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Beam Design

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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 Type—Solid Lumber Beam**

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**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

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**Example: Beam and Joist Attached with joist hangers**

Joist are attached to beams with metal joist hangers What type of beam is shown?

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**Beam Type—Glued Laminated**

Dimensional lumber placed horizontally and glued together

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**Beam Type—Parallel Strand (Parallam) Lumber Beam**

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**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

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**Beam Type—Truss I-Joist Beam**

Laminated or Solid wood (top and bottom chords) OSB or Plywood web

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**Beam Type—Box or Plywood Beam**

12” or 16” structure with plywood skin Designed by architect or engineer

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**Beam Type—Flitch Beam A sandwich of wood and steel**

An architect/engineer designed beam

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**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

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**Beam Type—Steel Beams Drawing Callouts:**

Shape, Nominal height x Weight/foot Example: W10x25 WEIGHT PER FOOT OF BEAM NOMINAL HEIGHT SHAPE

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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

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**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 R2 R3 R1 W = 900 #/ linear foot Span = 15’-0” Span = 10’-0”

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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.

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**Simple Beam Design Terminology Conditions of Design Joist/Rafter**

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

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**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

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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 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

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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# x 12 x 63 = 7560 TLD Select beam size from table 12’-0” 10’-0” BEAM 20’-0”

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**Solution = 4 x 14 Beam 7560 TLD w/ span of 12’ Roof Design Area 1/240**

Floor Design Area 1/360 Solution = 4 x 14 Beam

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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

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**Example of Using Steel Table**

30’-0” 18’-0” BEAM Calculate load: 18 x 30 x 60 = TLD = 32.4 KIPS Selected Beam S18 x 54.7

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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 Conditions: Height = 4.5’, Load = 19.4 kips**

Solution: 2 ½ Dia x 5.79 PIPE COLUMN

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**Wood Post Table Conditions: Height = 4 feet, Load = 23,000**

Solution: 4x6 WOOD POST

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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

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**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

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**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

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