Masonry walls restrained by dissipative tie-rods. Part 1 - Energy-based approach

Dissipative Tie-rods (DTs) are innovative tie-rods capable of controlling the out-of-plane rocking of masonry walls during earthquakes. The installation of a DT in a masonry wall, considered as an equivalent rigid block, realizes a two-degree-of-freedom dynamic system whose equations of motion are expressed here in terms of energy. Considering such an energy-based approach, a numerical method making use of experimental results is described with the purpose of defining an equivalent damping ratio to be used in conventional approaches such as non-linear kinematic analyses or discrete/finite element analyses where energy loss at impacts cannot be computed through coefficients of restitution. The methodology delivers an estimation of damping ratios ranging from 32 % to 44 % for walls of remarkably different geometries restrained by DTs, showing its robustness and reliability.