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Structural Behaviour (structural + behaviour)

Distribution by Scientific Domains

Engineering	60%
Chemistry	30%

Distribution within Engineering

Numerical Methods & Algorithms	50%
General & Introductory Architecture	33%

Selected Abstracts

Tragverhalten von Verbundbauteilen aus bewehrtem UHFB und Stahlbeton

BETON- UND STAHLBETONBAU, Issue 8 2009
Cornelius Oesterlee Dipl.-Ing.
Baustoffe; Bauwerkserhaltung/Sanierung; Bauausführung; Versuche Abstract Ultra-Hochleistungs-Faserbetone (UHFB) eignen sich aufgrund ihrer hohen Festigkeiten, des hohen Verformungsvermögens und der geringen Permeabilität zur Verbesserung und Instandsetzung bestehender Betonbauten. Mit dünnen Schichten von bewehrtem UHFB, die auf bestehende Stahlbetonbauteile aufgetragen werden, können der Tragwiderstand und die Gebrauchstauglichkeit deutlich gesteigert werden. In einer umfangreichen Versuchsreihe wurden die Eigenschaften von mit zusätzlich zu den Fasern auch mit Stabstahl bewehrtem UHFB untersucht. Die Bewehrung des UHFB mit Stabstählen ist vorteilhaft, um den Verfestigungsbereich des UHFB zu erweitern, seinen Tragwiderstand zu erhöhen und die Streuung seiner mechanischen Eigenschaften zu reduzieren. Zur Bewehrung können hoch- oder niederfeste Stähle mit unterschiedlichen Oberflächenstrukturen zum Einsatz kommen. Abschließend werden zwei Anwendungen vorgestellt. Structural Behaviour of Composite Elements Combining Reinforced Ultra-High Performance Fibre-Reinforced Concrete (UHPFRC) and Reinforced Concrete Due to their high strengths, high deformability and low permeability Ultra-High Performance Fibre-Reinforced Concretes (UHPFRC) are suitable for the improvement and rehabilitation of existing concrete structures. Thin layers of reinforced UHPFRC that are applied to existing concrete members, increase both the load bearing capacity and the serviceability. By comprehensive experimental studies the behaviour of UHPFRC with additional bar reinforcement was investigated. The reinforcement of UHPFRC is advantageous in order to increase the strain hardening capacity of UHPFRC, its load bearing capacity and to reduce the scatter of its mechanical properties. Low or high strength steel grades with various surface characteristics can be used as reinforcement of UHPFRC. Finally two on site applications are presented. [source]

Structural behaviour of synthetic Co2SiO4 at low temperatures

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 6 2008
Andrew Sazonov
Synthetic Co2SiO4 has an olivine structure with isolated SiO4 groups (space group Pnma) and shows magnetic ordering below 50,K. Single-crystal neutron diffraction was applied to determine precise crystal structure parameters at low temperatures. No structural phase transition was revealed in the temperature range 2.5,300,K. Lattice parameters were determined by high-resolution X-ray powder diffraction between 15 and 300,K. There is a clear evidence of an anomalous thermal expansion related to the magnetic phase transition which can be attributed to magnetostriction. [source]

Seismic performance of a 3D full-scale high-ductile steel,concrete composite moment-resisting frame,Part II: Test results and analytical validation

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 14 2008
A. Braconi
Abstract This paper presents the results of a multi-level pseudo-dynamic seismic test program that was performed to assess the performance of a full-scale three-bay, two-storey steel,concrete composite moment-resisting frame built with partially encased composite columns and partial-strength beam-to-column joints. The system was designed to develop a ductile response in the joint components of beam-to-column joints including flexural yielding of beam end plates and shear yielding of the column web panel zone. The ground motion producing the damageability limit state interstorey drift caused minor damage while the ultimate limit state ground motion level entailed column web panel yielding, connection yielding and plastic hinging at the column base connections. The earthquake level chosen to approach the collapse limit state induced more damage and was accompanied by further column web panel yielding, connection yielding and inelastic phenomena at column base connections without local buckling. During the final quasi-static cyclic test with stepwise increasing displacement,amplitudes up to an interstorey drift angle of 4.6%, the behaviour was ductile although cracking of beam-to-end-plate welds was observed. Correlations with numerical simulations taking into account the inelastic cyclic response of beam-to-column and column base joints are also presented in the paper together. Inelastic static pushover and time history analysis procedures are used to estimate the structural behaviour and overstrength factors of the structural system under study. Copyright © 2008 John Wiley & Sons, Ltd. [source]

A structural model for the seismicity of the Arudy (1980) epicentral area (Western Pyrenees, France)

GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2007
Noalwenn Dubos-Sallée
SUMMARY The Western Pyrenees presents a diffuse and moderate (M, 5.7) instrumental seismicity. It nevertheless historically suffered from strong earthquakes (I = IX MSK). The seismic sources of these events are not yet clearly identified. We focus on the Arudy (1980) epicentral area (M= 5.1) and propose here the reactivation of early Cretaceous normal faults of the Iberian margin as a potential source. The late Cretaceous inversion of this basin, first in a left-lateral strike-slip mode and then in a more frontal convergence, resulted in a pop-up geometry. This flower structure attests of the presence of a deep crustal discontinuity. The present-day geodynamic arrangement suggests that this accident is reactivated in a right lateral mode. This reactivation leads to a strain partitioning between the deep discontinuity that accommodates the lateral component of the motion and shallow thrusts, rooted on this discontinuity. These thrusts accommodate the shortening component of the strain. The distribution of the instrumental seismicity fits well the structural model of the Arudy basin. Whatever the compressive regional context, the structural behaviour of the system explains too the extensive stress tensor determined for the Arudy crisis if we interpret it in terms of strain ellipsoid. Indeed numerical modelling has shown that this concomitant activity of strike-slip and thrust faulting results in an extensive component that can rise 50 per cent of the finite strain. We identify too a 25,30 km long potential seismic source for the Arudy area. The size of the structure and its potential reactivation in a strike-slip mode suggest that a maximum earthquake magnitude of ,6.5 could be expected. The extrapolation of this model at the scale of the Western Pyrenees allows to propose other potential sources for major regional historical earthquakes. [source]

Modelling the structural behaviour of a dam affected by alkali,silica reaction

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 1 2006
Eduardo M. R. Fairbairn
Abstract In this work we present an alkali,silica reaction (ASR) thermo-chemo-mechanical expansion model, whose main feature is to represent the stress-induced anisotropy by means of a classical smeared cracking model. This model considers the influence of temperature and humidity in the development of ASR. Since cracking occurs generally at the beginning of the swelling process, it is suggested that the assessment of the reaction characteristics in free expansion tests could be attained considering a cracked specimen. Hence, an inverse analysis is used to determine ASR parameters. The model was applied to the 3D simulation of alkali,silica expansion in a real gravity dam. We computed the displacements at the crest of the block comparing it with measures taken in situ for the last 25 years. The good correlation between experimental and numerical data displays the accuracy of the model, indicating its potentialities for engineering applications. Copyright © 2005 John Wiley & Sons, Ltd. [source]

An augmented Lagrange multiplier approach to continuum multislip single crystal thermo,elasto,viscoplasticity

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 7 2005
C. C. Celigoj
Abstract The material and structural behaviour of single crystals is going to be investigated. On the constitutive level the concept of ,generalized standard materials (gsm)' is used to set up the equations for finite deformation multislip single crystal thermo,elasto,viscoplasticity within a continuum slip theory. The only two scalar quantities needed are a thermodynamic potential and a dissipation potential. The resulting evolution equations for the internal (viscoplastic) variables are discretized in time and solved via a backward Euler scheme, using an ,augmented Lagrange multiplier method' for satisfying the multiple constraints, thus circumventing the cumbersome and less robust ,active set strategies'. As a computational reference frame serves the Eulerian setting. The structural behaviour (non-linear coupled thermomechanics) is solved in a staggered algorithm: in an isothermal mechanical phase via q1(displacements)/p0(pressure)/j0(jacobian)-finite elements and in an isogeometric thermal phase via q1(temperatures)-finite elements, followed by an isogeometric and isothermal update phase of the internal variables. Numerical results of the simple isothermal shear test of a single face-centred cubic (fcc) crystal and of the thermomechanical behaviour of a geometrically imperfect strip consisting of initially equally oriented (0/45/30 in Euler angles) fcc-crystals under tension and plane strain conditions are given. Copyright © 2005 John Wiley & Sons, Ltd. [source]

The p -version of the finite element method for three-dimensional curved thin walled structures

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 7 2001
A. Düster
Abstract In this paper we present an implementation of a three-dimensional p -version for structural problems of solids with almost arbitrarily curved surfaces. Applying the blending function method, complex structures can often be modelled by a few p -elements, being the basis for a higher order approximation. Numerical examples will demonstrate, that the p -version with anisotropic Ansatz spaces allows to predict the structural behaviour of three-dimensional plates and shells with approximately the same amount of degrees of freedom as in the two-dimensional case, yet significantly more accurate due to the three-dimensional model. Furthermore, it is advantageous to compute complex structures exclusively with three-dimensional discretizations as no special elements are needed to model the transition from dimensionally reduced formulations like plates or shells to fully three-dimensional solid elements. Using the p -version with anisotropic Ansatz spaces the whole structure can be efficiently discretized with solid elements, even if the aspect ratio of the elements becomes very large. Copyright © 2001 John Wiley Sons, Ltd. [source]

An ordered low-temperature phase of barium nitroprusside trihydrate studied by neutron diffraction

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2003
G. Chevrier
Crystals of barium pentacyanonitrosylferrate trihydrate (barium nitroprusside trihydrate), Ba[Fe(CN)5(NO)]·3H2O, have been studied by neutron diffraction in order to examine the structural behaviour of the compound in the 20,120,K temperature range and to determine the structure at 105,K. The results show the existence of a new crystal phase of the compound at 80,K (with a duplicated a parameter), which still exists at 20,K. The crystal structure at 105,K shows a rearrangement of the water molecules, which results in an ordered structure with P1 symmetry. Two of the four independent nitroprusside cations are rotated by 4.5° around the [100] direction. [source]

Numerische Modellierung von Holz und Verbindungselementen in Holz-Beton-Verbundkonstruktionen

BAUTECHNIK, Issue 6 2005
Marco Grosse Dipl.-Ing.
Durch die Anwendung der FEM können auch komplexe Strukturen berechnet werden, die sich nicht mehr als Stab- oder Flächentragwerke abbilden lassen. Es ist daher naheliegend, auch das Tragverhalten von Bauteilen oder Bauteilkomponenten in Abhängigkeit von verschiedenen Einflußparametern mit Hilfe von FE-Modellen zu simulieren. Um dabei aber Versagensmechanismen abbilden zu können, ist es notwendig, das Materialverhalten der Baustoffe im Nachbruchbereich zu berücksichtigen. Es wird ein konstitutives Materialmodell für den Werkstoff Holz vorgestellt, welches das räumlich anisotrope und vom Beanspruchungsmodus abhängige, nichtlineare Tragverhalten einbezieht. Durch die Kombination mit einem leistungsfähigen Betonmodell ist es möglich, Holz-Beton-Verbundkonstruktionen zu untersuchen. Anhand der Simulationen von Scherversuchen mit verschiedenen Schubverbindungselementen soll die Leistungsfähigkeit solcher numerischer Modelle verdeutlicht werden. Numerical modelling of timber and connection elements used in timber-concrete composite structures. Complex load carrying structures that can not be reproduced as framework ore simple surface models can be calculated using the Finite Element Method. Therefore it seems desirable to simulate the structural behaviour of members or components considering several influence parameters with the help of FE-models too. However, to model the failure mechanism it is necessary to take into account the material behaviour in the critical and post critical range. An adequate numerical model for timber that considers the specific anisotropic and load dependent strength and degradation behaviour is introduced. In combination with an capable model for concrete it is possible to examine timber concrete composite structures. The effectiveness of such models is verified by simulations of shear tests with several fastener elements. [source]

Molecular Distortion Effect on ff-Emission in a Pr(III) Complex with 4,7-Diphenyl-1,10-Phenanthroline

CHEMPHYSCHEM, Issue 9 2007
Ayumi Ishii
Abstract The electronic and structural behaviour of a Pr(III) complex with 4,7-diphenyl-1,10-phenanthroline, [Pr(bathophen)2(NO3)3], is investigated with respect to the effect of configuration changes on the Pr(III) centre. [Pr(bathophen)2(NO3)3] luminesces from the excited states of the ligand and the metal ion. The fluorescence, ff-emission (1D2,3H4), and phosphorescence bands appear at 394, 608.2 and 482 nm, respectively, in the solid state. In acetonitrile, the complex also shows multiple emissions. From the time-resolved emission and the lifetime measurements, the excitation energy-transfer in [Pr(bathophen)2(NO3)3] is clarified, that is, the upper excited triplet level of the ligand acts as an energy donor, while the 1D2 levels of Pr(III) is the acceptor. Additionally, the emission phenomena of the complex can be modified by molecular distortion, particularly by rotation of the phenyl groups in the ligand. [source]