1. Floor Systems & Framing of Floors
Residential Architectural Drafting

2. Floor System Types — Conventional Dimensional Lumber Framing

3. Floor System Types — Open Web Floor Joist

4. Floor System Types — Truss Joist Floor Framing

5. Floor System Types — Post and Beam Floor Framing

6. Design Criteria for Structural Loading
Load Types
Dead loads
Live loads
Dynamic loads

7. Dead Loads
Definition: (DL) loads that make up the actual weight of the structure, such as walls, floors, roofs and any permanently fixed loads such as furnace, air conditioner or other service equipment. Materials that make up the walls, such as, studs, plywood, insulation, sheet rock, nails, glue, etc. are DL.
Building codes specify a minimum of 10#/sq ft for floors and ceilings, DL = 10#/sqft

8. Live Loads
Definition: (LL) loads that are fluctuating and changing through the use of the building. These loads include: people, furniture, and exterior weather related items such as, ice, snow, rain, etc.
Building codes specify the amount of live load upon type of use or occupancy. Codes differ, common residential LL = 40#/sq ft

9. Dynamic Loads
Definition: loads imposed on the structure by outside natural forces, such as wind and earthquake.
Wind loads
Shear wall design used to resist wind pressure
Uplift forces placed upon the roof
Earthquake loads
Seismic loads causing lateral forces on entire structure

10. Typical Loads for Residential Construction
See Text

11. Framing Spacing Practices
Code based, acceptance varies
Spacing Options
12” OC
16” OC
19.2” OC
24” OC
Common Spacing

12. Load Consideration for one Joist
Considering 12” OC joist spacing
Considering 16” OC joist spacing
Considering 19.2” OC joist spacing
Considering 24” OC joist spacing
12”
15’-0” SPAN
1’ X 15’ = 15 SQFT X 50 = 750#
16”
12’-0” SPAN
1.33’ X 12’ = SQFT X 50 = 798#
19.2”
18’-0” SPAN
1.6’ X 18’ = 28.8 SQFT X 50 = 1440#
24”
10’-0” SPAN
2’ X 10’ = 20 SQFT X 50 = 1000#

13. Sizing Joist Using Span Tables
Loading reactions of wood members
For every action there is an equal and opposite reaction, creates a “state of rest”
Two types of actions or stresses
Fiber Bending Stress (Fb)--a bending stress
Modulus of Elasticity (E)--stiffness of structure
considered as the deflection or amount of sag when structural members are given a load.
Deflection Allowances (Stiffness)
Floor = 1/360
Roof = 1/240

14. Table Values Look up values for lumber type & grade See Text
Normal Duration for fiber stress (Fb)
Typical consideration for floor loads
Modulus of Elasticity (E)
See Text
Fb = fiber
stress in
bending
E = Modulus
of Elasticity
(Stiffness)

15. Construction Lumber Considerations — Wood Type & Quality
Wood Type Available in Area
Douglas Fir-Larch (North)
Hemlock-Fir (North)
Spruce-Pine-Fir (North)
Southern Pine
Wood Quality or Grade Value
Select Structural (Best)
No. 1/No. 2 (Normally specified)
No. 3 (Worst)

16. E Fb Required: Find the Fiber Stress in Bending and the
Modulus of Elasticity of a 2x8 Douglas fir-Larch
for grade No.1/No.2 (see text) E Fb
DOUGLAS FIR-LARCH

17. Hem-Fir Fb E Required: Find the Fiber Stress in Bending and the
Modulus of Elasticity of a 2x10 Hemlock-Fir
for grade No.1/No.2
Hem-Fir Fb E

18. Joist Sizing & Spacing Problem #1: Span = 11’-8” Hem-Fir
See Text
Problem #1:
Span = 11’-8”
Hem-Fir
1st Step--find E:
E = 1.6
Joist Sizing & Spacing 1
2nd Step--Use E and find size to fit span 2 *
3rd Step--find Fb value (2x8):
Fb = 1,380
Value
is under
1,380
so it
works!
4th Step--determine
if Fb works with E
Solution = (E controls failure--all fits) 4

19. Joist Sizing & Spacing See Text Problem #2: Span = 14’-9” Douglas Fir
1st Step--find E:
E = 1.6 1
2nd Step--Use E and find sizes to fit span
3rd Step--find Fb value (2x10):
Fb = 1,045 2
4th Step-determine
if Fb works with E
Value
is over
1045 it 4
doesn’t
work!
5th Step--using Fb
find working column
Solution: 16 OC(Fb is tendency to failure) 4 5

20. Span Table (not in text)
Loads
40 LL
10 DL
1--Lumber type
2--Lumber grade
3-Spacing
4--Span
Solution: DF 16” OC
will span 14’-11”

21. Handout on Structural Analysis #1
Use both charts in text
Remember that if all values in the “E” column apply and work then the modulus of Elasticity is the tendency of failure
If values are adjusted in the Fb row then the Fiber stress in bending is the tendency of failure

22. Beam Design

23. Anything wrong here?

24. Beam Types 1--Solid timber beam 2--Built-up dimensional lumber beam
3--Glued Laminated beam
4--Parallel strand lumber beam (PSL)
5--Laminated veneer lumber beam (LVL)
6--Truss I-Joist beam
7--Box or Plywood beam
8--Flitch beam (wood and steel)
9--Steel beams

25. Beam Type—Solid Lumber Beam

26. Beam Type—Built-up Dimensional Lumber Beam
Dimensional lumber (2x6, 2x8, 2x10, 2x12) nailed and/or glued together
Vertical placement

27. Beam and Joist Attached with joist hangers
Joist are attached to beams with metal joist hangers
What type of beam is shown?

28. Beam Type — Glued Laminated
Dimensional lumber placed horizontally and glued together

29. Beam Type — Parallel Strand Lumber Beam
See classroom example

30. Beam Type — Laminated Veneer Lumber Beam
Laminated Veneer Lumber (LVL)
Made of ultrasonically graded douglas fir veneers with exterior adhesives under heat and pressure
1 3/4” wide x (5 1/2 to 18”) depth

31. Beam Type — Truss I-Joist Beam
Laminated or Solid wood (top and bottom chords)
OSB or Plywood web

32. Beam Type — Box or Plywood Beam
12” or 16” structure with plywood skin
Designed by architect or engineer

33. Beam Type — Flitch Beam
A sandwich of wood and steel

34. Beam Type — Steel Beams S shape (American Standard shape)
Often called an I-beam
W & M shapes
Wide flange design
C shape
Channel shape
S--
I Shape
W or M
Shape
C--Channel

35. Beam Type — Steel Beams Drawing Callouts:
Shape, Nominal height x Weight/foot
Example: W10x25

36. Reaction
Reaction is the portion of the load that is transferred to the bearing points of the beam
A simple beam reaction to a load would be at the end supports. Each end would support or be required to carry half the total load

37. Calculating the Reactions of a Beam
Total load on beam should equal reaction loads:
25 x 900 = 22500#
R1 = 15/2 x 900# = 6750#
R2 = 10/2 x 900# = 4500#
R3 = (15/2 + 10/2) x 900 =11250#
Reaction formula R = wl 2
W = uniform load l = length of span
W = 900 #/ linear foot
Span = 10’-0”
Span = 15’-0” R1 R3 R2

38. Simple Beam Design
Simple beam has a uniform load evenly distributed over the entire length of the beam and is supported at each end.
Uniform load = equal weight applied to each foot of beam

39. Simple Beam Design Terminology Joist/Rafter Beam/Girder Post/Column
Span
Tributary area
Conditions of Design
Uniform load over length of beam
Beam supported at each end
Tributary area of beam
15’-0”
Beam span

40. Simple Beam Design Tributary area Total Load on Beam
16’ x 15’ = 240 sq ft
Total Load on Beam
240 x 50#/sq ft = 12,000#
Load at each supporting end
12,000/2 = 6000#
Tributary area of beam
15’-0”
Beam span

41. Determine the size of a Solid Wood Beam using Span Table
1)Determine the tributary area and calculate the total load (W) for the beam x 12 x 63 = 7560 TLD
Select beam size from table
LL = 50# DL = 13#
12’-0”
10’-0”
BEAM
20’-0”

42. 7560 TLD w/ span of 12’
Solution = 4 x 14 Beam

43. Reading the Steel Table
Table values of load are given in kips
1 kip = 1000 lbs
Shape and nominal size across the top
Weight per foot is given below designation
Span is located along the left side of table

44. Example of Using Steel Table
30’-0”
18’-0”
BEAM
Calculate load: 18 x 30 x 60 = TLD
Select Beam W18 x 40

45. Steel I-Beam Table

47. Glued-Laminated Beam Table

48. Columns and Post

49. Steel Column Table

50. Wood Post Table

51. Load Considerations First floor loads (DL + LL) = 50#/sq ft
First floor partitions (DL) = 10#/sq ft
Second floor loads (DL + LL) = 50#/sq ft
Second floor partitions (DL) = 10#/sq ft
If Truss design no loads on interior structure(DL)
If rafter/ceiling joist design (DL) = 20#/sq ft
Roof load regionally varies (LL) = 20-50#/sq ft

52. Beam Sizing and Post Spacing
Trial & Error Method
1--Locate tributary area
2--Determine various conditions placing post to shorten the beam span
3--Go to tables & choose beam
4--Smaller beams are less expensive and usually better

53. Crawl Space Floor Joist, Beam/Post

54. Handout on Structural Analysis #2
Before doing calculations sketch problem to visualize conditions
Calculate the tributary loads for beams and columns conditions
Use Handout charts and tables and select beams and columns for conditions