THE NORTHBROOK CORPORATE CENTER Redesign of the Lateral Load Resisting System

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

1150 Northbrook Drive, Philadelphia, PA

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

Building Statistics

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

STRUCTURAL SYSTEM

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

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

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

BRACED FRAME DESIGN CONTROLLING LATERAL FORCES

BRACED FRAME DESIGN DISTRIBUTION OF LATERAL FORCES

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

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

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

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

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

BRACED FRAME DESIGN Force distribution equation: Distribution of Lateral Forces

BRACED FRAME DESIGN Distribution of Lateral Forces

BRACED FRAME DESIGN Distribution of Lateral Forces

BRACED FRAME DESIGN Distribution of Lateral Forces

BRACED FRAME DESIGN Distribution of Lateral Forces

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

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

BRACED FRAME DESIGN Beam Design LRFD Manual – Specifications section I4 Combined Compression and Flexure in Composite Beams Plastic Moment Analysis Maximum Moment = wl 2 /8 Plastic Moment Capacity - LRFD Tables and by hand Deflection Check – Lower Bound Elastic Moment of Inertia Beams Sizes have not changed significantly

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

BRACED FRAME DESIGN Displacement Check

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 $ per connection TOTAL $199,800

COST COMPARISON CM – Breadth Study REDESIGNED SYSTEM COST ESTIMATE RS Means Shear Connection in Braced Frame: 8 bolts and 72 inches of welding $ per braced connection $ 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

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

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

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

ARCHITECTURAL REDESIGN NEW DESIGN ELECRICAL ROOM

ARCHITECTURAL REDESIGN New handicap parking spaces New Design

ARCHITECTURAL REDESIGN New parking spaces NEW DESIGN

ARCHITECTURAL REDESIGN NEW DESIGN

SUMMARY Braced Frames can successfully resist the lateral forces 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 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 frames create an obstacle in the garage Braced frame system is 33% more cost efficient Braced frame system is 33% more cost efficient In the process of architectural redesign one parking space is lost In the process of architectural redesign one parking space is lost

CONCLUSION Braced frame system is more feasible system for the North Brook Corporate Center if the following conditions are true: Braced frame system is more feasible system for the North Brook Corporate Center if the following conditions are true: 1. All calculations are accurate 2. Change to the interior space of the garage floor level is acceptable 3. Change in the flexibility of the interior space layout is insignificant relative to the cost of the system

REFERANCES

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