RETHINKING MULTIFAMILY RESIDENTIAL

Transcription

1 RETHINKING MULTIFAMILY RESIDENTIAL Presented by: Neil Wexler, PhD PE Ali Maher, PE

2 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

3 ABOUT US- IN-HOUSE STEEL DETAILING WES Consultants, LLC Design Assist 3D Modeling Coordination Assistance with accurate bids Engineering of Connections Constructability IPD Tracking

4 HOUSING MARKETS High End Market Rate Affordable The big question: How to deliver quality buildings at affordable prices?

5 REVIEW OF POPULAR STRUCTURAL SYSTEMS FOR HOUSING 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

6 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

7 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

8 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

9 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

10 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

11 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

12 INTRODUCTION TO THE STAGGERED TRUSSES SYSTEM Variation on Steel and Plank System. Earlier system- channels for web diagonals & verticals

13 HOW DOES IT WORK?

14 STAGGERED TRUSSES HISTORY Bill Lemessurier (William James Lemessurier) First presented at 1966 AISC conference 1 st Building constructed in Story residential in Minneapolis

15 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

16 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

17 OUR STAGGERED TRUSSES PROJECTS

18 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.

19 CASE STUDY SUMMER HOUSE, STAMFORD CT Summer House, Stamford CT

20 SUMMER HOUSE, STAMFORD CT- TYP FLOOR PLAN Trusses located 26 on center.

21 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

22 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

23 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.

24 STEEL DETAILING

25 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

26 THE OOSTEN, BROOKLYN NY- CHALLENGES Many Amenities 20 variation between street grades along the building perimeter First floor at grade features 40 different elevations

27 THE OOSTEN, BROOKLYN NY

28 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

29 221 EAST MAIN STREET, RIVERHEAD NY

30 29 WEST 138TH STREET, NEW YORK NY Beacon Towers 29 west 138 th Street, New York NY 240,000 SF, Two 8 Story Architect: ABS Architects Structural Engineer: Wexler Associates

31 52 EAST 4 TH STREET, NEW YORK NY The Bowrey 52 East 4 th Street, New York NY 150,000 SF, 15 Story Architect: Scarano & Associates Architects Structural Engineer: Wexler Associates

32 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

33 DISCUSSION, QUESTIONS