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A senior design presentation in Structural Engineering

A senior design presentation in Structural Engineering

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Capstone Design Presentation Capstone Design Presentation Presentation Transcript

  • Structural Design of Office Building with Design Variations for Natural Hazardous Environments Nkonyeasua G. Adaikpoh Tennessee State University, Department of Architectural Engineering April 15, 2009
  • Introduction Mr. Moneybags International has decided to expand his company’s offices to 3 new markets. In a bid to move quickly he hires a Structural Engineer to perform a feasibility design per his requirements and thereafter report the results and cost. Structural Analysis and Design - Nkonyeasua G. Adaikpoh
  • Design Evolution Architectural Components Governing Texts: 1. International Building Code (IBC 2006) 2. Architectural Graphics Standards 3. The Architect’s Studio Companion Structural Analysis and Design - Nkonyeasua G. Adaikpoh
  • Locations Characteristics All in the downtown areas of the cities. Stiff soils – well compacted Disaster prone – added lateral forces San Francisco New Orleans Oklahoma City In San Andreas Caused damage Gently rolling fault zone. of $1 Billion+ in hills & shrubs Pleasant 2005 Temperate, sub- weather Hurricanes humid climate Earthquakes Tornadoes Structural Analysis and Design - Nkonyeasua G. Adaikpoh
  • Disaster Definitions Earthquakes Hurricanes Tornadoes Ground shaking Severe cyclones Violent storms caused by originating over characterized by tectonic equatorial whirling funnels processes. regions, of wind moving Measured on the accompanied by at great speeds. Richter torrential rain, Measured on an magnitude scale, lightning, & enhanced Fujita in magnitudes. winds with scale, in speeds >74mph categories. Measured on a Saffir-Simpson scale, in categories. USGS NOAA NOAA
  • Effects on Buildings Earthquakes Hurricanes Tornadoes Photo courtesy USGS and NGDC Stan Honda/AFP/Getty Images © How Stuff Works
  • Requirements Translation
  • Preliminary Design Occupancy classification – B - Business 3-Hour Noncombustible construction Type I-A Sprinklered building Unlimited height and area Site cast concrete system Two-way post-tensioned flat plate slab with 30’ x 30’ bays 300’ maximum travel distance Open plan
  • Planning Maximum travel distance – 300ft
  • Shear Wall Stiffness Distribution – Code compliant b h Area, Ai xi dx (xi- dy (yi- Ix =bh3/12 + Iy =bh3/12 + % % Tower Shape (in) (in) (in2) (in) Aixi (in3) yi (in) Aiyi (in3) xbar) ybar) Adx2 (in4) Ix TOWER Ady2(in4) Iy TOWER stiffness x stiffness y Tower 2 - Tower 1 - Top right Top left 252130 32760 480 15724800 1381 45241560 -421.05 360.40 5854056115 4301279897 stair - 228106 -24168 480 -11600640 1381 33376008 -421.05 360.40-4262040695 1592015420 -3116512746 1184767152 42.22% 22.82% 132 252130 32760 0 43243200 1381 45241560 418.94 360.40 5796018744 4301279897 stair 132 - 228106 -24168 0 -31901760 1381 33376008 418.94 360.40-4219224847 1576793897 -3116512746 1184767152 41.82% 22.82% Tower 4 - Bottom Tower 3 - Bottom left elevator 110232 25520 805 20543600 640 16332800 -96.054 -380.59349925238.7 3811194440 - - 86208 -17888 805 -14399840 640 11448320 -96.054 -380.59 100550905.1 249374333.6 -2526694458 1284499982 6.61% 24.74% right stair 128256 32768 988 32374784 640 20971520 86.945 -380.59426667210.7 4925603018 - - 104232 -24128 988 -23838464 640 15441920 86.945 -380.59 74173893.91 352493316.8 -3386866861 1538736157 9.35% 29.63% SUM = 33456 30145680 34145184 3770676967 5192770442 100.00% 100.00% Center of stiffness for the building xbar = 901.1in = 75.1ft ybar = 1020.6in = 85.0ft Ix = 3770676967in4 Iy = 5192770442in4
  • Shear Wall Stiffness Distribution – Code compliant Column stiffness check Largest column size = 36 x 36 in Area, Ai Aiyi Ix =bh3/12 Shape b (in) h (in) (in2) xi (in) Aixi (in3) yi (in) (in3) (in4) 6IX (in4) Iy =bh3/12 (in4) 6Iy (in4) Column 36 36 1296 18 23328 18 23328 139968 839808 139968 839808 Check: IWALL ≥ 6ICOLUMNS Smallest IX WALL = 249374333.6 > 839808in4 Smallest IY WALL = 1184767152 > 839808in4 ACI 318 Code discussion on slenderness and stiffness
  • Architectural Programming Shape from McCormac & Nelson Open plan - 30ft x 30ft grid Dimensions - 150ft x 120ft Floor Area - 17,100sf Building Area - 17,100sf x 20 floors Occupant load- 100sf/occupant Egress requirement- 0.2”/occupant Min. egress width/floor = 0.2” x 171 occupants = 34.2” Exit stairway - 30” clear
  • Architectural Plans South elevation Typical Floor Plan
  • Architectural Plans Section and partial 3-D view
  • Design Evolution Summary Mixed use structure with parking for all occupants in same building. Single use structure, 20 Mid-rise building floors, regular floor plan in 3 locations in 3 locations.
  • Design Evolution Structural Components Governing Texts: 1. International Building Code (IBC 2006) 2. ASCE/SEI 7-05 Minimum Design Loads for Buildings and Other Structures 3. ACI 318-05 Building Code Requirements for Structural Concrete 4. Building Codes Illustrated 5. Building Structures Illustrated Structural Analysis and Design - Nkonyeasua G. Adaikpoh, EIT
  • Structural Effects/Requirements Produce lateral forces which the building must resist via a LFRS – Lateral Force Resisting system. Aims: Durability Ductility Reliability
  • Structural Requirements LFRS – Shear Walls Diaphragm – 2-way flat slabs Aims: Durability Ductility Reliability
  • Loading Dead Load: 8” slab - 100psf Partition - 10psf MEP - 8psf Ceiling - 2psf Misc. - 5psf Total - 125psf
  • Loading Live Load: 80 psf – considering light storage, and partition locations
  • Loading: Wind Loads V = 150mph, New Orleans MWFRS is ex = 2.75 In designed to resist ey = 300.625 In Case 1 high hurricane and PE-W PN-S ForceN-S tornado force Heights (ft) 15 PWx 7.0 PLx -37.3 (psf) 44.4 ForceE-W (kips) 39.9 PWy 7.0 PLy -37.3 (psf) 44.4 (kips) 49.9 winds. 30 45 11.4 14.2 -37.3 -37.3 48.7 51.5 43.8 46.4 11.4 14.2 -37.3 -37.3 48.7 51.5 54.8 58.0 60 16.3 -37.3 53.7 48.3 16.3 -37.3 53.7 60.4 75 19.0 -37.3 56.4 50.7 19.0 -37.3 56.4 63.4 90 20.0 -37.3 57.4 51.6 20.0 -37.3 57.4 64.5 105 21.0 -37.3 58.4 52.5 21.0 -37.3 58.4 65.6 120 21.0 -37.3 58.4 52.5 21.0 -37.3 58.4 65.6 135 23.5 -37.3 60.9 54.8 23.5 -37.3 60.9 68.5 150 25.0 -37.3 62.3 56.1 25.0 -37.3 62.3 70.1 165 26.0 -37.3 63.3 57.0 26.0 -37.3 63.3 71.3 180 27.0 -37.3 64.3 57.9 27.0 -37.3 64.3 72.4 195 27.8 -37.3 65.1 58.6 27.8 -37.3 65.1 73.2 210 28.5 -37.3 65.9 59.3 28.5 -37.3 65.9 74.1 225 29.3 -37.3 66.7 60.0 29.3 -37.3 66.7 75.0 240 30.1 -37.3 67.5 60.7 30.1 -37.3 67.5 75.9 255 30.9 -37.3 68.2 61.4 30.9 -37.3 68.2 76.8 270 31.6 -37.3 68.9 62.0 31.6 -37.3 68.9 77.6 285 32.3 -37.3 69.6 62.7 32.3 -37.3 69.6 78.3 300 33.0 -37.3 70.3 63.3 33.0 -37.3 70.3 79.1 305 33.2 -37.3 70.5 63.5 33.2 -37.3 70.5 79.4
  • Loading: Wind Loads Designed to withstand Code-required wind loads Includes torsional moments due to eccentricity of the shear walls and quartering winds.
  • Loading: Wind Loads Wind loading animation – 100% amplification
  • Loading: Seismic Loads Seismic Loads Development Chapter 11, 12, and 14 in ASCE/SEI 7-05 code
  • Loading: Seismic Load Development Steps to Seismic Design 1. Determine the mapped 6. Determine Seismic Importance Factor, I maximum considered 7. Determine seismic base shear, V earthquake (MCE) spectral 8. Distribute V over the height of the response SS and S1. building 2. Determine if the structure is 9. Determine redundancy coefficient, ρ exempt from seismic 10. Determine seismic load effects, E and EM requirements 11. Check drift control requirements 3. Determine seismic design Base shear distribution over the height of the building - San Francisco requirements (SDC) Story MTx MTy Height Height Weight Force F (kip- (kip- 4. Determine Analysis Level (ft) (ft) (kips) W i Hi k Cvx (kips) ft) ft) 1 15 15 3240 571320 0.003 8 48 60 procedures 2 15 30 3240 2147072 0.012 30 180 225 3 15 45 3240 4657801 0.025 65 391 489 5. Determine R, Response 4 5 15 15 60 75 3240 3240 8068892 12356971 0.044 0.067 113 173 678 1038 847 1298 Modification Coefficient 6 7 15 15 90 105 3240 3240 17504439 23497225 0.095 0.128 245 329 1471 1974 1838 2468 8 15 120 3240 30323630 0.165 425 2548 3185 9 15 135 3240 37973664 0.207 532 3190 3988 10 15 150 3240 46438621 0.253 650 3902 4877 Total 150 32400 183539635 1.000 2570
  • Loading: Seismic Loads Designed to withstand Code required seismic loads OTM shown
  • Loading: Seismic Loads Seismic loading animation – 100% amplification
  • Loading: Seismic Loads Seismic loading animation – 50% amplification
  • Design: pca Column – Shear Wall Design
  • Design: pca Column – Column Design
  • Construction Comparison San Francisco New Orleans Oklahoma City Less building – More building – Same building as 10 floors 20 floors for New Orleans Special R.C. Ordinary R.C. Wind speed is Shear Walls Shear Walls less in Oklahoma Column Column than for New dimensions – 28” dimensions– 30” Orleans, but the x 28” x 30” disasters exact Rough concrete Rough concrete - similar forces – 6730yd3 11000 yd3 Rough concrete - Reinforcing – Reinforcing - 11000 yd3 375 tons 700 tons Reinforcing - 700 tons Structural Analysis and Design - Nkonyeasua G. Adaikpoh, EIT
  • Concluding summary San Francisco New Orleans Oklahoma City More building – 20 More building – 20 Less building – 10 floors floors floors About twice as 54% more rebar 46% less much rebar More than twice reinforcing bars 61% more concrete the amount of SF’s 39% less concrete than SF concrete. Cost - $161.85/sf, Cost - $139.90/sf, $45, 328,000 total Cost - $ 139.90/sf, $27,677,000 total $45,328,000 total Structural Analysis and Design - Nkonyeasua G. Adaikpoh, EIT
  • F.A.Q. • Isn’t the building a tall building? The Council of tall buildings states that “A tall building is not defined by its height or number of stories. The important criterion is whether or not the design is influenced by some aspect of “tallness.” It is a building in which “tallness” strongly influences planning, design and use. It is a building whose height creates different conditions in the design, construction and operation from those that exist in “common” buildings of a certain region and period. • Did you consider the soils in designing? Yes, e.g. the seismic design category is based on a mixture of the location on the earth, the soil type, and the surrounding environment. • Why didn’t you consider flood loads in your design since the areas you mentioned frequently have flooding? Flood loads are inconsequential to commercial construction once the building is above a certain height, and the wave crest won’t have a significant effect on the building. • How about the cost of land and building in these places? Well the client would have already sourced the amounts for land in the 3 locations and the building costs differ but I used a national average. Structural Analysis and Design - Nkonyeasua G. Adaikpoh, EIT
  • F.A.Q. Contd. • What are rigid diaphragms? Rigid diaphragms according to the ASCE 7-05 code are diaphragms of concrete slabs or concrete filled metal deck with span-to-depth ratios of 3 or less in structures that have no horizontal irregularities. • Did you consider P-delta effects in your design considering the height of the building? Yes, in the analysis and design software, RISA-3D and pca-Column I specified the program to calculate P-Δ effects. Structural Analysis and Design - Nkonyeasua G. Adaikpoh, EIT
  • Acknowledgements • Russell Skrabut, PE, LEED AP • C.W. Yong, PE, LEED AP • Professor Michael Samuchin, PE, LEED AP Structural Analysis and Design - Nkonyeasua G. Adaikpoh, EIT
  • THE END San Francisco New Orleans Oklahoma City QUESTIONS? More building – 20 More building – 20 Less building – 10 floors floors floors About twice as 54% more rebar 46% less much rebar More than twice reinforcing bars 61% more concrete the amount of SF’s 39% less concrete than SF concrete. Cost - $161.85/sf, Cost - $139.90/sf, $45, 328,000 total Cost - $ 139.90/sf, $27,677,000 total $45,328,000 total Structural Analysis and Design - Nkonyeasua G. Adaikpoh, EIT