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Acterna Headquarters

This presentation outlines the structural redesign proposal for the Acterna Headquarters in Germantown, Maryland. The existing building is a six-story office building, and the goal is to eliminate intermediate column lines, update to the IBC 2000 code, and create column-free areas.

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Acterna Headquarters

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  1. Germantown, Maryland Acterna Headquarters John M Sekel The Pennsylvania State University Architectural Engineering 2003 Senior Thesis Presentation Structural Emphasis

  2. Presentation Overview • Existing Building • Proposal • Structural Redesign • Construction Considerations • Architecture Redesign • Mechanical Considerations • Conclusions and recommendations John M Sekel

  3. Existing building • Project Team • Owner: Milestone Industrial, LLC • Architect: Hickok, Warner, Fox Architects • Structural Engineer: Structural Design Group • MEP Engineer: Girard Engineering • General Contractor: L.F. Jennings John M Sekel

  4. Existing Building • General • New corporate campus for Acterna Corporation • Site clearly visible off I-270 outside Washington, D.C. • Six story, 187,500 sf office building • 253’x126’ building footprint • $10 million construction cost • BOCA 1996 design code John M Sekel

  5. Existing Building • Structural • Floor framing • Composite beam and slab construction • 50 ksi wide flange shapes • 30’x25’ typical bays • 3 ¼” lightweight concrete slab on 2” metal decking • 2 – transfer girders over conference room on level 1 • Foundations • Spread footing foundations • 4” first floor slab on grade John M Sekel

  6. Existing Building • Structural • Lateral Frames • 2 – braced frames in each direction John M Sekel

  7. Existing Building • Typical framing plan John M Sekel

  8. Existing Building • Mechanical • VAV boxes with electric duct heaters and reheat coils with VFD • 2 – 15000 cfm VAV A/C units per floor • 2 – 350 ton cooling towers • Plate and frame heat exchanger • Electrical/Lighting • 277/480 volt, 3-phase, 4 wire system • 4000 amp primary switchboard • 2000 amp secondary switchboard • 2’x4’ 277 volt florescent fixtures John M Sekel

  9. Presentation Overview • Existing Building • Proposal • Structural Re-design • Construction Considerations • Architecture Re-design • Mechanical Considerations • Conclusions John M Sekel

  10. Proposal • Structural design goals • Eliminate intermediate column line outside of core • Use long span steel from core to exterior • Economize the structure • Design for ease of construction • Update to IBC 2000 code John M Sekel

  11. Proposal • Architectural design goals • Reflect structural changes in the façade • Open interior spaces, column free areas • Add glazing to lessen “hole-punch” look • Emphasize the drum shape • Predominant architectural feature John M Sekel

  12. Proposal • Construction goals • Reduce construction cost • Reduce construction schedule time • Design building for ease of construction • Mechanical considerations • Analyze impact of façade design on system John M Sekel

  13. Presentation Overview • Existing Building • Proposal • Structural Re-design • Construction Considerations • Architecture Re-design • Mechanical Considerations • Conclusions John M Sekel

  14. Structural depth • Framing Re-design Overview • New bay size outside of core 30’x50’ • 50 ksi wide flange shapes • Most readily available shapes • Possible options • 3 ¼” lightweight concrete slab on 2” metal deck • 2 hour fire rating • Re-size frames for additional gravity load • IBC 2000 lateral loads John M Sekel

  15. Structural depth • Economic steel design measures • Redundant shapes • Simple shear tab connections • Efficient spacing and span direction • Efficient bay size Original 1.5 * 25’ = 37.5’ Redesign 1.5 * 30’ = 45’ Use 50’ to maintain core size John M Sekel

  16. Structural Depth • New framing plan John M Sekel

  17. Structural Depth • New gravity member sizes • Typical Girders • Original: W18 • New Design: W24 • Typical Beams • Original: W14 • New Design: W24 • Typical Interior Column • Original: W12x65 • New Design: W14x120 • Typical Exterior Column • Original: W10x54 • New Design: W14x90 • Deflection criteria controls (L/360) John M Sekel

  18. Structural Depth ƒn calculation 0.18 √[g/(Δg+Δj)] 3.19 Hz • Vibration Analysis • Typical bay analyzed • Wj=157.8 kips • Δj=1.040” • Wg=156.8 kips • Δg’=0.191” • Po=65 lb • β=0.03 • W=157.6 kips ap/g calculation [Po e^(-0.35ƒn)]/βW 0.45%g John M Sekel

  19. Structural Depth • ap/g vs. fn chart • Most accurate between 4 and 8 Hz • Combined mode frequency is 3.19 Hz • Peak acceleration is 0.45% of g • Meets acceptable criteria for office buildings • 0.64% of g at 3.19 Hz John M Sekel

  20. Structural Depth • New Braced Frame Sizes • Original frame layouts and geometries were maintained • Frames 1 & 4: Inverted “V” • Frames 2 & 3: Diagonal • All web members are TS 10”x10”x5/16” • Column sizes increased for higher gravity load • Designed for member strength and drift • Foundations • Spread foundation system • Size and depth increased due to greater load John M Sekel

  21. Presentation Overview • Existing Building • Proposal • Structural Redesign • Construction Considerations • Architecture Redesign • Mechanical Considerations • Conclusions John M Sekel

  22. Construction Breadth • Cost Comparison • RS Means cost estimate for both systems • Cost includes material, labor and equipment John M Sekel

  23. Construction Breadth • Schedule Comparison • Fewer beams to place • Typical floor original: 222 members • Typical floor redesign: 127 members • Fewer columns and foundations • 16 columns removed in redesign • 30% reduction in structure construction time Original Design 20 days foundations 9 weeks superstructure Redesign 14 days foundations 6 ½ weeks superstructure John M Sekel

  24. Presentation Overview • Existing Building • Proposal • Structural Redesign • Construction Considerations • Architecture Redesign • Mechanical Considerations • Conclusions John M Sekel

  25. Architectural Breadth • Reflect change in floor framing Square box-like windows Long, continuous windows John M Sekel

  26. Architectural Breadth • Increase glazing • Emphasize the drum • Vertically spanning glass John M Sekel

  27. Architectural Breadth John M Sekel

  28. Architectural Breadth John M Sekel

  29. Architectural Breadth John M Sekel

  30. Architectural Breadth John M Sekel

  31. Presentation Overview • Existing Building • Proposal • Structural Redesign • Construction Considerations • Architecture Redesign • Mechanical Considerations • Conclusions John M Sekel

  32. Mechanical Breadth • Increase in cooling load • Greater glazing area on facade • Carrier hourly analysis program analysis • Additional 1.5 tons of cooling required per floor • Original system capacity is 92 tons per floor • 1.6% increase • Most likely will not need to resize equipment • Further analysis required John M Sekel

  33. Presentation Overview • Existing Building • Proposal • Structural Redesign • Construction Considerations • Architecture Redesign • Mechanical Considerations • Conclusions John M Sekel

  34. Conclusions • Insignificant cost difference by implementing new system • Shorter construction time • Faster cost return • Improvement to building architecture • Greater tenant flexibility with interior spaces • Good selling point for owner • More notable exterior façade Final Recommendation: Use re-designed structural system John M Sekel

  35. Thank You • Structural Design Group • Mike Weiss • LF Jennings • Kevin Malpass • AE Faculty and staff • Prof. Parfitt, Dr. Geschwinder, Dr. Hanagan • AE classmates • Chris Flynn, Tim Nolan • My parents and roommates for their encouragement and support John M Sekel

  36. Questions? ? ? ? ? ? John M Sekel

  37. Structural Depth • Building Height Comparison John M Sekel

  38. Structural Depth • Plenum heights • 11 ¾” increase per floor • 5’-10 ½” total building height increase John M Sekel

  39. Structural depth • Plenum comparison John M Sekel

  40. Structural Depth • Deflections and camber John M Sekel

  41. Structural Depth • Connections John M Sekel

  42. Structural Depth • Drift John M Sekel

  43. Structural Depth • Drift John M Sekel

  44. Construction Breadth • Working crews • RS Means assumes a steel crew of the following: • (2) Steel foremen • (5) Steel workers • (1) Welder • (1) Welding machine • (1) Oiler operator • (1) Crane operator • (1) 90 ton crane • The daily operating cost for this crew is $4091.40. John M Sekel

  45. Construction Breadth • Crane reach • 60 ton crane • 4 ton pick at 60’ • W21X182 frame column John M Sekel

  46. Construction Breadth • Project delivery system John M Sekel

  47. Construction Breadth • Linear footage comparison • Original structure: 43,300 feet • Redesigned structure: 32,700 feet • Additional cost is hidden in fabrication and materials John M Sekel

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