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PLAZA AT PPL CENTER Allentown, PA Economical Design Considerations for Steel Construction Amy S. Graver - Structural Option Spring 2003 Senior Thesis.

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Presentation on theme: "PLAZA AT PPL CENTER Allentown, PA Economical Design Considerations for Steel Construction Amy S. Graver - Structural Option Spring 2003 Senior Thesis."— Presentation transcript:

1 PLAZA AT PPL CENTER Allentown, PA Economical Design Considerations for Steel Construction Amy S. Graver - Structural Option Spring 2003 Senior Thesis

2 Plaza at PPL Center Amy S. Graver - Structural PRESENTATION OUTLINE  Introduction  Economical Design Considerations  Moment Frame Comparisons  Braced Frame Design  Composite Floor Evaluation  Mechanical Re-Design  Conclusions INTRODUCTION

3 Plaza at PPL Center Amy S. Graver - Structural  Owner: Liberty Property Trust  Primary Tenant: PPL EnergyPlus  Architect and Landscape: Robert A. M. Stern Architects  Structural Engineers: Thornton-Tomasetti  MEP, Fire Protection: PPL Energy Services Mid-Atlantic, LCC  Construction Manager: L.F. Driscoll  Architect of Record: Kendall/Heaton Associates, Inc.  Civil Engineers: Pennoni Associates  Lighting Consultant: Quentin Thomas Associates, Inc. INTRODUCTION PROJECT TEAM

4 Plaza at PPL Center Amy S. Graver - Structural INTRODUCTION LOCATION LINDEN STREET HAMILTON STREET PLAZA AT PPL CENTER TOWER AT PPL CENTER NORTH BUILDING PROPOSED PARKING GARAGE N. EIGHTH STREET N. NINTH STREET N. TENTH STREET

5 Plaza at PPL Center Amy S. Graver - Structural INTRODUCTION BUILDING FACTS Size  $29 million base building cost, $19 million tenant specific costs  256,000 sq. ft.  200,000 sq. ft. to be leased by PPL Corporation Uses  8-story Multi-use Building  First Floor: Retail Space  Floors 2-6: Office Space for PPL EnergyPlus  Floors 7-8: Energy Securities Trading Floors

6 Plaza at PPL Center Amy S. Graver - Structural INTRODUCTION BUILDING FACTS Architecture  LEED Gold Certification  Central Atrium  Winter Gardens and Roof Top Garden  Glass Façade with Strips of Pre-cast Concrete Panels

7 Plaza at PPL Center Amy S. Graver - Structural Foundation  Partial Basement w/ Poured Concrete Walls  Continuous Concrete Spread Footings Gravity System  Composite Steel Beams  Composite Deck  14’-20’ Stories  30’x42’ Bays  Typical Sizes  Beams: W18  Columns: W14 INTRODUCTION STRUCTURE

8 Plaza at PPL Center Amy S. Graver - Structural INTRODUCTION STRUCTURE Lateral System Moment Frame A Moment Frames B/C Moment Frame D  East-West: Moment Frames  North-South: Braced Frames A D B C

9 Plaza at PPL Center Amy S. Graver - Structural PRESENTATION OUTLINE ECONOMY  Introduction  Economical Design Considerations  Moment Frame Comparisons  Braced Frame Design  Composite Floor Evaluation  Mechanical Implications  Conclusions

10 Plaza at PPL Center Amy S. Graver - Structural CONSIDERATIONS ECONOMY  Low Seismic Design  Braced Frames  Partial Composite Construction % of Construction Costs

11 Plaza at PPL Center Amy S. Graver - Structural PRESENTATION OUTLINE MOMENT FRAME COMPARISONS  Introduction  Economical Design Considerations  Moment Frame Comparisons  Braced Frame Design  Composite Floor Evaluation  Mechanical Re-Design  Conclusions

12 Plaza at PPL Center Amy S. Graver - Structural SEISMIC DESIGN Allentown, PA  Not Considered a High Seismic Area  Seismic Design Category B Under More Recent Codes  Seismic Can Control  Subject to Seismic Provisions when R>3 MOMENT FRAME COMPARISONS

13 Plaza at PPL Center Amy S. Graver - Structural SEISMIC DESIGN Ductility  Lower Base Shear with Increased Ductility Response Modification Factor  To account for ductility of a system  C s is indirectly proportional to R  Since V= C s W, a l ower R-Factor corresponds to a higher base shear MOMENT FRAME COMPARISONS

14 Plaza at PPL Center Amy S. Graver - Structural SEISMIC DESIGN Applied Code: IBC 2000  References AISC Seismic Provisions & Supplement 1  Connections must be designed by Seismic Provisions if R>3 AISC Seismic Provisions for Structural Steel Buildings  Connections must be stronger than connected members  Classifies moment frames based on a rotation criteria MOMENT FRAME COMPARISONS

15 Plaza at PPL Center Amy S. Graver - Structural Connection Moment Capacity per AISC MpMp MpMp 1.1R y M p MuMu Connection Moment Capacity per FEMA 350 1.1R y M p MuMu Response Modification Factor R=8 R=6 R=4 R=3 Four Types of Moment Frames  Special Moment Frames (SMF)  Intermediate Moment Frames (IMF )  Ordinary Moment Frames (OMF)  Steel Systems not Detailed for Seismic Resistance Required Rotation θ=0.4 radians θ=0.2 radians None DESIGN STATEMENT MOMENT FRAME COMPARISONS

16 Plaza at PPL Center Amy S. Graver - Structural Comparison  SMF  IMF  OMF  R=3 DESIGN STATEMENT MOMENT FRAME COMPARISONS Decreasing R-Factor Increasing Base Shear Less Stringent Detailing Larger Members Smaller Connections More EconomicalFaster Construction DifferencesResults

17 Plaza at PPL Center Amy S. Graver - Structural Connection Design  FEMA 350: rotation criteria  SMF & IMF  LRFD Manual: strength design  OMF & R=3 Web-Bolted, Flange-Bolted Connections  Approved for Seismic Use  Tested by Federal Emergency Management Agency (FEMA)  Meets Rotation Requirements for SMF and IMF CONNECTIONS MOMENT FRAME COMPARISONS

18 Plaza at PPL Center Amy S. Graver - Structural Included Costs  Material Costs  Fabrication Labor  Erection Labor Excluded Costs  Quality Inspection  Special Fabrication Procedures COST COMPARISON MOMENT FRAME COMPARISONS

19 Plaza at PPL Center Amy S. Graver - Structural R=3 SMF Actual Loads Design Capacity of Members Strong Column, Weak Beam Smaller Members CONNECTION COMPARISON MOMENT FRAME COMPARISONS Moment Frame A W18x60 W24x62 W14x74W14x99 Deeper Beams Heavier Columns

20 Plaza at PPL Center Amy S. Graver - Structural COMPARISON MOMENT FRAME COMPARISONS

21 Plaza at PPL Center Amy S. Graver - Structural 1000 hrs. of Fabrication Time  Cost of Stiffeners  Saves 3 weeks  Critical Path  Added Float  Start Later Erection  Remains on Critical Path  Dependent on Sitework and Foundation SCHEDULE EFFECTS MOMENT FRAME COMPARISONS 3 weeks

22 Plaza at PPL Center Amy S. Graver - Structural PRESENTATION OUTLINE BRACED FRAME ANALYSIS  Introduction  Economical Design Considerations  Moment Frame Comparisons  Braced Frame Design  Composite Floor Evaluation  Mechanical Re-Design  Conclusions

23 Plaza at PPL Center Amy S. Graver - Structural Results of the Moment Frame Comparison  Low Seismic is More Economical  Connections Drive Cost Try Braced Frames in East-West Direction  Eliminates 410 Moment Connections  Works Within the Proposed Floor Plan DESIGN STATEMENT BRACED FRAME DESIGN

24 Plaza at PPL Center Amy S. Graver - Structural Chevron Braced  Adequate for Proposed Openings  14’ Minimum Floor-to-floor Height  Accommodates a Double Door Tenant Fitout  Rooms along column grids  30-year lease Try Braced Frames ARCHITECTURE BRACED FRAME DESIGN

25 Plaza at PPL Center Amy S. Graver - Structural FLOOR PLANS BRACED FRAME DESIGN Existing Moment Frames Proposed Braced Frames

26 Plaza at PPL Center Amy S. Graver - Structural DESIGN BRACED FRAME DESIGN Seismic is the Governing Lateral Force for Members  Concentric Braced Frame  R=3  V=1182K Typical Sizes  W14 Columns and Braces to Match North-South Direction  W24x68 Beams

27 Plaza at PPL Center Amy S. Graver - Structural COST COMPARISON BRACED FRAME DESIGN Included Costs  Moment frame members now sized for gravity only  Additional cost of connections above a typical shear connection

28 Plaza at PPL Center Amy S. Graver - Structural Additional Time Savings  Fabrication  Not on the critical path  Adds 3 weeks of float  Erection  On the critical path  Project Completion: 3 weeks earlier SCHEDULE BRACED FRAME DESIGN Project Complete: April 30, 2003 Project Complete: April 12, 2003

29 Plaza at PPL Center Amy S. Graver - Structural PRESENTATION OUTLINE COMPOSITE FLOOR EVALUATION  Introduction  Economical Design Considerations  Moment Frame Comparisons  Braced Frame Design  Composite Floor Evaluation  Mechanical Re-Design  Conclusions

30 Plaza at PPL Center Amy S. Graver - Structural Cost of 1 Shear Stud = 10lbs. of Steel  $0.50 Material Cost  $1.50 Labor Cost Try Partial Composite  Is a heavier beam with fewer shear studs more economical? DESIGN STATEMENT COMPOSITE CONSTRUCTION

31 Plaza at PPL Center Amy S. Graver - Structural FLOOR PLANS COMPOSITE CONSTRUCTION Floors 2-6 Existing: 100% Composite Re-design: 90% Composite W18x35 [48] W18x35 [44]

32 Plaza at PPL Center Amy S. Graver - Structural FLOOR PLANS COMPOSITE CONSTRUCTION Floors 1, 7-8 Existing: 100% Composite Re-design: 40% Composite W18x40 [48] W21x44 [24]

33 Plaza at PPL Center Amy S. Graver - Structural COMPARISON COMPOSITE CONSTRUCTION Total Building Savings

34 Plaza at PPL Center Amy S. Graver - Structural PRESENTATION OUTLINE MECHANICAL RE-DESIGN  Introduction  Economical Design Considerations  Moment Frame Comparisons  Braced Frame Design  Composite Floor Evaluation  Mechanical Re-Design  Conclusions

35 Plaza at PPL Center Amy S. Graver - Structural Composite Beam Comparison  W18 to W21  3” decrease in usable ceiling plenum Original Design  28”x12” SA duct below beams  Air Flow Rate = 2500CFM  Air Velocity = 1150FPM  Static Pressure Drop = 0.1in.w.g. DESIGN STATEMENT MECHANICAL EFFECTS

36 Plaza at PPL Center Amy S. Graver - Structural Initial Size Problems  9” duct height is required to maintain existing plenum  To supply 2500CFM at 0.1in.w.g.,  42”x9” required  Does not meet the 4-to-1 width-to-height ratio RE-DESIGN MECHANICAL EFFECTS

37 Plaza at PPL Center Amy S. Graver - Structural SOLUTION MECHANICAL EFFECTS Design  2500CFM First 16’  1900CFM Past Branch Results  Turning Vanes in Elbow  4-to-1 Ratio past Branch  Maintains Design Criteria 34”x9”42”x9” 600CFM VAV Box

38 Plaza at PPL Center Amy S. Graver - Structural PRESENTATION OUTLINE MECHANICAL RE-DESIGN  Introduction  Economical Design Considerations  Moment Frame Comparisons  Braced Frame Design  Composite Floor Evaluation  Mechanical Re-Design  Conclusions

39 Plaza at PPL Center Amy S. Graver - Structural Cost Savings  Moment Frames with R=3...$22,000  Braced Frames........... $100,000  Composite Construction.....$5,300 Time Savings  Moment Frames with R=3... Fabrication: 3 weeks  Braced Frames........... Fabrication: 6 weeks........... Erection: 3 weeks ECONOMY CONCLUSIONS

40 Plaza at PPL Center Amy S. Graver - Structural Braced Frames are Most Economical Lateral System  Feasible with architectural layout  $100,000 cost savings  Project Completion: 3 weeks earlier Deeper, Heavier Beams with Less Composite Action  Increases floor depth  Ceiling plenum height retained with shallower duct RECOMMENDATIONS CONCLUSIONS

41 Plaza at PPL Center Amy S. Graver - Structural ACKNOWLEDGMENTS CONCLUSIONS Pennoni Associates: Civil Engineer  Frank Adams, P.E., AIA  Jeff Ott, P.E.  Ed Sander, P.E.  The Adams Division Thornton-Tomasetti: Structural Engineer  Hi Sun Choi, P.E. L.F. Driscoll: Construction Manager  Ed Jackowski Stewart-Amos Steel  Curt Zeigler A huge thank you to everyone one who answered questions, provided information and offered support… your time and efforts are greatly appreciated. AE Faculty  Dr. Hanagan, P.E.  Walt Schneider, P.E.  Professor Parfitt, P.E.  Jonathan Dougherty AE Class of 2003  Rebecca Mittel  Melissa Rosol My Family and Friends  Last but certainly not least…

42 Plaza at PPL Center Amy S. Graver - Structural QUESTIONS CONCLUSIONS ?

43 Plaza at PPL Center Amy S. Graver - Structural QUESTIONS CONCLUSIONS ?

44 Plaza at PPL Center Amy S. Graver - Structural RESULTS MECHANICAL EFFECTS  Higher Air Velocity to Maintain Air Flow Rate  Increased noise through diffusers  Not a large enough increase to impact occupants  Duct meets industry standard for 4-to-1 ratio


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