USRC Dimensions and Definitions
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The Three Dimensions of Safety, Damage and Recovery Provide Definitions of Your Buildings Performance In A Major Disaster

Due to many factors including but not limited to variations in construction, differing site conditions, and variations in natural and man-made events, the performance evaluation of a single building includes a significant amount of uncertainty.  The USRC Dimensions and Definitions are intended to provide a consistent set of definitions for the performance evaluation of buildings but do not eliminate the uncertainty.

SEISMIC HAZARDS: 

  • Performance evaluations for a given level of earthquake shaking will vary across possible earthquakes of different strengths and occurring at different distances from the building.
  • The ratings below, when used for earthquake performance, correspond to the average performance given a single earthquake with ground shaking corresponding to that required for the design of a new building.

OTHER HAZARDS: 

  • Ratings for other hazards will be developed by the USRC in the near future.

SAFETY

The SAFETY rating dimension reflects the expected state of the building in terms of exiting the building, injury, and loss of life. A SAFETY rating in this context is an indicator of the risk of personal injuries of various types and seriousness, as well as loss of life.

SAFETY: The potential for people in the building to get out after a disaster and avoid bodily injuries or loss of life. A safety rating is required in all building evaluations.
Injuries and blocking of exit paths unlikely: Expected performance results in conditions unlikely to cause injuries or to keep people from exiting the building.
Serious injuries unlikely: Expected performance results in conditions that are unlikely to cause serious injuries.
Loss of life unlikely: Expected performance results in conditions that are unlikely to cause loss of life.
Loss of life possible in isolated locations: Expected performance results in conditions associated with partial collapse or falling objects, which have a potential to cause loss of life at some locations within or around the building.
Loss of life likely in the building: Expected performance results in conditions associated with building collapse, which has a high potential to cause death within or around the building.

DAMAGE

The DAMAGE rating dimension reflects an estimate of the cost to repair the building after an event, such that it can continue to be used as it was at the time the rating was last issued.

DAMAGE is defined as a percentage of the building’s overall replacement cost, a common insurance concept measuring how much it would cost to construct a new building approximately the same as it was prior to the event. DAMAGE includes the cost of damage to all structural, architectural, mechanical, electrical and plumbing components of a building but does not include the cost of damage to the contents. Contents values may vary depending on how the building was being used at the time of the event. Separately, content damage can be estimated and reported once the contents are defined. DAMAGE is furthermore determined without consideration of overall market conditions in effect following the event, such as post-event increases in local construction costs, and it does not include factors such as business interruption associated with loss of use or occupancy restrictions, design fees, permit fees, historic preservation, or mandatory upgrades triggered by building code regulations. 

DAMAGE: Repair cost as a percentage of the building’s overall replacement cost including structural, architectural, mechanical, electrical and plumbing systems. It does not include damage caused by breaks/leaks in water and gas pipes or contents damage.
Minimal damage: Repair Cost likely less than 5°/o of building replacement cost.
Moderate damage: Repair Cost likely less than 10°/o of building replacement cost.
Significant damage: Repair Cost likely less than 20°/o of building replacement cost.
Substantial damage: Repair Cost likely less than 40°/o of building replacement cost.
Severe damage: Repair Cost likely greater than 40°/o of building replacement cost.

RECOVERY

The RECOVERY dimension is an estimate of the time until a property owner or tenant is able to enter and use the building for its basic intended functions.

A RECOVERY rating represents a minimum timeframe to carry out needed repair and to remove major safety hazards and obstacles to occupancy and use. This rating does not address several other factors that can delay the time to regain function, including but not limited to: the condition of external infrastructure (e.g. utilities, transportation) that provide access and services to the building; damage or the post-event state of building contents; or the condition of adjacent buildings.

The complexity and time needed to restore a building to usable condition can increase quickly in relation to the degree of damage. Delays in design, financing, and construction may include time until arrival of special-order equipment or materials, increased prices, a lack of available local design professionals or contractors in a community where many buildings have been damaged, and longer than usual permitting and inspection wait times. Separately, these factors can be estimated and reported, but the actual total time impact of these factors is highly uncertain.

RECOVERY: An estimate of the MINIMUM timeframe to carry out sufficient repairs and to remove major safety hazards and obstacles to regain occupancy and basic functions ofthe building, but not necessarily restore full functionality.
Within hours to days: The expected performance will likely result in people being able to quickly re-enter and resume use of the building from immediately to a few days, excluding external factors.
Within days to weeks: The expected performance may result in delay of minimum operational use for days to weeks , excluding external factors.
Within weeks to months: The expected performance may result in delay of minimum operational use for weeks to months, excluding external factors.
Within months to a year: Expected performance may result in delay of minimum operational use for months to a year.
More than one year: Expected performance may result in delay of minimum operational use for at least one year or more.

RATING PLACARD

Buildings that achieve a verified rating with minimum thresholds in each of the three dimensions of Safety, Damage and Recovery will receive either a BRONZE, SILVER, GOLD or PLATINUM designation, reflecting their expected level of performance. These designations can be displayed on the buildings themselves and with plaques and certificates. 


DISCLAIMER

USRC Rating Definitions have been derived from technical publications originally developed by the Structural Engineers Association of Northern California (SEAONC). SEAONC granted the USRC permission to use these documents. Any differences between USRC Ratings and related SEAONC documents are solely the work of the USRC and do not reflect any opinion, endorsement, or approval by SEAONC.

While US codes and engineering practices are among the most advanced in the world, evaluations of building performance subject to natural disasters include a significant amount of uncertainty: unknowns related to forecasting actual event location, size and duration, the actual intensity to which the building is subject, and the quality of the building design and construction. Current building analysis, evaluation and correlation methods do not address or remove all these sources of uncertainty.