TOWERS CRESCENT BUILDING B Mike Synnott Structural

OVERVIEW Site Information Historical Breadth Existing Structure Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt OVERVIEW Site Information Historical Breadth Existing Structure Proposal Design for Gravity Design of Lateral Resistance Cost Analysis Conclusion

Site Information Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Site Information

Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Location: Vienna, Virginia 9 Stories Height – 122’ 9” Occupancy - Retail/Office 1 of 3 Buildings On Site Red – Towers Crescent Original building Blue – Building B Green – Building C Buildings B & C Based off Original Building

History Breadth Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt History Breadth

Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Original Towers Crescent Building  Original Site Plan to have 3 Identical Buildings Total Square Footage – 450,000 sf/Building New Design to Create 5 Smaller Buildings Total Square Footage – 900,000 sf 2 of the 5 Buildings Built, 1 in Design, 2 in Planning Design of Building B Based Off Original Building Due To Architectural Importance, Height Of Building B Not Considered in Analysis

Philip Johnson Architect of Original Building Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Philip Johnson Architect of Original Building Designer of Such Buildings as: The Glass House – 1949 Crystal Cathedral – 1980 AT&T Headquarters – 1984 Transco Tower – 1983 Transco Tower AT&T Headquarters Crystal Cathedral The Glass House

Existing Structure Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Existing Structure

Floor System: Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Floor System: 210’ x 110’ Footprint 2 Typical Bay: 40’ x 30’ 30’ x 30’ Composite Steel Floor 2” Metal Deck 3 ¼” Slab Shear Studs to Transfer Load

Lateral Resistance System Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Lateral Resistance System Steel Braced Frames 4 Frames North/South Direction 2 Frames East/West Direction Limits Drift to 1.5” < 3.68” Allowable Drift North/South Frames East /West Frames

Proposal Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Proposal

Design 2 Alternate Structures and compare to Existing Structure Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Design 2 Alternate Structures and compare to Existing Structure First Alternate Structure: Column Layout Same As Existing Structure Two Way Concrete Flat Slab Beams Spanning Between All Columns Two Way Post Tensioning Shear Walls

Second Alternate Structure: Addition Row of Columns Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Second Alternate Structure: Addition Row of Columns Two Way Concrete Flat Slab Drop Panels Shear Walls Resisting Lateral Loads

Design for Gravity Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Design for Gravity

First Alternate Structure Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt First Alternate Structure Floor System Typical Bays: 40’ x 30’ 30’ x 30’ 9”, Post Tensioned, Flat Slab Interior Beams – 16” x 18” Exterior Beams – 24” x 24”

Post Tensioning Longitudinal Tendons Lateral Tendons Spaced 10’ O.C. Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Post Tensioning Lateral Tendons Spaced 5’ O.C. 15 Strands Along Beams 2 Strands Between Beams Profile Points: At Ends - 17.5" At Mid-span - 3" Longitudinal Tendons Spaced 10’ O.C. 25 Strands For Most 27 For 40’ Spans Profile Points: At Ends - 21" At Mid-span - 3.5"

Column Design Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Column Design

Second Alternate Structure Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Second Alternate Structure Floor System Typical Bay: 30’ x 27.5’ 7” Flat Slab 7” Drop Panels

Column Design Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Column Design

Design of Lateral Resistance Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Design of Lateral Resistance

Both Alternate Structures Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Both Alternate Structures Shear Walls Located Around All Openings in Slab 12” Thickness Total Drift – 0.79” < 3.68” Allowable Drift Deflection of North/South Facing Walls Deflection of East/West Facing Walls

Cost Analysis Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Cost Analysis

Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Construction Times Existing Structure – 51 Days Alternate 1 – 135 Days Alternate 2 – 126 Days

Conclusion Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Conclusion

When Not Considering Height Changes: Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt When Not Considering Height Changes: Not Considered due to Architectural Constraints Existing Structure Most Efficient Design Lowest Cost Shortest Construction Time Simple Design When Considering Height Changes: Ignoring Architectural Constraints Second Alternate Structure Most Efficient 18” per floor saved - 13'-6" Total Much Lower Overall Cost ~ $45 million vs. $48 million

Questions? Towers Crescent Building B Mike Synnott Structural Option Advisor – Kevin Parfitt Questions?

1st Alternate Structure 2nd Alternate Structure