2. What Are We Looking For?
Number of hazardous concrete buildings in California.
1.
2.
3.
Estimate number of pre-1980 concrete buildings in specific
jurisdictions.
◦ Capture buildings constructed with 1973 UBC or earlier
Extrapolate to estimate number in state.
Perform studies to determine which are most hazardous. (PEER)
Category
Number
Total Number of Buildings
A
Total Number of Concrete Buildings
B
Pre-1980 Buildings
C
Pre-1980 Concrete Buildings
D
4. Concrete Building Types
Count
Data
City Buildings
X
County Buildings
Optional – Other
Databases
Available1
X
State Buildings
X
Post Offices
X
County and State Courthouses
X
Federal Office Buildings and Courthouses
X
Hospitals Regulated by OSHPD
X
Utility-Owned Bldgs. Including Substations
X
X
Grade K-12 Public Schools
UC and CSU
X
Community Colleges
X
1
volunteers must indicate if they counted these building types
Do Not
Count
Data
5. Concrete Building Types
Count
Data
Prisons
X
Special Districts including Pump Stations and
Buildings at Treatment Plants
X
Churches
X
Port Buildings
X
Regional, County, and city Parks
Optional – Other
Databases
Available1
X
1
volunteers must indicate if they counted these building types
Do Not
Count
Data
6. Concrete Building Types
Count
Data
Concrete Frame with Masonry Infill
X
1-Story Cast-in Place Concrete with wood Roof
(including walls with pilasters)
X
Concrete Shear Wall with Steel Gravity Frame
X
Mixed Construction2
Do Not
Count
Data
X
Wood-frame residential on Conc. Podium
Optional – Other
Databases
Available1
X
Tilt-ups
X
Dual System with Concrete Shear Wall3
X
X
Parking Garages
Buildings Whose Concrete Elements are
Limited to Fire Walls Between Sections
X
Buildings Whose Concrete Elements are
Limited to Basement or Retaining Walls
X
Includes horizontal additions of concrete as well as buildings with concrete lateral
load systems in one direction only.
2
Do not need to make exceptional efforts to verify whether a building has a dual
system or not, but if you know, don’t count it
3
7. Concrete Building Types
Count
Data
Retrofitted Buildings4
X
Buildings in Areas Scheduled for
Redevelopment
X
Building-like Nonbuilding Structures5
Do Not
Count
Data
X
Abandoned Buildings
Optional – Other
Databases
Available1
X
X
Nonbuilding-like Nonbuilding Structures6
Concrete Structures Supported on Piers or
Wharfs over Water
X
Buildings used for storage – No Occupancy
X
4
Obtain approximate retrofit date is possible.
5
Includes campanile, substation and pumping stations.
6
Includes silos, tanks, bridges, canopies, covered walkways and monuments.
Do not include concrete block buildings without concrete walls.
9. Strategy
“Walk” the City (bike ride actually)
◦ Focus in commercial districts and where larger buildings are located
Used knowledge of City
Alternate approach would be to use Google
Contact Building Official and ask for help
◦ Assessor data
◦ Zoning map
◦ Sanborn maps
Visit library
Re-walk part of the City
Review Sanborn maps again
Walk small part of the City one more time
10. Walk the City
“Walk” the City
◦ Use knowledge of the City to:
Identify the buildings already known to be concrete
Look in likely locations like commercial districts
◦ Record data on form that would provide more than information
currently required by the Coalition including photograph
◦ Troublesome areas:
No access to some military installations
Some buildings are conglomerations of building types
Modified buildings
Supplies
–
–
–
–
–
Map
Clip board
Camera
Previous lists
Panniers
11. Envisioned Survey Form
Address
Number Torsional? Frame
of
or Shear
Stories
Wall
Photo
Other
1 Main
2
Yes,
corner
building
Frame
with
masonry
infill
1, 2
Adjacent wood frame
buildings with no gap at
property lines
2 3rd St
2
No
Shear
wall
3, 4
See what appears to be
wall anchors at roof
66 Oak
1
Yes, open
front
?
5, 6
It looks like concrete,
should verify
53 Elm
3
No
Frame
7, 8
Looks like first floor is
soft story, much greater
floor height
12. Data Sheet Used
No. of Stories
1
Irregularities
Open front
Occupancy
Commercial
Adjacency
One side
Condition
No deterioration observed
Comments
Verified concrete
Brick veneer
Parapet bracing
1538 Webster/Alameda Pizza +
13. Tricks to Identify Concrete Buildings
Walk behind the building
– fewer architectural
finishes
◦ Look for form boards
Look inside
Look for elevated
floor/cripple wall –
probably wood
◦ Vents
Knock on wall
Differentiate from tiltups
Look for retrofit
17. Contact Building Official
Building officials generally have excellent information about
their jurisdictions
◦ Could ask him/her to estimate number of concrete buildings
◦ Ask which areas are post-1980 construction
◦ Where would older concrete buildings like be found?
Mr. Greg McFann was very helpful
◦ Had member of his staff access the Assessor data
Total number of buildings in Alameda 18,868
Total number of pre-1980 buildings Alameda – 12,674
◦ Provided zoning map that helped identify residential districts that
can be eliminated
◦ Provided access to Sanborn Maps
21. Sanborn Maps
• Used by the insurance industry and updated until
about mid-1980s in Alameda. SERENDIPTY!
• Able to get through the book in about 4 hours with
assistance of Marguerite Bello, S.E.
• Issues:
Some buildings uncertain, require field verification.
Some buildings may have been torn down but Building
Official said that is a rare occurrence.
Large portion of the City – Naval Air Station – not
covered by Sanborn Maps.
24. What if Sanborn Maps Had Been Older?
Need to find an approach for estimating the
number of concrete buildings not included on
Sanborn maps that were constructed prior to
1980.
◦
◦
◦
◦
Use of historic aerial photos
Building department records
Guidance from building official
Judgment/Estimates
25. Library Search
Lots of historic buildings listed in studies.
◦ Attempting to get buildings qualified for National
Historic Building Register
Lots of studies authored by Woody Minor –
Architect
Discovered lots of interesting things about
Alameda unrelated to the study.
26. Library Search
Walking Tour of Alameda’s Historic Downtown & Civic
Center District. 1977
Unreinforced Masonry Buildings Survey. 1980.
Woodruff Minor
California Department of Parks and Recreation – Historic
Resources Inventory. Webster Street Commercial Area.
Survey of Pre-1945 Commercial Buildings, City of
Alameda. Woodruff Minor.
Historic Commercial Buildings of Alameda. 1993.
Woodruff Minor.
A Guide for Historical Research in Alameda. The
Alameda Architectural/History Survey. Woodruff Minor.
1979.
Alameda: The Island City. 1941.
27. Sample Data from Library Reference
Building Name Historic
Building Name Current
Address #
Address Street
Reinf.
Conc.
Age
Stories
Structure Type
Comments
Gibson, William W., Machine Shop/Neptune
Bowl
Fred's Wrench-house
647
Buena Vista Ave
Yes
1938, 1939
1
Two rectangular shapes built separately into one
RC walls with corrugated metal roof building
Alameda Printing Company
Schroeder-Dent, Inc.
741
Buena Vista Ave
Yes
1933, 19641965
1
RC with gable roof.
Neptune Court
Neptune Court
600
Central Ave
1925-1926
4
Wood frame
Safeway Store/New Island Market
Thrifty Jr. Drug Store
704-710
Central Ave
Yes
1941, 1955
1
Marina Court
Marina Court
726-736
Central Ave
Browning, Henry, Garage
None
650
Naval Air Lockers/Courtesy Cleaners
Divers Exchange
Luben Bros. West End Livery Stable Hay Barn
Tony's Body & Fender Works
Britt's Hotel/Encinal Hotel/Pioneer
Hotel/Croll's
Croll's or Croll Building
Black, Henry and Catherine, Rental House
None
Addition in back in 1964-1965 to house
equipment
RC, probably with wood roof
1955 is CMU 2-story residential addition
1918, 1923
Wood frame
Group of 10 buildings of mixed use
Haight
1916
Wood frame
649
Pacific Ave
1941
1
651
Pacific Ave
1893
1&2
1423-A
Wood frame
1 story garage and 2 story barn
Wood frame
1879, 1907,
1908, 19781982
Webster Street/ Central
1400-1410/705 Ave
BrIck
Multiple phases.
Webster Street
1895
1
Wood frame
1878-1879,
1907-1908
Probst, Louis and Maria, Building
Santos Liquors
1425-1431
Webster Street
2
Wood frame
Stelling, Martin, Building
None
1432-1436
Webster Street
Yes
1941
1
RC and brick walls
Original plus addition
Lucky Store No. 9
Grand Auto Store
1440
Webster Street
Yes
1941, 1969
1
RC
Gutted by fire in 1967. Garage bay and
fenestration added at that time.
Alameda/Savings Bank/American Trust
Co./Wells Fargo Bank
Trans Pacific National Bank
1442
Webster Street
Yes
1917, 1946
Brick, RC
Original brick, 1-story east addition RC
Stelling, Martin, and Scales, Dixie Building
None
1443-1453A
Webster Street
Yes
1941
1
RC Piers with brick infill
Alameda Dairy Co.
Tillies
1500
Webster Street
Yes
1916, 1940
1
Wood frame and concrete
Concrete storage room added in rear
28. Building List
Developed list of buildings by combining
◦ List from initial walkthrough
◦ List from Sanborn Map
◦ Lists from library research.
Number of locations where there were
conflicts
◦ 10-15% of buildings
Did some verification with Google maps
29. Re-walk the City
Sanborn maps identified a large number of buildings I did not
observe during initial walkthrough
◦
◦
◦
◦
Some turned out to be demolished
Some were inaccurately identified by maps
Some were correctly identified – I missed them in walkthrough
Some were behind other buildings, often small garage type
structures for residences or canopies for multi-unit residences
My initial walkthrough seems to have included 85% of final
total.
◦ Probably good enough.
30. Revisit Sanborn Maps
After re-walking there were still a number of
structures where my walkthrough disagreed with
the Sanborn maps, but there was some uncertainty
due to limited access.
◦ Made one more visit to the City to look at the Sanborn
maps.
I noticed some things during the second review of
the maps that I had missed the first time.
I made one more trip to a few buildings to come to
a final conclusion.
31. Added Up My Buildings
There are a number of buildings that I did not
count because:
◦ They were unoccupied storage buildings
◦ They are wood warehouses separated into sections by
concrete firewalls
◦ They are podium structures with concrete block shear walls
Southshore Center buildings extensive remodel –
best estimate is 6 additional pre-1980 concrete
buildings.
Ended up with 24 pre-1980 buildings not sure
about.
32. Summary of Alameda Data
Number
Final Count
Total Number of Buildings
Total Number of Concrete Buildings
Pre-1980 Buildings
Pre-1980 Concrete Buildings
Tilt-up Buildings
Schools with Concrete Buildings
Chipman
Alameda High
Encinal High
…..
18,868
138 + k(24)
12,674
126 verified + k (24)
(24 uncertain)
68 (not included above)
Note: this is all we are
asking be done. Lists and
photographs are extra efforts
that are appreciated but not
necessary.
If you count schools, etc.
Identify them in your list.
33. Summary
Initial walkthrough identified about 85% of total
buildings
Relying on Sanborn Maps alone would not have
been relatively accurate.
◦ Error: inaccurate structure type assignment
Large military presence resulted in areas where
Sanborn Maps did not address.
◦ Identification of building age primarily based on judgment
Many of buildings counted are obviously not high
seismic risks.
◦ One-story, lots of shear walls.
◦ Not your job to figure out now.
34. Summary
Older buildings of mixed construction due
additions are problematic.
◦ Counted buildings with significant concrete
portions.
It is quite possible that a number of podium
type residential structures were missed
(parking under wood frame residential
structures).
Add photo
35. Summary
Southshore – main shopping, was constructed in
1950s, added onto and recently remodeled.
◦ The construction type is uncertain.
◦ Had to assume number of old concrete buildings.
◦ Theoretically if they are high risks they may have been
retrofitted.
◦ Data should be available at City Hall
36. Summary
Walking into a number of structures could decrease
the uncertainty in the number of structures.
Included count of tilt-up buildings for
completeness
◦ Problems with addresses changing in newer buildings
constructed in the 1980s.
Concrete schools and hospitals were observed and
noted but not counted.
Editor's Notes
Tilt-ups – known deficiencies, different ordinance
