Experimental investigation of multi-material aluminum-to-steel and GFRP-to-steel bonded and bolted/bonded connections

Abstract : Through an experimental study, this paper describes the behavior of single-lap bonded, bolted and bolted/bonded connections for configurations with minimum geometric parameters proposed in design references. Two types of multi-material connections are considered: Glass Fiber Reinforced Polymer (GFRP)-to-steel and aluminum-to-steel. At first, the behavior of multi-material bonded connection using methacrylate and epoxy adhesives is evaluated. Then experimental results of bolted connections are presented. Finally, the contribution of adhesive in GFRP-to-steel and aluminum-to-steel bolted connections is investigated. Test results show that on single-lap simply bonded joints, failures mostly occur at the substrate to adhesive interface. Sanding the GFRP plate was found to improve the connection strength. Despite their lower elastic modulus, methacrylate adhesives with larger elongation provides better strength due to their high resistance in peeling. For bolted/bonded joints, the adhesive was found to improve the elastic behavior and the strength of GFRP-steel joints while its effect for aluminum-steel joints was not apparent due to reduce bonded surface and the high strength performance of the bolted plates

Effect of geometric parameters on the behavior of bolted GFRP pultruded plates

Abstract : This paper presents the effect of geometric parameters on the behavior of bolted GFRP pultruded plates for civil engineering applications. After a literature review, results of an experimental analysis investigating the behavior of GFRP-to-steel single-lap bolted connections are presented. Then, a finite element analysis validated by experimental data is used to evaluate the effects of the end-distance, side-distance, gage, pitch and plate properties on the strength and failure mode of the connection. A critical examination of geometric recommendations proposed in design references is presented. Bearing failure caused by contact of the bolt on the GFRP plate is usually defined as the preferred failure mode. With highly orthotropic plate, this type of failure was found to be less likely to occur when loading is applied in the pultruded direction. The investigation showed that the minimum end-distance and pitch-distance recommended by design references usually produce a connection with the maximum capacity. However, it was found that the minimum side-distance recommended by these references does not necessarily lead to the maximum capacity for one-bolt and for two-bolt in a column connections

Effect of geometrical parameters of aluminum-to-steel bolted connections

Abstract : Through experimental and numerical studies, this research work aims to provide directions on the optimal geometric configuration for single-lap and double-lap bolted connection between aluminum alloy 6061-T6 and steel. From experimental test results, the effects of different geometric parameters on the joint strength were discussed. These parameters include the end-distance, the side-distance, the pitch-distance, the plate thickness and the joint eccentricity. Then, the experimental results were compared to predicted results using design references and geometric recommendations proposed by design references were critically examined. The experimental study was complemented by finite element (FE) analysis to extend the study to a larger range of parameters. In addition to the analysis of the geometric parameters listed above, the effects of the gage-distance on the joint strength were studied in the FE analysis. The experimental and finite element results show that a careful selection of geometric parameters can result in the high improvement of the connection strength and failure mode. Limiting the side-distance to the minimum recommended value was found to limit the strength of a connection with two bolts in a column to that of the one-bolt connection. In most cases, bearing was found to govern the strength of the connections. The calculated bearing strengths were found to underestimate significantly the connection strength. Based on these analyses, maximum geometric parameters beyond which there is no further increase of the joint capacity were evaluated and optimum geometric parameters were proposed

Analyse par éléments finis de plaques de matériaux composites

Nous étudions dans ce travail le comportement de matériaux composites contenant un défaut interne, lorsqu'ils sont soumis à des charges axiales. Les matériaux étudiés sont constitués d'un assemblage de lamelles transversalement isotropes, dont deux des axes principaux sont dans le plan de la plaque. Les lamelles internes sont traversées par un défaut de forme circulaire. L'analyse est exécutée en utilisant un programme d'éléments finis en trois dimensions basé sur un élément prismatique triangulaire à six noeuds, et dont la fiabilité a été démontrée. Les contraintes sont analysées spécialement aux alentours du défaut pour trois types de matériaux. La modification de la rigidité des éléments soumis à des efforts plus grands que ceux permis par un critère de contrainte maximum permet d'étudier la propagation des dommages dans la plaque. Cette étude est effectuée pour un seul matériau

Évaluation des processus et des effets d'un programme de référence-évacuation des urgences obstétricales au Mali

Également publié dans le rapport final du projet comme annexe CCe chapitre traitera de l'évaluation d'un programme de référence-évacuation des urgences obstétricales dans un pays à faibles ressources, le Mali. Cette évaluation, qui est toujours en cours, consiste en une analyse de l'implantation et des effets du programme. Elle répond aux besoins d'information des acteurs locaux et régionaux qui ont participé activement à son implantation, et ce, dans une région spécifique du Mali. Nous décrirons tout d'abord le programme ainsi que le contexte dans lequel il s'inscrit. Nous présenterons ensuite succinctement les principales approches utilisées dans l'analyse de l'implantation et le protocole d'évaluation retenu. Enfin, nous détaillerons le processus d'évaluation et présenterons les résultats obtenus et les leçons apprises jusqu'à ce jour