On the Use of Singular Vectors for the Flexibility-Based Damage Detection under the Assumption of Unknown Structural Masses

The main purpose of this work is to investigate the usability of easily obtainable parameters instead of the modal traditional ones, in the context of a flexibility-based damage detection procedure, under the assumption of unknown structural masses. To this aim, a comparison is made between two different approaches: the first involves the calculation of the flexibility matrix by using traditional modal parameters, such as natural frequencies and modal vectors, normalized to unitary values, while the second involves the use of singular vectors, obtained through a simple matrix factorization. The modal parameters and the singular vectors necessary for the implementation of the damage detection procedure are evaluated through two different techniques: the Eigensystem Realization Algorithm and a wavelet-based procedure, for which a variant is proposed by introducing the energy reassignment concept into the original algorithm. Through the latter approach, in particular, it is possible to obtain a high number of singular vectors even in the case of reduced availability of sensors. The study is performed under the assumption of nonstationary excitation, in order to achieve general results, and the effectiveness of the procedures is evaluated through simulated tests regarding different structural schemes

Enhancing Psychological Sexual Health of People With Spinal Cord Injury and Their Partners in an Italian Unipolar Spinal Unit: A Pilot Data Study

Like the slogan of the American Consortium for Spinal Cord Medicine says, “No injury, no matter how serious, can take away your ability to have a relationship, experience love, and experience the attraction between two people.” However, people with spinal cord injury (SCI) have to fight with their own and societal attitudes and stereotypes that limit sexuality to the physiological functions of genitalia, phallocentric primacy of sexual pleasure, and sexual attractiveness of perfect bodies. The scope of the present study is to evaluate the impacts of a psychoeducational intervention in a personal growth group on the sexual life of seven people with SCI and four of their partners particularly their sexual interest and satisfaction, depression, and anxiety. Due to the small samples size, nonparametric statistical tests were used to compare pre- and post-outcome measures for all participants: patients and the partners group. Possible effects of gender were also considered. The effectiveness of the psychoeducational intervention was clearly apparent, showing a high effect size in improving sexual interest and satisfaction, and the opportunity and ability to enjoy sexuality. A reduction of anxiety was also observed for all participants, although it may not have been related to the psychoeducational intervention. Moreover, the intervention significantly improved the opportunity and ability to enjoy sexuality for the partner and patient group. No effect was found on depression. This was the first initiative in Italy aiming to address the sexual life and not only to cure the sexual dysfunction of people with SCI. The positive, clear evidence of the validity of the Love & Life project’s intervention bodes well for new psychoeducational initiatives that in Italy meet the sexual needs of people with SCI and their partners, providing adequate education and psychological support, involving partners, and creating a space to talk among peers

A Procedure for the Displacement-Based Seismic Assessment of Infilled RC Frames

open3noThe aim of this study was to propose an extension of the displacement-based assessment procedure for infilled reinforced concrete (RC) frames. Two fundamental steps of the displacement-based approach were studied: the determination of the equivalent viscous damping and the definition of the limit-state displacement profile. The proposed criteria were derived by examining the results of two different numerical investigations regarding the nonlinear seismic response of single- and multi-story infilled RC frames. Lastly, the effectiveness of the method was verified through comparisons, in terms of displacement demand, with the results of nonlinear dynamic analyses.embargoed_20170412Landi, Luca; Tardini, Annalisa; Diotallevi, Pier PaoloLandi, Luca; Tardini, Annalisa; Diotallevi, Pier Paol

Sistema di prefabbricazione e di edificazione

Il sistema di prefabbricazione edile semplifica molti aspetti della costruzione di un edificio e risulta particolarmente idoneo per le strutture in zona sismica e nelle situazioni di emergenza abitativa (ad esempio nei paesi in via di sviluppo). La messa in opera pu\uf2 essere eseguita con le ricorrenti attrezzature di cantiere senza particolari accorgimenti per la solidarizzazione ed il completamento in opera (iniezione, saldature, presollecitazioni, ecc.). il sistema \ue8 composto da tre componenti: \u2022 pilastri ad L; \u2022 pannelli con funzione di trave; \u2022 pannelli con funzione di solaio. I componenti possono essere facilmente impilati per rendere pi\uf9 semplici e vantaggiose le operazioni di trasporto e di stoccaggio in cantiere. Gli elementi strutturali orizzontali rendono piano l\u2019intradosso dei solai eliminando cos\uec la presenza di travi "ricalate" (o travi con l\u2019anima sporgente dall\u2019intradosso del solaio), rendendo inoltre assolutamente libera la partizione interna degli ambienti. L\u2019invenzione consiste in un sistema innovativo di realizzazione della costruzione di edifici pluripiano grazie ad un apposito sistema di montaggio. Gli aspetti innovativi del sistema riguardano: a) la tipologia dei singoli elementi strutturali; b) il dispositivo di accoppiamento e solidarizzazione. a) Gli elementi strutturali verticali hanno una forma ad L con lati di lunghezza variabile in funzione delle esigenze strutturali ed altezza pari ad un interpiano. Dimensioni e spessori degli elementi sono organizzati su un reticolo modulare che definisce gli intervalli strutturali sui quali pu\uf2 essere liberamente impostata l\u2019architettura dell\u2019edificio. Sono accoppiati agli elementi strutturali verticali, semplici elementi strutturali orizzontali a pannelli le cui dimensioni si adattano al reticolo modulare con un limitato numero di tipi. b) Nella realizzazione di edifici a pi\uf9 piani, gli elementi verticali vengono preliminarmente solidarizzati con un semplice dispositivo avente la doppia funzione di regolazione in fase di montaggio e di continuit\ue0 delle principali armature verticali. Il getto integrativo dei solai realizza la completa continuit\ue0 e monoliticit\ue0 degli elementi strutturali verticali e orizzontali. Il sistema assume pertanto la caratteristica di una iperstaticit\ue0 diffusa costituendosi spontaneamente un sistema di controventamento in due direzioni ortogonali. Questa caratteristica lo rende particolarmente idoneo per costruzioni in zona sismica. Vantaggi: - Presenza di componenti che possono essere agevolmente impilate a vantaggio delle operazioni di stoccaggio e di trasporto in cantiere - La rapidit\ue0 dei tempi di esecuzione dei lavori, che risulta molto utile anche nelle simulazioni di emergenza nelle quali bisogna intervenire con tempistiche brevi (dopo un terremoto) - La semplicit\ue0 della messa in opera che non richiede l\u2019impiego di manodopera qualificata - La possibilit\ue0 di rendere libera la ripartizione interna degli ambienti ,grazie ad apposita soluzione tecnica, che elimina la presenza di travi "ricalate

Vibration-based structural damage detection using a decentralized network with limited sensors

One of the main purposes of modal identification is to estimate the structural mechanical properties, in order to detect a possible damage over time. Several researches have been conducted recently to implement identification techniques based on the assumption of modest number of sensors. Such methods are needed both in the case of decentralized systems of wireless smart sensors, where operating units interact with each other in small groups, and in the case of repeated tests, carried out to identify large structures with a low availability of sensors. In this paper we propose a hybrid adaptive technique for natural vibration-based dynamic identification in the time-frequency domain. The proposed method involves the introduction of a novel procedure for decoupling the modal responses contained in the recorded signals, led by a clustering-based decomposition and reconstruction process; subsequently, decoupled signals, considered as single degree of freedom responses, are subjected to identification procedures in time domain, with the aim of studying the trend of instantaneous modal parameters. Since the procedure involves the real time estimation of dynamic parameters through a wavelet-based technique, it is particularly suitable for non-stationary signals. From the estimated parameters, a structural damage detection procedure is applied by using a flexibility-based technique. In order to test the effectiveness of the proposed method, the identification and damage detection procedures are simulated on a finite element model that represents a reinforced concrete plane frame

On the Use of Singular Vectors for the Flexibility-Based Damage Detection under the Assumption of Unknown Structural Masses

The main purpose of this work is to investigate the usability of easily obtainable parameters instead of the modal traditional ones, in the context of a flexibility-based damage detection procedure, under the assumption of unknown structural masses. To this aim, a comparison is made between two different approaches: the first involves the calculation of the flexibility matrix by using traditional modal parameters, such as natural frequencies and modal vectors, normalized to unitary values, while the second involves the use of singular vectors, obtained through a simple matrix factorization. The modal parameters and the singular vectors necessary for the implementation of the damage detection procedure are evaluated through two different techniques: the Eigensystem Realization Algorithm and a wavelet-based procedure, for which a variant is proposed by introducing the energy reassignment concept into the original algorithm. Through the latter approach, in particular, it is possible to obtain a high number of singular vectors even in the case of reduced availability of sensors. The study is performed under the assumption of nonstationary excitation, in order to achieve general results, and the effectiveness of the procedures is evaluated through simulated tests regarding different structural schemes

Modal testing through forced sine vibrations of a timber footbridge

The work aims at performing the dynamic modal identification of the long-span laminated timber footbridge built on the Marecchia River near Rimini, Italy. A first sine vibration test has been performed adopting a mechanical shaker just after the footbridge construction in 2000 in order to check the structural behavior that has been assumed in the project. A second test has been replicated in 2005 using the same excitation and almost the same test set-up adopted in the first one. The dynamic modal extraction is performed on the FRFs through both the peak picking method, applied together with the half power bandwidth technique, and the circle-fit method. The orthogonal properties of the identified mode shapes are verified through the Modal Assurance Criterion (autoMAC). Finally, the results obtained for the two tests and through the two techniques are mutually compared. It is worth noting that the FRFs, evaluated for different intensity levels of the exciting force, reveal an inherent non-linear behavior of the footbridge. The analyses also show that the first natural frequencies of the structure are included in the frequency range of the human step and this could lead to unpleasant feelings for the pedestrians

Influenza della misura di intensità sismica sulla valutazione della probabilità di collasso di strutture in cemento armato

L’obiettivo di questo lavoro è stato quello di valutare l’influenza della scelta di differenti misure di intensità sismica sul calcolo della probabilità di collasso di nuove strutture intelaiate in cemento armato. In ambito affidabilistico questi parametri di misura possono essere utilizzati come fattori di scala di registrazioni sismiche reali per effettuare analisi dinamiche incrementali. Si sono presi in considerazione quattro indicatori scalari caratteristici della “forza” di un sisma: l’accelerazione e la velocità di picco del terreno, l’accelerazione spettrale in corrispondenza del periodo fondamentale della struttura e una media delle accelerazioni spettrali in un intervallo di periodi correlati con quello fondamentale. Per il confronto si è scelto di adottare il metodo “2000 SAC/FEMA” specializzato alle strutture in cemento armato. Tale metodo consente di ottenere in forma chiusa la probabilità di collasso sismico di un edificio in un dato sito. Scelta un’area dotata di forte sismicità all’interno del territorio italiano e adottata una legge di attenuazione ad essa consistente, si sono ricavate le curve di pericolosità al sito per gli edifici esaminati in funzione delle differenti misure di intensità. I telai analizzati sono stati progettati in accordo con l’Eurocodice 8 per una zona di prima categoria della classificazione sismica nazionale. Le curve di domanda sono state ottenute tramite analisi dinamiche incrementali, monitorando sia la crisi per flessione che quella per taglio dei vari elementi strutturali. La probabilità di collasso, in funzione delle differenti intensità di misura, è stata valutata combinando ogni singolo valore di probabilità associato ai due meccanismi scelti