2015 structures congress - one jackson square
TRANSCRIPT
Case Study: One Jackson SquarePhilip Murray, PE
Karl Rubenacker, PE, SEApril 23RD, 2015
ASCE Structures Congress 2015
Project Team• Hines• KPF • SLCE• GMS• Flack & Kurtz• RA Consultants• Vollmer• Cerami• Hunter Roberts
ASCE Structures Congress 2015
New Building Information• Luxury Residential
Development• Condominium • ~ 3 dozen Apartments• 56,000 SF Residential• 9,000 SF ground floor
retail• 11 Stories
ASCE Structures Congress 2015
Site Background Information• NYC Subway Eighth Ave.
Line 1932• NYC Sells Lot to Private
Developer 1948• Attempt at Development
1980• Parking Lot Until this
Project
ASCE Structures Congress 2015
Challenges
• Subway tunnel below two-thirds of site
• MTA substation next door
• >250,000 Riders pass under site each day
ASCE Structures Congress 2015
More Challenges
• Historic Landmark District• Neighboring URM Buildings • Active Community• Straddles 2 Zoning Districts• Six-sided Irregular Lot
ASCE Structures Congress 2015
Solutions• Sensitivity to NYCTA Issues
during design• Care during construction• Structure vertical load
within allowable• No lateral load imposed
on tunnel• Isolation of the building
from Subway Vibration
ASCE Structures Congress 2015
NYC Transit Approval Process
• Multiple meetings w/NYCTA staff• Multiple drawing & calculation
submittals• Adjustments to design• Duration ~ 9 months
ASCE Structures Congress 2015
Subway Protection Measures
• Preconstruction survey• Monitoring during construction• Limitation on equipment• Lateral support during excavation• Limitation on construction
ASCE Structures Congress 2015
Monitoring
• 15 points in tunnel• Twice/week during foundation work• Once/story during superstructure work• 3 months & 6 months after topping
out
ASCE Structures Congress 2015
Caissons
• 24 inch round caisson, reinforced concrete core
• Socketed into the bedrock• Fixed top & bottom• Approx 40 kip lateral load• Approx 750 kip vertical load• Bedrock ~ 45’ below grade
ASCE Structures Congress 2015
Isolation Springs and Bearings
ASCE Structures Congress 2015
Isolation Spring
Isolation Lateral Bracing
Isolators
• Spring assembly pads used to isolate the building laterally from the subway tunnel
• Reduces acoustic transmission, for residential viability
• Lateral bearings provide resistance to base shear
ASCE Structures Congress 2015
Engineering Data
• Building weight ~ 22,000 kip• Seismic base shear ~ 1000 kip (R=3)• Building period ~ 0.9 sec/cycle• Wind base shear ~ 500 kip• Wind base shear ~ 250 kip
ASCE Structures Congress 2015
Superstructure Data
• Concrete flat plate• Irregular column layout• Typically 8” slab thickness• Punching shear reinforcement• Transfer floor 16” thick
ASCE Structures Congress 2015