Comparative studies of three tropical wood species under compressive cyclic loading and moisture content changes

Abstract

ABSTRACT 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 (MC) levels. According to the French requirement, NF EN 408, 90 samples are taken from these three species. The experimental campaign consists 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 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 MC 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. Besides, the phenomenon of densification, which occurs during the five loading cycles, is carried out with the constancy of compressive strength in the three species.