Several biological materials are complex assemblies of semi-flexible filaments. They form out-of-equilibrium systems, driven by the consumption of chemical energy. Two lengthscales are usually considered to study the mechanics of these systems : the microscopic lengthscale (at the scale of single filaments) and the macroscopic lengthscale (at the material scale). The first is tackled using numeripar Serge - Thèses hors de l'EDPIF