The $4.6 Billion Unreinforced Masonry MandateJul 26 2017 · 0 comments · NISHKIAN DEAN, Seismic ·0
By Edwin T. Dean, PE, SE
Unreinforced masonry (URM), or the use of stone or brick masonry for structural walls, was a common approach in Portland building construction from the late 1800s to as recently as the 1950s. These buildings range in size from small one-story residences to large 10- or 12-story buildings, most with wood-framed floors with some structural steel or cast-iron components. Many of these buildings are historically registered and represent a valuable part of the City’s cultural heritage. Several are public buildings used for government operations or public schools. The characteristic of concern for this type of building construction is that they are extraordinarily vulnerable to earthquake damage, where even moderate ground shaking could result in partial collapse.
Earthquake occurrences in other West Coast cities, such as Loma Prieta in 1989 in the San Francisco Bay Area and Northridge in 1994 near Los Angeles, have demonstrated that this type of construction is susceptible to devastating collapse and associated loss of life and property damage. There were many URM buildings that were damaged in these events, including those that had been seismically strengthened. This damage represented a very significant economic cost, though fortunately not a large number of deaths and URMs did not represent the deadliest type of buildings. These cities now have URM mandates: in the Bay Area, this was largely put into place after the Loma Prieta event, and in Los Angeles it had been implemented prior to the Northridge event.
The Portland metro area has so far been spared from a major earthquake in recent history, though geoscientists believe that large damaging earthquakes are possible. Beginning in the 1980s, the building codes have progressively increased the seismic design requirements in recognition of the potential for such natural disasters. The rate at which URMs have been retrofitted to resist earthquakes on par with current code requirements has been slow.
The City of Portland’s Unreinforced Masonry (URM) Building Policy Committee (Committee) estimates that since 1995, roughly 8% of URMs have been demolished. Of those that remain, about 5% have been fully retrofitted and about 9% have been at least partially upgraded. At that rate, it could take almost another 100 years for the URM building inventory in Portland to be either strengthened or demolished. Based on the risks posed by URM buildings to public safety, the Committee is proposing a tiered retrofit approach, requiring URM upgrades to buildings over a defined period of time. See our prior blog article, Portland Poised to Mandate URM Building Seismic Strengthening, for more background information on this.
The Committee proposal to require seismic strengthening of URM buildings is a tiered approach based on the buildings’ use and occupancy. The only exceptions to these recommended requirements are for one- and two-family homes and URM buildings that were previously seismically strengthened to an acceptable defined standard.
The Committee has defined four categories or classes of URMs with differing levels of seismic strengthening requirements and time horizons to complete them. The classes range from 1 to 4 with Class 1 for Critical Buildings and Essential Facilities and Class 4 for Low-Occupancy structures. In between these, Class 2 is for Schools and High-Occupancy structures (Churches and Theaters), and Class 3 is for is the largest class of building (approximately 2/3 of all URMs) and covers every other URM building not in the other classes. The City has compiled a detailed inventory of the buildings and the classification that they would fall under. The timeframe for implementation of the seismic strengthening varies by Class, but generally requires a seismic assessment in 3 or 5 years and strengthening implementation in 10 to 20 years.
Step 1 – A seismic assessment (ASCE 41-13) with a schematic seismic upgrade strategy including detailed cost estimates must be completed within three or five years.
Step 2 – Parapets, cornices and chimneys must be braced, and the roof must be attached to walls within 10 years.
Step 3 – All floors must be attached to walls and the roof must be sheathed within 15 years.
Step 4 – A complete retrofit must be performed within 20 years.
Separately, the Portland Bureau of Emergency Management and Bureau of Development Services commissioned Goettel & Associates, Inc. to prepare a Benefit-Cost Analysis of the Proposed Seismic Retrofit Ordinance. The report was published on November 23, 2016, and concluded, “The benefit-cost results indicate that the benefits of the URM building seismic retrofits current under consideration exceed the retrofit costs for the defined “typical building” for each URM Class of buildings.” The Committee intends to present their codified recommendations for mandatory seismic strengthening of URM to City Council for adoption. The City Councils adoption of the mandatory ordinance will start the clock and require building owners to either strengthen their URM buildings, demolish them, or face growing fines and the eventual loss of the use of their buildings.
Cost to Implement
The implementation of this mandatory ordinance will have a significant financial impact on the building owner. The objective of such an ordinance from the City’s perspective would be to reduce the life-safety risk these buildings pose to the occupants and those people who may be nearby these buildings in the event of an earthquake. The benefit-cost analysis demonstrated that there was a net benefit to the seismic strengthening; however, those benefits are not directly correlated to the financial return of the building. The Committee in its recommendations were not able to identify anything more than $5M in available Urban Renewal Area (URA) capital funds to assist building owners with the high costs of implementing the seismic strengthening. There are also possible State and Federal tax exemptions or credits and funding from the State Seismic Rehabilitation Grant Program (SRGP) for schools and emergency service facilities and potentially the sale of Floor Area Ration (FAR) transfers to another site. Additionally, the current Committee recommendations do not provide any material relief to buildings with “special considerations,” meaning those with occupants needing affordable housing, schools, religious or non-profit users, or historic structures. The Committee report does not identify the total cost to implement the required mandate. The cost-benefit study identifies the current costs to seismically retrofit or strengthen the four classes of building types on a square-foot basis in Table 15 of their report. Combining these square foot costs with the building areas contained in the inventory list provides the following total costs:
Table 1: Estimated Total Retrofit Costs Based on BDS Inventory
|URM Class||UPGRADE||Cost per Square Foot||No. of Buildings||AREA in Square Foot||TOTAL||AVG per Building|
|Class 1||Immediate Occupancy||$111.45||10||49,329||$5,487,717||$549,772|
|Class 2||Damage Control||$82.62||92||3,253,423||$268,797.808||$2,921,715|
|Class 3||Life Safety||$68.77||220||8,379,527||$576,260,072||$2,619,364|
|Class 4||Modified Bolts Plus||$51.00||1,339||10,915,945||$556,713,195||$415,768|
This would indicate that the cost to implement this mandate, if all the buildings are strengthened, to be on the order of $1.4 billion. However, this amount is an oversimplification. Faced with these costs, which in many cases exceeds the economic value of the property, it is reasonable to assume that many building owners will either abandon the properties or opt to have the buildings torn down until market conditions favor the cost of rebuilding. This will particularly impact buildings at the lowest economic value, such as those being used for affordable housing. The mandate will also allow the seismic assessments to be performed and permit the seismic strengthening to be implemented over a period of up to 20 years, assuming that building owners will wait as long as possible to seismically strengthen their buildings. When this is factored in, and the time-value of the construction costs at a 4% annual escalation are accounted for in the total cost to implement this regulation, the total costs rises to approximately $4.6 billion. Again, this assumes that all the recommended buildings will be strengthened and the reality is that many will not due to the financial restraint.
“total cost to implement this regulation, rises to approximately $4.6 billion”
The URM Building Policy Committee will continue meetings and prepare final recommendations. These recommendations will be taken up by the Portland City Council, possibly as soon as the fall of 2017. At that point, the Council will need to decide if it will implement the recommendations, or some aspects of the recommendations, as an ordinance mandating seismic strengthening of URM buildings, or continue with the status quo as required by Title 24.85. Nishkian Dean will continue to monitor the development of this important issue that affects many of our clients.
- City of Portland, DRAFT Unreinforced Masonry (URM) Building Policy Committee Report, July 2017
- City of Portland, Chapter 24.85 Seismic Design Requirements for Existing Buildings
- City of Portland, URM Buildings Seismic Retrofit Policy Information website
- City of Portland, Unreinforced Masonry (URM) Seismic Retrofit Project website
- Benefit-Cost Analysis of the Proposed Seismic Retrofit Ordinance City of Portland, by Kenneth A. Goettel Goettel & Associates Inc., November 23, 2016
- Portland Poised to Mandate URM Building Seismic Strengthening, by Edwin T. Dean, August 2016
Edwin T. Dean, PE, SE is Vice President and Managing Principal of Nishkian Dean a structural engineering consulting firm in Portland, Oregon.
 City of Portland Policy Committee, DRAFT Unreinforced Masonry (URM) Building, Policy Committee Report, dated October 2016, pg. 8
 Kenneth A. Goettel, Benefit-Cost Analysis of the Proposed Seismic Retrofit Ordinance, City of Portland, November 23, 2016, pg. iv
 Religious facilities would be provided relief from completing steps 3 & 4.
 Kenneth A. Goettel, Benefit-Cost Analysis of the Proposed Seismic Retrofit Ordinance, City of Portland, November 23, 2016, Table 15, pg. 31