Transcript Document 7324646

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Discussion Topics--Beam Types
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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
Beam Type—Solid Lumber Beam
Beam Type—Built-up
Dimensional Lumber Beam
• Dimensional lumber (2x6, 2x8, 2x10, 2x12)
nailed, screwed, and/or glued together
• Vertical placement—
– Large size placed
vertical
Example: Beam and Joist
Attached with joist hangers
• Joist are
attached
to beams
with
metal
joist
hangers
• What type
of beam
is shown?
Beam Type—Glued Laminated
• Dimensional lumber placed horizontally
and glued together
Beam Type—Parallel Strand
(Parallam) Lumber Beam
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
Beam Type—Truss I-Joist Beam
• Laminated or Solid wood (top and bottom
chords)
• OSB or Plywood web
Beam Type—Box or Plywood Beam
• 2x @ 12” or 16” structure with plywood skin
• Designed by architect or engineer
Beam Type—Flitch Beam
• A sandwich of wood and steel
• An architect/engineer designed beam
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
CChannel
Shape
Beam Type—Steel Beams
• Drawing Callouts:
– Shape, Nominal height x Weight/foot
– Example: W10x25
SHAPE
NOMINAL
HEIGHT
WEIGHT PER FOOT OF BEAM
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
Calculating the Reactions of a Beam
• Total load on beam should equal reaction
loads:
Reaction formula
R = wl
2
• R1 = 15/2 x 900# = 6750#
– 25 x 900 = 22500#
W = uniform load
• R2 = 10/2 x 900# = 4500#l = length of span
• R3 = (15/2 + 10/2) x 900 =11250#
W = 900 #/ linear foot
R1
Span = 15’-0”
Span = 10’-0”
R3
R2
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.
Simple Beam Design
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Joist/Rafter
Beam/Girder
Post/Column
Span
Tributary area
Tributary area
of beam
• Conditions of
Design
– Uniform load over length of beam
– Beam supported at each end
15’-0”
• Terminology
Simple Beam Design
– 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”
• Tributary area
Table Design Considerations
• Total lbs of load and span
• Lbs of load per (lineal) foot
• Deflection Allowances (Stiffness)
– Floor = 1/360: Meaning an allowance of 1”
deflection for every 360” span, structure is
solid with little deflection
– Roof = 1/240: Meaning an allowance of 1”
deflection for every 240” span, structure
springs or deflects more than floors
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, LL = 50#,
DL = 13#, therefore TL = 63#
10 x 12 x 63 = 7560 TLD
20’-0”
• Select beam size from table BEAM
10’-0”
7560 TLD w/ span of 12’
Roof Design
Area 1/240
Floor Design
Area 1/360
• Solution = 4 x 14 Beam
Crawl Space
Floor Joist, Beam/Post
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
Example of
Using Steel
Table
BEAM
18’-0”
• Calculate load:
18 x 30 x 60 =
32400 TLD =
32.4 KIPS
•Selected Beam
S18 x 54.7
Glued-Laminated Beam Table
Design Data: Span 18’, Load per linear feet = 674#
Columns and Post
Reading Column Tables
• Determine the column load
• Establish the height of column
• Set the column size by height and load
Steel Column Table
Conditions: Height = 4.5’, Load =
19.4 kips
Solution: 2 ½ Dia x 5.79 PIPE COLUMN
Wood Post Table
Conditions: Height = 4 feet, Load =
23,000
Solution: 4x6 WOOD POST
Load Considerations
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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
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
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