principals
chris c. van vleet, p.e.
gary j. lewis, p.e.
North Clackamas School District
Seismic Study Phase One
Review and Preliminary Evaluation
of all District Sites
January 2013
consulting engineers
18660 s.w. boones ferry road
tualatin, oregon 97062
(503) 885-8605 phone
(503) 885-1206 fax
2 Contents
Foreword ........……………………………………………………………….. 4
Scope
…..………………………………………………………………… 5
Definitions …………………………………………………………………….. 6
Summary …………………………………………………………………….. 8
Typical Structural Concerns
…………………………………………….. 10
Oregon Earthquake Code History
…………………………………….. 13
Alder Creek M.S. …………………………………………………………….. 16
Aldenwald E.S.
…………………………………………………………….. 17
Bilquist E.S.
....………………………………………………………….. 18
Campbell E.S. (vacant) …………………………………………………….. 19
Clackamas E.S. (current Charter School)
…………………………….. 20
Clackamas H.S. East (former Sunrise M.S.) …………………………….. 21
Clackamas H.S. West …………………………………………………………. 22
Concord E.S.
…………………………………………………….............. 23
Happy Valley E.S. / M.S. …………………………………………………….. 24
Lewelling E.S.
…………………………………………………………….. 25
Linwood E.S. / Soujourner..………………………………………………….. 26
Milwaukie E.S.
…………………………………………………………….. 27
Milwaukie H.S.
…………………………………………………………….. 28
Mt. Scott E.S.
…………………………………………………………….. 29
New Urban H.S. Oak Grove Ctr.
…………………………………….. 30
Oak Grove E.S.
…………………………………………………………….. 31
Oregon Trail E.S. …………………………………………………………….. 32
Putnam H.S.
…………………………………………………………….. 33
Riverside E.S.
…………………………………………………………….. 34
Rock Creek M.S. …………………………………………………………….. 35
Rowe M.S.
…………………………………………………………….. 36
Sabin Schellenberg Center North
…………………………………….. 37
Sabin Schellenberg Center South
…………………………………….. 38
Scouters Mountain E.S. …………………………………………………….. 39
Spring Mountain E.S.
…………………………………………………….. 40
Sunnyside E.S.
…………………………………………………………….. 41
Verne Duncan E.S. …………………………………………………………….. 42
View Acres E.S. …………………………………………………………….. 43
Whitcomb E.S.
…………………………………………………………….. 44
Wichita Center
…………………………………………………………….. 45
3 Spreadsheet
…………………………………………………………….. 46
Aerial Photos
…………………………………………………………….. 47
Alder Creek M.S.……………………………………………………………. 48
Aldenwald E.S. …………………………………………………………….. 49
Bilquist E.S.
....………………………………………………………….. 50
Campbell E.S. (vacant)…………………………………………………….. 51
Clackamas E.S. (current Charter School) …………………………….. 52
Clackamas H.S. East (former Sunrise M.S.)…………………………… 53
Clackamas H.S. West ……………………………………………………… 54
Concord E.S. …………………………………………………….............. 55
Happy Valley E.S. / M.S.
…………………………………………….. 56
Lewelling E.S. …………………………………………………………….. 57
Linwood E.S. / Soujourner..……………………………………………… 58
Milwaukie E.S. …………………………………………………………….. 59
Milwaukie H.S. …………………………………………………………….. 60
Mt. Scott E.S. …………………………………………………………….. 61
New Urban H.S. Oak Grove Ctr. …………………………………….. 62
Oak Grove E.S. …………………………………………………………….. 63
Oregon Trail E.S.
…………………………………………………….. 64
Putnam H.S.
…………………………………………………………….. 65
Riverside E.S. …………………………………………………………….. 66
Rock Creek M.S.…………………………………………………………….. 67
Rowe M.S.
…………………………………………………………….. 68
Sabin Schellenberg Center North …………………………………….. 69
Sabin Schellenberg Center South …………………………………….. 70
Scouters Mountain E.S.…………………………………………………… 71
Spring Mountain E.S. …………………………………………………….. 72
Sunnyside E.S. …………………………………………………………….. 73
Verne Duncan E.S.
…………………………………………………….. 74
View Acres E.S.…………………………………………………………….. 75
Whitcomb E.S. …………………………………………………………….. 76
Wichita Center …………………………………………………………….. 77
4 FOREWORD
Phase one of this seismic study was prepared at the request of Garry Kryszak,
Capital Projects Manager for the North Clackamas School District (NCSD), The
overall seismic study is planned for two Phases: Phase One is a preliminary
screening & review of all district sites excepting Administration Facilities and
Facilities Operations buildings. Phase Two will involve preparation of scopes of
work and construction cost estimates for all buildings or portions of buildings that
are found in Phase one to require seismic upgrades or major repairs.
The general purpose of Phase One is to identify level of seismic performance of
District buildings and determine which are Low Risk and need no further
investigation, as well as those that ate Medium Risk or High Risk and should be
further investigated.
The general purpose of Phase Two will be to determine the level of risk in the
identified Medium Risk and High Risk buildings, prepare scopes of work for
remediation of their deficiencies, and determine approximate construction
budgets for that work. We understand that the information will be used to
prioritize projects and develop bond requests for funds to upgrade the buildings
accordingly.
5 SCOPE
Phase one of the NCSD study involved information gathering, review of available
documents, walk-throughs of some sites and buildings, and compiling that
information in this report.
No detailed seismic calculations were prepared or detailed analyses made of the
structures of the buildings for this report. Some of the buildings or portions of
buildings were previously analyzed by Lewis & Van Vleet Engineers or by other
engineering firms, and some buildings have been partially upgraded seismically,
and results of those analyses were considered.
Many school buildings of similar vintage were constructed of similar materials,
had similar designs, and will experience similar issues during a significant
seismic event (earthquake). We have observed those common traits and
weaknesses in seismic analyses and upgrade designs for schools in other
districts, and for other types of buildings that are of similar construction. The
inherent weaknesses of buildings built at different times to differing standards,
along with building components that have been known to perform poorly in
earthquakes have also been considered in the seismic evaluation of the NCSD
buildings.
We have been asked to group the NCSD buildings into three classifications: Low
Risk, Medium Risk, and High Risk. Definitions of those classifications, and
performance characteristics that would cause a building to be included in each
classification, are included in the “Definitions” section of this report.
A common life / safety issue addressed in more detailed seismic evaluations than
this Phase one report is the performance of nonstructural elements of the
building. Typical nonstructural issues include the support and bracing of
mechanical and piping components, suspended ceilings, attachments of cabinets
and bookshelves, partition bracing, and many other things. Nonstructural issues
are not addressed in Phase one of the report. Even newer structures that meet
the standards for “Low Risk” facilities can have nonstructural issues that are
potentially hazardous. However, those issues can often be addressed by
maintenance staff rather than by a general contract for construction.
6 DEFINITIONS
Seismic
Relating to earthquakes and ground motion
UBC / IBC
Uniform Building Code or International Building
Code – Past and current basis for seismic
design in Oregon.
Seismic Zone
Site coefficient in earlier codes used to
determine design seismic forces for broad
geographic areas
Acceleration Coefficient
Site coefficient in current codes used to
determine design seismic forces based on
local site characteristics
URM
Unreinforced masonry (brick, stone, terra cotta,
etc.)
Pier
An individual wall element (between openings
or between opening and end of wall)
Diaphragm
A roof, floor, or wall element with capacity to
transfer lateral forces to other elements
Lateral Bracing
Elements that resist forces from wind,
earthquakes, etc.
Base Shear
The design earthquake lateral force to be
applied to the base of a building
Capacity Demand Ratio
The ratio of the capacity of a structure to resist
earthquake forces to the Code required
capacity
Eccentricity
The difference between the location of the
center of mass of a building or building level
(and center of applied earthquake force) to the
center of the building’s resistance to lateral
movement
7 DEFINITIONS (cont.)
Low Risk
For purposes of this report, a structure or
portion of a structure that meets current
Building Codes
Medium Risk
For purposes of this report, a structure that is
predominantly safe for occupants in the event
of a major seismic event but portions of the
building need upgrades
High Risk
A structure or portion of a structure in need of
major repairs or seismic upgrades, and that
poses significant life / safety risks to occupants
8 SUMMARY
The school facilities within the North Clackamas School District range in date of
construction from 1916 to as recently as a few years ago, and they range in
construction materials from historic unreinforced brick and clay tile to modern
reinforced concrete and masonry, steel, and wood. As a result, performance
under the loads of a design or lower level earthquake will also vary significantly.
Even within some individual properties, the ages and expected seismic
performance covers a wide spectrum. For instance, Sunnyside elementary has
many phases and types of construction, with buildings from 1944 to 1999, and
expected seismic performance risk levels from low to high. Milwaukie High
School has similar differences, with construction dates from 1925 to 1999 and
risk levels from low to high.
Most of the district structures evaluated in this preliminary report (about 75%)
were found to be in the low to medium risk categories, while only 25% of the
structures are high risk or have high risk elements. Some of the district buildings
were previously high or medium seismic risk structures, but have since had full or
partial upgrades that have reduced those risk levels. The “School Evaluations”
section of this report provides short descriptions of buildings on each property
and the evaluated seismic risk level for those buildings. The spreadsheet near
the end of this report condenses that information into a chart for a quick
overview.
Following is a listing of the buildings in each risk category (Low, Low/Medium,
Medium, Medium/High, and High). Note that some sites may have buildings in
more than one category.
Low Risk
Ardenwald ES, Bilquist ES gymnasium, Campbell ES gymnasium,
Clackamas ES 2002 addition, Clackamas HS West, Happy Valley ES and MS,
Lewelling ES gymnasium, Linwood ES 2008 additions, Milwaukie HS
grandstands / 1993 construction / 1999 construction, Mt. Scott ES, Oak Grove
ES 1999 / 2010 additions, Oregon Trail ES, Rex Putnam HS auxiliary gymnasium
& auditorium, Rock Creek MS, Rowe MS 2001 addition, Sabin Occupational
Skills Center one-story wood buildings, Scouter’s Mountain ES, Spring Mountain
ES, Sunnyside ES 1999 play structure, Verne Duncan ES, View Acres ES play
structure, Whitcomb ES gymnasium, and Wichita Center play structure.
9 Low / Medium Risk
Sunnyside ES 1976-1988 additions.
Medium Risk
Aldercreek MS and grandstands, Bilquist ES, Campbell ES
classrooms /core building / play structure, Clackamas ES 1957 addition,
Clackamas HS East, Concord ES play structure, Lewelling ES, Linwood 1967 /
1988 additions, Milwaukie ES, Milwaukie HS 1971 auditorium, Oak Grove
Center, New Urban HS gymnasium, Oak Grove ES original 1963 building, Rex
Putnam HS original 1962 building / grandstands, Riverside ES / play structure,
Rowe MS 1962 and 1967 buildings, Sunnyside ES 1992 addition, and View
Acres ES.
Medium / High Risk
Sabin Occupational Skills Center (North) original
1967/1968 buildings, Sabin / Schellenberg Center South, and Wichita Center
main building.
High Risk Clackamas ES original 1938 building / 1953 addition, Concord ES
(partially upgraded), Milwaukie HS original 1925 / 1938/ 1949 / 1953 additions,
New Urban HS, Sunnyside ES original 1944 building / 1955 / 1960 / 1962 / 1967
additions, Whitcomb ES.
10 TYPICAL STRUCTURAL CONCERNS
The following comments refer to design and construction practices encountered
in our observation of the subject buildings and the construction documents for
those buildings. The comments are also based on our knowledge of common
earthquake failures and hazards.
VENEERS
Veneers are those surface attachments to a structure that are intended to
provide weather protection and improve the appearance of a structure. Brick,
stone, terra cotta, and other similar materials are supported on the building
foundation or on ledgers or floors above the base of the structure, and are laid in
mortar. Veneers are also tied or adhered to the structural walls (masonry, studs,
etc.) for the resistance of lateral loads from wind or earthquake.
Older brick veneer walls were constructed of an inner structural masonry wall
and an outer finish veneer layer. They were often (but not always)
interconnected by laying some bricks at right angles to the structural wall, and
mortaring the ends into the both the structural wall and the veneer layer,
spanning the air gap between the layers. These are called collar ties, and are
often spaced in every sixth or seventh course of brick vertically, and may be in
continuous strips in those courses.
A later development was to use light gauge (16 to 24 gauge) corrugated steel
ties to connect the veneer to a concrete or framed backing wall. Tie spacing can
vary significantly, as spacing requirements have been tightened as codes have
advanced and their performance during earthquakes has been recorded. Some
older ties are corrugated strips that are mortared into a masonry structural wall’s
bed joints, as well as the veneer mortar joints. At concrete and framed walls,
fasteners usually anchor the ties to the structure and they are mortared into the
veneer bed joints. The veneer attachment was not usually well specified on the
drawings and was often determined by the mason’s preferences.
In later years, steel relieving angles were incorporated into masonry veneer.
They are support angles roughly every story above the second floor that are
intended to relieve the overall weight of the stacked masonry on the lower
courses. The relieving angle is attached to the structural wall or floor, and
supports the weight of the brick between it and the next relieving angle above,
while the veneer ties fasten the brick to the structural wall for lateral loads.
11 Current brick ties are heavier gauge and galvanized, and are designed to anchor
to a heavy gauge wire that runs in the mortar joint . Older ties could weather and
deteriorate to the point of failure, or could slip out of the mortar joint under
seismic loading.
Requirements for anchorage of veneer are very high compared to past
requirements and methods. Load reversals and high earthquake forces have
contributed to failures of older veneer ties, with falling veneer being a significant
risk to life / safety. As a result, veneer ties are commonly upgraded (at a
minimum) around exit areas of schools. Failed veneer can block exit doors or
injure those evacuating from a building.
UNREINFORCED MASONRY (URM)
URM refers to the early type of brick masonry structural walls that were used as
recently as the early 1960’s. The term also refers to unreinforced concrete block,
clay tile, terra cotta, stone masonry, and other types of masonry construction for
walls, fireplaces, and chimneys. Chimneys are a common URM issue with older
school buildings, and those that project high above a roof can be a hazard to
some distance away from a building.
URM walls are a major safety hazard during and after a significant earthquake.
Interior URM walls and partitions are often not well attached to the structure and
can collapse to adjacent floors at great risk to building occupants. Exterior URM
walls can also collapse inward, but more often fall outward and supported floors
and roofs can collapse as a result. Failure of URM walls is a leading cause of
earthquake related fatalities, often involving persons outside of the building.
Building entries and walkways adjacent to the building are areas of greatest risk.
A URM hazard can be addressed by removing the URM walls and replacing
them with another structural system, or by externally reinforcing the URM walls
(with anchored studs or reinforced shotcrete on one side, for example).
PARAPETS
Parapets are projections of walls above the level of the roof. URM parapets are
by far the most likely type to fall back onto the roof or to fall to the ground below.
But even reinforced concrete or masonry parapets and the walls supporting them
can fail by becoming detached from the roof structure and falling away from the
building to the ground below. A common seismic reinforcement is to brace
12 parapets to the roof with steel kickers and / or to upgrade wall attachments to
floors and roofs. Based on more recent earthquake damage, Code requirements
for masonry and concrete wall attachments to bracing roofs and floors is much
higher today than even 20 years ago.
ENTRIES
Entry areas are a special concern relative to earthquakes, as they often have
unique architectural conditions for the purpose of identifying the access points
into a building. Those conditions include high gable roofs, large windows,
projections from walls, large columns, etc. Often those features are not well
attached or designed, and are likely to fail in a significant seismic event. As an
example, a gabled brick wall at a roof over the main entrance to Molalla High
School collapsed in the 1993 Scotts Mills earthquake. That collapse occurred on
a Saturday, or there likely would have been casualties with the mass of brick that
fell. Some number of years ago, our firm designed an upgrade to the entries /
exits at Concord Elementary School in the NCSD. The main entrance was very
similar to the one that collapsed in Molalla.
Entries constitute a special hazard because of the combination of special
features along with the strong tendency of students and staff to run out of a
building when shaking starts. Entries typically provide the greatest life safety
hazard during moderate earthquake. Entries have been upgraded at NCSD’s
Milwaukie Elementary through replacement of URM with reinforced masonry
walls, and at other locations through reinforcement or selective demolition.
IRREGULARITIES
Structural irregularities are discontinuities in the layout of the building in the
horizontal and vertical planes. Horizontal irregularities include tees in the plan, Lshaped buildings, notches, etc. Vertical irregularities are primarily differences in
roof elevation between attached areas of a building. Irregularities are locations
where horizontal diaphragms and vertical lines of shear resistance are not well
attached and the building can experience damaging differential movement in an
earthquake.
13 OREGON EARTHQUAKE CODE HISTORY
Following are seismic requirements from uniform Codes of various years. The
first Code was published in 1927, but we have only been able to obtain the 1937
and later Codes.
1937 Seismic requirements are voluntary. Multnomah, Washington, and
Tillamook Counties were designated as Risk Zone 1 (the lowest of the
three zones), while the rest of Western Oregon was Risk Zone 2. Seismic
coefficients for Risk Zone 1 were 2% of dead load plus half of the live load
for the whole building, 5% for bearing walls, 25% for parapets and
appendages, and 5% for towers, tanks, and chimneys. Those coefficients
were doubled for Risk Zone 2.
1943 Overturning moments are not to exceed 2/3 of resisting moments.
1949 Map change moves Multnomah, Wshington, and Tillamook counties to
Risk Zone 2, and only the dead load need be multiplied by the coefficient
(except full live load is added in warehouses). For the whole building, the
seismic coefficient varies with the number of stories above, and the other
coefficients doubled to 10%, 50%, and 10%, respectively.
1952 Building separation was established as 1” + 0.5” per ten feet of height.
1955 Seismic coefficients for warehouses were to be applied to the dead load
plus 50% of the live load.
1958 Nominal changes
1961 Earthquake regulations were moved from the Code Appendix (as being
optional) in the the body of the Code. A minimum of 200 pounds per
linear foot capacity was required for anchorage of masonry and concrete
walls to the floors and roof. Code formulas changed to be significantly
more complex, horizontal torsion was to be considered, and unreinforced
masonry shear walls were no longer allowed.
1964 Nominal changes
1967 Nominal changes
14 1970 A map change was made reducing seismic design forces for Central and
Eastern Oregon, and requirements for ductility were expanded.
1973 Effective July 1, 1974, the State of Oregon adopted a statewide building
code, based on Oregon edits to the UBC.
1976 The formula for the seismic coefficient was expanded to include five
modifiers to the seismic weight. An Importance Factor was added ,
increasing design requirements for essential facilities (fire stations,
hospitals, etc.) and for high occupancy structures (over 300 persons in
one room).
1979 Toenailing or nails in withdrawal are no longer allowed for resistance of
wall to floor or roof connections.
1982 Nominal changes.
1985 Soil coefficient determination simplified.
1988 Seismic zones were increased in portions of Oregon (2b). Horizontal and
vertical irregularities must be considered in the seismic force
determination. Torsional load requirements were increased.
1994 Western Oregon was changed to Seismic Zone 3.
1998
15 School Evaluations
Following are individual observations of the construction phases of the school
buildings. See the appendix for aerial photographs of the sites with approximate
years of building construction listed. Those years are listed in the individual
observation sections.
16 Alder Creek Middle School
Alder Creek Middle School, at 13801 SE Webster Road in Milwaukie, was
originally constructed as the original Clackamas High School facility. The original
building was constructed in 1957, with subsequent additions in 1958 and 1961.
The grandstand was originally built in 1958, with additional work in 1963.
Construction is primarily one-story wood frame for the school building (some twostory and some basement exist), and steel, concrete, and masonry for the
grandstand structure. There are both plan and vertical structural irregularities in
the building, Many of the exterior walls that should be lines of resistance are
mostly window openings, with few lateral load-resisting elements. Cross walls in
the classroom wings do not appear to have been designed for seismic
resistance, but will have some capacity. Some areas of the building have had
localized seismic improvements during subsequent remodels, but the building
remains largely as it was constructed in the 1950’s.
We classify the Alder Creek Middle School building as Medium Risk, and the
grandstand as Medium Risk as well.
17 Ardenwald Elementary School
Ardenwald Elementary School, at 8950 SE 36th Avenue in Milwaukie, was
constructed in 2008 as a replacement for a structurally deficient building. The
building was designed to standards that are consistent with current Codes.
We classify the Ardenwald Elementary School building as Low Risk.
18 Bilquist Elementary School
Bilquist Elementary School, at 15708 SE Webster Road in Milwaukie, was
originally constructed in 1960. One subsequent addition was built to the east in
1965 and another in 2008 on the east end of the earlier addition. The detached
gymnasium building was built in 2000.
Construction is primarily one-story wood frame for the school building (a small
two-story area also exists). Some bearing walls are under-reinforced masonry,
and connections of those walls to the structure for out-of-plane loads do not meet
current Code. The north and south exterior walls have minimal shear wall, and
are mostly windows. The east wall of the easternmost addition has no shear
elements. There are both plan and vertical structural irregularities in the building,
Cross walls in the classroom wings do not appear to have been designed for
seismic resistance, but will have some capacity. Brick veneer on many of the
exterior walls is unlikely to have adequate anchorage for current codes, but walls
are generally short so the risk is minimized.
We classify the Bilquist Elementary School building as Medium Risk, and the
gymnasium as Low Risk.
19 Campbell Elementary School
Campbell Elementary School, at 11326 SE 47th Avenue in Milwaukie, was
originally constructed in 1956 as a group of small pod buildings and a central
administration and core building. Another identical pod was added in 1958, a
small addition to the core building was added in 1979, a covered play structure
was built in 1992, and a detached gymnasium was built in 2000.
Construction is one-story wood frame for the pods, and a combination of wood,
steel, concrete, and masonry for the core building. The play structure is a wood
framed roof with steel columns and wood knee braces. The gymnasium is tilt-up
concrete walls with a steel framed roof. The pod buildings do not have adequate
shear walls or holdowns, and some were at one time analyzed by this firm and
had seismic upgrades designed that were not later constructed. The core
building also has lateral elements that should be upgraded. There are plan
structural irregularities in the pod building, and both plan and vertical irregularities
in the core building. Brick veneer on many of the exterior walls is unlikely to have
adequate anchorage for current codes, but walls are generally short so the risk is
minimized. The play structure is well-designed, but seismic design loads are
significantly lower than current Code standards.
We classify the 1950’s Campbell Elementary School pod and core buildings as
Medium Risk, the play structure as Medium Risk, and the gymnasium as Low
Risk.
20 Clackamas Elementary School
The former Clackamas Elementary School, at 15301 SE 92nd Avenue in
Clackamas, was originally constructed in 1938. Subsequent additions were built
in 1953, 1957, and 2002. The building is currently used as a charter school.
The 1938 building had bearing walls of unreinforced or lightly reinforced
concrete, with a wood framed roof. The 1953 addition also had concrete walls
and wood roof framing, and there was some reinforcement added to the walls in
that design (not enough for current Code). Both the original building and addition
have wall to roof connections that do not meet current Code capacity
requirements, and appear to have insufficient shear walls.
The 1957 addition was a detached building to the west of the prior construction.
It is primarily wood framed, without adequate shear walls for current Code. The
south wall of the multi-purpose room has concrete piers supporting roof beams,
and the pier reinforcement is minimal, with tie spacing too high for seismic forces.
The 2002 addition infilled a notch in the building’s south wall, and added shear
walls in that area only. Wind originally controlled over seismic for the design of
the play structure in 1977. Although seismic design loads are now significantly
higher than in 1977, the original wind design loads may be adequate for current
seismic levels.
We classify the Clackamas Elementary School buildings as High Risk for the
original building and its addition, Medium Risk for the detached 1957 addition,
and Low Risk for the 2002 addition.
21 Clackamas High School East
Clackamas High School East, at 14331 SE 132nd Avenue in Clackamas, was
originally constructed as Sunrise Middle School in 1990. One subsequent
addition was built in 1992. The 1990 building was designed for Seismic Zone 2,
and the 1992 addition for Seismic Zone 2B. Both design standards are
significantly lower than current Code requirements, and some detailing
requirements are less than current Code as well.
We classify the Clackamas High School East building as Medium Risk since it
should be looked at in more detail as to its design capacity, but any upgrade
work there may not be significant.
22 Clackamas High School West
Clackamas High School West, at 14486 SE 122nd Avenue in Clackamas, was
constructed in 1999 as a replacement high school for the current Alder Creek
Middle School. It was designed for Seismic Zone 3, which is equivalent to
current Code design. Some detailing requirements of the current Code may not
be included in the design, but it essentially meets current Code.
We classify the Clackamas High School East building as Low Risk.
23 Concord Elementary School
Concord Elementary School, at 3811 SE Concord Road in Milwaukie, was
originally constructed in 1935 as an unreinforced masonry building. A
subsequent addition was built to the east in 1947. The detached play structure
was built in 1977. A partial seismic upgrade was made to the school in 2001.
Construction of the original building was lightly reinforced concrete basement
walls and unreinforced multi-wythe brick walls above, with a wood framed floor
and roof structure. The hazard was mitigated in 2001 with seismic upgrading of
the entry / exit areas and of the high gymnasium exterior wall and stage area.
The class room URM walls were not upgraded at that time due to budget
constraints, and still constitute a significant hazard. The play structure was
originally designed in 1977, when Code seismic design loads were substantially
lower than they are today. However, Code wind design loads have changed little
since that time.
The seismic load is minimized by the low mass of the play structure roof, so wind
loads would have originally controlled the design over seismic. Although seismic
design loads would now be significantly higher than in 1977, the original wind
design loads may still be adequate to control over current seismic loads. Seismic
connection requirements have changed since the original construction, though,
and should be improved.
We classify areas of the Concord Elementary School building as High Risk, and
the play structure as Medium Risk.
24 Happy Valley Elementary and Middle School
Happy Valley Elementary and Middle Schools, at 13865 SE King Road in Happy
Valley, was constructed in 2008 / 2009 as a replacement for the original school
building which stood on the site. It was designed for current Code
We classify the Happy Valley Elementary and Middle School building as Low
Risk.
25 Lewelling Elementary School
Lewelling Elementary School, at 5325 SE Logus Road in Milwaukie, was
originally constructed in 1962 as three separate buildings. Two are mirror
images of each other, including covered play area roofs connecting classroom
pods. A detached gymnasium was built in 2000.
The building is primarily one-story wood frame walls with wood roofs, and brick
veneer on the exterior walls. The seismic design load was significantly lower
than current Code, and some exterior walls are primarily windows with minimal
shear walls. Cross walls were also constructed as partitions rather than shear
walls, although they have some level of shear resistance. The gymnasium is tiltup concrete walls with a steel roof.
We classify the Lewelling Elementary School classroom and commons buildings
as Medium Risk, and the gymnasium as Low Risk.
26 Linwood Elementary School
Linwood Elementary School, at 11909 SE Linwood Avenue in Milwaukie, was
originally two separate buildings constructed in 1967. Subsequent additions
were built in 1988 and 2008.`
Construction of the original building was reinforced structural brick masonry, with
current Code-compliant vertical reinforcement and K-web horizontal
reinforcement which does not meet current Code. The masonry walls were
topped with boxed wood sections that supported the wood roof framing and
created a weak hinged connection for seismic bracing out-of-plane at the tops of
the walls. Code design loads for the 1967 and 1988 buildings were significantly
lower than current Code as well.
We classify the 1967 and 1988 Linwood Elementary School buildings as Medium
Risk, and the 2008 additions as Low Risk.
27 Milwaukie Elementary School
Milwaukie Elementary School, at 11250 SE 27th Avenue in Milwaukie, was
originally constructed in 1916 as an unreinforced masonry and concrete building.
A subsequent addition was built to the east in 1948. A major seismic upgrade
was made to the school in 2011.
Construction of the original building and addition was lightly reinforced concrete
basement walls and unreinforced masonry walls above, with a wood framed floor
and roof structure. The hazard was mitigated in 2011 with seismic upgrading of
the north and south entry / exit areas, interior cross walls and corridor walls, and
of the gymnasium entry walls. Some elements of the building still constitute a
seismic risk, but the safety of the building is much improved.
We classify the Milwaukie Elementary School building as Medium Risk
subsequent to the upgrade work.
28 Milwaukie High School
Milwaukie High School, at 11300 SE 23rd Avenue in Milwaukie, was originally
constructed in 1925 as Union High School, an unreinforced concrete and clay tile
building with a detached boiler room Subsequent additions were built in 1938,
1949, 1953, 1964, 1971, 1993, and 1999. The grandstand was built in 1964 and
seismically upgraded in 1999. A partial seismic upgrade was made to the 1938
gymnasium building in 1964.
Construction of the original building was lightly reinforced or unreinforced
concrete basement walls and unreinforced concrete and clay tile walls above,
with a wood framed floor and roof structure and some steel long-span trusses. In
1938 a detached gymnasium was built of lightly reinforced concrete walls with
steel trusses and a wood roof structure. Also in 1938 an addition was made to
the original school building, of similar construction to the original. In 1949,
another (3-story) addition was made to the original building. Once again, it used
lightly reinforced concrete walls and wood floor and roof structure. A 1953
addition to the gymnasium was also constructed similarly to the original gym, and
in 1964, steel strapping was added to the gym roof as part of a remodeling
project. The grandstands were added in 1963, and in 1993 were remodeled and
upgraded to Seismic Zone 3. The separate auditorium building was constructed
in 1971, and another reinforced concrete building was built in 1993 and
expanded in 1999.
The older buildings have a number of seismic hazards, and we classify them as
High Risk due to unreinforced high chimneys, unreinforced parapets, underreinforced walls, deficient connections between elements, and overloaded
diaphragms.
We classify the grandstands as Low Risk due to the upgrade, the 1971 building
as Medium Risk due to design load capacity, and the 1993 and 1999 buildings as
Low Risk.
29 Mt. Scott Elementary School
Mt. Scott Elementary School, at 11201 SE Stevens Road in Happy Valley, was
constructed in 1988.
Construction of the original building was reinforced concrete and wood framed
walls with a wood framed floor and roof structure. Openings in the exterior walls
are relatively small and although the building was designed to Seismic Zone 2
forces which are significantly lower than current Codes, it should perform well in
an earthquake.
We classify the Mt. Scott Elementary School building as Low Risk.
30 New Urban High School / Oak Grove Center
New Urban High School and Oak Grove Center, at 1901 SE Oak Grove Blvd. in
Milwaukie, are two separate adjacent buildings with an adjacent detached
gymnasium. The east building was the original structure, and little information on
its age or construction is available. The west building (Oak Grove Center) was
built in 1955 as Oak Grove Grade School, and expanded to the north in 1959.
The detached gymnasium was built in 1957.
Construction of the original building appears to be vintage 1930’s or 1940’s, and
it had an addition built to the south at a later date. Exposed framing connections
we observed have little or no fasteners, and it is likely that the building is a
significant seismic risk in other ways as well. The 1955 Oak Grove Center
building has a gymnasium with well-reinforced concrete walls, and good
connections between the gym roof beams and the concrete walls. The building is
one-story wood frame with some partial height and full height concrete walls, but
bands of windows are common on the east and west instead of shear walls.
Cross walls also should be upgraded to resist seismic forces. The gymnasium is
wood framed, and some steel columns and strongbacks were added as part of a
later strengthening.
We classify the New Urban High School building as High Risk, the 1955 Oak
Grove Center building as Medium Risk, and the gymnasium as Medium Risk.
31 Oak Grove Elementary School
Oak Grove Elementary School, at 2150 SE Torbank Avenue in Milwaukie, was
originally constructed in 1963. One subsequent addition was built in 1999 and
the addition to the 1999 play structure was built in 2010.
Construction is primarily one-story wood frame at the low roof areas and
reinforced concrete walls at the high-roofed multi-purpose room. Design loads
were much lower than current Codes due to the year of design, and connections
between concrete walls and the roof are also significantly weaker than current
Code requires. The 1999 addition was designed for Seismic Zone 3, similar to
current Code, and the 2010 play structure addition was built to current Code
We classify the Oak Grove Elementary School original building as Medium Risk,
and the additions as Low Risk.
32 Oregon Trail Elementary School
Oregon Trail Elementary School, at 13895 SE 152nd Avenue in Clackamas, was
originally constructed in 1992 with subsequent additions in 1993, 1997, and
2009. The 1992, 1993, and 1997 designs were to Seismic Zone 3, and the 2009
addition was to current Code. There are significant horizontal and vertical
irregularities.
We classify the Oregon Trail Elementary School building as Low Risk.
33 Rex Putnam High School
Rex Putnam High School, at 4950 SE Roethe Road in Milwaukie, was originally
constructed in 1962. A grandstand facility was constructed in 1965, an auxiliary
gymnasium to the northeast of the school building in 2000, and an auditorium
building west of the gymnasium in 2001.
Construction is primarily one-story concrete tilt-up and cast-in-place walls, with a
wood roof structure. The wall reinforcement conforms to current Code
minimums, but may not be adequate for out-of-plane bending forces. We
understand that the exposed aggregate wall facing materials on part of the north
wall of the original school building have delaminated from the concrete walls due
to water intrusion, and have been repaired. It is likely that further delamination
will or may have already occurred, and those materials could be a falling hazard
in a seismic event. Connections between the walls and roof have lower capacity
than required by current Code. The grandstand structure was built to low seismic
design criteria, and should be upgraded similarly to the related Milwaukie High
School grandstand.
We classify the Rex Putnam High School building as Medium Risk, the
grandstands as Medium Risk, and the auxiliary gymnasium and auditorium as
Medium Risk.
34 Riverside Elementary School
Riverside Elementary School, at 16303 SE River Road in Milwaukie, was
originally constructed in 1955, with subsequent additions in 1958, 1969, and
1992. A detached covered play structure was built in 1976.
Construction of the original building is concrete foundation and retaining walls for
the lower level, with wood bearing walls on the daylight basement side. The
upper floor has wood bearing walls, along with wood floor and roof framing. The
building has significant brick veneer. The 1958 and 1969 additions were similar
construction, except that the gymnasium in the 1958 addition had concrete tilt-up
walls at two sides. All three phases of construction had large banks of windows
in the wood framed walls, with few shear walls or structural cross walls. The
gymnasium tilt wall connections are also lighter than current Code requires. The
1999 library addition was designed for Seismic Zone 2B, and thus to a much
lower design standard than current code. Wind originally controlled over seismic
for the design of the play structure in 1977. Although seismic design loads are
now significantly higher than in 1977, the original wind design loads may be
adequate for current seismic levels.
There was a partial seismic upgrade to the main entry area in the recent past, but
most of the building was not improved.
We classify the Riverside Elementary School building as Medium Risk, and the
detached play structure as Medium Risk.
35 Rock Creek Middle School
Rock Creek Middle School, at 14797 SE Parklane Drive in Happy Valley, was
constructed in 2010 to current Code requirements. There are significant
horizontal and vertical structural irregularities.
We classify the Rock Creek Middle School building as Low Risk.
36 Rowe Middle School
Rowe Middle School, at 3606 SE Lake Road in Milwaukie, was originally
constructed in 1962, with subsequent additions in 1967 and 2001.
Construction of the original building is reinforced precast and cast-in-place
concrete walls with a wood roof and a steel-framed balcony. The 1967 addition
is of similar construction. The 2001 wing addition was designed for Seismic
Zone 3, and substantially meets current Code.
The 1962 and 1967 buildings appear to lack adequate structural cross walls, and
adequate connections between the concrete walls and roof. There are some
horizontal irregularities in the structure.
We classify the 1962 and 1967 Rowe Middle School buildings as Medium Risk,
and the 2001 addition as Low Risk.
37 Sabin-Schellenberg Center North
The original Sabin Occupational Skills Center, at 14211 SE Johnson Road in
Milwaukie, was originally constructed in 1967 as three attached square modules,
with a separate detached module constructed in 1968. Two small one-story
wood framed residential-style buildings also sit on the site.
Construction of the modules is reinforced concrete perimeter piers supporting a
wood roof, and wood framed support walls and beams at the interior. The
concrete in the piers is minimally constrained by steel ties, indicating a risk of pier
failure in a seismic event. In addition, the module buildings were designed for
Seismic Zone 2B forces, substantially lower than current Code.
We classify the original Sabin Occupational Skills Center buildings as Medium to
High Risk, and the detached wood structures as Low Risk.
38 Sabin Schellenberg Center South
Sabin Schellenberg Center South, originally Clackams Middle School, at 14450
SE Johnson Road in Milwaukie, was originally constructed in 1967. One
subsequent addition was built to the North in 1976.
Construction is tilt-up concrete for the high gymnasium and commons walls, with
a wood framed roof, and steel /concrete upper floors. Other areas are built with
wood bearing walls and wood roof framing. The buildings were designed for
Seismic Zone 2, and detailing of connections is deficient compared to current
Code. Concrete wall to roof connections could fail through cross-grain bending
of wood ledgers, instigating significant collapse. Some areas of the low roofed
building has inadequate shear walls and are mostly windows.
We classify the Sabin Schellenberg Center South building as Medium to High
Risk.
39 Scouters Mountain Elementary School
Scouters Mountain Elementary School, at 10811 SE 172nd Avenue in Happy
Valley, was constructed in 2009 to current Code requirements. There are
significant horizontal and vertical structural irregularities.
We classify the Scouters Mountain Elementaray School building as Low Risk.
40 Spring Mountain Elementary School
Spring Mountain Elementary School, at 11645 SE Masa Lane in Happy Valley,
was constructed in 1999 for Seismic Zone 3 forces. The design forces are
substantially equal to current Code requirements. There are significant
horizontal and vertical structural irregularities.
We classify the Spring Mountain Elementary School building as Low Risk.
41 Sunnyside Elementary School
Sunnyside Elementary School, at 13402 Se 132nd Avenue in Clackamas, had its
first segment constructed in 1944 at the northeast corner of the site. In 1955, a
cafeteria building was attached to the south side of the original building. An
adjacent wing to the west was constructed in three phases in 1960, 1962, and
1967, while a play structure addition was also attached to the west side of the
original building in 1967. A structure to the south of the west wing was added in
1976, 1978, 1987, and 1988, with another structure west of that in 1992. Finally,
a play structure was attached to the 1992 building in 1999.
Construction varies throughout the complex. We will list our rating of each
segment with its description.
The original building was wood framed walls and roof, with mostly glass on the
north and east sides. Structural cross walls are also deficient. We rate this
building High Risk.
The 1955 addition was unreinforced concrete masonry (CMU) walls with wood
arches and roof framing. The CMU walls do not extend to the roof, or are very
high, and only some have been braced since the original construction. We rate
this building High Risk.
The 1960, 1962, and 1967 west wing is wood framed walls and roof, and is
deficient in shear walls on the east and west sides. Structural cross walls are
also needed. These were designed for Seismic Zone 2 forces only. We rate this
building High Risk.
The 1976-1988 buildings are wood frame with small window openings. Although
only designed for Seismic Zone 2, we believe these buildings will perform well
and rate them Low to Medium Risk.
The 1992 addition is wood framed as well, and is designed to Seismic Zone 2B.
We rate it Medium Risk.
Last, the 1999 Playshed was designed for Seismic Zone 3 forces and we rate it
Low Risk.
42 Verne Duncan Elementary School
Verne Duncan Elementary School, at 14898 SE Parklane Drive in Happy Valley,
was constructed in 2009 to current Code requirements. There are significant
horizontal and vertical structural irregularities.
We classify the Verne Duncan Elementary School building as Low Risk.
43 View Acres Elementary School
View Acres Elementary School, at 4828 SE View Acres Road in Milwaukie, was
originally constructed in 1965, with a subsequent addition in 1968. It was
remodeled in 2001, but without seismic upgrades in the budget. A detached
covered play structure was built in 1976.
The original building is mostly one-story wood framed, but with some two-story
and three-story (attic) areas. There are some lightly reinforced concrete and
masonry bearing walls, and significant areas of brick veneer. The floor over the
basement areas is reinforced concrete. The 1968 addition is lightly reinforced
block walls and wood roof framing. Both the original building and addition were
designed to Seismic Zone 2, as was the play structure. Wind originally controlled
over seismic for the design of the play structure in 1977. Although seismic
design loads are now significantly higher than in 1977, the original wind design
loads may be adequate for current seismic levels.
We classify the View Acres Elementary School building as Medium Risk, and the
detached play structure as Medium Risk.
44 Whitcomb Elementary School
Whitcomb Elementary School (formerly Milwaukie Grade School), at 7400 SE
Thompson Road in Milwaukie, was originally constructed in 1958, with a
subsequent addition to the building in 1959 and a detached gymnasium addition
in 2000.
Construction of the original building is wood framed walls with brick veneer and
significant windows, and some unreinforced brick cavity walls. The roof is wood
framed. The 1959 addition also includes unreinforced masonry and brick veneer,
and a covered play area roof at the south end between classroom clusters. The
play area roof does not appear to have a complete lateral load-resisting system,
and has hinges in the system that is present. Several exterior walls of the school
building are mostly glass, with inadequate shear walls. Cross walls in the
classroom areas are also non-shear and should be strengthened.
The 2000 gymnasium was constructed with concrete tilt-up walls and a steel
framed roof, to Seismic Zone 3 forces. Detailing of connections is good.
There was a significant remodel of the building in 2001, but no seismic upgrades
were included.
We classify the Whitcomb Elementary School building as High Risk, and the
detached gymnasium structure as Low Risk.
45 Wichita Center
Wichita Center (formerly Wichita Grade School), at 6031 SE King Road in
Milwaukie, was originally constructed prior to 1940. The building currently
houses Head Start programs and other functions. An addition to the original
building was constructed in 1940 and another in 1946. In 1978 a covered play
structure was added north of the 1940 building.
Construction of the original building and the 1940’s additions is wood bearing
walls with brick veneer, unreinforced or lightly reinforced concrete walls, and
wood roof structure. The attached play structure is wood framing with steel
posts. A partial seismic upgrade was done in 2011 to the south wall only, but a
2001 remodel did not include seismic upgrades.
We classify the Wichita Center building as Medium and High Risk, and the
attached play structure as Low Risk.
46
NORTH CLACKAMAS SCHOOL DISTRICT PROPERTIES SEISMIC ASSESSMENT 2012
SCHOOL
BUILDINGS
ADDRESS
CONSTR. DATE.
STUDY RISK LEVEL
ALDER CREEK M.S.
1 + GRANDSTAND
13801 SE Webster Rd., Milwaukie, OR 97267
1957/1958/1961 - Grandstand 1958
Building Medium / Grandstand Medium
ARDENWALD ELEM.
1
8950 SE 36th Ave., Milwaukie, OR 97222
2008
Low
BILQUIST ELEM.
1 + GYM/PLAY SHED
15708 SE Webster Rd., Milwaukie, OR 97267
1960/1965/2008 - Gym 2000
Building Medium / Gymnasium Low
CAMPBELL ELEM. (VACANT)
7 + PLAY SHED
11326 SE 47th Ave., Milwaukie, OR 97222
1956/1958/1979 - Gym 2000
Building.Medium / Play Shed Medium / Gym Low
CLACKAMAS ELEM. (LEASED)
2 + PLAY SHED
15301 SE 92nd Ave., Clackamas, OR 97015
1938/1939/1953/1957/2002 Play Shed 1977
1938-1939 High / 1953-1957 Medium /
2002 Low / Play Shed Medium
CLACKAMAS H.S. EAST
1
14331 SE 132nd Ave., Clackamas, OR 97015
1990/1992
Medium / Low
CLACKAMAS H.S. WEST
1 + GRANDSTAND
14486 SE 122nd Ave., Clackamas, OR 97015
1999
Low
CONCORD ELEM.
1 + PLAY SHED
3811 SE Concord Rd., Milwaukie, OR 97267
1935/1948 - Play Shed 1977
Building High / Play Shed Medium
HAPPY VALLEY ELEM & M.S
1
13865 SE King Rd., #B, Happy Valley, OR 97086
2008/2009
Low
LEWELLING ELEM.
4 + MODULAR
5325 SE Logus Rd., Milwaukie, OR 97222
1962 - Gym 2000
Building Medium / Gymnasium Low
LINWOOD ELEM.
2
11909 SE Linwood Ave., Milwaukie, OR 97222
1967/1988/2008
1967 - 1988 Medium / 2008 Low
MILWAUKIE ELEM.
1
11250 SE 27th Ave., Milwaukie, OR 97222
1916/1948/Upgrade 2011
Medium
MILWAUKIE H.S.
6 + GRANDSTAND
11300 SE 23rd Ave., Milwaukie, OR 97222
1925/1938/1949/1953/1971/1999
Grandstand 1963, Upgrade 1993
1925-1953 High / 1971 Medium /
1993-1999 Low / Grandstands Low
MT. SCOTT ELEM.
1
11201 SE Stevens Rd., Happy Valley, OR 97086
1988
Low
NEW URBAN H.S./ OAK GROVE CENTER
3
1901 SE Oak Grove Blvd., Milwaukie, OR 97267
New Urban1930 to 1950
Oak Grove Ctr. 1955/1959 - Gym 1957
New Urban HS High / Oak Grove Ctr. Medium /
Gymnasium Medium
OAK GROVE ELEM.
1 + GYM/PLAY SHED
2150 SE Torbank Ave., Milwaukie, OR 97222
19631999/2010
1963 Medium / 1999-2010 Low
OREGON TRAIL ELEM.
1
13895 SE 152nd Dr., Clackamas, OR 97015
1992/1997/2009
Low
PUTNAM H.S.
2 + GRANDSTAND
4950 SE Roethe Rd., Milwaukie, OR 97267
1962/2000/2001 - Grandstand1965
Buildings Medium / Grandstand Medium
RIVERSIDE ELEM.
2 + PLAY SHED
16303 SE River Rd., Milwaukie, OR 97267
1955/1958/1969/1992 - Play Shed 1976
Building Medium / Play Shed Medium
ROCK CREEK M.S.
1
14897 SE Parklane Dr., Happy Valley, OR 97015
2010
Low
ROWE M.S.
2
3606 SE Lake Rd., Milwaukie, OR 97222
1962/1967/1999/2001
1962-1967 Medium / 1999-2001 Gym Low
SABIN-SCHELLENBERG CENTER NORTH
2 + 2 WOOD FRAME
14211 SE Johnson Rd., Milwaukie, OR 97267
1967/1968 - Wood frame unknown
Medium / Wood Frame Low
SABIN-SCHELLENBERG CENTER SOUTH
3
14450 SE Johnson Rd., Milwaukie, OR 97267
1967/1976
Building Medium / Gymnasiums High
SCOUTERS MTN. ELEM.
1
10811 SE 172nd Ave., Happy Valley, OR 97086
2009
Low
SPRING MTN. ELEM.
1
11645 SE Masa Lane, Happy Valley, OR 97236
1999
Low
SUNNYSIDE ELEM.
4 + 2 MODULAR
13402 SE 132nd Ave., Clackamas, OR 97015
1944/1955/1960/1962/1967/1975/
1978/1987/1988/1992/1999 Play
1944-1955-1960-1962-1967 High / 1976-1978-1987-1988
Low to Medium / 1992 Medium / 1999 Low
VERNE DUNCAN ELEM.
1
14898 SE Parklane Dr., Happy Valley, OR 97015
2009
Low
VIEW ACRES ELEM.
1 + PLAY SHED
4828 SE View Acres Rd., Milwaukie, OR 97267
1965/1968 - Play Shed 1976
Building Medium / Play Shed Medium
WHITCOMB ELEM.
2 + 3 MODULAR
7400 SE Thompson Rd., Milwaukie, OR 97222
1958/1959 - Gym 2001
Building High / Gym Low
WICHITA CENTER (ADMIN / HEAD START)
1
6031 SE King Road, Milwaukie, OR 97222
Pre-1940/1940/1946/ - Play Shed 1978
Building High-Medium / Play Shed Low
47 Aerial Photographs
Following are aerial photographs of each site downloaded from Google Earth
with approximate year of construction for each building. These serve as site
plans to help identify structures when referencing the individual school
evaluations and the spreadsheet.
feet
meters
1958 / 1963
1952
ORIGINAL
UNKNOWN
1957
1952
1000
300
ALDER
CREEK
MIDDLE
SCHOOL
48
feet
meters
ALL
2008
100
ARDENWALD
ELEMENTARY
SCHOOL
400
49
feet
meters
1960
1960
100
400
2008
2000 GYM
1965
BILQUIST
ELEMENTARY
SCHOOL
50
1956
1956
feet
meters
1956
1979
1956
1992
PLAY
1956
1956
100
400
1958
CAMPBELL
ELEMENTARY
SCHOOL
2000
GYM
51
1957
feet
meters
2002
1953
1977
PLAY
1953
1939?
1938
1938
1938
1939?
100
CLACKAMAS
ELEMENTARY
SCHOOL
300
52
feet
meters
1992
1990
1992
1990
1990
1992
1990
1992
1992
1990
1990
1990
700
CLACKAMAS HIGH
SCHOOL EAST
200
53
feet
meters
ALL
1999
1000
CLACKAMAS HIGH
SCHOOL WEST
400
54
feet
meters
1977
PLAY
1935
1948
1935
1935
100
400
CONCORD
ELEMENTARY
SCHOOL
55
feet
meters
ALL 2008 / 2009
200
HAPPY
VALLEY
ELEMENTARY
& MIDDLE
SCHOOLS
700
56
feet
meters
1962
1962
1962
100
2000
400
LEWELLING
ELEMENTARY
SCHOOL
57
feet
meters
2008
2008
1967
200
800
LINWOOD
ELEMENTARY
SCHOOL
1967 2008
1967
1967
2008
1967
1988
2008
58
feet
meters
1916
1916
1916
1916
1948
1948
1948
300
100
MILWAUKIE
ELEMENTARY
SCHOOL
59
1971
feet
meters
1971
1971
1999
1925
1949
1963
1949
1925
1938
1925
1938
GYM
1925
1993
1953
200
MILWAUKIE
HIGH
SCHOOL
700
60
feet
meters
ALL
1988
200
MT. SCOTT
ELEMENTARY SCHOOL
600
61
feet
meters
1957
1959
1940'S?
1955
1950'S?
300
100
NEW URBAN
HIGH SCHOOL &
OAK GROVE
CENTER
62
feet
meters
1999
1999
1999
1963
2010
1963
1963
1999
300
100
OAK GROVE
ELEMENTARY
SCHOOL
63
feet
meters
2009
1997
1992
1992
2009
1992
1997
1992
1992
1992
1992
1992
100
OREGON
TRAIL
ELEMENTARY
SCHOOL
400
64
feet
meters
1962
UNKNOWN
1962
1962
1962
1962
1965
1000
REX PUTNAM
HIGH SCHOOL
400
65
feet
meters
1976
PLAY
1992
1958
1958
1958
1955
1969
100
RIVERSIDE
ELEMENTARY
SCHOOL
400
66
feet
meters
ALL
2010
600
200
ROCK
CREEK
MIDDLE
SCHOOL
67
feet
meters
1967
1999
2001
1962
1962
1962
1962
1967
1962
100
ROWE
MIDDLE
SCHOOL
600
68
feet
meters
1967
1967
1967
100
1968
600
SABIN
SCHELLENBERG
CENTER
NORTH
69
feet
meters
1976
1967
1967
1967
100
500
SABINSCHELLENBERG
CENTER
SOUTH
70
feet
meters
ALL
2009
100
500
SCOUTERS MTN.
ELEMENTARY
SCHOOL
71
feet
meters
ALL
1999
100
400
SPRING
MOUNTAIN
ELEMENTARY
SCHOOL
72
feet
meters
1978
1987
1988
1992
1999
PLAY
1967
1962
1960
100
1975
1944
1955
1967
1944
500
SUNNYSIDE
ELEMENTARY
SCHOOL
73
feet
meters
ALL
2009
100
400
VERNE
DUNCAN
ELEMENTARY
SCHOOL
74
feet
meters
1965
1968
1965
1965
1968
100
1976
PLAY
ACRES
ELEMENTARY
SCHOOL
400 VIEW
75
feet
meters
1958
1958
2001
1958
1958
1959
1959
1959
1959
100
1959
1959
WHITCOMB
ELEMENTARY
SCHOOL
400
76
feet
meters
1940
1946
1940
1940
1940
1978
ORIG
. ?
1946
300
100
WICHITA
CENTER
77
principals
chris c. van vleet, p.e.
gary j. lewis, p.e.
NCSD SEISMIC PHASE 2 ESTIMATE METHODOLOGY
Nine North Clackamas School District sites have been selected to have preliminary cost estimates made of
seismic upgrades in Phase 2, because they fell into the “Medium-High” or “High” risk categories in Phase 1.
Those sites are Clackamas Elementary School, Concord Elementary School, Milwaukie High School, New
Urban High School, Sabin-Schellenberg Center North, Sabin-Schellenberg Center South, Sunnyside Elementary
School, Whitcomb Elementary School, and Wichita Center.
The attached spreadsheet contains square foot seismic upgrade cost factors and square footages for those
schools and projects total seismic upgrade design and construction costs for each site. The square foot costs
selected were averages of costs obtained from several sources, primarily a recent (2009) report and construction
cost estimate for twelve schools in the Portland Public School District. We have modified some of those
numbers for conditions in the NCSD schools. Note that these are rough estimates only, and are not based on
actual design of upgrades for any of the schools or from actual detailed cost estimating. Actual construction
costs can vary greatly depending on access at a site, extent of seismic deficiencies, desired performance level
after the upgrade, and other factors. These estimates are based on construction type, and on our limited
knowledge of existing conditions at the sites. Also note that these estimates assume that the seismic upgrades
will be standalone projects, so that repair of finishes is included in the cost estimate. If seismic upgrade work is
coupled with school renovations, the actual costs of the seismic portions of the projects could be approximately
half of the estimates listed since the finish repairs could be included in the renovation budgets.
The estimates assume the following:
•
•
•
•
•
Ceiling systems are not adequately braced, and will need to be removed and replaced or have bracing
installed if not required to be removed for access in the upgrade project.
Some whole rooms may need finishes replaced due to inability to match finishes removed in the upgrae
project.
Slabs and structural floors may have to be partially removed and replaced to construct new foundations
or access areas for upgrade work.
Upgrade work may require some window infill in areas with insufficient shear walls.
Plywood shear walls, steel moment or braced frames, or reinforced masonry / concrete shear walls may
be required to provide adequate seismic strength, depending on the existing construction and mass of the
structure.
consulting engineers
18660 s.w. boones ferry road
tualatin, oregon 97062
(503) 885-8605 phone
(503) 885-1206 fax
•
•
•
•
•
Floor and roof diaphragms may also need to be upgraded or added in most projects.
Unreinforced or lightly reinforced concrete and \ or masonry walls may require installation of a grid of
adhered dowels for connection to new adjacent reinforced masonry or concrete walls.
Connections are commonly required for concrete or masonry walls (either currently reinforced or
unreinforced) to prevent out-of-plane failures. Connections are also commonly required to be improved
for in-plane connections to have capacity to transfer lateral loads from floors and roofs to those walls.
Chord members and collectors (drag struts) will commonly be required to provide continuity throughout
the building to prevent seismic separations at walls and in the floors and roofs.
Brick veneer that is not adequately attached to backing material, or has inadequate backing material, will
require new ties to be installed to existing or new backing.
We understand that these estimates are intended for District planning and budgeting, and we encourage you to
contact us if you need further clarification or more information.
Gary J. Lewis, S.E.
consulting engineers
PAGE 1
18660 s.w. boones ferry road
tualatin, oregon 97062
(503) 885-8605 phone
NORTH CLACKAMAS SCHOOL DISTRICT MEDIUM / HIGH SEISMIC RISK PROPERTIES UPGRADE ESTIMATE 2013
SCHOOL
TYPE OF USE
FLOORS
CLACKAMAS E.S. (LEASED)
Charter Elementary School
2
CONCORD E.S. ((Partiallyy Upgraded)
pg
)
MILWAUKIE H.S.
(Gymnasium Partially upgraded)
NEW URBAN H.S.
Elementaryy School
PH. 1 RATING
CONSTR. TYPE
SQUARE FT. EST. $ / SQ. FT. EST. TOTAL COST
1938 Building
High
Lightly Reinf. Conc. Walls (LRCW)
16,250
$70
$1,137,500
1939 Building Addition
High
LRCW
5400
$70
$378,000
2
1935/1948 Building
g
High
g
Unreinforced Masonryy (URM)
(
)
46,800
,
$35
$
$1,638,000
$ ,
,
3
1925 School Building
High
LRCW & URM
48,200
$65
$3,133,000
3
1938 Building Addition
High
LRCW & URM
8865
$65
$576,225
3
1949 Building Addition
High
LRCW
23,466
$70
$1,642,620
1
1938 Gymnasium
High
LRCW
16,386
$70
$1,147,020
1
1953 Gymnasium Addition
High
LRCW
15,366
$70
$1,075,620
1
Shop Building
High
LRCW & URM
4,800
$35
$168,000
2
1930's School Building
High
LRCW & URM
33,500
$65
$2,177,500
2
1950's School Addition
High
LRCW & URM
10,740
$65
$698,100
1
1967/1968 Buildings
Medium-High
Reinforced Concrete & Wood
61,440
$45
$2,764,800
1
1967 Gymnasiums
Medium-High
Reinforced Concrete Walls
22,020
$45
$990,900
1
1967 Classrooms
Medium-High
Wood Framed
28,800
$20
$576,000
1
1944 Buildings
High
Wood Framed
5960
$20
$119,200
1
1955 Cafeteria Building
High
Unreinforced Conc. Masonry
4738
$65
$307,970
1
1960/1962/1967 Classrooms
High
Wood Framed
12,340
$20
$246,800
High School
High School
SABIN-SCHELLENBERG CENTER N.
Vocational High School
SABIN-SCHELLENBERG CENTER S.
Vocational High School
SUNNYSIDE E.S.
BUILDING
Elementary School
WHITCOMB E.S.
Elementary School
1
1958/1959 Buildings
High
Wood Framed / URM
53,180
$20
$1,063,600
WICHITA CENTER (Partially Upgraded)
Head Start
1
1930's/1940/1946 Building
Medium-High
Wood Framed / URM
36,316
$35
$1,271,060
principals
chris c. van vleet, p.e.
gary j. lewis, p.e.
NCSD SEISMIC – CONCORD ELEMENTARY SCHOOL
At the request of North Clackamas School District, we have prepared this more in-depth review of the seismic
issues at Concord Elementary School. The school, at 3811 SE Concord Road in Milwaukie, was partially
seismically upgraded in 2000 / 2001, but significant seismic hazards were not addressed at that time. This letter
report will address seismic hazards in general, the structural systems at Concord, previous upgrades at Concord,
remaining seismic retrofits to be done, and relative risks.
Seismic awareness in Oregon was practically nonexistent before the early 1960’s, and the region was believed
to be seismically and volcanically inactive. Structural Codes, such as they were, did not include mandatory
provisions for seismic loads until 1961, and those first mandatory values were much lower than current
requirements. Over the ensuing years, based on emerging knowledge and on effects of local and distant
earthquakes, the requirements were gradually increased. In 1935 when the main school building was built at
Concord Elementary, and again in 1948 when the east classroom addition was built, the materials, methods, and
details of construction were low-capacity compared to current standards.
SEISMIC STANDARDS
Trying to assess the short-term risks to life / safety can be an exercise in statistics, with very few data points. A
recent report by Oregon State University found that the recurrence interval for a subduction zone earthquake
along the southern Oregon coast may have been as low as 250 years, contrary to the 300 to 500 years previously
believed. The theories of the strength and frequency of these massive earthquakes along the coast are evolving,
but what is almost universally accepted is that we have had regular great earthquakes, and we are currently
overdue for a magnitude 8.5 or 9 earthquake off the coast of the Pacific Northwest. It is expected that such an
earthquake would affect the Portland area similarly to a local magnitude 7.0 strike-slip fault earthquake, but
with a duration of four or more minutes. Portland has several local strike-slip faults as well, and they are
expected to eventually generate local earthquakes up to magnitude 6.5, with no predictions on when they might
occur.
consulting engineers
18660 s.w. boones ferry road
tualatin, oregon 97062
(503) 885-8605 phone
(503) 885-1206 fax
NCSD Seismic – Concord Elementary School – Page 2
Current seismic design forces are based on soil conditions at the site and their affect on seismic accelerations,
on the ductility (flexibility) of the structure, and on the importance (usage) of the structure. The acceleration
coefficients used in determining design coefficients are based on expected earthquake intensity, and those
coefficients are reduced based on the other factors noted above, in order to arrive at design forces. Those forces
are less than the expected actual forces, and buildings are expected to sustain damage but not collapse if
designed to those forces.
EXISTING CONDITIONS
The original 1935 school building at Concord Elementary was constructed with a wood-framed roof system.
That roof was minimally attached to the unreinforced brick and clay tile double-wythe walls at the building
exterior and to the wood framed corridor and interior demising walls. The main floor framing was also wood
framing, and the basement walls were unreinforced or minimally reinforced concrete up to grade and masonry
above (creating a weaker hinge point partially up the walls. Again, connections between the main floor and the
walls were minimal in comparison to current requirements. The 1948 addition was of similar construction to
the 1935 building, with similar issues.
PREVIOUS UPGRADES
In the year 2000, some improvements were planned for Concord Elementary, and our firm was retained as
structural engineers for that work. We had been employed by a firm in 1993 that had evaluated and designed
repairs for the Molalla High School building after the Scotts Mills earthquake that year. Molalla High School
was built similarly to Concord Elementary, and had significant damage that could have taken lives had the
earthquake not happened during spring break. Brick entry walls collapsed around and onto the main entry / exit
of the school. That entry was almost identical to the west entry at Concord, and we were asked to provide a
preliminary seismic report for Concord Elementary School. Estimates were prepared for a full seismic upgrade
at Concord based on our findings, but the budget was limited and only the entry areas and the east wall of the
gymnasium were strengthened for out of plane forces (blowout). Our year 2000 estimate for full upgrade of the
building to life / safety performance level (where the building is damaged but still repairable and is designed to
survive the earthquake relatively intact) was one million dollars or more. The estimate to complete upgrades to
life / safety level in the recent Phase 2 evaluation of Concord Elementary was $1,638,000, based on a unit cost
of $35 per square foot and on the work that has already been completed. With inflation and with the work not
occurring along with a building remodel (where finish repairs can be included in the remodel budget), those
estimates are compatible.
In 2000 / 2001, reinforcement was designed for limited unreinforced masonry (URM) areas around the four
main entries / exits at Concord, for the entire east wall of the 1948 addition (required to provide a safe exit path
between that wall and the property line fence to the east), and for the east wall of the gymnasium. That work
comprised a total of 435 lineal feet of wall (measured separately for each level of the building). The remaining
non-upgraded URM walls that adjoin classroom and staff areas total an additional 973 lineal feet.
NCSD Seismic – Concord Elementary School – Page 3
RECOMMENDED UPGRADES
The existing unreinforced exterior walls should also be upgraded to provide adequate in-plane shear capacity
for the seismic loads of the building structure. Even if the walls are designed to resist seismic loads out of plane
(blowout), if the in-plane forces in an earthquake exceed their limited shear capacity, the pier elements between
window openings could fail. Failure of the exterior wall piers would cause the entire exterior load-bearing
walls to fail, and the perimeter of the roof to collapse into classroom and staff support areas. This problem was
considered in planning the limited year 2000 upgrade, with the concept that in an earthquake, students would be
advised to move to the interior hallways if inside the building, and move away from the exterior walls if
outside. Since the interior corridors are likely to sustain significant damage but not collapse, and the exits have
been strengthened, this compromise allows the students and staff to evacuate the building safely. There are still
areas inside and outside the perimeter of the building that would be very hazardous to occupy during an
earthquake. Many of the NCSD schools have similar areas of risk, with long bands of windows without
significant solid walls to resist seismic shear.
The in-plane shear issues at Concord Elementary are similar to those other NCSD buildings, except that the
URM exterior piers exacerbate the problem since they are brittle and subject to complete failure when seismic
cyclical bending and shear loads are applied. In a full seismic upgrade, new shear elements (walls or braced
frames) would be added to the existing piers, with some window infill required to provide adequate shear
element length at the perimeter. For the 1935 building, the west wall overall length is 212 feet, and although 64
total feet of that length is full height masonry piers, they are all limited to about 4 feet or 6 feet in length and 8
1/2"inches thick. In addition, there are some 8 1/2” x 17” unreinforced masonry piers between windows that
are almost 9 feet tall within the openings, and they support a tributary length of the roof of 10 feet. Failure of
those small piers at both ends of a bank of windows would cause collapse of the exterior part of the roof within
a classroom.
The north and south endwalls of the 1935 building are about 78 feet long overall, with only four 4’foot long
wall piers each for a total of 16 feet per end. Also, the north side of the 1948 addition is 133 feet long with only
three 8’-9” piers, a 6 foot pier, and a 4 foot pier, for a total of about 36 feet. These piers will suffer major
damage due to in-plane and out of plane loading in a design earthquake, and reinforcement of the piers will
need to be substantial in most cases due to limited individual and total lengths of walls.
The partition walls between classrooms and the corridor walls are wood framing with lath and plaster, and have
some ability to resist in-plane shear loads. However, that ability is limited due to the brittleness and weakness
of the plaster, and major damage and loss of plaster can be expected. A long-duration earthquake could cause
major damage to those walls. Upgrading those walls would be relatively easy. The plaster finish would be
removed from one or both faces, blocking would be installed between studs, holdowns would be installed, and
plywood sheathing with a gypsum board finish would be applied to one or both faces of the walls. In addition,
top and bottom connections to structure would be strengthened, foundations or support beams added, and the
“shear wall” would be extended to the roof to provide a complete load path from roof to foundation.
The roof of Concord Elementary is very irregular, with both vertical and horizontal irregularities. The damage
that would occur from areas of the roof structure separating from one another during a significant earthquake
should not be a major life / safety issue, but providing continuity strapping to limit those separations should
prevent significant roof damage and leaks that could delay occupancy after an earthquake. Areas that are not
currently sheathed with plywood should be upgraded with new plywood, along with continuity strapping.
NCSD Seismic – Concord Elementary School – Page 4
In our evaluation comments in 2000, we addressed the chimney collapse potential at Concord. It was decided
not to remove or brace the chimney at that time because the collapse hazard area was in a relatively unoccupied
area behind the school. That work should be included in a full upgrade project.
Also in 2000, we noted that some of the mortar joints in the URM walls, both inside and outside the building,
were deteriorated. Those mortar joints should be repointed during wall upgrade work. We have attached a
letter and diagram we prepared in September 2001 following the first phase of seismic upgrades at Concord
Elementary School. Those documents are a good guideline as to the areas of the school that have not been
strengthened, and they reflect the thrust of the work then to upgrade the building to allow for evacuation, but
not necessarily to prevent partial collapse.
The earthquake we design for could occur tomorrow, or 100 years from now. Economics prevent us from
taking the safest course which would be to upgrade every structure now, but we should continue to work to
remove buildings, particularly school buildings, from the hazardous category.
We trust that this information serves your needs, and encourage you to contact us for additional information if
needed.
Gary J. Lewis, S.E.