554-556 Third Avenue NY, New York

1
554-556 Third Avenue NY, New York

• Michelle L. Mentzer
• Structural Option

2
Outline

• Building Information
• Structural Background
• Problem Statement
• Proposal
• Structural Design
• Architecture
• Construction Management
• Conclusions

3
Design Team

• Owner
• Maidman Development
• Architect
• H. Thomas OHara Architects
• Structural Engineer
• DeSimone Consulting Engineers
• CM
• BrawnMade Construction
• Tishman Staff
• MEP Engineer
• MGJ Associates

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Location

• Midtown Manhattan

• 37th Street and Third Avenue

5
Building Information

• 30 Stories
• 120,000 sq. ft.
• 3600 sq. ft. Footprint
• Residential occupancy
• Ground floor
• Retail space
• Residential lobby
• Fifth floor
• Fitness room
• Living units

Ground Floor
Fifth Floor
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Building Information

• Residential occupancy
• Floors 2-24
• Marriott ExecuStay Suites
• Floors 25-30
• Double height condominiums

Floor 8-24
Floor 25-30
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Structural Background

• Gravity System
• Flat plate concrete construction
• Floors 6-30 cantilever over buildings on 2 sides
• Flat plate supports cladding load at cantilevers
• Column walks shift loads toward building interior
• Post-tensioning in slabs and columns near walks
• Mat Foundation

8
Structural Background

• Column Walk
• Column 12 on floor 5
• Column 18 on floor 8
• Resembles a wall between levels

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Structural Background

• Lateral System
• Wind loads govern for design loads
• Shear wall core
• Relatively uniform throughout building
• Link beams connect walls above door openings
• Extends above main roof to enclose penthouse

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Problem Statement

• Architectural style limited by thin cantilever
  slabs that cannot support heavy cladding
• ADOSS model proved slabs would fail with heavy
  cladding load
• Metal panels are the only option

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Proposal

• Develop an additional support system capable of
  carrying excess cladding loads
• Steel trusses at roof level
• Tension members hanging from trusses carry loads
• Change façade through architectural precast
  panels and roof trusses
• Determine impact these changes have on
  construction schedule, site layout and cost

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Structural Design

• Truss Design
• Braced frames replace shear walls above roof
• System modeled in RISA
• Applicable load cases considered
• Continuous top bottom chords
• Pins at all other locations
• Fixed supports at columns and shear walls

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Structural Design

• Supporting Columns
• Located wherever a truss joint coincides with a
  column/shear wall
• Connections not necessarily centered on column

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Structural Design

• Truss and Braced Frame Member Sizes
• Maximum consistency
• Lightest weight sections where possible
• All wide flange shapes

W14x90
W21x83
W14x211
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Structural Design

• Truss Connections
• Heavy bracing type connections at truss joints
• Base plate and anchor bolts connect bottom chord
  to columns or shear walls

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Structural Design

• Tension Members
• W14x22, W14x34, W14x68
• Largest members at top
• Reduce size as allowable
• Hanger connection
• Tension splices where necessary

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Structural Design

• Slabs
• No gravity load transferred from cladding to
  slabs
• Cladding directly supported by columns
• Angles welded to column flanges and bolted to
  panels
• Lateral ties from panels to slab
• Transfer wind forces to rigid diaphragm

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Structural Design

• Column Walk
• Added compression in column creates more tension
  in slab near column 18 on level 8
• Initially gravity load is fully vertical
• As core reinforcement in column slants, gravity
  force creates horizontal component at slab level
• Horizontal tension at level 8 is resisted by
  post-tensioning
• One additional 1 3/8 Dywidag in level 8 slab
• Original design calls for 5 Dywidags

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Structural Design

• Column Capacities
• Column capacities checked at critical locations
  using PCA Column
• All support columns checked for gravity loads and
  moments from eccentricity
• Dimensions and reinforcement increase in some
  areas
• Exterior columns not supporting truss also
  checked
• Supporting extra loads directly from cladding
• Sufficient as designed to carry cladding loads

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Structural Design

• Tension in Columns
• Created by moment from cantilevered truss
• Resisted by reinforcement in concrete

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Structural Design

• Shear in Columns
• Lateral loads from trusses and braced frames
  transferred directly to columns at roof level
• Rigid diaphragm redistributes load at floor
  thirty
• Where columns are in tension, shear reinforcement
  takes full shear load
• Several columns require additional shear
  reinforcement at roof level

22
Structural Design

• Adjusted Column Sizes

23
Structural Design

• Overturning Moments
• 0.9D1.6W load case critical
• Overturning caused by combination of wind and
  truss forces
• Building overturning resisted by self weight and
  foundation
• Safety factor (critical case)2.5
• Moments cause tension and compression in opposite
  flanges of shear wall core
• Spreadsheets used to check reinforcement for
  tension and compression in shear walls
• Sufficient as designed to resist tension and
  compression loads

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Architecture
Cladding

• Precast architectural panels
• Architectural Precast Association
• Acid-etched medium with yellow pigment
• Red and beige tones blend with surroundings
• Hint of yellow sets it apart and ties in idea of
  light associated with the name Aurora

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Architecture

• Truss Design
• Similar truss idea used in IBM Building,
  Baltimore, MD
• Shape of trusses emphasizes cantilevers
• Maximum symmetry possible
• Add interest and detract from tall slender
  penthouse
• Visible from street level

26
Architecture

• Column Dimensions Changes
• West window shifts
• No other substantial changes to layout necessary

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Architecture
Before
After
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Construction Management

• Sequencing
• Finish pouring concrete before erecting steel
• Enclosures cannot begin until after steel work is
  complete
• Crane only needed for one task at a time

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Construction Management
Site Logistics

• Tower crane capacity 8 tons
• Maximum member weight 5 tons
• Maximum panel weight 7.5 tons
• Street parking behind crane

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Construction Management

• Schedule Impact
• Durations from MC2
• Steel adds approx. 1.5 months to schedule
• Panels take about the same amount of time to hang
• Overall extension of schedule 1.5 months

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Construction Management

• Cost
• Initial overall cost
• R.S. Means 18.2 million
• Structural steel
• MC2 220,000
• Panels (MC2)
• Metal panels 960,000
• Architectural precast panels 2,200,000
• Proposal adds 1.5 million or 8.6 of initial cost

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Conclusions

• Trusses add architectural interest and allow use
  of a heavier cladding system
• No substantial interruptions to interior layout
• 1.5 million cost increase
• 1.5 month schedule increase

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Conclusions

• Recommendation
• Revenue from architectural enhancements will not
  likely offset added costs and schedule delays
• Use original metal panel cladding system

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Acknowledgements

• DeSimone Consulting Engineers
• Penn State AE Faculty
• AE Class of 2003
• My Family

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Questions