Friction characterization testing of fabric felt material used in precast structures

Felt material is sometimes employed in precast wall-slab-wall structures featuring no mechanical devices for the wall-slab connection. This implies that the frictional properties of these felts should be high enough to permit horizontal lateral forces on a building to be carried through them, preventing the sliding of slabs on precast walls and eventually their unseating. In light of this, friction testing of fabric felt material has been undertaken, combining triplet-monotonic and cyclic-symmetric tests, with a view to characterize this material, allowing not only an estimate of the shear force transferred, in actual buildings, between the slabs and the precast walls underneath them, but also a likely force-displacement relationship that may be employed in numerical modeling efforts. Comparisons with data from a recent full-scale building test corroborate the results obtained by the two-step experimental investigation presented in this paper, thus adding further weight to the modeling recommendations herein provided.