modeling parameters evidenced by reported numerical and analytical studies. In the current study, a probabilistic sensitivity analysis is performed by nonlinear static (PNSA) and nonlinear dynamic analyses (PNDA) on a base-case infilled frame structure incor-porating structural (beam, column) and non-structural (masonry infill) components behavior. Therefore, the state-of-the-art models of the most effective sources of nonlinear response employed herein as fiber section to depict the axial-moment interaction in frame components, bi-diagonal eccentric strut to capture the cracking and crushing of masonry infill, and the shear failure in columns caused by infill-frame interaction. Finally, results are illustrated by tornado plots incorporating probabilistic sensitivity to material and component parameters for operational (O), damage (D), life safety (L), and collapse (C) limit states. Results state that the building response is significantly affected by the modeling parameters of infill characteristics, mass source, and the damping of the structure
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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