1,865 research outputs found
Push-Over Analysis of RC Frame with Corroded Rebar
As known, the Italian building heritage largely consists of reinforced concrete frames designed before the '80s, which are, in many cases, built in the absence of specific anti-seismic criteria. Moreover, many of them, today, are characterized by bad structural conditions. Moreover, the problem of the structural conditions of the existing buildings, and their residual strength capacity, is often linked to the deterioration induced by the corrosive phenomena, which end up having a big impact on steel rebar mechanical properties. In this work, in order to investigate the influence of corrosion-damage on seismic response of existing reinforced concrete structures, a study has been carried out by analysing the non-linear behaviour of a reinforced concrete frame. The strength deterioration and reduction of the cross-section of steel rebar have been investigated and taken into account in the numerical analysis. This work shows the way in which the corrosion levels affected the push-over response, and the numerical results have been deeply analysed
Un criterio di selezione dell’input sismico per l’analisi dinamica non lineare delle strutture
Viene proposto un metodo di selezione di accelerogrammi naturali da impiegare nell’analisi dinamica non lineare
al passo. Allo scopo di valutare la capacitĂ dei parametri di intensitĂ sismica di rappresentare il potenziale di
danneggiamento del sisma, sono stati analizzati gli spettri delle correlazioni tra i parametri di intensitĂ sismica che
caratterizzano le registrazioni accelerometriche ed i parametri cinematici, energetici e di danno rappresentativi della
risposta strutturale di un sistema ad un grado di libertà . In tale ambito, è stato definito un nuovo parametro di
intensità sismica in forma integrale, l’Accelerazione di Picco Efficace per la Struttura (SEPA - Structure Effective
Peak Acceleration), che è risultato fortemente correlato con i parametri di risposta della struttura in tutto il campo
dei periodi e per qualsiasi livello di non linearità della risposta. Successivamente è stato proposto un metodo di
selezione degli accelerogrammi, in grado di tenere conto delle due componenti di ogni accelerazione sismica, in
grado di fornire set di accelerogrammi compatibili con un prefissato spettro di risposta e che singolarmente siano
coerenti con l’intensità sismica da esso rappresentato, riducendo la dispersione delle caratteristiche delle
registrazioni che caratterizzano i campioni scelti sulla base dei metodi presenti in letteratur
Increasing the Capacity of Existing Bridges by Using Unbonded Prestressing Technology: A Case Study
External posttensioning or unbonded prestressing was found to be a powerful tool for retrofitting and for increasing the life
extension of existing structures. Since the 1950s, this technique of reinforcement was applied with success to bridge structures
in many countries, and was found to provide an efficient and economic solution for a wide range of bridge types and conditions.
Unbonded prestressing is defined as a system in which the post-tensioning tendons or bars are located outside the concrete crosssection
and the prestressing forces are transmitted to the girder through the end anchorages, deviators, or saddles. In response to
the demand for a faster and more efficient transportation system, there was a steady increase in the weight and volume of traffic
throughout the world. Besides increases in legal vehicle loads, the overloading of vehicles is a common problem and it must also
be considered when designing or assessing bridges. As a result, many bridges are now required to carry loads significantly greater
than their original design loads; and their deck results still deteriorated by cracking of concrete, corrosion of rebars, snapping of
tendons, and so forth. In the following, a case study about a railway bridge retrofitted by external posttensioning technique will be
illustrated
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Synchrotron X-Ray Microdiffraction Investigation of Scaling Effects on Reliability for Through-Silicon Vias for 3-D Integration
Synchrotron x-ray microdiffraction has been applied to TSV characterization in various studies for nondestructive inspection with submicron resolution due to its high beam intensity and penetration depth. In this paper, the application of this technique to TSV investigations is examined and the correlation of the plastic deformation to the microstructure and extrusion behavior along with the effect of TSV dimensional scaling is examined. It is shown that the variability of the copper microstructure and resulting TSV behavior requires a larger number of samples in order to report statistically significant observations. The role of the microstructure in creating statistical scatter is demonstrated through microdiffraction measurements of grain orientation correlated with the observed peak widening, which shows that degraded TSV reliability is largely due to the high elastic anisotropy of copper. After taking the statistical variations into account, the scaling effect was clearly observed, with larger plastic deformation in 2ÎĽm diameter TSVs than in 5ÎĽm diameter TSVs consistent with microstructure variations. This is confirmed by TSV extrusion measurements, which show that the magnitude and statistical spread of the via extrusion for the 2ÎĽm diameter TSVs is higher than that of the 5ÎĽm diameter TSVs. These results, validated by thermomechanical simulation, demonstrate first that large sample sizes are required in copper TSV investigations due to high variability, which is not improved with scaling
Shear capacity in concrete beams reinforced by stirrups with two different inclinations
A model for the estimation of shear capacity in Reinforced Concrete (RC) beams with web reinforcement is provided by introducing a generalization of classical plastic Nielsen’s model, which is based on the variable-inclination stress-field approach. The proposed model is able to predict the shear capacity in RC beams reinforced by means of stirrups having two different inclinations and longitudinal web bars.
A numerical comparison with the results of experimental tests and those provided by a Finite Element Model (FEM) based on the well known theory of Modified Compression Field Theory (MCFT) is carried out for validating the robustness of the proposed model.
Finally, a set of parametrical analyses demonstrates the efficiency of the proposed double transverse-reinforcement system in enhancing the shear capacity of RC beam
The artificial retina for track reconstruction at the LHC crossing rate
We present the results of an R&D study for a specialized processor capable of
precisely reconstructing events with hundreds of charged-particle tracks in
pixel and silicon strip detectors at , thus suitable for
processing LHC events at the full crossing frequency. For this purpose we
design and test a massively parallel pattern-recognition algorithm, inspired to
the current understanding of the mechanisms adopted by the primary visual
cortex of mammals in the early stages of visual-information processing. The
detailed geometry and charged-particle's activity of a large tracking detector
are simulated and used to assess the performance of the artificial retina
algorithm. We find that high-quality tracking in large detectors is possible
with sub-microsecond latencies when the algorithm is implemented in modern,
high-speed, high-bandwidth FPGA devices.Comment: 3 pages, 3 figures, ICHEP14. arXiv admin note: text overlap with
arXiv:1409.089
Inkjet Printing of Controlled ZnO Nanoparticles Layering
Controlled layering of functional material can produced a versatile film with specific chemical and physical proprieties for desirable applications. This article presented inkjet multilayer structures of ZnO nanoparticles of specific layer morphology and thickness for the development of devices where a high surface-to-volume ratio is required (e.g. micro gas sensors). Stacked multilayers were stratified through a multi-run printing process suitable to produce large-square pattern on flat silicon support. The formation of a multilayer structure was demonstrate through an extended structural characterization of the resulting film. Printed layer morphology was investigated with optical and scanning electron microscopies; atomic force microscopy profiling characterizations were conducted over the entire printed area to evaluate the pattern reproducibility. Finally, a preliminary study as gas sensing film was performed, using the alcohol/ZnO interaction experiments
Simulation and performance of an artificial retina for 40 MHz track reconstruction
We present the results of a detailed simulation of the artificial retina
pattern-recognition algorithm, designed to reconstruct events with hundreds of
charged-particle tracks in pixel and silicon detectors at LHCb with LHC
crossing frequency of . Performances of the artificial retina
algorithm are assessed using the official Monte Carlo samples of the LHCb
experiment. We found performances for the retina pattern-recognition algorithm
comparable with the full LHCb reconstruction algorithm.Comment: Final draft of WIT proceedings modified according to JINST referee's
comment
A Specialized Processor for Track Reconstruction at the LHC Crossing Rate
We present the results of an R&D study of a specialized processor capable of
precisely reconstructing events with hundreds of charged-particle tracks in
pixel detectors at 40 MHz, thus suitable for processing LHC events at the full
crossing frequency. For this purpose we design and test a massively parallel
pattern-recognition algorithm, inspired by studies of the processing of visual
images by the brain as it happens in nature. We find that high-quality tracking
in large detectors is possible with sub-s latencies when this algorithm is
implemented in modern, high-speed, high-bandwidth FPGA devices. This opens a
possibility of making track reconstruction happen transparently as part of the
detector readout.Comment: Presented by G.Punzi at the conference on "Instrumentation for
Colliding Beam Physics" (INSTR14), 24 Feb to 1 Mar 2014, Novosibirsk, Russia.
Submitted to JINST proceeding
First prototype of a silicon tracker using an artificial retina for fast track finding
We report on the R\&D for a first prototype of a silicon tracker based on an
alternative approach for fast track finding. The working principle is inspired
from neurobiology, in particular by the processing of visual images by the
brain as it happens in nature. It is based on extensive parallelisation of data
distribution and pattern recognition. In this work we present the design of a
practical device that consists of a telescope based on single-sided silicon
detectors; we describe the data acquisition system and the implementation of
the track finding algorithms using available digital logic of commercial FPGA
devices. Tracking performance and trigger capabilities of the device are
discussed along with perspectives for future applications.Comment: 9 pages, 7 figures, Technology and Instrumentation in Particle
Physics 2014 (TIPP 2014), conference proceeding
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