554 556 Third Avenue NY New York Michelle

554 -556 Third Avenue NY, New York Michelle L. Mentzer Structural Option

554 -556 Third Avenue – The Aurora Outline n n n n Building Information Structural Background Problem Statement Proposal Structural Design Architecture Construction Management Conclusions Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Design Team n n n Owner ¨ Maidman Development Architect ¨ H. Thomas O’Hara Architects Structural Engineer ¨ De. Simone Consulting Engineers CM ¨ Brawn. Made Construction ¨ Tishman Staff MEP Engineer ¨ MGJ Associates Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Location Midtown Manhattan 37 th Street and Third Avenue Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Building Information n n 30 Stories 120, 000 sq. ft. 3600 sq. ft. Footprint Residential occupancy ¨ Ground floor n n ¨ Ground Floor Retail space Residential lobby Fifth floor n n Fitness room Living units Fifth Floor Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Building Information n Residential occupancy ¨ Floors n Marriott Execu. Stay Suites ¨ Floors n 2 -24 Floor 8 -24 25 -30 Double height condominiums Floor 25 -30 Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Structural Background Gravity System n. Flat plate concrete construction n. Floors 6 -30 cantilever over buildings on 2 sides ¨Flat plate supports cladding load at cantilevers n. Column walks shift loads toward building interior n. Post-tensioning in slabs and columns near walks n. Mat Foundation Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Structural Background n n n Column Walk Column 12 on floor 5 Column 18 on floor 8 Resembles a wall between levels Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Structural Background n n 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 Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Problem Statement Architectural style limited by thin cantilever slabs that cannot support heavy cladding n ADOSS model proved slabs would fail with heavy cladding load n Metal panels are the only option n Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Proposal n Develop an additional support system capable of carrying excess cladding loads ¨ Steel trusses at roof level ¨ Tension members hanging from trusses carry loads n n Change façade through architectural precast panels and roof trusses Determine impact these changes have on construction schedule, site layout and cost Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Structural Design n n n Michelle L. Mentzer – Structural Emphasis 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

554 -556 Third Avenue – The Aurora Structural Design n n Michelle L. Mentzer – Structural Emphasis Supporting Columns Located wherever a truss joint coincides with a column/shear wall Connections not necessarily centered on column

554 -556 Third Avenue – The Aurora Structural Design Truss and Braced Frame Member Sizes n Maximum consistency n Lightest weight sections where possible n All wide flange shapes W 21 x 83 W 14 x 90 W 14 x 211 Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Structural Design n n Truss Connections Heavy bracing type connections at truss joints Base plate and anchor bolts connect bottom chord to columns or shear walls Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Structural Design Tension Members n W 14 x 22, W 14 x 34, W 14 x 68 ¨ Largest members at top ¨ Reduce size as allowable n n Hanger connection Tension splices where necessary Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Structural Design Slabs n No gravity load transferred from cladding to slabs Cladding directly supported by columns ¨ Angles welded to column flanges and bolted to panels ¨ n Lateral ties from panels to slab ¨ Transfer wind forces to rigid diaphragm Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Structural Design Column Walk n 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 ¨ n One additional 1 3/8 “ Dywidag in level 8 slab ¨ Michelle L. Mentzer – Structural Emphasis Original design calls for 5 Dywidags

554 -556 Third Avenue – The Aurora Structural Design n n Column Capacities Column capacities checked at critical locations using PCA Column All support columns checked for gravity loads and moments from eccentricity ¨ Dimensions n 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 Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Structural Design n n Michelle L. Mentzer – Structural Emphasis Tension in Columns Created by moment from cantilevered truss Resisted by reinforcement in concrete

554 -556 Third Avenue – The Aurora Structural Design Shear in Columns n Lateral loads from trusses and braced frames transferred directly to columns at roof level n Rigid diaphragm redistributes load at floor thirty n Where columns are in tension, shear reinforcement takes full shear load n Several columns require additional shear reinforcement at roof level Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Structural Design Adjusted Column Sizes Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Structural Design Overturning Moments n 0. 9 D+1. 6 W load case critical ¨ n Building overturning resisted by self weight and foundation ¨ n Overturning caused by combination of wind and truss forces 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 ¨ Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Architecture n Cladding Precast architectural panels ¨ Architectural Precast Association ¨ Acid-etched medium with yellow pigment n n Michelle L. Mentzer – Structural Emphasis Red and beige tones blend with surroundings Hint of yellow sets it apart and ties in idea of light associated with the name “Aurora”

554 -556 Third Avenue – The Aurora Architecture n Truss Design Similar truss idea used in IBM Building, Baltimore, MD n Shape of trusses emphasizes cantilevers n Maximum symmetry possible n Add interest and detract from tall slender penthouse n Visible from street level Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Architecture n n Michelle L. Mentzer – Structural Emphasis Column Dimensions Changes West window shifts No other substantial changes to layout necessary

554 -556 Third Avenue – The Aurora Architecture Before Michelle L. Mentzer – Structural Emphasis After

554 -556 Third Avenue – The Aurora Construction Management Sequencing n Finish pouring concrete before erecting steel n Enclosures cannot begin until after steel work is complete n Crane only needed for one task at a time Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Construction Management Site Logistics n n Michelle L. Mentzer – Structural Emphasis Tower crane capacity = 8 tons Maximum member weight = 5 tons Maximum panel weight = 7. 5 tons Street parking behind crane

554 -556 Third Avenue – The Aurora Construction Management n n Schedule Impact Durations from MC 2 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 Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Construction Management n Cost Initial overall cost ¨ n Structural steel ¨ n R. S. Means = $18. 2 million MC 2 =$220, 000 Panels (MC 2) Metal panels = $960, 000 ¨ Architectural precast panels = $2, 200, 000 ¨ n Proposal adds $1. 5 million or 8. 6% of initial cost Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Conclusions n Trusses add architectural interest and allow use of a heavier cladding system n No substantial interruptions to interior layout n $1. 5 million cost increase n 1. 5 month schedule increase Michelle L. Mentzer – Structural Emphasis

554 -556 Third Avenue – The Aurora Conclusions Recommendation n Revenue from architectural enhancements will not likely offset added costs and schedule delays n Use original metal panel cladding system Michelle L. Mentzer – Structural Emphasis

Acknowledgements De. Simone Consulting Engineers Penn State AE Faculty AE Class of 2003 My Family

554 -556 Third Avenue – The Aurora Questions Michelle L. Mentzer – Structural Emphasis