Proposed features/building:soft storey
|Soft Storey Building|
|Status:||Proposed (under way)|
|Definition:||a building where any one level is significantly more flexible (less stiff) than those above and below it|
The tag building:soft_storey is to provide a way to identify buildings in which at least one storey is significantly more flexible or weak in lateral load resistance than the storeys above and below it (70% or greater reduction from one floor to the next according to the current International Building Code (IBC) definition ). This condition can occur in any conventional construction type and is typically associated with buildings in which one or more storey have windows, wide doors, large unobstructed commercial spaces, or other openings in places where a shear wall would normally be required for stability as a matter of earthquake engineering design. (according to the Wikipedia definition) .
There are currently (January 2019) ~13,000 buildings using the building:soft_storey key. These tags were added in an effort to map buildings in OSM for Open Cities Kathmandu, a 2012 project a supported by the Global Facility for Disaster Reduction (GFDRR) and the World Bank. The key was not proposed formally.
Aside from Kathmandu, structures with soft-storeys are present in many areas globally. In case of an earthquake, ground shaking causes such structures to sway and sometimes collapse. A soft-storey collapse can have particularly disastrous consequences considering that they crush cars and kill people occupying the open areas.
Many places have ongoing retrofit or reinforcement programs. However, even if retrofitted, identifying these buildings is vital to disaster preparedness and damage assessment. Rather than making buildings earthquake-proof, retrofitting aims to make them earthquake-safe, meaning that hopefully they'll still be standing when the shaking stops. Despite these improvements, retrofitted buildings still won't meet the structural standards of modern construction.
This tag should be used by trained surveyors, using a detailed manual like FEMA's handbook Rapid Visual Screening of Buildings for Potential Seismic Hazards or other similar manuals.
Check official sources or use an assessment worksheet, like the one provided by FEMA to identify soft storey buildings.
The tag needs to be applied carefully. Although citizen responders can be trained to spot soft storey buildings (and this is included in training as part of the U.S. national community preparedness programs such as CERT) only a detailed analysis by structural engineers can definitively identify one. The best way for confirmation is by either obtaining open data released from an official source, like San Francisco Department of Building Inspection (DBI). Alternatively, one can use an assessment worksheet like the one provided by FEMA.
This information will be critical in disaster preparedness and damage assessment; The San Francisco Bay Area alone has about 138,000 soft storey units in varying stages of retrofitting. According to one government report, two-thirds of the uninhabitable housing units in a major quake will likely be soft-storey residential buildings.
How to map
A building can have soft_storey status as
- yes when assessed as having one or more soft story.
- reinforced, if reinforcing measures have been put in place. When known, one can add in the tag 'source:soft_story' the source of the information, such as San Francisco DBI work permit.
- The value no is for buildings that are assessed as having no soft storeys. Don't use no for buildings that have been reinforced.
This draft has been discussed first on Tagging mailing list.
Please comment on the discussion page.
- I approve this proposal. --Smaffulli (talk) 23:17, 10 February 2019 (UTC)
- I approve this proposal. --Nicomar (talk) 23:18, 10 February 2019 (UTC)
- I approve this proposal. --EcoAndrewTRC (talk) 01:22, 11 February 2019 (UTC)
- I approve this proposal. The tag is important and useful, and the proposal is well documented. --Alan (talk) 05:59, 11 February 2019 (UTC)
- I approve this proposal. --smz (talk) 10:48, 11 February 2019 (UTC)
- I approve this proposal. --LeifRasmussen (talk) 13:00, 11 February 2019 (UTC)
- I approve this proposal. --mnorelli (talk) 17:31, 11 February 2019 (UTC)
- I approve this proposal. The meaning is clear, the text can be improved for clarity. Not a tag for my area, but for those who want it here it is. --Warin61 (talk) 02:26, 15 February 2019 (UTC)