U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590

Skip to content U.S. Department of Transportation/Federal Highway AdministrationU.S. Department of Transportation/Federal Highway Administration

Bridges & Structures

Steel Girder Design Flowchart Chart 3

  1. Obtain Design Criteria Design Step 3.1

    Commentary for 1: Includes project specific design criteria (such as span configuration, girder configuration, initial spacing of cross frames, material properties, and deck slab design) and design criteria from AASHTO (such as load factors, resistance factors and multiple presence factors).

  2. Select Trial Girder Section Design Step 3.2

  3. Composite section?

  4. Compute Section Properties for Composite Girder S6.10.3.1 Design Step 3.3

    Commentary for 4: Considerations include: Sequence of loading (S6., Effective flange width (S4.6.2.6)

  5. Compute Section Properties for Noncomposite Girder S6.10.3.3 Design Step 3.3

  6. Compute Dead Load Effects S3.5.1 Design Step 3.4

    Commentary for 6: Includes component dead load (DC) and wearing surface dead load (DW).

  7. Compute Live Load Effects S3.6.1 Design Step 3.5

    Commentary for 7: Considerations include: LL distribution factors (S4.6.2.2), Dynamic load allowance (S3.6.2.1)

  8. Combine Load Effects S3.4.1 Design Step 3.6

    Commentary for 8: Includes load factors and load combinations for strength, service, and fatigue limit states.

  9. Check Section Proportion Limits S6.10.2 Design Step 3.7

    Commentary for 9: Considerations include: General proportions (, Web slenderness (, Flange proportions (

  10. Are section proportions adequate?

  11. Composite section?

  12. Compute Plastic Moment Capacity S6. & Appendix A6.1 Design Step 3.8

  13. Determine if Section is Compact or Noncompact S6.10.4.1 Design Step 3.9

    Commentary for 13: Considerations include: Web slenderness, Compression flange slenderness (N only), Compression flange bracing (N only), Ductility (P only), Plastic forces and neutral axis (P only)

  14. Compact section?

  15. Design for Flexure - Strength Limit State S6.10.4 (Flexural resistance in terms of moment) Design Step 3.10

  16. Design for Flexure - Strength Limit State S6.10.4 (Flexural resistance in terms of stress) Design Step 3.10

    Design for Shear S6.10.7 Design Step 3.11

  17. Commentary for 17: Considerations include: Computations at end panels and interior panels for stiffened or partially stiffened girders, Computation of shear resistance, Check D/tw for shear, Check web fatigue stress (S6.10.6.4), Check handling requirements, Check nominal shear resistance for constructability (S6.

  18. Transverse intermediate stiffeners?

    Commentary for 18: If no stiffeners are used, then the girder must be designed for shear based on the use of an unstiffened web.

  19. Design Transverse Intermediate Stiffeners S6.10.8.1 Design Step 3.12

    Commentary for 19: Design includes: Select single-plate or double-plate, Compute projecting width, moment of inertia, and area, Check slenderness requirements (S6., Check stiffness requirements (S6., Check strength requirements (S6.

  20. Longitudinal stiffeners?

    Commentary for 20: If no longitudinal stiffeners are used, then the girder must be designed for shear based on the use of either an unstiffened or a transversely stiffened web, as applicable.

  21. Design Longitudinal Stiffeners S6.10.8.3 Design Step 3.13

    Commentary for 21: Design includes: Determine required locations, Select stiffener sizes, Compute projecting width and moment of inertia, Check slenderness requirements, Check stiffness requirements

  22. Is stiffened web most cost effective?

  23. Use unstiffened web in steel girder design.

  24. Use stiffened web in steel girder design.

  25. Design for Flexure - Fatigue and Fracture Limit State S6.6.1.2 & S6.10.6 Design Step 3.14

    Commentary for 25: Check: Fatigue load (S3.6.1.4), Load-induced fatigue (S6.6.1.2), Fatigue requirements for webs (S6.10.6), Distortion induced fatigue, Fracture

  26. Design for Flexure - Service Limit State S2. & S6.10.5 Design Step 3.15

    Commentary for 26: Compute: Live load deflection (optional) (S2., Permanent deflection (S6.10.5)

  27. Design for Flexure - Constructability Check S6.10.3.2 Design Step 3.16

    Commentary for 27: Check: Web slenderness, Compression flange slenderness, Compression flange bracing, Shear

  28. Check Wind Effects on Girder Flanges S6.10.3.5 Design Step 3.17

    Commentary for 28: Refer to Design Step 3.9 for determination of compact or noncompact section.

  29. Have all positive and negative flexure design sections been checked?

  30. Were all specification checks satisfied, and is the girder optimized?

  31. Draw Schematic of Final Steel Girder Design Design Step 3.18

  32. Return to Main Flowchart


1 go to 2
2 go to 3
3 if yes go to 4
3 if no go to 5
4 and 5 go to 6
6 go to 7
7 go to 8
8 go to 9
9 go to 10
10 if no go to 2
10 if yes go to 11
11 if no go to 13
11 if yes go to 12
12 go to 13
13 go to 14
14 if yes go to 15
14 if no go to 16
15 and 16 go to 17
17 go to 18
18 if no go to 20
18 if yes go to 19
19 go to 20
20 if no go to 22
20 if yes go to 21
21 go to 22
22 if no go to 23
22 if yes go to 24
23 and 24 go to 25
25 go to 26
26 go to 27
27 go to 28
28 go to 29
29 if no go to 13 and repeat flexural checks
29 if yes go to 30
30 if no go to 2
30 if yes go to 31
31 go to 32
<< previous Contents next >>
Updated: 06/27/2017
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000