Search results for " dynamic analysis."
showing 10 items of 16 documents
Biomechanical properties and histomorphometric features of aortic tissue in patients with or without bicuspid aortic valve
2020
Background We sought to investigate and compare biomechanical properties and histomorphometric findings of thoracic ascending aorta aneurysm (TAA) tissue from patients with bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV) in order to clarify mechanisms underlying differences in the clinical course. Methods Circumferential sections of TAA tissue in patients with BAV (BAV-TAA) and TAV (TAV-TAA) were obtained during surgery and used for biomechanical tests and histomorphometrical analysis. Results In BAV-TAA, we observed biomechanical higher peak stress and lower Young modulus values compared with TAV-TAA wall. The right lateral longitudinal region seemed to be the most fragile zon…
Improving angle stability by switching shunt reactors in mixed overhead cable lines. An Italian 400 kV case study
2019
Stringent environmental constraints make the construction of new transmission overhead lines more and more difficult. Alternatively, today it is possible to use cable lines for high (HV) and extra-high (EHV) voltage systems. The configuration of the so-called mixed lines can create some problems in the operation of the electrical system, both during steady-state and transient conditions. In particular, the system stability is one of the main concerns when analyzing the dynamic response of power systems. In this paper, the study of angular stability of a system containing a mixed line is presented: a specific control logic applied to the shunt reactors of the mixed line is proposed as improv…
Seismic response of steel frames with reduced beam sections
2003
This study concerns the effectiveness of weakening on the beams of fully and partially restrained connection steel frames in order to locate plastic hinges far from the joints. Two types of non-linear analysis, for geometry and constitutive law are developed: static pushover analysis, in which the structure is subjected to constant vertical loads and to horizontal loads linearly increasing up to collapse; and incremental dynamic analysis, in which the structure is subjected to uniformly scaled ground motions. Applications for four-bay frames with three and nine stories designed according to the EC3 code and for Italian 1st-category seismic areas are developed in order to evaluate the influe…
Preliminary investigations on indirect competition among Italian employers’ associations, and the relevant effects on collective bargaining
2022
Le associazioni dei datori di lavoro sono attori importanti per il sistema delle relazioni industriali e della contrattazione collettiva. I datori di lavoro e i sindacati in genere negoziano gli standard di lavoro in termini di salari e condizioni di lavoro per conto rispettivamente delle aziende associate e dei dipendenti. Sebbene la maggior parte della letteratura sulle relazioni industriali si sia concentrata principalmente sulla forza associativa e sulla densità associativa delle associazioni dei datori di lavoro, in questa pubblicazione a cura di Michele Faioli e Silvio Bologna, gli autori si discostano da questa prospettiva e si concentrano sul funzionamento e sulla governance, ovvero…
Nonlinear Response of RC Structures: Statistical Effects of Artificial Ground Motions
2020
The selection of seismic inputs for nonlinear dynamic analysis is widely debated, mainly focusing on the advantages and disadvantages provided by the choice of natural, simulated or artificial records. However, most of the available technical codes do not provide always the same suggestions and well-defined procedures for the generation of artificial ground motions. Considering that the strategy of the generation of accelerograms makes some doubts raise about the possible effect on the structural response, the work aims to investigate on the differences of the structural behavior by using accelerograms nominally equivalent but different in terms of stationarity. This paper presents a compar…
AN ACCURATE MODEL FOR STEADY-STATE AND DYNAMIC ANALYSIS OF THE SICILIAN NETWORK WITH HVDC INTERCONNECTIONS
2021
Sicily is one of the first Italian regions for installed power from renewable energy plants, especially photovoltaic and wind plants, and a crucial point for the Mediterranean energy hub. Its role as nexus between the European and the African Continents is becoming more and more significant due to the realization in a short time of the so called Tyrrhenian link and the High Voltage Direct Current (HVDC) connection with Tunisia. In this framework, the paper presents a model of the Sicily power generation and transmission system, including the Tyrrhenian link and two equivalent buses representing the Sardinian power network and the rest of the Continental Europe (CE) synchronous area, for both …
Shake-table testing of a stone masonry building aggregate: overview of blind prediction study
2023
Bulletin of earthquake engineering (2023). doi:10.1007/s10518-022-01582-x special issue: "Adjacent Interacting Masonry Structures"
On the convergent parts of high order spectral moments of stationary structural responses
1986
The paper deals with the evaluation of the convergent parts of the high spectral moments of linear systems subjected to stationary random input. An adequate physical meaning of these quantities in both the time and frequency domains is presented. Recurrence formulas to obtain the high convergent cross spectral moments of any order are given in the case of white noise input.
Incremental dynamic based fragility assessment of reinforced concrete structures: Stationary vs. non-stationary artificial ground motions
2017
Abstract Artificial and natural records are commonly employed by researches and practitioners to perform refined seismic assessments of structures. The techniques for the generation of artificial records and their effectiveness in producing signals which are significantly representative of real earthquakes are still debated as well as results of the consequent seismic assessment to expect from their application. The paper presents an in-depth comparative study highlighting the effect of employing different typologies of artificial ground motion records on seismic assessment results, especially addressing seismic fragility curves. Three sets of 50 stationary, nonstationary evenly modulated a…
EVALUATION OF FRAGILITY OF INFILLED FRAME STRUCTURES SUBJECT AFTERSHOCKS BY MEANS OF DOUBLE INCREMENTAL DYNAMIC ANALYSIS APPROACH
2018
The paper investigates the role of masonry infill walls on the seismic fragility of reinforced concrete structures subject to mainshock/aftershock sequences. An assessment framework aimed at determining aftershock fragility curves of bare frames and infilled frames is presented. The framework is based on a Double Incremental Dynamic Analysis (D-IDA) approach, which provides the adoption of ground motions defined by combining a fixed intensity mainshock with a set of variable intensity aftershocks. Mainshock (MS) intensity is scaled several times and combined with the same set of aftershocks (AS). Chord-rotation and shear limit states are specifically defined to consider the influence of mas…