Tension estimates in cable stayed bridges

A benchmark problem on an existing cable-stayed bridge was recently proposed. Recorded signals are available for standard working conditions and for special events (typhoons!). In this contribution, the authors report their attempt to detect significant variations in the cable tension during these extreme events

conceiving meta structures for civil engineering applications

Abstract The concept of meta-structure is well established in the literature, and its implementations by 3D printing are typically discussed. Attempts to extend their applications to the civil engineering field found an obstacle in the significant masses that such applications would require. This contribution investigates the feasibility and the potential of a meta-structure design, which is consistent with the civil engineering requirements

validation of a data fusion based solution in view of the real time monitoring of cable stayed bridges

Abstract A precise assessment of the displacements induced by external actions on cables-stayed bridges may be currently challenging and costly when conventional structural health monitoring (SHM) solutions are applied. In order to bypass the drawbacks of wired solutions and the use of expensive equipment, a novel approach is proposed. A Kalman filter-based data fusion of multiple responses is adopted. A GPS receiver and a three-axial accelerometer are used as sensors. The GPS accuracy is enhanced exploiting the satellite corrections provided by a single reference station. The proposed system is validated in situ on the "Tesa" timber footbridge

Fibre Optic Methods for Structural Health Monitoring. Branko Glisic and Daniele Inaudi, John Wiley & Sons, Chichester, 2007. No. of pages: 262. ISBN 978-0470-06142-8

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Local effects induced by dynamic load self-heating in NiTi wires of shape memory alloys

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Seismic resilience timber connection-adoption of shape memory alloy tubes as dowels

This study investigates a novel timber dowel-type connection system using superelastic shape memory alloy (SMA) bar and tubes as dowels, in order to provide self-centering effect. Double-shear connections with SMA and mild steel dowels were tested under dynamic loadings at different displacement levels. The results showed that SMA dowel-type connections have good self-centering behaviours and can mitigate the residual deformation effectively compared with steel dowel-type connections after excessive deformation; although the steel dowel-type connections present higher strength. These tests reveal that the connection with tube dowels show higher equivalent viscous damping ratio than those use solid bar as tube would allow larger deformation to dissipate energy. To demonstrate application of the benefit of this system, an analytical model of a 3-storey timber framed structure was built for parametric study. The results showed that the structures with conventional dowel-type type connections exhibit large unrecoverable deformation after timber framed structures experience an earthquake. In comparison, those with the connections developed in this project show limited unrecoverable deformation due to the self-centering capacity of the connections

LOCAL POSITIONING SYSTEMS VERSUS STRUCTURAL MONITORING: A REVIEW

SUMMARY Structural monitoring and structural health monitoring could take advantage from different devices to record the static or dynamic response of a structure. A positioning system provides displacement information on the location of moving objects, which is assumed to be the basic support to calibrate any structural mechanics model. The global positioning system could provide satisfactory accuracy in absolute displacement measurements. But the requirements of an open area position for the antennas and a roofed room for its data storage and power supply limit its flexibility and its applications. Several efforts are done to extend its field of application. The alternative is local positioning system. Non-contact sensors can be easily installed on existing infrastructure in different locations without changing their properties: several technological approaches have been exploited: laser-based, radar-based, vision-based, etc. In this paper, a number of existing options, together with their performances, are reviewed. Copyright © 2014 John Wiley & Sons, Ltd

Comparing the efficiency of different structural skeleton for base isolated domes

The structural concept of the dome dates back to the Pantheon in Rome. It is used as the cover of many churches and mosques all around the world. Light solutions, with a well-visible dome-shaped truss skeleton, are often preferred in modern architecture. Base isolation techniques can be adopted to mitigate the seismic effects. This paper aims to investigate the efficiency of different designs for the truss skeleton. To solve the problem, one has to assign the constraints, the materials and the geometry of the dome, its supporting structure and the isolation devices (number, locations, and type). The screening of the effects of different scheme assumptions on structural behaviour provides a better insight into the problem

Familial ALS-superoxide dismutases associate with mitochondria and shift their redox potentials

Recent studies suggest that the toxicity of familial amyotrophic lateral sclerosis mutant Cu, Zn superoxide dismutase (SOD1) arises from its selective recruitment to mitochondria. Here we demonstrate that each of 12 different familial ALS-mutant SOD1s with widely differing biophysical properties are associated with mitochondria of motoneuronal cells to a much greater extent than wild-type SOD1, and that this effect may depend on the oxidation of Cys residues. We demonstrate further that mutant SOD1 proteins associated with the mitochondria tend to form cross-linked oligomers and that their presence causes a shift in the redox state of these organelles and results in impairment of respiratory complexes. The observation that such a diverse set of mutant SOD1 proteins behave so similarly in mitochondria of motoneuronal cells and so differently from wild-type SOD1 suggests that this behavior may explain the toxicity of ALS-mutant SOD1 proteins, which causes motor neurons to die

Performance of Fixed-Parameter Control Algorithms on High-Rise Structures Equipped with Semi-Active Tuned Mass Dampers

The present study investigates the performance of fixed parameter control algorithms on wind-excited high-rise structures equipped with semi-active tuned mass dampers of variable damping. It has been demonstrated that the algorithms that increase significantly the performance of the controlled structure do so at the expense of damper strokes. When the maximum damper strokes are capped to progressively lower limits, the efficacy of different algorithms, measured through a number of performance objectives, drastically alters totally changing the performance ranking of them and pointing out the need for an extensive study of the interplay between loading, control algorithm and allowable stroke within the design of semi-active tuned mass dampers devices