1 / 44

Forging New Generations of Engineers: Loads and Structural Members

This article explores the purpose, stability, strength, and economic value of loads and structural members in engineering. It discusses different types of loads, load paths, and the design process for a steel-framed retail building. Calculations and design considerations for interior and exterior beams, girders, columns, and footings are presented. The article also includes comparisons and design results for various structural elements.

ronaldrogers
Download Presentation

Forging New Generations of Engineers: Loads and Structural Members

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Forging new generations of engineers

  2. Loads and Structural Members

  3. Purpose • Stability • Strength • Economic Value

  4. Types of Loads • Dead • Live • Wind • Impact/Shock/Vibration • Seismic

  5. Loads and Load Paths Snow, Movable Furniture, and Occupancy = LL Permanent Fixtures and Weight of Structural Materials = DL Ground Reaction

  6. Dead Load Live Load Structural Efficiency Structural Efficiency

  7. Factor of Safety Live Loads * 1.7 Dead Loads * 1.4

  8. Beam Types • Simple • Continuous • Cantilever • Moment fixed at one end

  9. Pin Connection Roller Connection Fixed Support Supports

  10. Load Distribution • Uniform Loading Concentrated Loading Combination Loading

  11. Columns F (External) Designed for compression. Additional loads can cause bending in the columns. WCOL (External) WFTG (External) RSoil (External)

  12. Building Design Problem • A Steel Framed Retail Building with Concrete Floors and Flat Roof

  13. Steps in Design Process • Plan/ Layout Structural Grid • Establish loads • Size the members • Evaluate and Compare to preliminary design • Redesign

  14. Structural Elements Exterior Beam Interior Beams Girders Footing Column

  15. Framing with Foundation Plan Design Area

  16. Beam C.2-3 Tributary or Contributing Area Tributary Area 6’- 0” Tributary Width Girder 2AD Column A-2

  17. Roof Beam C.2-3 Data • Dead Load=(DL) • 1/8” thick steel plate 10 lb/ft2 • Roofing material 10 lb/ft2 • Suspended Ceiling 2 lb/ft2 • Mechanical/ Electrical Items 10 lb/ft2 • Total DL 32 lb/ft2 • Live Load=(LL) • Snow Total LL 20 lb/ft2 • Assumed Beam Weight per ft. • W12 x 16 Total 16 lb/ft • Tributary widthTotal 6’- 0” • Span = LTotal 16’- 0”

  18. Interior Roof Beam C.2-3 Calculations • Load = (DL + LL) x Tributary width • (32 lb/ft2 + 20 lb/ft2 ) x 6.0 ft = 312.0 lb/ft • Add the Assumed Beam Weight of 16 lb/ft • Total Uniform Load (W1) = Load + Beam Weight per ft. • 312.0 lb/ft + 16 lb/ft= 328.0 lb/ft • Use 328.0 lb/ft for Uniform Load (W1)

  19. Interior Roof Beam C.2-3 Calculations • End Reaction Forces of Beam C.2-3 • (W1 x L) / 2 = R2 = R3 • 328.0 lb/ft x 16 ft / 2 = 2,624.0 lb • Maximum Moment Force of Beam C.2-3 • (W1 x (L)2) / 8 = Mmax • 328.0 lb/ft x 162 ft2 / 8 = 10,496.0 ft-lb • Use 10,496.0 ft-lb for Moment (M)

  20. Roof Beam C.2-3 Moment and Shear Shear Diagram Moment Diagram

  21. Exterior Beam A.2-3 Calculations • Beam Load • W = (DL + LL)½(Trib.width) • W = (52 lb)1/2(6 ft) = 156 lb/ft • Total Uniform Load on Exterior Beam • W = Load + Beam weight per ft. • W = 156 lb/ft + 16 lb/ft = 172.0 lb/ft

  22. Exterior Beam A.2-3 Calculations • Reaction Forces • (W)(L)/8 = R2 =R3 • (172.0 lb/ft)(16 ft)/2 = RA2 = RA3 = 1376.0 lb Shear Diagram

  23. Fb = (Yield Strength) (36,000 psi) =24,000 psi Fb = Allowable Bending Stress Allowable Bending Stress = Fb • A36 Structural Steel – 36,000 psi

  24. = Section Modulus (S) Fb = 24,000 psi M = 10,496 ft-lb 10,496 ft-lb x 12 in/ft 24,000 lb/in2 SRequired = SRequired = 5.248 in3

  25. MDSolids Design Roof Beam C.2-3

  26. MDSolids Design Roof Beam C.2-3

  27. Deflection limited to: Beam C.2-3 Deflection (16ft)(12 in/ft) 360 = .533 in.

  28. Beam C.2-3 Comparisons SELECT

  29. Girder 2AD Data Girder 2AD Span Length is 18 feet. Concentrated Load = 5248 lb Uniform Load = 24 lb/ft

  30. Girder 2AD Calculations • End Reaction Forces of Girder 2AD • P1 + (W x L) / 2 = RA =RD • 5248 lb + (24 lb/ft x 18 ft) / 2 = 5464 = • RA =RD • 5,464 lb

  31. Girder 2AD Calculations • Maximum Moment Force of Girder 2AD • (W1 x L2) / 8 + P1 d = M • 24.0 lb/ft x 182 ft2 / 8 + 5248 lb x 6 ft = 32,460 ft-lb • Use 32,460.0 ft-lb for Moment (M)

  32. Girder 2AD Moment and Shear Shear Diagram Moment Diagram

  33. = Fb = 24,000 psi 32,460 ft-lb x 12 in/ft 24,000 lb/in2 SRequired = Girder Section Modulus (S) M = 32,460 ft-lb SRequired = 16.23 in3

  34. Girder 2AD Section Modulus (S)

  35. Design Results (18’) X (12)in.ft 360 = Deflection Limit = Deflection Limit = 0.6”

  36. Loads on Column and Footing Roof Loads Column A-2 Soil Bearing Reaction

  37. Loads on Column - Footing • Column Self Weight • 15 ft x 20 lb/ft (estimated) = 300 lb • Girder Reaction Force = 5,464 lb • Ext. Beams x 2 = 2(1,376 lb) = 2,752 lb • Total 8,516 lb • Use 9,000 lbs

  38. Available Soil Bearing Capacity • Soil Capacity Available=3000 lb/ft2 - 150lb/ft2 = 2850 lb/ft2 = qnet Footing wt. = (1 ft)(150 lb/ft3) = 150 lb/ft2 Allowable Soil Bearing Capacity= 3000 lb/ft2

  39. 9000 lb 2850 lb/ft2 Area = Sizing the Footing • Load Column = 9,000 lbs Soil Capacity Available= 2850 lb/ft2 = qnet =1.78 ft Use 2’- 0” x 2’- 0” Square Footing

  40. The Solutions: • Beam C.2-3 W10x12 • Girder 2AD W12x19 • Column A-2 W12x22 • Footing 2’ x 2’

  41. Steps in Design Process • Plan/ Layout Structural Grid • Establish loads • Size the members • Evaluate and Compare to preliminary design • Redesign

  42. Structural Layout for our building

  43. References: Examples Morrow, H.W. (1998). Statics and Strength of Materials, Upper Saddle River, NJ: Prentice Hall

  44. Credits: Writer: Gary Platt Content Editor: Sam Cox & Wes Terrell Production Work: CJ Amarosa Publisher: CJ Amarosa – Project Lead The Way Virtual Academy for Professional Development – www.pltw.org

More Related