Northside Piers – Brooklyn, NY
Structural System Redesign
Jeremiah Ergas
AE 482 – 5th Year Senior Thesis
Structural Option
April 15th, 2008
Faculty Consultant: Dr. Ali Memari
Presentation Outline
 Intro

Intro
 Building Overview
 Redesign Goals
 Slab Design
 Shear Wall Design
Construction Management
Conclusions
Acknowledgements
Questions???
Presentation Outline
 Intro
Building Background – Location
Northside Piers - 4 North 5th Street, Brooklyn, NY
Manhattan

Overview
 Building
Building
Background
North East United States
 Redesign Goals
 Slab Design
 Shear Wall Design
Construction Management
Conclusions
Acknowledgements
Questions???
Presentation Outline
Building Background - Architecture
 Intro
- 29 Story Condominium Tower

Overview
 Building
Building
Background
- 176 units
 Redesign Goals
- Two typical floor plans
(7500SF and 6200SF)
 Slab Design
 Shear Wall Design
Construction Management
Conclusions
Acknowledgements
Questions???
- Glass Cladding System that allows
for floor to ceiling views
- No drop ceiling over living spaces
Presentation Outline
Building Background – Structural System
 Intro

Overview
 Building
Building
Background
 Redesign Goals
 Slab Design
 Shear Wall Design
Construction Management
Conclusions
Acknowledgements
Questions???
- Flat plate two-way mild reinforced slab
- Irregular Column Scheme
- Shear Walls around central core with
additional wall
Presentation Outline
Redesign Goals
 Intro
 Building Overview
Redesign Goals

Redesign
Goals
 Redesign
Goals
 Slab Design
 Shear Wall Design
-
Make structure more cost effective
-
Meet or improve serviceability of structure
Structural Elements Studied
-
Floor Slab System - Mild reinforced vs. Post-Tensioned?
-
Shear Wall System - More optimal layout?
Construction Management
Other Disciplines Considered
Conclusions
Acknowledgements
Questions???
-
Construction Management
-
Acoustics
-
Mechanical Exhaust Risers
Slab Design - Introduction
Presentation Outline
 Intro
Slab Redesign Goals
 Building Overview
Make slab more cost effective
-
Meet or improve serviceability of structure
Why Post-Tensioned System?
 Redesign Goals

SlabDesign
Design
 Slab
-
26th–Roof
 Shear Wall Design
-
No room for beams
-
Tendons improve slab efficiency
-
Tendons reduce deflections
Design Method
Construction Management
Conclusions
3rd–25th Floor
-
RAM Concept with Post-Tensioned spreadsheets
-
Must meet ACI318-05
Design Loads (Floor)
Acknowledgements
Questions???
Design Loads (Balconies)
-
40psf Live
-
60psf Live
-
30psf Super
-
15psf Super
Presentation Outline
Slab Design – Current System
3rd–25th Floor Typical Slab
 Intro
26th-Roof Typical Slab
 Building Overview
 Redesign Goals

SlabDesign
Design
 Slab
26th–Roof
 Shear Wall Design
Construction Management
3rd–25th Floor
Conclusions
Acknowledgements
- 8” Slabs with #5’s @ 12” o/c on Top and Bottom going both ways
Questions???
- Additional bars added as shown on plan
Presentation Outline
Slab Design – Current System
3rd–25th Floor Long-Term Deflection
 Intro
26th-Roof Long-Term Deflection
 Building Overview
 Redesign Goals

SlabDesign
Design
 Slab
26th–Roof
 Shear Wall Design
Construction Management
Conclusions
3rd–25th Floor
Maximum Long-Term Deflection: 0.67”
Maximum Long-Term Deflection: 0.74”
Acknowledgements
ACI318 Limit (30’ Span): L/480 = 0.75”
Questions???
Slab Design – Post-Tensioned System
Presentation Outline
 Intro
 Building Overview
3rd–25th Floor Tendon Plans
Column Shifted
26th-Roof Tendon Plans
Column Added
 Redesign Goals

SlabDesign
Design
 Slab
26th–Roof
 Shear Wall Design
Construction Management
3rd–25th Floor
Conclusions
Acknowledgements
Questions???
Maximum Long-Term Deflection: 0.48”
Maximum Long-Term Deflection: 0.49”
Slab Design – Post-Tensioned System
Presentation Outline
 Intro
Tendon Stress
 Building Overview
- 35% Banded tendon Load-Balancing Percentage
- 40% Uniform tendon Load-Balancing Percentage
 Redesign Goals

SlabDesign
Design
 Slab
- Maximum P/A of 320psi
26th–Roof
Design Details
 Shear Wall Design
Construction Management
Conclusions
Acknowledgements
Questions???
3rd–25th
Floor
- 7” Slabs
- ½” Unbonded Tendons
- Typical Profile heights of 5.75” and 1.25”
- Typically #4 bars @ 24”o/c at bottom, both ways
-Top reinforcing at columns and walls
Slab Design – Comparisons/Conclusions
Presentation Outline
Serviceability Comparison
 Intro
- Maximum Long-Term Deflections reduced by about 30%
 Building Overview
- Both slabs meet the IBC requirement for a 2-hr fire rating
- The difference in Sound Transmission Level is almost imperceptible (57-56)
 Redesign Goals
Cost Comparison

SlabDesign
Design
 Slab
26th–Roof
 Shear Wall Design
Construction Management
3rd–25th Floor
Conclusions
Acknowledgements
- $36,000 will be saved if the story height is decreased by 1”
Questions???
Shear Wall Design - Introduction
Presentation Outline
 Intro
Shearwall Redesign Goals
 Building Overview
 Redesign Goals
Make shear walls more cost effective
-
Meet or improve serviceability of structure
Design Method
 Slab Design
 Shear
Design

ShearWall
Wall
Design
-
ETABS with shear wall spreadsheets
-
Must meet ACI318-05
Lateral Loads
3rd–25th Floor
Construction Management
Conclusions
-
Wind Loads were found from a wind tunnel test
-
Wind produced base moments almost twice that of seismic
Serviceability Issues
Acknowledgements
Questions???
-
Original Shear Walls
Viewed from South West
-
Story Drift must be less than L/600
-
Building acceleration must be less than 15 milli-g
Shear Wall Design – Current Layout
Presentation Outline
 Intro
Original Shear Walls
Original Shear Walls
Viewed From South West
Viewed From North East
Original Shear Walls Plan
 Building Overview
 Redesign Goals
 Slab Design
 Shear
Design

ShearWall
Wall
Design
3rd–25th Floor
Construction Management
Design Information
8ksi concrete below 14th floor
Conclusions
6ksi concrete above 14th floor
Serviceability
Total deflection: 3.80” (H/1004)
Acknowledgements
Questions???
Original Shear Walls
Viewed from South West
-
Torsional deflection: 2.82 milli-rad
-
Max story drift: H/759
Shear Wall Design – Considered Layouts
Presentation Outline
Modified Original
 Intro
Additional Wall
 Building Overview
 Redesign Goals
 Slab Design
 Shear
Design

ShearWall
Wall
Design
3rd–25th Floor
Construction Management
Conclusions
Acknowledgements
Questions???
Original Shear Walls
Viewed from South West
Shortened Wall
Core Only
Opposite Wall Only
Shear Wall Design – Considered Layouts
Presentation Outline
 Intro
 Building Overview
 Redesign Goals
 Slab Design
 Shear
Design

ShearWall
Wall
Design
3rd–25th Floor
Construction Management
Conclusions
Acknowledgements
Questions???
Original Shear Walls
Viewed from South West
Shear Wall Design – Alternate Layout
Presentation Outline
Original Shear Walls
Original Shear Walls
 Intro
Viewed From North East
Viewed From South West
 Building Overview
Original Shear Walls Plan
 Redesign Goals
 Slab Design
 Shear
Design

ShearWall
Wall
Design
3rd–25th Floor
Construction Management
Conclusions
Serviceability
Total deflection: 3.81” (H/1002)
Acknowledgements
Questions???
Original Shear Walls
Viewed from South West
Torsional deflection: 2.49 milli-rad
Shear Wall Design – Comparison/Conclusions
Presentation Outline
Serviceability Comparison
 Intro
- New layout reduced torsional deflections by 12%
 Building Overview
- Both layouts have equivalent total deflections and story drifts
 Redesign Goals
Cost Comparison
 Slab Design
 Shear
Design

ShearWall
Wall
Design
3rd–25th Floor
Construction Management
Conclusions
Acknowledgements
Questions???
Original Shear Walls
Viewed from South West
Presentation Outline
 Intro
 Building Overview
 Redesign Goals
 Slab Design
 Shear Wall Design
Construction
Management

Construction
Management
Conclusions
Acknowledgements
Questions???
Construction Management – Schedule Comparison
Schedule Comparison
Presentation Outline
 Intro
 Building Overview
 Redesign Goals
 Slab Design
 Shear Wall Design
Construction
Management

Construction
Management
Conclusions
Acknowledgements
Questions???
Construction Management – Schedule Comparison
Schedule Comparison
Presentation Outline
 Intro
 Building Overview
 Redesign Goals
 Slab Design
 Shear Wall Design
Construction
Management
 Construction
Management
Conclusions
Acknowledgements
Questions???
Construction Management – Construction Issues
Typical Floor Plan (Ground-11th Floor)
Overall Conclusions
Presentation Outline
 Intro
 Building Overview
Serviceability
Exceeded?
More Cost
Effective?
 Redesign Goals
 Slab Design
 Shear Wall Design
Construction Management
Conclusions
 Overall Conclusions
Acknowledgements
Questions???
Post-Tensioned Slab
New Shear Wall Layout

30% less long
term deflection

20% Cheaper

12% less torsional
deflection

5% Cheaper
Acknowledgements
Presentation Outline
 Intro
Thanks to:
 Building Overview
McLaren Engineering
Toll Brother’s Inc.
 Redesign Goals
FxFowle Architects
Dr. Ali Memari
 Slab Design
 Shear Wall Design
The entire AE Department Faculty and Staff
All of the practitioners who participated in the discussion boards
All my friends and family
Construction Management
The Class of 2008
Conclusions

Acknowledgements
Acknowledgements
Questions???
Presentation Outline
 Intro
 Building Overview
 Redesign Goals
 Slab Design
 Shear Wall Design
Construction Management
Conclusions
Acknowledgements
Questions???
Any Questions???
Presentation Outline
 Intro
Existing Ceiling Link Beam Height:
7’-9”
Reduction due to thinner slab:
1”
Reduction for shear walls:
3”
Potential New Ceiling Link Beam Height:
7’-5”
 Building Overview
 Redesign Goals
 Slab Design
 Shear Wall Design
New York City Limit:
Construction Management
Conclusions
Acknowledgements
Questions???
7’-0” (Gives 5” for finishes)
Presentation Outline
 Intro
 Building Overview
 Redesign Goals
 Slab Design
 Shear Wall Design
Construction Management
Conclusions
Acknowledgements
Questions???
Presentation Outline
 Intro
 Building Overview
 Redesign Goals
 Slab Design
 Shear Wall Design
Construction Management
Conclusions
Acknowledgements
Questions???