Sustainable development and climate change

In 1987, the authors of Our common future argued that unless the world embraced and operationalized sustainable development, it would risk being overwhelmed by a series of interlocking crises related to population growth, urbanization, poverty and environmental degradation. Since then, many authors have argued that the world is on a worst case scenario trajectory. Post‐Rio assessments of progress towards sustainable development have been largely negative. Since 1987, climate change has added a new stressor to the mix while shortening the time frame for transformation. In the context of accelerating change and converging stresses is the concept of sustainable development as compelling today as it was twenty years ago? Is it reasonable to believe there are means by which to reduce poverty and simultaneously protect the environment? This article briefly reviews the global challenges that first stimulated the concept of sustainable development and asks how contemporary processes of global change are affecting both these challenges and this approach to addressing them. While there are some grounds for optimism, several variables are identified that make sustainable development increasingly difficult to design and implement. The article concludes with an evaluation of how these difficulties might be overcome, and why it is essential that we try.     

NONLINEAR ANALYSIS OF REINFORCED CONCRETE SHEAR WALL UNDER EARTHQUAKE LOADING

A constitutive model for predicting the cyclic response of reinforced concrete structures is proposed. The model adopts the concept of a smeared crack approach with orthogonal fixed cracks and assumes a plane stress condition. Predictions of the model are compared firstly with existing experimental data on shear walls which were tested under monotonic and cyclic loading. The same model is then used in the finite element analysis of a complete shear wall structure which was tested under a large number of cyclic load reversals due to earthquake loading at NUPEC's Tadotsu Engineering Laboratory. Two different finite element approaches were used, namely a two-dimensional and a three-dimensional representation of the test specimen. The ability of the concrete model to -reproduce the most important characteristics of the dynamic behaviour of this type of structural element was evaluated by comparison with available experimental data. The numerical results showed good correlation between the predicted and the actual response, global as well as local response being reasonable close to the experimental one.     

SHAKING TABLE DYNAMICS: RESULTS FROM A TEST-ANALYSIS COMPARISON STUDY

This paper presents the results of a comprehensive comparison study between the analytically predicted and experimentally identified dynamics of the shaking table system built recently in the Structural Engineering Laboratory at Rice University in Houston, Texas. The primary objectives of the research presented here are two-fold: (1) to shed light into the dynamic performance of asmall-tc-medium size, uni-axial, servo-hydraulic, displacement-controlled shaking table system, and (2) to validate a linearised dynamic model of the system (in the form of the total shaking table transfer function) developed earlier by the authors from basic principles. The analytical model incorporates the inherent dynamic characteristics of the various components of the shaking table system (i.e. controller, servovalve, actuator, test specimen, and reaction mass) and their dynamic interaction.

The test-analysis correlation study performed over a wide range of operating and payload conditions provides useful information on the sensitivity of the shaking table transfer function to control gain parameters and how it can be used to tune the shaking table controller for optimum performance under various payload conditions. The good test-analysis correlation results obtained validate the analytical shaking table model, show its robustness, and provide keen insight into the underlying coupled dynamics of a shaking table system. In order to achieve this good test-analysis correlation, it was crucial to include a time delay in the analytical model of the shaking table system (innovative feature of the model to account for the time lag in the response of the servovalve-actuator system). The expected significant dynamic interaction between payload and shaking table is also confirmed by this study.     

Typologie et vitalité des communautés francophones minoritaires au Canada

La vitalité des communautés francophones minoritaires du Canada, souvent expliquée par les conjonctures démographique et institutionnelle et par le contexte politico-juridique, souffre encore d'une relative rareté de travaux empiriques illustrant l'action de ces facteurs à l'échelle des communautés. Cette rareté n'a pas permis jusqu'à maintenant d'élaborer une véritable analyse de l'effet de milieu sur la vitalité communautaire des minorités francophones. Notre étude se propose de mieux caractériser la présence francophone dans l'espace canadien hors Québec et, ce faisant, les milieux dans lesquels se construit la vie française au pays. Elle se fonde sur l'idée que la présence francophone, caractérisant un lieu donné, profite également d'un contexte plus large dont les ressources ne peuvent faire autrement que de rejaillir sur la communauté locale. À l'idée de présence localisée , nous ajoutons l'idée de présence contextualisée pour mieux faire le lien entre présence et vitalité communautaire. Une méthode originale est présentée ici qui permet de mettre en application cette complémentarité entre ces deux types de présence. Prenant la forme d'une typologie des milieux francophones minoritaires, elle fournit un nouvel éclairage sur la situation des populations francophones du Canada. Une analyse exploratoire des comportements linguistiques de ces populations selon les milieux issus de la typologie montre qu'une telle approche est susceptible d'ouvrir la voie à une meilleure appréhension de la vitalité communautaire en milieu minoritaire.