In-plane stiffening and strengthening of timber floors for the improvement of seismic behaviour of URM buildings

Abstract

The seismic vulnerability of URM buildings is strongly influenced by the strength and stiffness of timber floors. In this work, a steel strengthening solution is proposed to improve the in-plane stiffness of timber floors. The solution consists of placing underneath the wooden floors a steel grid of thin plates and angles at the perimeter to connect to the walls of the existing building. The connections between steel elements were done with screws. The strengthening solution proposed was numerically modelled in SAP 2000 and experimentally checked. A cyclic shear test was carried out on a real scale timber floor strengthened with the steel structure proposed. This test allowed the evaluation of the failure mode, force-displacement diagrams, and of various behavioural parameters such as floor resistance and in-plane stiffness. The experimental cyclic test showed that the strengthened timber floor considerably increased the floor resistance and in-plane stiffness. A proposal to model the stiffening solution is offered.