California State University Dominguez
Hills -Library Addition and Seismic Upgrade
Owen was commissioned
to provide structural seismic retrofit solutions for
the upgrade of the Main Library. The ERC Library is
located in the center of the CSUDH campus and houses
study areas and book stacks at lower levels and administrative
offices on the fifth floor. The building is a five-story
concrete shear wall structure with a partial basement,
built in the late 1960s.
Owen conducted structural
analysis to evaluate the building and make recommendations
for seismic upgrade. On review of the existing drawings
we concluded that The Main Library seismic performance
was "POOR" and was expected to experience
appreciable damage in structural and non-structural
systems during a strong earthquake causing loss of
lives.
In order to improve
the current seismic performance of the building from
"POOR" to a "GOOD" rating, Owen
studied different viable alternatives for seismic
strengthening. Two schemes developed. The retrofit
solutions were based on adding new concrete shear
walls combined with the application of gunite on existing
walls; the most cost effective method with least interruption
in building occupancy enabling the majority of proposed
work around the perimeter. The retrofit included a
total of 180 linear feet of new 18-inch thick four
to five-story high reinforced concrete shear walls;
as well as the application of 6-inch thick gunite
on the existing walls around the North side of the
building. Other structural elements are: new 30-inch
diameter 25 to 35 feet long cast-in-place concrete
piles and caps for support,
The work required
for non-structural elements includes: bracing of existing
ceiling, improvement of existing bracing for bookshelves
and stack;, improving the connections of the perimeter
stud wall to concrete slabs at the third and fourth
levels, and providing braces for mechanical equipments
at the roof.
University of California Irvine Seismic
Upgrade - Crawford Hall Athletic Building, Irvine,
CA
This is a two-part
project to seismically upgrade and expand the athletic
facilities. The first part consists of seismic strengthening
of the existing athletic facilities including the
Gymnasium and Office buildings .It included structural
analysis, seismic retrofit; an HVAC upgrade, expansion
of the weight training and sports medicine facilities;
women's and men's locker room improvements; upgrades
of the entry lobby and student plaza; and ADA compliance.
The 3-story Gymnasium has a concrete ground floor
and a mezzanine with steel roof. Lateral load-resisting
system includes concentric steel braces at the top
and concrete shear walls at the ground floor. Office
building is a single story structure with precast
concrete columns and steel truss roof system. The
lateral load resisting system includes chevron steel
braces.
The seismic strengthening
of the buildings included the work required to upgrade
the building to "GOOD" rating as defined
by The University of California Regency's Policy
for Seismic Safety. The work required for seismic
strengthening was designed in accordance with the
requirements of California Building Code (CBC),
Edition 1998. The scope of strengthening includes
the work required on lateral-load resisting system
to support exiting mezzanine and mechanical rooms
and providing structural design for new elevator
shaft and stairwells, as well as, lateral bracing
of the precast concrete panels and non-structural
components and equipments.
The second phase
involved the new design of a 26,292 gross square-foot
expansion featuring a new aquatics building; a 130-seat
multi-purpose auditorium with grandstands; large
conference room; sports support facility with aquatic
offices, team rooms, restrooms and ticketing facilities;
as well as a new academic study center. The project
is currently in construction.
San Diego Court Facilities, San
Diego, CA
Owen was selected by the County
of San Diego to provide seismic assessment of the
downtown San Diego court facilities. The downtown
courthouse facility includes five separate buildings
ranging from four to seven stories. The structures
include complete or partial basement, mezzanines,
and penthouses. Based on a preliminary review of
the AOC report, the structural system included concrete
slabs over steel beams supported by encased steel
columns and spread footings. The lateral-load-resisting
system generally includes punched concrete shear
walls at parameters.
Phase I included
developing computer models for each of the five
buildings; determination of seismic loading per
FEMA-356; conducting limited analysis on deficient
structural components as required by Tier-2; and
reassessment of the AOC report. Phase II included
, a schematic scheme for seismic rehabilitation
of those buildings that will remain.
John Wayne Airport Parking Structures, Santa Ana, CA
The John Wayne Airport and the
County of Orange selected Owen as prime to lead
an A/E team to perform the seismic strengthening
of its existing Northwest and Southwest parking
structures. The two parking structures are situated
to the North and South of the Thomas Riley Terminal
building of John Wayne Airport and each consists
of two structures separated by seismic joints.
Thus, the Northwest and Southwest parking structures
consist of four individual structural portions
with a combined total floor area of approximately
1,000,000 sf on four levels,. The structures were
designed and built in 1988-1991, based on the
1985 Edition of the Uniform Building Code (UBC).
Owen designed a structural remediation scheme
to correct the seismic deficiencies and improve
the seismic response of the structures to future
earthquakes and design structural repair to the
existing cracks in the concrete slabs and at the
deformed concrete beams and columns.
Loma Linda University, Medical Center - Review of Seismic Strengthening of the Main Hospital Building, Wings A & C
Owen was selected
by OSHPD for peer review of seismic strengthening
of the main hospital building of Loma Linda University
Medical Center. The project includes two separated
reinforced concrete structures (wings A &
C), built in 1967. Wing-A is a 6-story rectangular
building and Wing-C is 11-story club-shape building.
These buildings are connected together at the
first three levels and separated above with 4"
seismic gap.
The gravity
load-resisting system includes slab, beams, column
and walls supported by cast-in-place piles. Both
structures are laterally supported by perimeter
and interior poured-in-place concrete shear walls.
Shear wall discontinue below the 3rd floor level.
The evaluation
of the existing structural system indicated that
both buildings rated as Structural Performance
Category-One (SPC-1) and considered non-compliance
by OSHPD since they were designed and constructed
pre-1976. The seismic upgrade of these structures
brought them up to SPC-2. Strengthening included
a combination of conventional and state-of-knowledge
approaches. On the conventional side, the design
scheme included adding new shear walls, thickening
of the existing walls by shotcrete, adding new
drag and ties to the seismic separation at lower
levels.
Other advanced
schemes used in this approach included application
of FRP and Dampers. Fiber Reinforcing Polymer
(FRP).and jacketing are used to strengthen the
existing concrete columns supporting a discontinued
shear wall. Also included are Passive-type Hydraulic
viscous damper devices between the two structure
at the higher levels to avoid pounding under out-of-phase
seismic response.
