200 Minuteman Drive. New Design for Additional Floors and Vibration Sensitive Equipment. Brent Ellmann. Structural Option

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1 200 Minuteman Drive New Design for Additional Floors and Vibration Sensitive Equipment Brent Ellmann Structural Option Dr. Linda Hanagan - Consultant

2 Project Players Owner- Brickstone Properties Architects-Burt Hill Kosar Rittleman Associates Structural Engineers- Atlantic Engineering Services MEP Firm- H. F. Lenz Co. C M Firm- Gilbane Building Company Geotechnical Firm- Miller Engineering and Testing, Inc.

3 Existing Building Conditions Location: Andover, MA 3 stories with 200,000 square feet of office space Cost: $15 million Designed and built with PictureTel Inc. as primary tenant

4 Existing Structure Composite Floor System 4 inch slab + 2 inch deck W18x35 beams and W24x76 girders K Joist Roof System Square footings and strip footings Braced frames

5 Existing Structure Composite Floor System K Joist Roof System 22K6 joists supported by W24x55 girders W18x35 beams used to support rooftop AHUs Square footings and strip footings Braced frames

6 Existing Structure Composite Floor System K Joist Roof System Square footings and strip footings Square footings range in size from 5-0 x 5-0 to x Strip footings vary in size from 1-2 to 2-8 wide Braced frames

7 Existing Structure Composite Floor System K Joist Roof System Square footings and strip footings Braced frames Steel Tube and W shapes used as cross braces Maximum brace width limited to 10 to maintain wall thicknesses

8 Existing Mech./Elec./Arch. Mechanical 6 air handling units with DX cooling coils (25,000 CFM) and ducted supply with a plenum return VAV system 2 cast iron- sectioned boilers (Gross Output 2103 MBH) Electrical Main switchboard is a 480 Volt/2500 Amp switchboard Typical light is a three tube FO32/T-8 8 fluorescent fixture Architectural Insulated metal panels, with low-e reflective glazing, on the southern façade Northern facing curved facade is a limestone veneer, with low-e reflective glazing

9 Presentation Outline New Building Height and Floor Sizes by Code Mechanical (Breadth) Increased Air Handling Capacity Duct Sizing Boiler Design Electrical (Breadth) Increased switchboard capabilities Structural (Emphasis) Floor Vibration Study Braced Frame Design Foundation Design

10 Goals of New Design Maintain owner s original wishes while adding additional floors All steel building Open office plan to allow for future tenant changes Improve performance of floor under vibration excitement due to walking for sensitive equipment Allow for varying use of building by multiple tenants at once

11 Code Limits (Per 780 CMR: The Massachusetts State Building Code) Classified as a 2B Protected Building Maximum Height 85 (with sprinklers) Maximum Number of Stories 6 Stories (with sprinklers) Maximum Allowable Floor Area 74,250 square feet per floor

12 New Design 14-7 floor to floor heights clerestory maintained New building height is Floor Areas: First Floor: 67,765 sq. ft. 2 nd -5 th Floors: 65,800 sq. ft. Total Floor Area: 331,000 sq. ft.

13 Presentation Outline New Building Height and Floor Sizes by Code Mechanical (Breadth) Increased Air Handling Capacity Duct Sizing Boiler Design Electrical (Breadth) Increased switchboard capabilities Structural (Emphasis) Floor Vibration Study Braced Frame Design Foundation Design

14 Mechanical Design Each half of a floor has own dedicated AHU to maintain multi-tenant tenant capabilities 10 AHUs located on roof -25,000 cfm each All vertical runs from AHUs to floor are 84x32 rectangular ducts Two Zones Exterior Zone air supplied through linear diffusers attached to fan boxes (200 cfm) ) with reheat capability Interior Zone air supplied by VAV boxes (160 cfm) New Cast Iron Boilers 3500 A-G-14 A Series - net output of 3187 MBH (required output = 3050 MBH)

15 AHU Locations

16 Presentation Outline New Building Height and Floor Sizes by Code Mechanical (Breadth) Increased Air Handling Capacity Duct Sizing Boiler Design Electrical (Breadth) Increased switchboard capabilities Structural (Emphasis) Floor Vibration Study Braced Frame Design Foundation Design

17 Electrical Design

18 New Switchboard 3,500 Amp Busing 65,000 Amp Short Circuit Rating

19 Presentation Outline New Building Height and Floor Sizes by Code Mechanical (Breadth) Increased Air Handling Capacity Duct Sizing Boiler Design Electrical (Breadth) Increased switchboard capabilities Structural (Emphasis) Floor Vibration Study Braced Frame Design Foundation Design

20 Floor Vibration Criteria Goal: Allow for a variety of technology and research based companies to use this facility Design carried out using Design Guide 11 and the development of a spreadsheet Sensitive equipment limit set at that of laboratory robots Maximum Vibration Velocity 4,000 µin/sec

21 Compared Systems Original System New System

22 Comparison Beam Mode Girder Mode Combined Mode Original Composite System Frequency (Hz) Deflection (in.) N/A Beam Mode Girder Mode Combined Mode Non-Composite System Frequency (Hz) Deflection (in.) N/A Mid-Bay Flexibility 4.58 x 10-6 in/lb Mid-Bay Flexibility 3.62 x 10-6 in/lb Slow Walking Moderate Walking Fast Walking Vibration Velocities (µin/sec.) System 902 4,569 20,563 Max. Allow. 4,000 4,000 4,000 Slow Walking Moderate Walking Fast Walking Vibration Velocities (µin/sec.) System 667 3,377 15,199 Max. Allow. 4,000 4,000 4,000

23 Wind Braced Frame Design-Loads Basic Wind Velocity = 90 mph Exposure Category B Frequency = 2.00 Hz Pressure = 18 psf Seismic S S = 0.30 g and S 1 = 0.09 g T = 0.50 seconds Seismic Design Category B W = 35,390 kips; C S = 0.058; V = 2,053 kips

24 Critical Loading Low building height results in small wind pressures Building s location in an area of higher seismicity results in larger than normal seismic forces Wind Loads Seismic Loads Story Shear (K) Story Shear (K) Roof 5 th 4 th 3 rd Roof 5 th 4 th 3 rd C R I T I C A L 2 nd nd 150

25 Frame Locations Critical Design Frames

26 Frame H-34 H (N-S) Columns: W12x72 W12X152 Braces: Beams:

27 Frame H-34 H (N-S) Columns: W12x72 W12X152 Braces: W10x33 W10x49 Beams:

28 Frame H-34 H (N-S) Columns: W12x72 W12X152 Braces: W10x33 W10x49 Beams: W24x55 W27x84

29 Frame 3-HJ 3 (E-W) Columns: W12x72 W12X152 Braces: Beams:

30 Frame 3-HJ 3 (E-W) Columns: W12x72 W12X152 Braces: TS10x10x1/2 Beams:

31 Frame 3-HJ 3 (E-W) Columns: W12x72 W12X152 Braces: TS10x10x1/2 Beams: W24x94 W24x162

32 Foundation Design Square footings used under columns and strip footings used around perimeter of building Engineered soil placed under footings Compressive Strength = 6,000 psf 3,000 psi concrete used for all footings

33 Critical Frame Footings Worst Case Load: Axial Load = 1,620 Kips Moment = 220 foot- kips Double Layer of reinforcing steel needed to fit spacing requirements Pier size increased to 3-0 to handling bearing requirements

34 Uplift Force Problem: Earthquake forces develop large uplift on footings Solution: Grade Beam attaching to adjacent footings

35 Grade Beam 3-0 x 5-0 beam spanning over four square footings Double layer of steel used in both faces Bottom of beam lines up with bottom of footings

36 Conclusions Two floors can be added onto the original design New Building Height = Usable Office Space = 330,000 sq. ft. Mechanical Systems: Four more AHUs placed on roof (10 total) Boilers capacity increased by 1000 MBH each Electrical Systems: Dual Main-tie tie-main switchboard increased to a 3,500 amp busing switchboard

37 Floor System: Conclusions Change to a non-composite system to reduce floor vibrations to a level acceptable for a wider variety of sensitive equipment Braced Frames: Building s taller height and large lateral forces required stiffer frames Foundations: Grade beam added to handle large uplift forces developed on the square footings under the braced frames

38 Thank You Andrew Verrengia - Atlantic Engineering Services William McGhee - H.F. Lenz Dr. Linda Hanagan- Structural Consultant Katie Trail Electrical and Lighting Emphasis Sam Snyder Mechanical Emphasis Friends and Family

39 Questions???