**REFERENCES:**

MACHINERY'S HANDBOOK EIGHTEENTH EDITION

**NOTE:**

Always begin a new case by retrieving the original file. Direct entry of data in cells that

originally contain table lookups could cause functions to be lost, or incorrect calculations.

I format cells requiring entry colored

**RED**

; calculated values are black.

**BASIS:**

The usual method of calculating the moment of inertia of a built-up section involves the calculations

of the moment of inertia for each element of the section about its own neutral axis, and the

transferring of this moment of inertia to the previously found neutral axis of the whole built-up section.

A much simpler method that can be used in the case of any section which can be divided into

rectangular elements bounded by lines parallel and perpendicular to the neutral axis is the so-called

tabular method. * (continued below)*

**Fig. 1**

**Fig. 2**

This method is illustrated by applying it to the section shown in Fiq.1 and for simplicity of calculation

shown "massed" in Fig.2. The calculation may then be tabulated as shown in the following table. The

distance from the base to the neutral axis x-x is found by dividing the sum of the geometrical moments

by the area. The moment of inertia about the neutral axis is then found in the usual way by subtracting

the area multiplied by d

2

from the moment of inertia about the base.

Breadth

Height

Disp

Area

M

IDE

Section

b

h

1

y

b*( h

1

- y )

b*(h

1

2

-y

2

) / 2 b*(h

1

3

-y

3

) / 3

(from base)

Plate A

1.5

0.125

0.0000

0.1875

0.012

0.001

Plate B

0.531

0.625

0.1250

0.2655

0.100

0.043

Plate C

0.219

1.5

0.6250

0.1916

0.204

0.229

Plate D

0

0

0.0000

0.0000

0.000

0.000

Plate E

0

0

0.0000

0.0000

0.000

0.000

Plate F

0

0

0.0000

0.0000

0.000

0.000

Max. combined ht.

3.5

0.6446

0.315

0.272

·

distance from base to the neutral axis ......

d = M/A =

0.49

inches

·

moment of the entire section.....

I = IDE - A

*

d

2

= 0.119

in

4

**Print out using direct EXCEL commands.**

dmcoffman@aol.com

Consistent with GOOD ENGINEERING PRACTICE, t h e burden rests with t h e USER of these

spreadsheetst o review ALL calculations, and assumptions. The USER IS FULLY RESPONSIBLE for t h e

results or decisions based on calculations.

This Spreadsheet Requires MACROS t o b e ENABLED t o ASSURE proper operation. See t h e Workbook

Help Sheet for Additional Instructions on Use.

PROPERTIES of BUILT-UP BEAM & ANGLE SECTIONS

**<<<<<<<< Psafety © January 2001, by Don Coffman >>>>>>>>**

Theoriginator of these spreadsheet(s) specifically excludes all warranties, expressed or implied,as t o t h e

accuracy of t h e dataand other information set forth and assumes NO liabilityfor anylosses or damage

resulting from the use of the materials or application of the data.

1.5"

0.219"

0.125"

**x**

**x**

0.531"

0.49"

0.625"

1.5"

A

B

C

section

Psafety© January 2001