Po Portland Pu Public Schools Ju July 5, 2016 Summary y of - - PowerPoint PPT Presentation

Po Portland Pu Public Schools – Ju July 5, 2016

Summary y of Portland Building Stock

Steel Frames 1% Concrete Frames 1% Pre-Engineered Steel 4% Wood 48% Infilled Frames 1% Reinforced Masonry 13% Unreinforced Masonry 9% Concrete Shear Wall 17% Tilt-up concrete 6%

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:

• 29 (71%) caused by URM façades collapsing onto people

exiting from, or passing by, the buildings or in vehicles

• 4 died inside a URM building and 6 died in a neighboring

building (23% died inside)

• 1 chimney collapse inside home
• 2 free standing wall / other collapse

Heritage – Odeon Theater (partial demolish)

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

Be Best Practices

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 Standards Committee Support Committee Policy Committee

UR URM Seismic Retr trofit t Project

URM Seismic Retrofit Project Retrofit Standards Committee Support Committee Policy Committee URM Database Update

UR URM Seismic Retr trofit t Project UR URM Data tabase Up Update te

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.

Th The Risk

UR URM Data tabase

URM Seismic Retrofit Project Retrofit Standards Committee Support Committee Policy Committee URM Database Update

Re Retrofit Standards 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

Stakeholders Represented

Engineers Geologists Government Architects Historic Preservation

Meetings

Met six times between December 2014 and May 2015

Re Retrofit Standards Committee Charter

Current requirements in Title 24.85 be supplemented with active triggers that include mandatory seismic strengthening of all URM buildings

Re Retrofit Standards - Ke Key Recommendation

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

Wh Why Consider Mandatory Retrofits for URMs?

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
• ccupants and the public
• the occupancy type and occupant load of the

building

• the function of the building both before and after a

seismic event

UR URM Building Classificati tion

Seismic Risk Classification Description Upgrade Level

• Approx. # of

Bldgs. Highest Risk Lowest Risk URM Class 1 Critical buildings (Risk category1 IV buildings, power generating stations serving critical facilities, water facilities, and other public utilities) Operational performance level for a Design Level Earthquake and Life safety for Maximum Considered Earthquake (MCE)

(10)

URM Class 2 A. All school buildings and B. Risk category1 III buildings Damage Control performance level for a Design Level Earthquake and Limited Safety for MCE.

(88) 46 schools 36 churches 6 community ctrs/theatres

URM Class 3

• A. Buildings ≥ 4 stories or
• B. Buildings with ≥ 300 occupants
• r
• C. Residential buildings with ≥ 100

units Life Safety performance level under Design Level Earthquake and Collapse prevention for MCE

(221) Buildings ≥ 4 stories or Buildings ≥ 300 occupants

URM Class 4 All other URMs not categorized as URM Class 1, 2, 3, or 5 Life Safety performance level under Design Level Earthquake and Collapse prevention for MCE unless building qualifies for modified “Bolts Plus” standard

(1136) 1-3-story bldgs. with occupant load between 10-300

URM Class 5 1 and 2-story buildings with 0-10

• ccupants

Parapet bracing, wall tie in and wall bracing

(203) 1 and 2-story buildings with 0-10

• ccupants

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

• ccupy 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.

Pe Performance Standards

STEP 1 ASCE 41 Assessment2 and Geotechnical Report3 STEP 2 Parapet, cornice and chimney bracing and wall to roof attachment4,5 STEP 3 All bearing and exterior wall to floor attachments and

• ut-of-plane wall

strengthening4,5 STEP 4 Seismic upgrade completed4 URM Class 1 3 years

• 10 years

URM Class 2 3 years 10 years

• 20 years

URM Class 3 3 years 10 years 20 years 25 years with up to an additional 5 years with demonstrable hardship URM Class 4 3 years 10 years 20 years 25 years with up to an additional 5 years with demonstrable hardship URM Class 5 3 years 10 years 10 years

• Ti

Timeline for Seismic Upgrades

• 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

Re Retrofit Standards – Ad Additiona nal Recommend ndations ns

URM Seismic Retrofit Project Retrofit Standards Committee Support Committee Policy Committee URM Database Update

Se Seismic Su Support 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:

• Most life/safety benefit
• For the greatest number of buildings
• 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

URM Seismic Retrofit Project Retrofit Standards Committee Support Committee Policy Committee URM Database Update

Po Policy Committee

Ne Next Steps

• Hold public meetings in September
• Reconcile differences between Retrofit Standards

and Support Committees

• Evaluate level of effort/feasibility and expected

impact/benefit of code requirements and support tools

• Develop final recommendations

Qu Questions?