JAMES DEAN BAKER ALCOA CORPORATE CENTER STRUCTURAL OPTION 201 ISABELLA STEET

Transcription

1 JAMES DEAN BAKER STRUCTURAL OPTION ALCOA CORPORATE CENTER 201 ISABELLA STEET

2 PRESENTATION OUTLINE Introduction Existing Conditions Structural Existing Conditions Design Goals and Criteria Suspension Design Connections Cost Analysis & Schedule Impacts Constructability Process Daylighting Controls Design Results and Recommendations Conclusion

3 OWNERS: I N T R O D U C T I O N ~ Design Team ~ Aluminum Company of America ARCHITECT: ENGINEERS: The Design Alliance Atlantic Engineering Service (STRUCTURAL) Dodson Engineering (MECHANICAL) Hornfleck Engineering (ELECTRICAL) GENERAL CONTRACTORS: Turner Construction

4 ALCOA CORPORATE CENTER LOCATION EXISTING CONDITIONS 7 th th and 9 th St. Bridges bookend the building Along the Allegheny River North Shore of Pittsburgh

5 ALCOA CORPORATE CENTER EXISTING CONDITIONS Building Information Occupancy: Office Space, Company Headquarters Mid-Rise Structure, 6 Stories 236,200 sq. ft. of Flexible Office Space Below Grade Parking for 180 Vehicles Total Cost of 67 million dollars Completed in July of 1998

6 ALCOA CORPORATE CENTER Typical Floor Plan:

7 STRUCTURAL SYSTEMS FOUNDATION: FLOORING SYSTEMS: SUPERSTRUCTURE : ROOF: CONNECTIONS: MOMENT FRAMES: BRACED FRAMES: 1400 Auger Cast Friction Piles 6 composite floor slab with a raised floor plenum Steel Moment Frame (office Section) Steel Frame with Braced Frames (supporting area) Glass ceiling with structural steel framing Full Moment connections throughout the office area Office section of the building, full penetration welds Lateral resisting system mainly in north side of the structure

8 Existing Conditions Braced Frames: Types: I, II, III, IV Stiffness: I: 19.2 k/in II: 19.2 k/in III: 20.4 k/in IV: k/in TYPE III TYPE I TYPE I Lateral System Layout TYPE III TYPE IV TYPE II MOMENT FRAMES TYPE I Moment Frames: Type: I Stiffness: 55.6 k/in

9 DESIGN GOALS Add an Exposed Roof Truss System Support the Exterior of the Office Area Remove Full Moment Connections Add Pin Type Connections Establish Structurally Feasible Constructability and Cost Improve Lighting Controls

10 Typical Floor Layout Examples of the Areas to be Suspended

11 Beams: W 18 x 35 (typ.) W 24 x 55 (typ.) Connections Shear Type (inner) Seat Angles (outer) EXTERIOR BEAMS Office Section

12 Truss Systems Cable Tension Suspension System Options 4 Symmetrical Spans Two Large Spans Several Shorter Spans

13 SUSPENSION BRIDGE Truss Type Original Columns: New Columns: Original Connections: Full Moment Proposed Connections: Shear Welds Hangars: W12 x 30 (top) W10 x 19 (bottom)

14 SUSPENSION BRIDGE Truss Type Truss Type : Back to Back Channels: MC6 x 18 Plate Welded Connections: 3/8 welds Gusset Plate Connections: 1 thick plates Bottom Chord: W36 x 245 Extended Columns: W12 x 83

15 SUSPENSION BRIDGE Cable Tension Type OVERVIEW Original Columns: W 12 x 72 New Columns: W 12 x 83 Cable Connections: Clamp Type Cable Sizing: 7 Compact 0.6 diameter bundles of 270 ksi wires Buckling Difficulties in the columns Recommendation: Not Viable due to Aesthetics, and Story Connection difficulties

16 Truss Locations

17 Truss Configuration

18 Connections Truss Connections Welded Gusset Plate Connectors 12 Longitudinal Welds Required 3/8 E 70 xx Fillet Weld Both Sides of Both Channels

19 Hanger Connections Connect to the W 24 x 55 Beams via Angled Bolted Connections Connections Beams are Spliced at 2 Story intervals Ranging in Size from W W 12 x 30 in the Upper Levels W W 10 x 19 in the Bottom Levels Sizes Decrease as they go down the Building Due to Lower Cumulative Loads on the Hangers

20 COST BENEFIT ANALYSIS RS Means, $67,000 for Field Welds - $35,000 for Weld Inspections +$53,700 for Crew & Crane = $48,000 SAVINGS Pushes Schedule Back One Week Steel Erection Becomes Critical Path

21 INITIAL SCHEDULE

22 FINAL SCHEDULE

23 CONSTRUCTABILITY PHASE ONE PHASE TWO Friction Piles Foundations Sub Level Columns Inner Beams North Side Truss Placement Build Back Down the Outside, Connecting

24 LIGHTING CONTROLS Lightscape Rendering of the Daylighting in the Main Office Areas Use of Open Loop Photo Sensors which Sense Daylight and Electric Light Proportional Controllers

25 LIGHTING CONTROLS Proportional Controllers Produce a Voltage that is Inversely Proportional to the Detected Light Perform By Dimming the Electric Lights in a Linear Relationship According to Settings Zoning of the Office Spaces Two Zones in the Office Area Group Fixtures Run Parallel to the Windows Separate Control for Each Zone (outer & inner) Features of Control Independent Behavior Read their own Zone Target Illumination

26 DESIGN RESULTS Floor: Full Moment Connections are Removed. Camber must be Increased to 5.25 for Floor: the 60 ft. interior office beams Roof: Remains Largely Unchanged, Structurally. Columns are held at W 12 x 83. Span Beams on Roof Remain W 36 x 245 Roof: Suspension Systems: Symmetrical Dual Channel Truss Placed on Roof to Suspend the Exterior of the Structure Lighting: Controls Selected for Power Savings During Elevated Day Light Times Lighting: Cost: Modest Savings Foundations: Remain Unchanged

27 FINAL RECOMMENDATIONS Structural: Owners Consent I Recommend to build it to Pay Homage to the Bridges of the City of Pittsburgh Constructability Timing Becomes Critical

28 THANK YOU ALL OF THE AE FACULTY AND STAFF FRIENDS FAMILY ATLANTIC ENGINEERING SERVICE PERSONNEL JULES AND JEFF-FRY FRY FOR COMING OUT TO SEE THIS PRESENTATION. MUCH LOVE TO ALL THE PEEPS WHO PUT UP WITH MY HECTIC DAYS OF EXHAUSTION. I D LIKE TO OPEN THE FLOOR TO QUESTIONS PLEASE