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Here is the code listing (as requested) for the area moment of inertia and horizontal neutral axis for a composite body that is discretized with rectangles:

I001 LBL I

I002 SF 10

I003 EQN IXX and Neutral Axis **enter the text as an eqn**

I004 CF 10

I005 CLVARS

I006 INPUT N

I007 INPUT B (note: I have omitted line numbers from here on)

INPUT H

RCL H

2

/

RCL +T

RCL B

RCL * H

*

RCL +Q

STO Q

RCL B

RCL H

*

RCL +R

STO R

1

RCL +V

STO V

RCL Q

RCL / R

RCL - C

X^2

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RCL *A

RCL + I

STO I

RCL T

RCL H

2

/

+

RCL Q

RCL / R

-

X^2

RCL *B

RCL *H

RCL H

3

Y^X

RCL *B

12

/

+

RCL + I

STO I

RCL Q

RCL / R

STO C

RCL B

RCL * H

RCL + A

STO A

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RCL T

RCL +H

STO T

RCL V

RCL N

X>Y?

GTO I007

I= **This is the value of composite Ix for your cross-section**

C= **This is the location of Xbar, ie the X neutral axis**

RTN

LN=220 CK=704D

Here is an example for an I-beam:

XEQ I

ENTER

**screen will read: IXX AND NA (hit R/S to continue)**

N=3 **number of sections**

R/S

B=5 **width of bottom flange**

R/S

H=0.25 **height of bottom flange**

R/S

B=0.5 **width of web**

R/S

H=8 **height of web**

R/S

B=3 **width of upper flange**

R/S

H=0.25 **height of upper flange**

R/S

(Program halts to VIEW the area moment of inertia, units length^4)

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R/S

(Program halts to VIEW the location of the x centroidal axis)

R/S

The result should be

I = 54.6660 (units = length^4)

C = 3.9063 (units = length, measured from base)

Enjoy! I realize that this may now be shortened a bit, particularly in light ofthe new programming capabilities gained with the 35s. In progress!

code redoneMessage #7 Posted by Ralph on 9 Aug 2007, 8:01 a.m.,

in response to message #6 by Les Wright

I think this is more readable. I transcribe my programs in a spreadsheet. Makesline numbering easy.

I001 LBL II002 SF 10I003 IXX AND NEUTRAL AXISI004 CF 10I005 CLVARSI006 INPUT NI007 INPUT BI008 INPUT H

I009 RCL HI010 2I011 /I012 RCL+ TI013 RCL BI014 RCL * HI015 *I016 RCL+ QI017 STO QI018 RCL BI019 RCL HI020 *I021 RCL+ RI022 STO RI023 1I024 RCL+ VI025 STO VI026 RCL QI027 RCL/ RI028 RCL- CI029 X^2I030 RCL* AI031 RCL+ II032 STO II033 RCL T

I034 RCL HI035 2I036 /

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I037 +I038 RCL QI039 RCL/ RI040 -I041 X^2I042 RCL* BI043 RCL* H

I044 RCL HI045 3I046 Y^XI047 RCL* BI048 12I049 /I050 +I051 RCL+ II052 STO II053 RCL QI054 RCL/ RI055 STO C

I056 RCL BI057 RCL* HI058 RCL+ AI059 STO AI060 RCL TI061 RCL+ HI062 STO TI063 RCL VI064 RCL NI065 X>Y?I066 GTO I007I067 VIEW II068 VIEW C

I069 RTN

I added the view commands (67 and 68)

Edited: 9 Aug 2007, 8:18 a.m.