RETHINKING MULTIFAMILY RESIDENTIAL Convention/2017... · 2017. 5. 24. · RETHINKING MULTIFAMILY...
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RETHINKING MULTIFAMILY RESIDENTIAL SEAoA 51st Anniversary Convention and Conference Presented by: Neil Wexler, PhD PE Ali Maher, PE
Transcript of RETHINKING MULTIFAMILY RESIDENTIAL Convention/2017... · 2017. 5. 24. · RETHINKING MULTIFAMILY...
RETHINKING MULTIFAMILY RESIDENTIAL
SEAoA 51st Anniversary Convention and Conference
Presented by: Neil Wexler, PhD PE
Ali Maher, PE
ABOUT US- WEXLER ASSOCIATES
Founded 35 years ago
NYC Structural Engineers
Forensic Work
Active in various markets
BIM and IPD
Knowledgeable about systems
Steel Detailers
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ABOUT US- IN-HOUSE STEEL DETAILING
WES Consultants, LLC
Design Assist
3D Modeling
Coordination
Assistance with accurate bids
Engineering of Connections
Constructability
IPD
Tracking
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•High End
•Market Rate
•Affordable
The big question: How to deliver quality buildings at affordable prices?
HOUSING MARKETS
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•Cast in Place Concrete
•Steel And Metal Deck
•Steel and Plank
•Masonry and Plank
•Light Gauge Framing
•Wood
•Combinations of the above
•Specialty Systems- Girder Slab, IFC, Staggered Trusses with Plank Floors
REVIEW OF POPULAR STRUCTURAL SYSTEMS FOR HOUSING
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CONSIDERATIONS FOR CHOOSING A STRUCTURAL SYSTEM
Architectural considerations- Geometry
Cost Efficiency
Flexibility of Re-Use and Expansion
Construction Time
Durability and Fire-Resistance
Housing Market
Following Local Practice
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CAST IN PLACE CONCRETE
Advantages Uniform floor thickness
Very versatile – can be modified with admixtures for different effects
High compressive strength (4~8 ksi)
Fire resistant
Columns do not need to be on a grid
Disadvantages Fairly Expensive
Long curing time
Low tension strength (~0.4 ksi)
Fairly heavy material to work with
Columns and Shear walls take space
Difficult quality control
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STEEL FRAMING WITH METAL DECK AND CONCRETE FLOORS
Advantages High tensile and compressive strength (A36 Steel ~ 60 ksi)
Smaller members (columns, beams) than concrete.
Elastic and Ductile material
Advantageous in renovations.
Many shapes, sizes
Competitive Prices
Disadvantages• Floor assembly deeper that concrete (affects head
room)
• Longer lead time– limited quantities
• Susceptible to fire, rust, impurities
• Needs fire proofing and ceilings
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STEEL FRAMING WITH PRECAST PLANK FLOORS
Advantages Similar thickness of concrete floor (8”) with longer spans
(up to 30’) and lighter (hollow core)
Long clear spans eliminate columns and beams and allow for large open areas
Thicker plank can support a set back without steel
Competitive Prices
Disadvantages• Beams typically below plank- affecting headroom
• Longer lead time– limited quantities
• Requires a crane
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CMU WITH PRECAST PLANK FLOORS
Advantages Similar thickness of concrete floor (8”) with longer spans
(up to 30’) and lighter (hollow core)
Affordable system
Thicker plank can support a set back without steel
Competitive Prices
Disadvantages• Limit façade design
• Transfer level needed –deep girders typically
below plank- affecting headroom
• Longer lead time– limited quantities
• Requires a crane
• Height restriction
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WOOD, LIGHT GAUGE
Advantages Cheap, renewable resource, sustainable
Faster construction and reduced erection costs
Good in Tension – ~40 Mpa
Versatile and adaptable- modifications are simpler
Disadvantages• Limit façade design
• Not very hard
• Not very strong
• Height restriction
• Susceptible to fire, nature
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INTRODUCTION TO THE STAGGERED TRUSSES SYSTEM
Variation on Steel and Plank System.
Earlier system- channels for web diagonals & verticals
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HOW DOES IT WORK?
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STAGGERED TRUSSES HISTORY
Bill Lemessurier (William James Lemessurier)
First presented at 1966 AISC conference
1st Building constructed in 1968– 17 Story residential in Minneapolis
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AISC DESIGN GUIDE 14
AISC Design Manual 14 written by Neil Wexler, PhD PE and Feng-Bao Lin, PhD PE
Current trusses feature HSS for web diagonals & verticals
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BENEFITS OF STAGGERED TRUSSES
What are the benefits over alternative systems?
Cost
Erection time
Open space
Reduced loads at foundation
When designed in combination with precast concrete plank or similar floors, it results in a floor-to-floor height approximately equal to flat plate construction
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OUR STAGGERED TRUSSES PROJECTS
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CASE STUDY –STAGGERED TRUSSES- CT
Summer House, Stamford CT
334,000 SF, 21 Story, 230’ high
2400 Tons of steel.
Architect: Lessard Design
Structural Engineer: Wexler Associates
Fabricator: Ocean Steel Corp.
Erector: American Steel & Precast Erectors
Detailers: Ocean Steel Corp.
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CASE STUDY – SUMMER HOUSE, STAMFORD CT
Summer House, Stamford CT
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SUMMER HOUSE, STAMFORD CT- TYP FLOOR PLAN
Trusses located
26’ on center.
CASE STUDY- STAGGERED TRUSSES- NJ
Cliffside Park Towne Center
850,000 SF, 16 Story, 205’ high
3500 Tons of steel.
Architect: Virgona and Virgona Architects
Structural Engineer: Wexler Associates
Fabricator/Erector: Barone Steel
Detailers: Wes Consultants, LLC
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CLIFFSIDE PARK TOWN CENTRE, NJ
Typical residential floor plan
Added WTs for Improved erection methodology
Building braces for lateral
TRUSSES ABOVE AND BELOW PLANK
BRACES
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CLIFFSIDE PARK TOWN CENTRE, NJ
Detailing done using SDS2
Project delivered using IPD
Steel Model used for coordination with MEP and Interiors.
Project featured prefabricated wall panels.
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STEEL DETAILING
CASE STUDY- CAST IN PLACE CONCRETE, BROOKLYN NY
429 Kent Avenue. Brooklyn NY
500,000 SF, 8 Story
Architect: WASA Architects
Structural Engineer: Wexler Associates
Project Design completed using BIM
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THE OOSTEN, BROOKLYN NY- CHALLENGES
Many Amenities
20’ variation between street grades along the building perimeter
First floor at grade features 40 different elevations
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THE OOSTEN, BROOKLYN NYS
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CASE STUDY- WOOD CONSTRUCTION, RIVERHEAD NY
221 East Main Street. Riverhead NY
150,000 SF, 6 Story
Architect: Steven Jacobs Architects
Structural Engineer: Wexler Associates
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221 EAST MAIN STREET, RIVERHEAD NY
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29 WEST 138TH STREET, NEW YORK NY
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Beacon Towers – 29 west 138th Street, New York NY
240,000 SF, Two 8 Story
Architect: ABS Architects
Structural Engineer: Wexler Associates
52 EAST 4TH STREET, NEW YORK NY
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The Bowrey – 52 East 4th Street, New York NY
150,000 SF, 15 Story
Architect: Scarano & Associates Architects
Structural Engineer: Wexler Associates
SUMMARY- RETHINKING MULTIFAMILY
Communicate optional systems and demonstrate their features
Choose the right structural system for your project
Monitor material quantities
Use technology to assist in project optimization and delivery
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DISCUSSION, QUESTIONS
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