new design + retrofit
Post on 17-Feb-2022
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TENANT SHELL SPACE HVAC-MECH
TENANT SHELL SPACE
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SEISMICJOINT
REMAININGEXISTING STRUCTURE
NEW 2-STORYBUILD BACKSTRUCTURE
DEMOLISHEDPORTION OFATCT & T2
NEWMECHANICALFLOOR & ROOF
ONGOING TSAOPERATIONS
SFO TERMINAL 2 BUILD BACK AND RETROFIT
SEAONC/SEAOC 2020 EXCELLENCE IN STRUCTURAL ENGINEERING AWARDS
The San Francisco International Airport (SFO) Central TerminalBuilding (CTB) was dedicated in 1954 as the airport’s main terminal. Theupper floors of the CTB were transformed into an administrative officebuilding in 2000. In 2010, the flight operations portion of the CTB wasseismically retrofitted and remodeled into the current Terminal 2 (T2),recognized as the country’s first LEED Gold certified airport terminal. The CTB’s six-story concrete structure housed over 600,000 squarefeet, including the airport's original Air Traffic Control Tower (ATCT).Following completion of the new ATCT in 2016, SFO hired TurnerConstruction, AE3 Partners/Woods Bagot Joint Venture, and SimpsonGumpertz & Heger (SGH) to execute a $45 million design-build projectthat included demolition of the original control tower and upper fourstories of T2 and the “build back” of two stories above the existingstructure. The new two-story structure is programmed to accommodateairline lounges, office space, café, and exterior observation decks ateach end of the building. TSA screening for T2 is located directly belowthe “build back” at the 2nd level, which presented a major designchallenge as TSA could not be affected during construction. Advancedanalysis techniques and innovative connection detailing were necessaryto prove that the existing building and foundations could meet currentbuilding code requirements considering changes in design loads andminimal existing structure capacities. The new space was designed withsteel special moment frames (SMF) using SidePlate connections thatresulted in lighter beam and column member sizes and minimizedoverturning forces resulting from seismic loads. T2 now stands as a harmonious union between old and new at thegeographic center of SFO, prepared to serve the 5.5 million passengersthat will pass through its doors annually.
OVERVIEW SMF COLUMN BASE DETAIL
The SMF column bases are designed to emulate a pinnedconnection, minimizing moment demands on existing steelcolumns originally designed to resist gravity loads. Theintricate connection transfers shear forces through lug plateassemblies at the column flanges, compression forcesthrough bearing plates/grout, and tension forces through asplice connection between new and existing columnelements.
SHEAR TENSION COMPRESSION
δuplift
δ2%Drift
ROCKING FOUNDATION ANALYSIS
Higher level analysis included a rockingevaluation that avoided foundationretrofit. We performed a nonlinearpushover analysis to demonstrateequivalent Life Safe performance ofthe foundations supporting the newmoment frame columns. We modeledthe existing pile foundations withcompression-only gap elements thatsimulate lift-off of the cap from thesocketed piles. We demonstrate that ata design drift of 2% in the new addition,uplift in the foundation is less than the3 inch pile embedment into the pilecap.
POST-INSTALLED WELDED HEADED STUDS TO (E) BEAM FLANGE
(E) CONCRETE COLLECTOR RETROFIT
FRP DIAPHRAGM STRENGTHENING
EXISTING COLUMN COVER PLATE STRENGTHENING
FRP COLLECTORSEXISTING STRUCTURE RETROFIT
LFRS: SMF WITH SIDEPLATE CONNECTIONSSMF COLUMN SHEAR-AXIAL BASE CONNECTION
NEW TWO-STORY BUILD BACK STRUCTURE
NEW DESIGN + RETROFIT
BASE SHEAR VS ROOF DRIFT
FOUNDATION UPLIFT VS ROOF DRIFT
ROOF DRIFT (IN)
ROOF DRIFT (IN)
BASE
SH
EAR
(KIP
S)UP
LIFT
(IN
)
Vp
PROJECT TEAM
CONTRACTOR TURNER CONSTRUCTION
STRUCTURAL SIMPSON GUMPERTZ & HEGER
ARCHITECT AE3/WOODS BAGOT JOINT VENTURE
OWNER SFO INTERNATIONAL AIRPORT
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