Due to the unpredictable nature and ferocity of earthquakes, even the best quality seismic restraints can fail to prevent tall, heavy or narrow items from toppling. This is because:
- Effective restraint relies on the structural integrity of the wall or surface to which they are attached.
- Metal stud walls in modern office spaces are not designed to provide seismic bracing for heavy furnishings.
- Bracing heavy furnishings to an internal metal stud wall can cause the wall to collapse under seismic loading.
- This happed to a Government Department office in Wellington during the 2014 Seddon earthquakes after their handyman attached several cabinets to the wall.
- Drilling into or bracing to concrete support columns is not recommended as it could compromise the building itself.
- Additionally, earthquake forces can cause the failure or collapse of the items being restrained. This is particularly true for heavily loaded book shelves. A five shelf book case holds approx. 150-180kgs of files.
- Best results require sturdy furnishings such as metal cupboards to be bolted to the floor.
- Smaller items can still be attached to internal walls with flexible restraints such QuakeFlex®.