Influence of nails size and layout to obtain the reduction coefficient of moment of inertia for timber beams with composite cross section

ABSTRACT A significant portion of rural building’s roof is supported by timber trusses. Increasing distance between the trusses can be achieved by using composite cross sections ("T" and "I") for beams. With this, it is possible to reduce the number of columns and trusses, bringing significant savings in material and the desired cost reduction, mainly using wood from planted forests. The Brazilian Code ABNT NBR 7190:1997 establishes a coefficient (αr) for the reduction of the theoretical moment of inertia (Iteo) of 0.95 and 0.85, for beams with "T" and "I" composite profile, respectively. H...