Po Portland Pu Public Schools – Ju July 5, 2016
Summary y of Portland Building Stock Unreinforced Masonry Wood 9% Tilt-up concrete 48% 6% Infilled Frames 1% Reinforced Masonry 13% Concrete Shear Wall 17% Concrete Frames Pre-Engineered Steel 1% 4% Steel Frames 1% Of over 14,000 buildings surveyed, about 1,800 buildings were classified as unreinforced masonry (URM) buildings.
Un Unreinforced Masonry (UR URM) 42 deaths attributed to URMs: o 29 (71%) caused by URM façades collapsing onto people exiting from, or passing by, the buildings or in vehicles o 4 died inside a URM building and 6 died in a neighboring building (23% died inside) o 1 chimney collapse inside home o 2 free standing wall / other collapse
Heritage – Odeon Theater (partial demolish)
Be Best Practices Other cities in areas of moderate to high seismic risk have already adopted mandatory retrofit laws: • Berkeley • Los Angeles • Oakland • San Diego • San Francisco • Salt Lake City
UR URM Seismic Retr trofit t Project In May 2014 Portland City Council directed staff to develop policy recommendations to reduce the risk posed by unreinforced masonry (URM) buildings
UR URM Seismic Retr trofit t Project URM Seismic Retrofit Project Core Committee Retrofit Support Policy Standards Committee Committee Committee
URM Seismic Retr UR URM Data UR trofit t Project tabase Up Update te URM Seismic Retrofit Project URM Database Update Retrofit Support Policy Standards Committee Committee Committee
Th The Risk Total Number of URMs – 1,884 153 demolished URM buildings (8%) 87 fully upgraded URM buildings (4.6%) 160 partially upgraded URM buildings (8.5%) Conclusion: Only 13% of the URM buildings have been upgraded in some fashion since 1994.
UR URM Data tabase
Retrofit Standards Committee Re URM Seismic Retrofit Project URM Database Update Retrofit Support Policy Standards Committee Committee Committee
Re Retrofit Standards Committee Charter Committee Charge • Examine the existing URM seismic upgrade requirements established in Title 24.85 and the efficacy of the existing regulations • Consider if mandatory upgrades are feasible and should be required • If mandatory upgrades are proposed, determine the standard and performance levels
Re Retrofit Standards Committee Charter Stakeholders Represented Engineers Geologists Government Architects Historic Preservation Meetings Met six times between December 2014 and May 2015
Re Retrofit Standards - Ke Key Recommendation Current requirements in Title 24.85 be supplemented with active triggers that include mandatory seismic strengthening of all URM buildings
Wh Why Consider Mandatory Retrofits for URMs? URMs are the most vulnerable building types even during smaller seismic events
Wh Why Consider Mandatory Retrofits for URMs? • Current passive triggers in Title 24.85 have not been as effective in reducing the risk posed by URM buildings as originally hoped • Data gathered from other jurisdictions indicate better compliance rates for mandatory programs than those with non-mandatory programs
URM Building Classificati UR tion Retrofit Standards Committee created a five-tiered ranking or prioritization system based on the following factors: • the degree of risk posed by the building to its occupants and the public • the occupancy type and occupant load of the building • the function of the building both before and after a seismic event
Seismic Risk Classification Description Upgrade Level Approx. # of Bldgs. Highest Risk URM Class 1 Critical buildings Operational performance level (10) (Risk category 1 IV buildings, power for a Design Level Earthquake generating stations serving critical and Life safety for Maximum facilities, water facilities, and other Considered Earthquake (MCE) public utilities) A. All school buildings and URM Class 2 Damage Control performance (88) Risk category 1 III buildings B. level for a Design Level 46 schools Earthquake and Limited Safety 36 churches for MCE. 6 community ctrs/theatres URM Class 3 A. Buildings ≥ 4 stories or Life Safety performance level (221) Buildings ≥ 4 B. Buildings with ≥ 300 occupants under Design Level Earthquake stories or Buildings or and Collapse prevention for ≥ 300 occupants C. Residential buildings with ≥ 100 MCE units URM Class 4 All other URMs not categorized as Life Safety performance level (1136 ) 1-3-story bldgs. URM Class 1, 2, 3, or 5 under Design Level Earthquake with occupant load and Collapse prevention for between 10-300 MCE unless building qualifies for modified “Bolts Plus” standard Lowest Risk URM Class 5 1 and 2-story buildings with 0-10 Parapet bracing, wall tie in and (203) 1 and 2-story buildings with 0-10 occupants wall bracing occupants
Performance Standards Pe Design Level Earthquake for Class 2 Buildings Seismic hazard associated with ground motions that have a 20% probability of exceedance in 50 years or a mean return period of 225 years Maximum Considered Earthquake (MCE) for Class 2 Buildings Seismic hazard associated with ground motions that have a 5% probability of exceedance in 50 years or a mean return period of 975 years
Pe Performance Standards Buildings upgraded to Immediate Occupancy Structural Performance are expected to remain safe to occupy following an earthquake: • Very limited structural damage. Structural systems retain almost all their pre-earthquake strength and stiffness. • Risk of life threatening injury as a result of structural damage is very low. • Minor structural repairs might be appropriate but not required for re-occupancy.
Pe Performance Standards Buildings upgraded to Life Safety Structural Performance standard: • Suffer significant damage to the structure but retain some margin against partial or total collapse. • Damage has not resulted in falling hazards and Occupants can safely exit the building. • Injuries may occur but overall risk of life threatening injury as a result of structural damage is low. • Should be possible to repair the structure but for economic reasons it may not be practical.
Pe Performance Standards Damage Control Structural Performance Level is set as a midway point between Life Safety and Immediate Occupancy : • Provides for a greater margin of safety against collapse than Life Safety. • Control damage in such a manner as to permit to return to function more quickly than Life Safety but not as quickly as Immediate occupancy.
Pe Performance Standards Buildings upgraded to Collapse Prevention Structural Performance standard: • Incur substantial damage to structure and is on the verge of total or partial collapse after an earthquake. • Significant risk of injury from falling hazards might exist. • Structure might not be repairable and is not safe for reoccupancy.
Timeline for Seismic Upgrades Ti STEP 1 STEP 2 STEP 3 STEP 4 ASCE 41 Parapet, cornice All bearing and Seismic upgrade Assessment 2 and and chimney exterior wall to completed 4 Geotechnical bracing and wall floor Report 3 to roof attachments and attachment 4,5 out-of-plane wall strengthening 4,5 URM 3 years - - 10 years Class 1 URM 3 years 10 years - 20 years Class 2 URM 3 years 10 years 20 years 25 years with up Class 3 to an additional 5 years with demonstrable hardship URM 3 years 10 years 20 years 25 years with up Class 4 to an additional 5 years with demonstrable hardship URM 3 years 10 years 10 years - Class 5
Retrofit Standards – Ad Re Additiona nal Recommend ndations ns • Provide funding to create an inventory and develop seismic retrofit policies for other building types such as non-ductile concrete buildings that pose a significant hazard in an earthquake • Tenant notification • Real estate transfer disclosure • Building placards
Re Retrofit Standards – Ad Additiona nal Recommend ndations ns • Adopt a seismic rating system similar to the system developed by the US Resiliency Council • Provide funding to develop an educational program directed towards building owners and tenants
Re Retrofit Standards – Ad Additiona nal Recommend ndations ns • Adopt a seismic rating system similar to the system developed by the US Resiliency Council • Provide funding to develop an educational program directed towards building owners and tenants
Seismic Su Se Support Committee URM Seismic Retrofit Project URM Database Update Retrofit Support Policy Standards Committee Committee Committee
Ov Overview • Owner needs are complex and varied • Multiple tools are needed • Financial support should incent early action • Some building will have to be demolished • Public dollars should be invested where they leverage: o Most life/safety benefit o For the greatest number of buildings o At the least cost to the public
Fi Financial Assistance • Low-cost Loan and Grant Programs • Property Tax Exemption/Abatement • State Historic Tax Credit • Floor-Area-Ratio Density Bonus/Develop FAR marketplace • Expedited Permits and Review • Expand Trigger Exemptions to include Water/Storm Water Upgrades • Seismic Concierge
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