Identification of progressive collapse pushover based on a kinetic energy criterion

Menchel, K.,Massart, T.J.,Bouillard, Ph. Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.3

The progressive collapse phenomenon is generally regarded as dynamic. Due to the impracticality of nonlinear dynamic computations for practitioners, an interest arises for the development of equivalent static pushover procedures. The present paper proposes a methodology to identify such a procedure for sudden column removals, using energetic evaluations to determine the pushover loads to apply. In a dynamic context, equality between the cumulated external and internal works indicates a vanishing kinetic energy. If such a state is reached, the structure is sometimes assumed able to withstand the column removal. Approximations of these works can be estimated using a static computation, leading to an estimate of the displacements at the zero kinetic energy configuration. In comparison with other available procedures based on such criteria, the present contribution identifies loading patterns to associate with the zero-kinetic energy criterion to avoid a single-degree-of-freedom idealisation. A parametric study over a family of regular steel structures of varying sizes uses non-linear dynamic computations to assess the proposed pushover loading pattern for the cases of central and lateral ground floor column failure. The identified quasi-static loading schemes are shown to allow detecting nearly all dynamically detected plastic hinges, so that the various beams are provided with sufficient resistance during the design process. A proper accuracy is obtained for the plastic rotations of the most plastified hinges almost independently of the design parameters (loads, geometry, robustness), indicating that the methodology could be extended to provide estimates of the required ductility for the beams, columns, and beam-column connections.

Identification of progressive collapse pushover based on a kinetic energy criterion

K. Menchel,T.J. Massart,Ph. Bouillard 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.3

The progressive collapse phenomenon is generally regarded as dynamic. Due to the impracticality of nonlinear dynamic computations for practitioners, an interest arises for the development of equivalent static pushover procedures. The present paper proposes a methodology to identify such a procedure for sudden column removals, using energetic evaluations to determine the pushover loads to apply. In a dynamic context, equality between the cumulated external and internal works indicates a vanishing kinetic energy. If such a state is reached, the structure is sometimes assumed able to withstand the column removal. Approximations of these works can be estimated using a static computation, leading to an estimate of the displacements at the zero kinetic energy configuration. In comparison with other available procedures based on such criteria, the present contribution identifies loading patterns to associate with the zero-kinetic energy criterion to avoid a single-degree-of-freedom idealisation. A parametric study over a family of regular steel structures of varying sizes uses non-linear dynamic computations to assess the proposed pushover loading pattern for the cases of central and lateral ground floor column failure. The identified quasi-static loading schemes are shown to allow detecting nearly all dynamically detected plastic hinges, so that the various beams are provided with sufficient resistance during the design process. A proper accuracy is obtained for the plastic rotations of the most plastified hinges almost independently of the design parameters (loads, geometry, robustness), indicating that the methodology could be extended to provide estimates of the required ductility for the beams, columns, and beam-column connections.

Modelling of Stirrup Confinement Effects in RC Layered Beam Finite Elements Using a 3D Yield Criterion and Transversal Equilibrium Constraints

Peter Zoltan Berke,Thierry Jacques Massart 한국콘크리트학회 2018 International Journal of Concrete Structures and M Vol.12 No.5

Apart from its recognized strengthening effect for shear loading, the presence of stirrups in reinforced concrete results in an increase of the ductility of structural members and in the capacity of reaching higher longitudinal compressive stress levels provided by transversal confinement. These effects are usually represented phenomenologically in fibre beam models by artificially increasing the compressive strength and the ultimate compressive strain of concrete. Two numerical formulations for layered beam descriptions accounting explicitly for transversal confinement are implemented and assessed in this contribution. The influence of stirrups is incorporated by means of a multi-dimensional yield surface for concrete, combined with equilibrium constraints for the transversal direction involving concrete and steel stirrups, and with a concrete ultimate strain dependent on the hydrostatic stress. This contribution focuses on the numerical formulations of both frameworks, and on their assessment against experimental results available in the literature.

THE HELIOS-B PROJECT : TOWARDS HIGH SPEED FILE TRANSFERS BY SATELLITE BETWEEN HETEROGENEOUS COMPUTERS

A. Cohen,C. Hanon,T. Massart,N. Meulemans,P. Van Binst,R. Vandenbroucke 대한전자공학회 1987 IEEE Region 10 Conference Vol.- No.-

Evaluating high-resolution forecasts of atmospheric CO and CO₂ from a global prediction system during KORUS-AQ field campaign

Tang, Wenfu,Arellano, Avelino F.,DiGangi, Joshua P.,Choi, Yonghoon,Diskin, Glenn S.,Agustí,-Panareda, Anna,Parrington, Mark,Massart, Sebastien,Gaubert, Benjamin,Lee, Youngjae,Kim, Danbi,Jung, Ji Copernicus GmbH 2018 Atmospheric Chemistry and Physics Vol.18 No.15

<P><p><strong>Abstract.</strong> <span id='page11008'/>Accurate and consistent monitoring of anthropogenic combustion is imperative because of its significant health and environmental impacts, especially at city-to-regional scale. Here, we assess the performance of the Copernicus Atmosphere Monitoring Service (CAMS) global prediction system using measurements from aircraft, ground sites, and ships during the Korea-United States Air Quality (KORUS-AQ) field study in May to June 2016. Our evaluation focuses on CAMS CO and <span class='inline-formula'>CO₂</span> analyses as well as two higher-resolution forecasts (16 and 9<span class='thinspace'></span>km horizontal resolution) to assess their capability in predicting combustion signatures over east Asia. Our results show a slight overestimation of CAMS <span class='inline-formula'>CO₂</span> with a mean bias against airborne <span class='inline-formula'>CO₂</span> measurements of 2.2, 0.7, and 0.3<span class='thinspace'></span>ppmv for 16 and 9<span class='thinspace'></span>km <span class='inline-formula'>CO₂</span> forecasts, and analyses, respectively. The positive <span class='inline-formula'>CO₂</span> mean bias in the 16<span class='thinspace'></span>km forecast appears to be consistent across the vertical profile of the measurements. In contrast, we find a moderate underestimation of CAMS CO with an overall bias against airborne CO measurements of <span class='inline-formula'>−</span>19.2 (16<span class='thinspace'></span>km), <span class='inline-formula'>−</span>16.7 (9<span class='thinspace'></span>km), and <span class='inline-formula'>−</span>20.7<span class='thinspace'></span>ppbv (analysis). This negative CO mean bias is mostly seen below 750<span class='thinspace'></span>hPa for all three forecast/analysis configurations. Despite these biases, CAMS shows a remarkable agreement with observed enhancement ratios of CO with <span class='inline-formula'>CO₂</span> over the Seoul metropolitan area and over the West (Yellow) Sea, where east Asian outflows were sampled during the study period. More efficient combustion is observed over Seoul (<span class='inline-formula'><math xmlns='http://www.w3.org/1998/Math/MathML' id='M12' display='inline' overflow='scroll' dspmath='mathml'><mrow><mi mathvariant='normal'>d</mi><mrow class='chem'><mi mathvariant='normal'>CO</mi></mrow><mo>/</mo><mi mathvariant='normal'>d</mi><mrow class='chem'><msub><mi mathvariant='normal'>CO</mi><mn mathvariant='normal'>2</mn></msub></mrow><mo>=</mo><mn mathvariant='normal'>9</mn></mrow></math><span><svg:svg xmlns:svg='http://www.w3.org/2000/svg' width='77pt' height='14pt' class='svg-formula' dspmath='mathimg' md5hash='e15dbed157728345ac15fd0589ea867d'><svg:image xmlns:xlink='http://www.w3.org/1999/xlink' xlink:href='acp-18-11007-2018-ie00001.svg' width='77pt' height='14pt' src='acp-18-11007-2018-ie00001.png'/></svg:svg></span></span><span class='thinspace'></span>ppbv<span class='thinspace'></span>ppmv<span class='inline-formula'>⁻¹</span>) compared to the West Sea (<span class='inline-formula'><math xmlns='http://www.w3.org/1998/Math/MathML' id='M14' display='inline' overflow='scroll' dspmath='mathml'><mrow><mi mathvariant='normal'>d</mi><mrow class='chem'><mi mathvariant='normal'>CO</mi></mrow><mo>/</mo><mi mathvariant='normal'>d</mi><mrow class='chem'><msub><mi mathvariant='normal'>CO</mi><mn mathvariant='normal'>2</mn></msub></mrow><mo>=</mo><mn mathvariant='normal'>28</mn></mrow></math><span><svg:svg xmlns:svg='http://www.w3.org/2000/svg' width='83pt' height='14pt' class='svg-formula' dspmath='mathimg' md5hash='3be8931fd245903ba9a1c1d59edabca9'><svg:image xmlns:xlink='http://www.w3.org/1999/xlink' xlink:href='acp-18-11007-2018-ie00002.svg' width='83pt' height='14pt' src='acp-18-11007-2018-ie00002.png'/></svg:svg></span></span><span class='thinspace'></span>ppbv<span class='thinspace'></span>pp