beam desigm

7/30/2019 beam desigm

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Anything wrong here?


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Discussion Topics--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


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Beam TypeSolid Lumber Beam


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Example: Beam and Joist

Attached with joist hangers

Joist areattachedto beams

withmetaljoisthangers

What typeof beamis shown?


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Beam TypeGlued Laminated

Dimensional lumber placed horizontally

and glued together


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Beam TypeParallel Strand

(Parallam) Lumber Beam


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Beam TypeLaminated

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


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Beam TypeTruss I-Joist Beam

Laminated or Solid wood (top and bottom

chords)

OSB or Plywood web


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Beam TypeBox or Plywood Beam

2x @ 12 or 16 structure with plywood skin Designed by architect or engineer


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Beam TypeFlitch Beam

A sandwich of wood and steel An architect/engineer designed beam


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Beam TypeSteel Beams

S shape (American

Standard shape)

Often called anI-beam

W & Mshapes

Wide flange

design

C shape

Channel shape S--

I Shape

W or M

Shape

C-

ChannelShape


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Beam TypeSteel Beams

Drawing Callouts:

Shape, Nominal height x Weight/foot

Example: W10x25

NOMINAL HEIGHT

SHAPE

WEIGHT PER FOOT OF BEAM


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Reaction

Reactionis theportion of the loadthat is transferredto the bearing

points of the beam A simple beam

reaction to a loadwould be at the end

supports. Each endwould support orbe required tocarryhalf the total

load


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Calculating the Reactions of a Beam

25 x 900 = 22500#

R2R3R1

W = 900 #/ linear foot

Span = 15-0 Span = 10-0


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Simple Beam Design

Simple beam has a uniform load evenlydistributed over the entire length of the beamand is supported at each end.

Uniform load= equal weight applied to eachfoot of beam.


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Simple Beam Design

TerminologyJoist/Rafter

Beam/Girder

Post/ColumnSpan

Tributary area

Conditions ofDesign Uniform load over length of beam

Beam supported at each end

Tributary area

of beam 15-0


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Simple Beam Design

Tributary area

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 beam15

-0


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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 issolid with little deflection

Roof = 1/240: Meaning an allowance of 1deflection for every 240 span, structuresprings or deflects more than floors


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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

Select beam size from table

10-0

BEAM

20-0

7560 TLD / f 12


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7560 TLD w/ span of 12

Solution = 4 x 14 Beam

Roof Design

Area 1/240

Floor Design

Area 1/360


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Crawl Space

Floor Joist, Beam/Post


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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


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Example of

Using Steel

Table

Calculate load:18 x 30 x 60 =

32400 TLD = 32.4KIPS

18-0

BEAM

Selected Beam


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Glued-Laminated Beam Table

Design Data: Span 18, Load per linear feet = 674#


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Columns and Post


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Reading Column Tables

Determine the column load

Establish the height of column

Set the column size by height and load


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Steel Column Table

W d P t T bl


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Wood Post Table


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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

Si i


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Beam Sizing

and Post

SpacingTrial & Error Method1--Locate tributary area

2--Determine variousconditions placing post

to shorten the beam

span

3--Go to tables & choose beam

4--Smaller beams are less

expensive and usually

better


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Handout on Structural

Analysis #2 Before doing calculations sketch problem to

visualize conditions

Calculate the tributary loads for beams andcolumns conditions

Use Handout charts and tables and select

beams and columns for conditions


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