LINEAR VISCOELASTIC MODEL OF BORASSUS WOOD: RHEOLOGICAL PARAMETERS

The aim of the presentworkis to study the viscoelastic model of Borassus Aethiopum Mart whichis relevant for the characterisation of a Borassus Pre-stressedConcretebeam. Mechanical tests werecarried out mainly the creep test on typical Borassus Aethiopum Mart specimensfrom the Pahou-Ahozon forestgallery in southern Benin, Africa, subjected to a constant bending stress along the beam. The moisture content of the specimensis set at 12% and isobtained by kilndrying at ATC du Bois. The loadinglevel of the specimensis set at 20% of the failureload. A methodologystartingfrom the determination of the compressive and bending stresses of Borassus Aethiopum Mart for the identification of the optimal values of the dynamicelasticmodulus E and the dynamicviscosity constant η of Borassus Aethiopum Mart with the non-linear least squares methodapplied to the Kelvin Voigt rheological model. The instantaneousmodulus of elasticity E0 wasdeterminedfromHookeslaw. A series of validation tests wereperformed on the numerical model. Finally, a comparison of the numerical model with the rheologicalrepresentationconfirmed the previousresults.