Pull out testing of self-screwing retrofit wall to diaphragm anchorage system
Seismic performance of a newly developed self-screwing retrofit wall to diaphragm anchorage system was then investigated through two series of pull out tests. Unreinforced masonry (URM) buildings comprise of load-bearing URM walls and timber diaphragms, with or without a positive load path continuity at their interface. The pull out capacity (POC) of the anchorage system ranged from 13.01 kN to 23.12 kN when installed into typical heritage URM walls and between 9.54 kN to 12.16 kN when driven from side into two consecutive floor joists of a heritage timber diaphragm. Seismic assessment and upgrade of URM buildings is a complex process that involves analysing extremely heterogeneous non-linear materials in addition to large variations in material properties. The POC for anchors installed with excellent installation quality was observed to be 16% higher than that with average installation quality, whereas the installation in mortar joint and damp masonry resulted in a reduction of POC by 24% and 13% respectively.