Estudo sobre lajes mistas em madeira-concreto com parafusos autoatarraxantes

Abstract

The association of timber and concrete is structurally efficient and offers the advantages of increasing the stiffness of the composite element, in addition to reducing problems related to vibrations, acoustic insulation and the structure's own weight. In mixed structures, the materials of the composite element are positioned in such a way that their physical and mechanical properties are used efficiently, with the neutral axis positioned in such a way that the timber acts on the most tensioned portion and the concrete on the most compressed portion of the structural element. This paper aims to evaluate, experimentally, the structural behavior of two mixed beams in timberconcrete, with self-tapping screws inclined at 45º, installed in a line and in a zig-zag. From the push-out connection tests performed on four specimens, it was possible to obtain the medium value of the slip modulus of 86412 N/mm and medium value of rupture force of 145498 N. The bending stiffness of the beams was also estimated, as well as their efficiency, presenting a difference of 6,3% in relation to the values calculated according to the CEN EN 1995-1 standard for the beam with in line connectors and 2,5% for the beam with connectors installed in a zig-zag. The influence of connectors installed at 45° (working in traction) on the stiffness of the connection system was proven.