Allowable stress design by structural grade for nine plantation woods of Costa Rica

Abstract

Costa Rica has several species wood from forest plantations to supply the demand for end-user wood. However, this country does not have allowable stress design for different structural grade for these woods. This paper aims to show the allowable stress design values derived from clear wood for nine of plantation species used in commercial reforestation in Costa Rica. The mechanical properties analyzed were: static bending, compression parallel and perpendicular to grain and shear and tension parallel to grain. The results in clear wood specimens showed that Tectona grandis, Terminalia oblonga and Acacia mangium presented the highest values of MOE and MOR in static bending. In compression parallel and perpendicular, T. grandis showed the highest resistance. A. mangium and T. grandis were the plantation species with the highest strength in tension parallel to the grain. A. mangium and Cupressus lusitanica presented the highest values in shear parallel to grain. V. guatemalensis and Bombacopsis quinata showed lower resistance in all measured mechanical properties analyzed. The derivation of allowable stress design was possible to establish three groups of species. Group 1 is composed of A.mangium, T. grandis, T. amazonia and T. oblonga, with the highest allowable stress design. Group 2, with intermediate allowable stress design values, component species Gmelina arborea and C. lusitanica. Group 3 species, with lower allowable values, is grouped of Alnus acuminata, B. quinata and V. guatemalensis.