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THE NORTHBROOK CORPORATE CENTER

This proposal outlines the architectural and structural redesign of The Northbrook Corporate Center's lateral load resisting system, focusing on the use of braced frames for cost efficiency and improved flexibility of interior space.

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THE NORTHBROOK CORPORATE CENTER

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  1. THE NORTHBROOK CORPORATE CENTER Redesign of the Lateral Load Resisting System

  2. OUTLINE • Architectural Overview • Structural Overview • Proposal • Braced Frame Design • Breadth – Cost Comparison • Breadth – Redesign of Interior Space • Summary and Conclusion • References • Credits / Acknowledgements

  3. 1150 Northbrook Drive, Philadelphia, PA

  4. Architectural Overview • 5 Stories – 74 ft high • 109,000 SF of Office Area • Garage • Flexible Floor Layout • Brick • Curtain Glass Wall • Stone Tile • Flat Roof

  5. Building Statistics

  6. STRUCTURAL SYSTEM • 4 inch Concrete Slab • 9/16” – 26 GA. UFS form deck • Composite Steel Joist (26k7) • Steel Composite Girders (W18x35) • Steel Columns (W24x68) • Shallow Concrete Foundation

  7. STRUCTURAL SYSTEM

  8. STRUCTURAL SYSTEM Lateral Force Resisting System • Moment Frame • 150 Moment Connections per Story • 750 Moment Connections in the Building • Roof - 15 ft-k moment capacity • 3rd Story – 30 ft-k moment capacity • Garage – 2nd Story – 40 ft-k moment capacity Typical Moment Connection

  9. Problem – Moment Connections are too expensive Solution – Braced Frame System PROPOSAL

  10. MOMENT FRAME Flexible Floor layout No abstractions BRACED FRAME Cost efficient Simple connections Greater stiffness Smaller columns size in non-resisting frames PROPOSAL

  11. BRACED FRAME DESIGN CONTROLLING LATERAL FORCES

  12. BRACED FRAME DESIGN DISTRIBUTION OF LATERAL FORCES

  13. BRACED FRAME DESIGN PLACEMENT OF BRACED FRAMES • Design must preserve the flexibility of the original system • Diagonal braces are located in the frames with permanent walls • The design is symmetrical

  14. BRACED FRAME DESIGN Distribution of Lateral Forces • Relative Stiffness Analysis • Center of Rigidity : (0, 82.6) ft • Polar Moment of Inertia =362429 feet cubed

  15. BRACED FRAME DESIGN Distribution of Lateral Forces Case 1: Wind Parallel to Y axis

  16. BRACED FRAME DESIGN Distribution of Lateral Forces Case 2: Wind Parallel to X axis

  17. BRACED FRAME DESIGN Distribution of Lateral Forces Case 3: Wind at 45 degrees with the Y axis

  18. BRACED FRAME DESIGN Distribution of Lateral Forces Force distribution equation:

  19. BRACED FRAME DESIGN Distribution of Lateral Forces

  20. BRACED FRAME DESIGN Distribution of Lateral Forces

  21. BRACED FRAME DESIGN Distribution of Lateral Forces

  22. BRACED FRAME DESIGN Distribution of Lateral Forces

  23. BRACED FRAME DESIGN Distribution of Lateral Forces Axial Force in Each Member Braced Frame A

  24. BRACED FRAME DESIGN Column Design • LRFD Manual – Specifications section E-2 • Braced Frame Columns • Buckling about the y-y axis • Most columns have increased in size

  25. BRACED FRAME DESIGN Beam Design • LRFD Manual – Specifications section I4 • Combined Compression and Flexure in Composite Beams • Plastic Moment Analysis • Maximum Moment = wl2/8 • Plastic Moment Capacity - LRFD Tables and by hand • Deflection Check – Lower Bound Elastic Moment of Inertia • Beams Sizes have not changed significantly

  26. BRACED FRAME DESIGN Design of Diagonals • LRFD Manual – Specifications section E-2 • Flexural Forces due to self weight were ignored • Buckling about the y-y axis

  27. BRACED FRAME DESIGN Displacement Check

  28. COST COMPARISON CM – Breadth Study MOMENT CONNECTION COST ESTIMATE • Detailed Cost Estimate using RS Means • 750 moment connections in the building • Typical Moment Connection: 18 bolts and 60 inches of welding • $8.05 per bolt • $19.30 per linear ft of weld • $25 for the angles • Approximately $266.40 per connection • TOTAL $199,800

  29. COST COMPARISON CM – Breadth Study REDESIGNED SYSTEM COST ESTIMATE • RS Means • Shear Connection in Braced Frame: 8 bolts and 72 inches of welding • $240.20 per braced connection • $150.50 per non-braced connection • Total Cost of Connections: $118,182 • Added weight of Steel: 48,870 lbs • Steel - approximately $570 per ton • Total cost of added Steel: $13,928 • TOTAL cost of the braced system: $132,110

  30. Moment Connections: $199,800 Braced Frame: $132,110 Difference: $67,690 (33%) Columns in non-braced frames are expected to decrease in size, making the braced frame system even more cheaper. COST COMPARISON CM – Breadth Study Comparison

  31. Braced Frame “G” blocks two handicap parking spaces ARCHITECTURAL REDESIGN Breadth Study PROBLEM • Braced Frame “C” is an obstacle in the electrical room

  32. Number of parking spaces should be reserved Handicap parking spaces must have a loading area Distance between new wall and existing column should be more than 56 inches (width of the doors) Electrical Mechanical Systems Area should be approximately preserved ARCHITECTURAL REDESIGN POINTS OF CONSERNS

  33. ARCHITECTURAL REDESIGN NEW DESIGN ELECRICAL ROOM

  34. New handicap parking spaces ARCHITECTURAL REDESIGN New Design

  35. New parking spaces ARCHITECTURAL REDESIGN NEW DESIGN

  36. ARCHITECTURAL REDESIGN NEW DESIGN

  37. SUMMARY • Braced Frames can successfully resist the lateral forces • Flexibility of the interior space layout is preserved, however, in some cases braced frames extend beyond the boundaries of permanent wall • Braced frames create an obstacle in the garage • Braced frame system is 33% more cost efficient • In the process of architectural redesign one parking space is lost

  38. CONCLUSION • Braced frame system is more feasible system for the North Brook Corporate Center if the following conditions are true: • All calculations are accurate • Change to the interior space of the garage floor level is acceptable • Change in the flexibility of the interior space layout is insignificant relative to the cost of the system

  39. REFERANCES

  40. CREDITS AND ACKNOWLEDGEMENTS • Thanks to AE faculty and staff who made my experience at Penn State enjoyable. • Special Thanks to • Dr. Louis F. Geschwinder • M. Kevin Parfitt • Dr. Ali Memari • Thanks to my family and friends

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