16.4 Computer Program for Free Vibration Analysis of Framed Structures
581
Table 16.3 (continued)
25
CONTINUE
DO 7 J=LOCK,I1
EL=0.0
DO 9 K=1,N
9
EL=EL+U(K,I)*V(K,J)
EL=-2.*EL
Q=BD(I)-BD(J)
IF(ABS(Q/BD(J))-TOLVEC)30,30,10
30
CONTINUE
IF(ABS(EL/BD(J))-TOLVEC)40,40,10
40
CONTINUE
EL=0.0
GO TO 7
10
ELL=SQRT(Q*Q+4.*EL*EL)
IF(Q .LT. 0.0)ELL=-ELL
EL=EL/(Q+ELL)
DO 13 K=1,N
W(K,I)=W(K,I)-EL*V(K,J)
13
W(K,J)=W(K,J)+EL*V(K,I)
7
CONTINUE
8
CONTINUE
RETURN
END
**************************SUBROUTINE R8UERR******************************
SUBROUTINE R8UERR(ND,U,W,BD,ERR,N,M,NRQD,LOCK,TOLVEC,LET)
**
ESTIMATES ERRORS IN COMPUTING EIGENVECTORS
**
DIMENSION U(300,20),W(300,20),BD(20),ERR(20)
AN=N
DO 2 J=LOCK,M
ER=0.0
IF(BD(J))6,6,50
50
CONTINUE
DO 1 I=1,N
EL=U(I,J)-W(I,J)
1
ER=ER+EL*EL
GO TO 2
6
DO 8 I=1,N
EL=U(I,J)+W(I,J)
8
ER=ER+EL*EL
2
ERR(J)=SQRT(ER/AN)
5
IF(TOLVEC-ERR(LOCK))4,3,3
3
ERR(LOCK)=-ERR(LOCK)
LOCK=LOCK+1
IF(NRQD-LOCK)10,5,5
10
CONTINUE
LET=1
4
RETURN
END
*
emod = Young’s modulus of elasticity
*
dens = density of the material
*
nelm = n0. of elements
*
node = no. of nodes in the structure
*
area = cross sectional area of the member
*
ixx, lyy
izz = second moment
*
nod = nodal connectivity
*
nbp = no. of boundary points
*
nbd = boundary codes at each boundary point
*
ntv = half-band width
*
estif = elements element stiffness matrix
*
emas = element mass matrix
*
gstif = global stiffness matrix
*
nrgd = no. of frequencies to be calculated
*
frcq = natural frequency