Mechanical properties of Glued-laminated timber made up of mixed tropical wood species
Résumé
This paper deals with the experimental study devoted to cyclic compressive loading of three tropical species (Aucoumea Klaineana Pierre AKP, Milicia Excelsa ME and Pterocarpus Soyauxii PS) at different moisture content levels. According to the French requirement NF EN 408, 90 samples taken from these three species were dimensioned. The experimental campaign is compounded of static tests concerning 15 samples and cyclic tests performed on 75 samples. First, the samples are loaded into the static compressive test until their collapse, in order to obtain the mechanical characteristics of each species in terms of: (i) the modulus of elasticity, (ii) the maximal strength and (iii) the stress at the yield point. Then, each sample is loaded five times in cyclic compressive loading, following the paths of loading-unloading-reloading, at different moisture contents levels. The maximal load applied for each cycle corresponds to 10% of the collapse load of the AKP species. The results show a stiffening of the samples with the loading cycles. The stiffening is faster from the densest species to the least dense species, respectively. In addition, the phenomenon of densification, that occurs during the five loading cycles, is done with constancy of compressive strength in the three species.
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