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Re: Principal Axes Section Properties

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Zachary Goswick wrote:
> 
> Does anybody know where I would find section properties about the
> principal axes for a single unequal leg angle?  I there any kind of
> table or database to look in?
> 
 My previous message made a mistake in the attacment for the Basic
program.  here is another try.

Milo Ketchum
10 CLS:PRINT:PRINT
20 DIM X(20),Y(20),XA(20),YA(20)
30 PRINT "SECTION PROPERTIES BY COORDINATES"
40 PRINT
50 L=6:X(1)=0:Y(1)=0:X(2)=0:Y(2)=8:X(3)=1:Y(3)=8:X(4)=1:Y(4)=1
60 X(5)=6:Y(5)=1:X(6)=6:Y(6)=0
70 X(7)=X(1):Y(7)=Y(1)
80 A=0:K=0:J=0:I=0:R=0
90 PRINT "DESCRIPTION       PRESENT VALUE   REVISED VALUE"
100 PRINT "NUMBER OF NODES    = ";L;TAB(35);:INPUT LA
110 IF LA<>0 THEN L=LA
120 PRINT "POINT    X        Y           X           Y"
140 FOR I=1 TO L+1
150 IF I=L+1 THEN 220  
160 PRINT USING "## ####.###  ####.### ";I,X(I);Y(I);
170 PRINT TAB(31);:INPUT;X$:PRINT TAB(43);:INPUT;Y$
172 IF X$="" THEN XA(I)=VAL(X$)
174 IF Y$="" THEN YA(I)=VAL(X$)
175 PRINT
180 IF XA(I)<>0 THEN X(I)=XA(I)
190 IF YA(I)<>0 THEN Y(I)=YA(I)
200 IF X(I)=<.001 THEN X(I)=0
210 IF Y(I)=<.001 THEN Y(I)=0
220 X=X(I):Y=Y(I)
230 C=X(I+1):D=Y(I+1):X(L+1)=X(1):Y(L+1)=Y(1)
240 A=A-(D-Y)*(C+X)/2
250 J=J+((C-X)/8)*((D+Y)^2+(D-Y)^2/3)
260 M=M+((D-Y)/8)*((C+X)^2+(C-X)^2/2)
270 K=K+((C-X)*(D+Y)/24)*((D+Y)^2+(D-Y)^2)
280 N=N-((D-Y)*(C+X)/24)*((C+X)^2+(C-X)^2)
290 R=R+X*X*(D*D-Y*Y)/4+(C-X)^2*(D-Y)^2/72
300 R=R+(C-X)*(D-Y)*(2*X+C)*(Y+2*D)/18
310 NEXT I
320 B$="N"
330 PRINT:INPUT "REVIEW OR CORRECT DATA, (Y/N) ";B$
340 CLS:IF B$="Y" THEN 90   
350 J=J/A
360 M=-M/A
370 K=K-A*J*J
380 N=N-A*M*M
390 PRINT:R=-R-A*J*M
400 PRINT "PROPERTIES ABOUT CENTROID ":PRINT
410 PRINT "A = ";A
420 PRINT "I(X) = ";K
430 PRINT "I(Y) = ";N
440 PRINT "PROD OF INERTIA I(X,Y) = ";R
450 PRINT "A(BAR)(X) = ";J
460 PRINT "A(BAR)(Y) = ";M
470 P=ATN(-2*R/(K-N))/2
480 Q=P*180/3.1416
490 U=K*COS(P)^2+N*SIN(P)^2-R*SIN(2*P)
500 V=N*COS(P)^2+K*SIN(P)^2+R*SIN(2*P)
510 W=U+V
520 PRINT
530 S=(K-N)*SIN(2*P)/2+R*COS(2*P)
540 PRINT "ANGLE OF ROTATION - DEGREES = ";Q
550 PRINT "PROP. ABOUT ROTATED AXIS "
560 PRINT "       X AXIS, I = ";U
570 PRINT "       Y AXIS, I = ";V
580 PRINT "PROD. OF INERTIA = ";W:PRINT
590 INPUT "<ENTER> TO RETURN TO START WITHOUT CHANGING DATA ";Z
600 CLS:PRINT:PRINT:GOTO 80