1. Civil Engineering and Architecture
Structural Loads
Part 2
Civil Engineering and Architecture
Unit 6 Structures

2. In this lesson: Solve the Building Design Problem “Chase” the Load
Calculate Beam and Girder Loading
Select the Beam and Girder Size
Size the footings

3. Building Design Problem
A Steel Framed Retail Building with Concrete Floors and Flat Roof
Please click here to obtain Revit file of the building.

4. Second Floor Framing
Girder
Beam
Column
Footing

5. Design Steps

6. Load Chasing for this Problem
Calculate beam loading, obtain reactions
Transfer reaction loads to girder
Carry girder reactions to column then to footing

7. Foundation Plan

8. Partial 2nd Floor Framing Plan
Design Area

9. Tributary or Contributing Area
6’8” Width
Beam B.3
Column B-3
Girder 3BC

10. Calculating Beam Loading
Please click here to obtain “Steps for Calculating Beam Loading.”

11. Dead and Live Load Documents
Click Here for the Live Load Sheet
Click Here for the Dead Load Sheet

12. 2nd Floor Beam, Girder Calculations
2nd Floor Loading for Beam B.3 - Dead Load
Span Length 18’-0”
Dead Load
4” thick concrete slab lb/ft2
Flooring- Ceramic Tile lb/ft2
Partitions (Drywall with metal stud) lb/ft2
Suspended Ceiling lb/ft2
Mechanical/ Electrical Items lb/ft2
Total DL 80 lb/ft2
Assumed Dead Load Weight of Beam: 20 lb/ft

13. 2nd Floor Beam, Girder Calculations
2nd Floor Loading for Beam B.3 - Live Load
Live Load
Retail Space lb/ft2
Total Load DL + LL (per lineal foot of beam)
[80lb/ft lb/ft2 ] x ft = lb/ft
Add the Beam Weight of 20 lb/ft
Total DL + LL + Beam Weight = lb/ft
Use 1090 lb/ft

14. 2nd Floor Beam B.3 Calculations
MD Solids
Span Length is 18 feet.
Uniform Load w = 1090 lb/ft

15. 2nd Floor Beam B.3 Calculations
MD Solids – Shear and Moment Diagrams
Moment
Shear

16. Allowable Bending Stress
Allowable Bending Stress = Fb
(Yield Strength)
Fb =
A36 Structural Steel – 36,000 psi
(36,000 psi) = 24,000 psi
Fb =
(50,000 psi) = 33,000 psi
Fb =

17. Section Modulus = M = 44,145 ft-lbs Fb = 24,000 psi =
SRequired = in3

18. MDSolids Design Results B.3

19. Design Results for B.3- con.

20. Professional Development Lesson ID Code: 8009
Beam B.3 Deflection
Deflection limited to:
216 in
360 =
0.6 in
Professional Development Lesson ID Code: 8009

21. Beam B.3 Comparisons Beam Sz (in3) Deflection (inches) W10x22 23.2
0.7523
W12x22
25.4
0.5691
W14x22
29.0
0.4461
W10x26
27.9
0.6165
W12x26
33.4
0.4352
W14x26
33.5
0.3624
SELECT

22. Girder 3BC Calculations
Beam B.3
Span Length is 18 feet.
Uniform Load = 1090 lb/ft
P1 = P2 = (18ft)(1090 lb/ft)
P1 = P2 = 19,620 lb.

23. Girder 3BC Moment and Shear

24. Design Results Deflection Limit = = Deflection Limit = 0.666” Girder
Sz (in3)
Deflection (inches)
W16x45
72.7
0.5773
W18x46
78.8
0.4761

25. Footing Calculations

26. Footing Loads Loads Considered
Allowable Soil Bearing Capacity = 3000 lb/ft2
Loads Considered
Dead & Live load from 2nd floor and roof
Column’s weight (dead load)
Load from 1st floor slab
Dead load from footing

27. Roof Load
Roof Type: Corrugated Steel Deck with insulation and 5 ply membrane roof and gravel, located in Rochester NY.
Dead Load
Suspended Ceiling lb/ft2
Mechanical Equipment lb/ft2
Steel Deck lb/ft2
Insulation lb/ft2
Roof Membrane and Gravel lb/ft2
Roof Framing lb/ft2
Total DL 35 lb/ft2

28. Roof Load – Snow Snow Load Rochester, NY 55 lb/ft2 Total Load on Roof
DL + SL = 35 lb/ft lb/ft2 = 90 lb/ft2
Axial Load on Column B-3 from Roof
Tributary Area of Roof = 18 ft x 20 ft = 360 ft2
(DL + SL)(Trib. Area) = (90 lb/ft2)(360 ft2) = 32,400 lb

29. Loads on Column and Footing
1st Floor/ Slab Loads
Soil Bearing Reaction
Roof Loads
2nd Floor Loads
Column B-3

30. Loads on Column - Footing
Loads on the Column
2nd Floor
Girder x 2 = 2(20,120 lb) = 40,240 lb
Beams x 2 = 2(9,810 lb) = 19,620 lb
Roof
Concentrated Load = 32,400 lb
Column Self Weight
21 ft x 50 lb/ft (estimated) = 1,050 lb
Total 93,310 lb
Use 94,000 lbs

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

32. Use 6’-0” x 6’-0” Square Footing
Sizing the Footing
Load Column Footing = 94,000 lbs
Soil Capacity Available = lb/ft2 = qnet
Use 6’-0” x 6’-0” Square Footing

33. The Solutions: Beam B.3 W12x22 Girder B3B W16x45
Footing under Column B-3 6’ x 6’

34. Curriculum Alignment:
Unit 6 – Structural Engineering
Lesson 6.1 – Introduction to Structural Engineering
Act. 1.1 – Structural Calculations
Act. 1.2 – More Load Calculations
Lesson 6.2 – Roof Systems
Lesson 6.3 – Columns and Beams

35. References:
Jefferis, A. & Madsen, D.A. (2001). Architectural Drafting and Design, Albany, NY: Delmar
Kane, K. & Onouye B., (2002). Statics and Strength of Materials for Architecture and Building Construction, 2nd ed., Saddle River, NJ: Pearson Education, Inc
Shaeffer, R.E. (2002). Elementary Structures for Architects and Builders, 4th ed.. Columbus, OH: Prentice Hall
Manual of Steel Construction, 8th ed., American Institute of Steel Construction

36. Credits: Writer: Constance Bertucci Content Editor: Donna E. Scribner
Narration: Donna E. Scribner
PLTW Editor: Ed Hughes
Production: CJ Amarosa
Video Production: CJ Amarosa
Audio: CJ Amarosa
Project Manager: Donna E. Scribner